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  1. #1

    Default AQ130C - Changed Gearbox Ratio - Problem?

    Hi, have been reading this and just created an account to ask if running the 4 cylinder AQ130C (had twin Solex but I have someone replacing them with a twin choke weber) with a 1.61:1 ratio gerbox will damage the engine? Explanation: Whilst on her trailer (and having only just bought her!) somebody hit the stern drive with their trailer. The insurance covered everything but my local VP dealer would only use new parts and all they could get from VP was a 280's 1.61 not 2.15:1. The dealer said it wouldn't matter but on this thread it seems to be an issue. The prop will spin faster (correct?) so I had them replace the 14/15 prop with a new 15/11. She runs OK on the river (possibly 1800rpm instead of 1600rpm to get 8kmh) but also want to take her to the coast for relatively short bursts (an hour maybe) at her crusing speed of 22knots (should be around 4600rpm). If I must get the gearbox swapped I can (just need to find the 270's exhaust outlet - old gearbox damage has been welded). Many thanks, bye. Steve A.

  2. #2
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Its been been my experience that it is almost impossible to correctly "prop" the engine if the reduction ratio is not correct for the engine. By "correctly prop" I mean that prop that will allow the engine to rev to within the factory specified wide open throttle max rpm range as specified for that engine with your "normal" load in calm water. You can and will damage the engine if you run the engine without the "correct prop"...
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

  3. #3

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Thanks for the feedback. That's what I was understanding from another thread (AQ130 with 250 Outdrive). How iwill the engine be damaged? Overheating? Only a problem if I try to run her at fast engine speeds? She should cruise at 22knts at around 4600rpm (previos owner - old gearbox and prop). At present we're doing around 1800rpm with very occasional and short bursts (when nobodies about!) of 3000rpm. Will even that damage the engine? The temperature gauge has always remained well below half while we've owned her - but we've not yet had time to trailer to the coast.

  4. #4
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Quote Originally Posted by ThamesCruiser View Post
    Hi, have been reading this and just created an account to ask if running the 4 cylinder AQ130C (had twin Solex but I have someone replacing them with a twin choke weber) with a 1.61:1 ratio gerbox will damage the engine? Explanation: Whilst on her trailer (and having only just bought her!) somebody hit the stern drive with their trailer. The insurance covered everything but my local VP dealer would only use new parts and all they could get from VP was a 280's 1.61 not 2.15:1. The dealer said it wouldn't matter but on this thread it seems to be an issue. The prop will spin faster (correct?) so I had them replace the 14/15 prop with a new 15/11. She runs OK on the river (possibly 1800rpm instead of 1600rpm to get 8kmh) but also want to take her to the coast for relatively short bursts (an hour maybe) at her crusing speed of 22knots (should be around 4600rpm). If I must get the gearbox swapped I can (just need to find the 270's exhaust outlet - old gearbox damage has been welded). Many thanks, bye. Steve A.
    My WiFi is down this morning, so I’m using my iPhone and won’t be doing my usual blue font responses.

    Nut shelling this for you:

    The shop or dealer who did the repair did you a disservice by using the 1.61:1 reduction drive. That ratio is for the V-8 engines. Any marine mechanic who is worth his salt should have known better!

    As much as we would like for this to work…..... we cannot prop ourselves out of an incorrect ratio scenario. It simply does not work like that!

    A change of the transmission (aka gear box) will not change the final reduction. If you go back to the correct reduction (which I would highly recommend), you will need to find a lower gear unit of the correct ratio.
    You will also need to take the A & B dimensions for adjusting the vertical shaft bearing race shim pack.

    As for the exhaust outlet housing, I am not following you!
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  5. #5
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Quote Originally Posted by ThamesCruiser View Post
    Thanks for the feedback. That's what I was understanding from another thread (AQ130 with 250 Outdrive). How iwill the engine be damaged? Overheating? Only a problem if I try to run her at fast engine speeds? She should cruise at 22knts at around 4600rpm (previos owner - old gearbox and prop). At present we're doing around 1800rpm with very occasional and short bursts (when nobodies about!) of 3000rpm. Will even that damage the engine? The temperature gauge has always remained well below half while we've owned her - but we've not yet had time to trailer to the coast.
    ok....... do not confuse cruising rpm with wot rpm!
    wot rpm is a test rpm as to determine if the propeller and final drive reduction are in sync with the engine’s torque rating.

    If this is not correct, and if the engine cannot achieve the wot rpm, you will risk overburdening the engine at any rpm.

    At 1800 rpm the hull is likely NOT up on step, and yet it’s above hull speed. If so, this is not a good rpm to be running at for any duration.

    And again...... if you change to the correct reduction, it will involve changing the lower gear unit ONLY!
    Re-shimming will be imperative!!!


    .
    Last edited by RicardoMarine; 09-20-2018 at 02:08 PM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  6. #6

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    [QUOTE=RicardoMarine;622149]My WiFi is down this morning, so Iím using my iPhone and wonít be doing my usual blue font responses.

    Nut shelling this for you:

    The shop or dealer who did the repair did you a disservice by using the 1.61:1 reduction drive. That ratio is for the V-8 engines. Any marine mechanic who is worth his salt should have known better! It was a VP dealer. And they told me it wouldn't make any difference! Through looking at the www I suspected it was - and had them change the 14/15 prop to a brand new 15/11 (£200).

    As much as we would like for this to workÖ..... we cannot prop ourselves out of an incorrect ratio scenario. It simply does not work like that!

    A change of the transmission (aka gear box) will not change the final reduction. If you go back to the correct reduction (which I would highly recommend), you will need to find a lower gear unit of the correct ratio. It was only the lower gear unit (gearbox that includes the cavitation plate) that was changed due to the damage done by the guy's trailer. The VP dealer would only use brand new parts and all they could get was 1.61:1 (280 unit). The insurance company paid (£4070!) for a VP part no. 3860243. The oil they put in was VP part no. 21363429. Correct oil - not too thick? I've now had the one that got damaged (2.15:1) repaired (the casing had to be welded) and if I can get the exhaust outlet can have it put back on.
    You will also need to take the A & B dimensions for adjusting the vertical shaft bearing race shim pack. Thanks for the warning but I'll not be doing it myself - will have to trust someone I employ.

    As for the exhaust outlet housing, I am not following you! It's the 'diamond' shaped exhaust outlet that hangs below the cavitation plate. His trailer caught that and it was too badly distorted for the welder to repair for me.
    If anyone has a spare Ö!

  7. #7

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    ok....... do not confuse cruising rpm with wot rpm!
    wot rpm is a test rpm as to determine if the propeller and final drive reduction are in sync with the engine’s torque rating.

    If this is not correct, and if the engine cannot achieve the wot rpm, you will risk overburdening the engine at any rpm. I've not had a chance to do the WOT test unfortunately. On the river it's (pretty much) impossible. WOT is 5100rpm and cruising 500 below that - 4600rpm.

    At 1800 rpm the hull is likely NOT up on step, and yet it’s above hull speed. If so, this is not a good rpm to be running at for any duration. She's a Draco 2000DC (20' deepV Aqualift hull that weighs 1600kg (3500lbs) and will cruise at 22knts / 4600rpm. The previous owner told me all this - but that was with the other gearbox and prop. It's the 'overburdening' the engine at any speed that worries me. We can only do 4.5knts (although most do 5knts which is about 1800rpm) and we do that for an hour roughly before we slow down for the next lock. With this gearbox she's done this plus a few very short bursts of 3000rpm (just beginning / wanting to plane - should happen at about 3600 the previous owner said). What damage does overburden actually do? If not overheating does it damage the small / big end bearings? Something else? How quickly?

    And again...... if you change to the correct reduction, it will involve changing the lower gear unit ONLY!
    Re-shimming will be imperative!!!
    Last edited by ThamesCruiser; 09-20-2018 at 04:48 PM. Reason: spotten an error

  8. #8
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Again, we cannot prop ourselves out of an incorrect drive reduction!

    Also, the 280 lower unit does not need the external exhaust outlet housing!

    I would find another shop! These guys do not know what they are doing...... period!

    Just for sh!ts and giggles, ask them how many thousandths change to the shim value was required when they installed the new 280 lower gear unit!



    .
    Last edited by RicardoMarine; 09-20-2018 at 09:39 PM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  9. #9

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    An approved VP dealer! Wouldn't use reconditioned parts - had to be new which meant either use this one or the entire unit is too old - you need to replace everything! Will it have damaged the engine? As mentioned she's not overheated but bearings damaged or something else? What does overburbening actually do? Would it have done more damage if we'd had the time to take her to the coast and try to run around at high revs or doesnt matter what revs - just number of hours run at any speed? I told them she would be used occasionaly at the coast.
    The exhaust outlet is needed to get the now welded 270 (2.15:1) gearbox ready to be put back on. Got a spare anyone ...?
    should I not use the boat until the old, correct ratio gearbox has been reinstalled? Many thanks. SA

  10. #10
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Your fuel economy will suck and have a poor hole shot and cause the pistons to carbon up fouling the plugs.

  11. #11
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    I understand the insurance company’s protocol, and I understand that the insurance coverage required the shop to install new parts.
    However, that does not change the “fact” that the reduction used is incorrect for YOUR engine!

    Earlier I asked you to find out how much change in shim value was required when the shop installed the new lower gear unit.
    To further this.... (and for more sh!ts and giggles).... ask what type of gear oil they used!

    OK...... the 2.15:1 lower units seldom wear out. (the little 4 banger engines simply do not offer enough horsepower or torque to damage one)
    Due to the above, there are literally thousands of 2.15:1 lowers out there on the used market.
    Because of an abundant supply and a little demand, they do not fetch much money on the used market!
    In the past (during my 24 years of AQ series work), I have sold perfectly good 2.15:1 units for as low as $150.


    Now....... the 1.61:1 is a different story!
    These are installed exclusively behind the larger horsepower engines ....... both the small blocks and the big blocks. These do occasionally break and/or wear out. Because of this, the demand is much higher, therefore allowing these to fetch quite a bit more money.


    Now for my suggestion:

    Find a good used 2.15:1 in a 280 or 290 version. You should be able to find one at a very reasonable price.
    Learn how to take the A and B dimension readings.
    Learn how to make the change to the bearing race shim value.

    Install the 2.15:1 lower unit.
    Refill with the correct amount of 30W engine oil.

    Run an e-Bay auction for the brand new 1.61:1 lower unit.
    It may bring $2k or so!


    You will have now solved your gear reduction problem, and you will have put some money in your pocket.




    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  12. #12

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Hi, ****s and giggles?! If they've made me damage my own engine I should be speaking to a lawyer! Do you think they have? What should I look for?
    The oil they put in the drive was VP part no. 21363429. Correct oil - not too thick?
    I have no reason to think that my own (now repaired) 2.15:1 gearbox isn't OK - it only came off because of the damage caused by someone's trailer.
    Thanks for the selling my new one idea - about 4 months old and I guess less than 50 hours. Anyone interested?!
    still need to find the 270 exhaust outlet though!
    MT&BR, SA

  13. #13
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    If your original lower unit was replaced with a 280, why do you think that you need a 270 exhaust outlet housing?
    That housing will not work on a 280!

    The 280, 285, 290, SP and later exhaust outlet is integral with the main gear case.
    Whereas with the 250, 270 and 275, the exhaust outlet is a bolt-on piece.

    I think that itís time to see a few photos of your new lower unit!





    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  14. #14

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    [QUOTE=RicardoMarine;622238]If your original lower unit was replaced with a 280, why do you think that you need a 270 exhaust outlet housing?
    That housing will not work on a 280!
    From what Iíve learnt here Iím looking to have my now repaired 270, 2.15:1 ratio gearbox put back on (and then, hopefully sell the newly fitted 280 gearbox on eBay).

    The 280, 285, 290, SP and later exhaust outlet is integral with the main gear case.
    Whereas with the 250, 270 and 275, the exhaust outlet is a bolt-on piece.
    yes, I still have the outlet (and the bolt) but itís a bit distorted and will never again sit tightly to the underside of the cavitation plate.

    I think that itís time to see a few photos of your new lower unit!
    The new one is, as you describe with the exhaust a slot below the cavitation plate with two rubber flaps.

  15. #15
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    ......................
    Quote Originally Posted by ThamesCruiser View Post
    Quote Originally Posted by Rick
    I think that it’s time to see a few photos of your new lower unit!
    The new one is, as you describe with the exhaust a slot below the cavitation plate with two rubber flaps.

    The 280 lower unit was available with a back-flow prevention flapper as a production model only.
    In other words, a 280 would not have been equipped with a flapper unless it was an engine/drive package that was delivered with the original boat!
    Also, the 280 production flapper was one piece.... it was not split.

    If you have two flappers, or one split flapper, it is likely a 290 or SP lower gear unit..... which actually makes it more valuable.
    Last edited by RicardoMarine; 09-21-2018 at 06:57 PM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  16. #16

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Your fuel economy will suck and have a poor hole shot and cause the pistons to carbon up fouling the plugs.
    Hmmmmm! Thank you for that - petrol consumption has been far higher than the previous owner had suggested and obviously was running too rich (smell plus rough idling too). In fact, my mechanic and myself thought the twin Solex were finished and wouldnít keep their settings - hence heís currently installing the Weber twin choke conversion for me. Iím wondering now if the Solex were OK? Not that I mind too much - I think fitting the new Weber will be a good thing anyway.

  17. #17

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Definitely has two flappers but I donít have a photo to show you unfortunately! I do know it cost £4070!

  18. #18
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    A brand new 280, 285, 290, SP, SP-C, SP-C1, SP-C2 etc lower gear units would very likely all cost about the same.... or very close.

    As said..... the 280/285 would not have come over-the-counter with the back-flow prevention flapper, of which would have been a single piece flapper if it had been a production unit.

    The 290, SP, SP-C, SP-C1, SP-C2 etc lower gear units would have come with a flapper, but these would be split in the center, looking as though it was two of them.

    The 290 and first gen SP continued with the longer vertical shaft, and would require the early short vertical shaft spline coupler (same as what you had).
    The SP-C and later vertical shafts were shortened up, therefor requiring the longer vertical shaft spline coupler.
    If your invoice shows a p/n for a new spine coupler, it was most likely the long coupler, meaning that you would have a C or later lower unit.

    Not that it matters..... just an FYI for you.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  19. #19

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Click image for larger version. 

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  20. #20
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    In looking at the invoice I see:

    that p/n 3860243 is a 290 in the 1.61:1 reduction. No need for the long spline coupler.

    no p/n for any shims. I would be asking what was required for a new shim value when the new lower unit was installed.

    that they replaced the main suspension fork hinge pin bushings (what they are mis-calling pivot bushings).

    nothing pertaining to the PDS bearing. Dang.... this is so important too!

    that they did use the correct gear oil.


    When you area ready to re-install your 270 lower unit, I will show you how to take the A & B dimensions and to adjust the shim value.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  21. #21

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    In looking at the invoice I see:

    that p/n 3860243 is a 290 in the 1.61:1 reduction. No need for the long spline coupler.
    That's brilliant - thanks - I now know exactly what I'll be trying to sell on eBay. (Together with two Solex 44API and inlet manifold that may have been OK!)

    I'm hoping that I may have worked out why 'overburden' causes the engine to run rich. Does this sound logical / reasonable? The carburettor(s) were designed to provide a set amount of fuel & air for the engine to run at any certain speed driving the 2.15:1 gearbox and a reasonable range of prop sizes. But, because of the ratio mismatch they've introduced at any throttle position my engine is actually running more slowly than it should - so all the fuel isn't getting burnt properly.

    no p/n for any shims. I would be asking what was required for a new shim value when the new lower unit was installed.
    I'll ask but very much doubt they'll tell me - they were hardly willing to discuss anything even when they knew my insurance company were just about to pay them over £5000! Now?!

    that they replaced the main suspension fork hinge pin bushings (what they are mis-calling pivot bushings).

    nothing pertaining to the PDS bearing. Dang.... this is so important too!
    What is this? If I'm just about to get someone else to swap over the gearboxes I could get this done now. (I've just found out that you can get an exhaust bellows that includes a one way valve so I'll get that fitted now - potential for water in the exhaust manifold = better safe than sorry!

    that they did use the correct gear oil.
    That's a relief!

    When you area ready to re-install your 270 lower unit, I will show you how to take the A & B dimensions and to adjust the shim value.
    I'll not be doing the work myself but will be interested to know. Thanks. (I'm having to be careful though - I can't look as though I'm telling the guy who's doing the work how to do his job).

  22. #22
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Rick is talking about the PDS primary drive shaft. If you change the bellows you may as well do a complete service.
    PDS bearing and crosses and upper bellows
    water neck fitting and beaded gasket
    All new o-rings
    get it done now and you should have years of good service with proper preventive maint.

  23. #23
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Volvo Penta exhaust bellows p/n 876631 looks like the one without the internal flapper. They installed this style due to the lower unit having a flapper attached.
    Your 270 lower gear unit will still need the exhaust outlet housing.

    Your engine will use the single bearing PDS. This means that the PDS can be removed from AFT, and without pulling the engine.
    The bearing will be an industry standard 6206. Any good bearing supplier should have it, or can get it.

    Below (first image) is an example of what can occur if a PDS bearing fails at cruising speed.
    This is the mild damage..... it can be worse!

    Second image shows a V-8 single bearing PDS..... very similar to what you have with your OHC 4 banger.
    Pay no attention to my comments regarding sealed bearing -vs- open bearing conversion.
    Yours will be open and will have a grease port for lubrication.
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    Last edited by RicardoMarine; 09-23-2018 at 10:25 PM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  24. #24

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Update for this: my new Weber 32/36 DGEV has been fitted and has a matching electric fuel pump but I'm being told I need to run the bilge blower all the time running at low speed? The two side air vents (ducted to the fan unit) will then self vent as we move along. Sound right?
    I was told to collect her but my petrol vapour alarm kept going off (triggered repeatedly 2 - 3 minutes after I'd closed the engine cover - with the engine idling and not in gear). Smelt bit rich / petrolie too (hood up but one side left open).
    The original (2.15:1) gearbox and 14/15 prop are reinstalled and I have the virtually brand new 290 gearbox, 15/11 prop and 2x Solex waiting to go on eBay!

  25. #25
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    ...........................
    Quote Originally Posted by ThamesCruiser View Post
    Update for this: my new Weber 32/36 DGEV has been fitted and has a matching electric fuel pump
    Just an FYI....... the electric fuel pump requires a N/O Low Oil Pressure switch in the loop.
    This is a USCG requirement!


    but I'm being told I need to run the bilge blower all the time running at low speed?
    That is a good practice regardless!
    However, it requires a continuous duty bilge blower motor.


    The two side air vents (ducted to the fan unit) will then self vent as we move along. Sound right?
    The blower will connect to the vents that aim AFT.
    The blower hose will lay low in the engine bay where the heavier gasoline vapors will gravitate.
    The vents that aim FWD will bring in the fresh air.


    I was told to collect her but my petrol vapour alarm kept going off (triggered repeatedly 2 - 3 minutes after I'd closed the engine cover - with the engine idling and not in gear). Smelt bit rich / petrolie too (hood up but one side left open).
    The original (2.15:1) gearbox and 14/15 prop are reinstalled and I have the virtually brand new 290 gearbox, 15/11 prop and 2x Solex waiting to go on eBay!

    The new 1.61:1 lower gear unit should fetch some good money!
    That ratio is much more in demand.

    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  26. #26
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    re: "but I'm being told I need to run the bilge blower all the time running at low speed?
    That is a good practice regardless!
    However, it requires a continuous duty bilge blower motor.


    The two side air vents (ducted to the fan unit) will then self vent as we move along. Sound right?
    The blower will connect to the vents that aim AFT.
    The blower hose will lay low in the engine bay where the heavier gasoline vapors will gravitate.
    The vents that aim FWD will bring in the fresh air. "

    USCG recommendation is to run the bilge blower at idle and while moving at slow speed. "At cruise", the forward vent/rear vent combo should flow enough air without the blower running.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

  27. #27
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    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    I want as much cool air for my engines as possible, so I run my two (2) continuous duty squirrel cage blowers at all times my engines are running. Both pull air from low points within the engine bay.

    Your call!
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  28. #28

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    Hi, thanks to you both. I'm happy to run the blower continuously - just don't want it be used to hide something. Have asked they check everything again including did they create a small exhaust manifold leak when fitting the new inlet manifold.
    have also spoken with a boat safety guy (in the UK) and he's suggested the fan has to be both continuous rated and 'ignition prrotected' too. I've asked them to check and/or replace my existing fan unit.
    my petrol vapour alarm is very sensitive - my understanding from their info is that it's triggered at 10% of LEL. It's probably perfectly OK and I'm now thinking that with the fan running always if the alarm's AOK (if triggered then it must be a real problem and stop immediately and investigate).
    Regarding the fuel pump we don't have to stop the pump due to no oil pressure here (and you must need an overide button to get things started) and I was thinking of just having an oil pressure failure buzzer instead (still got the original light plus pressure gauge). What's their reason? The electric pump now fitted was sold by the weber supplier as a matching item (2.5 - 4.5psi) to the 32/36. With the engine not running but the pump running e.g. no oil pressure because of a problem or not yet been started is there any chance the pump might overcome the float controlled valves in the float bowl?
    Thanks, bye.

  29. #29
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    10,252

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    ........................
    Quote Originally Posted by ThamesCruiser View Post
    Hi, thanks to you both. I'm happy to run the blower continuously - just don't want it be used to hide something.
    Understood.

    Have asked they check everything again including did they create a small exhaust manifold leak when fitting the new inlet manifold.
    have also spoken with a boat safety guy (in the UK) and he's suggested the fan has to be both continuous rated and 'ignition prrotected' too. I've asked them to check and/or replace my existing fan unit.
    Make sure that you DO NOT use one of the In-Line or Turbo style blower motors.
    They are JUNK, very noisy and live a very short life.

    Click image for larger version. 

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    In stead, use a squirrel cage style in the continuous duty model.

    Click image for larger version. 

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    my petrol vapour alarm is very sensitive - my understanding from their info is that it's triggered at 10% of LEL. It's probably perfectly OK and I'm now thinking that with the fan running always if the alarm's AOK (if triggered then it must be a real problem and stop immediately and investigate).

    Regarding the fuel pump we don't have to stop the pump due to no oil pressure here
    While this is a USCG requirement here in the US, it should be a standard throughout the world.
    Worst case scenario:
    .....Your fuel line becomes severed or disconnected.
    .....The engine eventually stops.
    .....Fuel pump continues to operate while fuel is being pumped into the engine bay.
    .....The gasoline ignites, catches the boat on fire, you and/or your family and friends become severely injured, law suits occur, your Marine Insurance Policy does not cover the incident due to "negligence", etc. etc. etc.

    With a very simple to install N/O Low Oil Pressure switch and relay, this is avoided.


    (and you must need an overide button to get things started)
    Also very simple.
    You have two choices;
    1..... trigger the fuel pump relay with the starter motor solenoid circuit. The relay prevents "back-feed".
    2..... trigger the fuel pump relay with a "momentary helm switch". Must be a "momentary" switch in order to be legal here in the US!
    (I like this one best because you can prime the system without operating the starter motor)



    and I was thinking of just having an oil pressure failure buzzer instead (still got the original light plus pressure gauge). What's their reason?
    See above!

    The electric pump now fitted was sold by the weber supplier as a matching item (2.5 - 4.5psi) to the 32/36. With the engine not running but the pump running e.g. no oil pressure because of a problem or not yet been started is there any chance the pump might overcome the float controlled valves in the float bowl?
    The carburetor would need to be equipped with a float sensing circuit that would somehow be tied into the pump's relay.
    I have not seen anything like this for a carbureted engine.

    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  30. #30
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    2,921

    Default Re: AQ130C - Changed Gearbox Ratio - Problem?

    re: "The electric pump now fitted was sold by the weber supplier as a matching item (2.5 - 4.5psi) to the 32/36. With the engine not running but the pump running e.g. no oil pressure because of a problem or not yet been started is there any chance the pump might overcome the float controlled valves in the float bowl?
    The carburetor would need to be equipped with a float sensing circuit that would somehow be tied into the pump's relay.
    I have not seen anything like this for a carbureted engine. "


    My 2006 MERC 5.7L MIE with TKS carb (2bbl) has an electric fuel pump with an "no oil pressure" switch. Works fine. The electric fuel pump's output pressure is set so that won't overcome a carb float's cut off.


    Re" fresh air in engine compartment"... The bilge blower system is not intended to furnish cooling air or combustion air to the engine compartment. It is only intended to scavenge any possible gas fumes from the bottom of the bilge. When I reengined my boat and went from a raw water cooled 185 HP engine (@140 degrees) to a "fresh water cooled" 260 HP engine (@ 170 degrees), I installed 2, 2"x18" (approx) louvered vents in the engine box at the level of the flame arrester air inlet. This stopped the occasional vapor lock on hot days at dead low speeds.
    Last edited by sandkicker; 10-17-2018 at 12:14 PM.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

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