AQ170 slowing down & poor fuel econom...

Author Message   Philip Crossley New member Username: crozdog Post Number: 1 Registered: 05-2008 Posted on Tuesday, May 06, 2008 - 03:46 am:    Hi guys, I'm new here, but have already picked up a few ideas re converting to an electronic dizzy. I haven't done that yet, but thanks for the info. I have 22' half cabin cruiser which runs an AQ170 (b30) motor which is fitted with triple solex down draught carbs. When I bought it a year ago I replaced the points, leads, plugs, condensor and rotor (among other things). I couldn't find any timing marks, so did the timing by ear. It would pull 5200 rpm & get up and plane well. Since then, the top revs are dropping - it now does 3400 rpm tops under load, doesn't get onto a plane and drinks fuel like I can't believe. It will still hit 5000rpm when in neutral. Can anyone help with the following questions? 1. How can I find/recreate the timing marks? 2. Does this poor performance problem sound more like the carbies need tuning / syncing rather than a timing problem? 3. If it is the carbies, how do I sync them? I have the manual which describes adjusting the pins in the throttle levers (section 4-24), but doesn't say how to use the "uni-sync vacuum measuring device". 4. Do I need a "uni-sync" or is there some other way to adjust the vacuum of each carb? 5. Just how do you adjust the "vacuum" of a carby? The manual isn't clear how you do that. 6. Any other suggestions re what I can do to resolve this performance problem? Thanks in advance   Mike Advanced Member Username: mike77cj Post Number: 125 Registered: 06-2007 Posted on Tuesday, May 06, 2008 - 10:55 am:    First off, I highly advise NOT revving the engine up beyond 2500 rpm while in neutral. 1. The timing marks are located on the harmonic balancer (Part #27) and on the timing cover. The timing cover is directly behind the balancer. Clean up the balancer and paint the indentation with white out. It will make it easier to see with a timing gun. On the timing cover you will see a tab with marks and numbers. http://www.volvopentastore.com/CRANKSHAFT_AND_RELATED_PARTS_AQ170A/dm/cart_id.32 7823918--category_id.332330--list_time.1210085290--session_id.164829561--store_i d.366--view_id.317501 2. Could be many different things. Start with the easiest first and work your way down. Definately time the engine the proper way if you have never done so. 3. Did you properly stabalize the fuel over the winter? Could be a plugged jet, stuck float... 4. I believe a standard vacuum gauge can be set up to accomplish this. 5. Idle jets. 6. First time the engine. Ensure proper fuel flow. El always recommends running the engine from a jerry jug to eliminate anti-syphon problems. After timing it I would do a compression test as well, simple, quick and easy. That will give you insight into the 'mechanics' of the engine. Good luck.   Philip Crossley New member Username: crozdog Post Number: 2 Registered: 05-2008 Posted on Tuesday, May 06, 2008 - 08:44 pm:    Mike, thanks for your prompt informative reply. Unfortunately, I haven't seen a "tab with marks and numbers" behind the harmonic balancer - hence the question. I really want to identify the timing marks in order to time it properly. The manual I have doesn't have very clear pictures which doesn't help. As I live in Australia, when I try & access that site I get an error message saying "The Volvo Penta Online Store is only accessible to visitors located in the United States." Is there any chance you could copy the image & post it here or email me? That would be great if you could. The issues I describe were happening over our Summer. We have mild winters - it only gets down to about 6 degrees celcius (43*F), so we don't do any "winterising". How can you use a vacuum guage to help adjust the carbs? can you direct me to a link which explains it? Many thanks again for an informaive reply. Philip   El Pescador Senior Member Username: el_pescador Post Number: 3105 Registered: 02-2006 Posted on Wednesday, May 07, 2008 - 02:06 pm:    1) You should have a timing mark in the vibration damper indicating the TDC, and a pointer in the engine front cover. If you have no further references in your engine, you can use a timing light that lets you set the advance angle. Tey are a bit more expensive but well worth the expense. 2) If the revs are dropping, start taking a compression test followed by a tune-up, i.e. set the carbs, replace/inspect spark plugs, distributor cap& rotor, ignition wires, etc. 3) To use the uni-syn tool you will need an empty 3-pound coffee can. The open side of the can reportedly fits nicely in the place of the flame arrestor in a downdraft Solex carb, then you have to open a round hole in the bottom of the can big enough that you can cover it with the uni-syn tool. 4) Your best bet is a uni-syn tool. You cannot use a vacuum gauge to tune the carbs in your 170. The uni-syn is more a flow meter than a vacuum gauge, and it helps you to set the carbs by ensuring that each sucks the same amout of air at idle. 5) You have to adjust independently on each carb the position of the butterfly valve. Read carefully the Seloc manual (4-24 and 4-25). 6) To access some web pages, you will need to go through a "proxy server" if you live in Australia. Use Google to find out how to use a Proxy Server.   Philip Crossley New member Username: crozdog Post Number: 3 Registered: 05-2008 Posted on Tuesday, May 13, 2008 - 01:53 am:    Thanks for the info El. Am I right that you can't use a vacuum guage to sync as there isn't a vacuum connection on the carbs? I'm currently looking to see where i can find a Unisyn. Any ideas or recommendations re where to source one? I believe the Moss part number is #386-200 & Edelbrock is #4025. I have been advised i can sync the carbs using a piece of hose to listen to the suction in each carb. Has anyone had success with using this method? How good/bad is it? How can i tell if my motor is an AQ170A/B or C? Does it matter? Also, can anyone tell me what the bosch breaker points part number is to suit the Bosch #1 231 152 060 distributor? I have that info on the boat but can't get there for a while & would like to take the parts I need with me so I can save a trip. Thanks   Morten Ringvold Senior Member Username: haffiman37 Post Number: 2726 Registered: 04-2006 Posted on Tuesday, May 13, 2008 - 03:03 am:    That is the way I used to do it, but You might need some experience. A bit more than what I will describe here on the board. Try to buy/borrow a uni-synch tool.

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