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Aq 260 timing/issues

C

Chm

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I believe I have seen a post like his before but I did not see any answers for it. I have an 84 bayliner contessa with the aq 260 in her. She was getting up there in hours so I replaced it with a new 300 horse Volvo pent 5.7 engine. When I first bought her I could not get her above 2000 rpms and did a full tune up and adjusted the point gap and timing then had no problems with her. I then switched to a new electronic ignition and again had no problems with her. When I got her back from the shop and was finally able to take her to the lake I cannot get her above 3000 rpms. The shop said they set the timing at 2 degrees btdc and the manual says 8 btdc. What should the exact timing be for her and is there anything else I should look for. I brought her to the shop to fix the problem but it only does it under load and the shop guy never showed up at the lake to see what she was doing like he said he would before I had to get her out. I am hauling her down to Florida then taking her across to the Bahamas in about three weeks so I do not have a lot of time to have him try something then take her to the lake then him take her back then back to the lake etc.
Any help would be appreciated thanks
 
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I do not know if it makes a big difference in timing but they said they were getting more horse power out of the 86 and up engines so it is not an 84 5.7 it is the 86 up to I believe 92 5.7 that was put in her.
 
Setting BASE advance is just that.... BASE advance.
We start on BASE.... and we idle on BASE.
Your progressive advance and total advance RPM are of much more importance.

Let's start by telling us which ignition system you have on this new engine!



BTW, it's all about ignition advance having the last word in where the LPCP will be.
LPCP = location of peak cylinder pressure.... of which should be between 12* and 14* ATDC.
This is NOT a spark advance number in degrees.... this is a crankshaft angle when the greatest amount of gas burn expansion occurs ATDC.

A lazy ignition advance will cause a lazy LPCP.



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As the boat is in the shop and I have all the paper work in her I am not 100% certain but I believe it is a Petronix electronic ignition kit that did great before she went to the shop.
 
I have been doing some research on the distributor and problems others have had and from what I gather is that my old engine was the 76-85 engine and they replaced it with an 86-92 engine I believe. From what I have looked at is that after 85, so 86 on used a different distributor, starter, and some other newer parts. The boat shop guy said the only thing that he needed to switch out was a new fly wheel. Is this true or is there quite a bit I need to go "discuss" with the shop?
 
Chm said:
I have been doing some research on the distributor and problems others have had and from what I gather is that my old engine was the 76-85 engine and they replaced it with an 86-92 engine I believe. From what I have looked at is that after 85, so 86 on used a different distributor, starter, and some other newer parts. The boat shop guy said the only thing that he needed to switch out was a new flywheel. Is this true or is there quite a bit I need to go "discuss" with the shop?
Click to expand...

All Marine SBCs can use the same Marine ignition distributor style........... however, each marinizer will go with their own preference.

I do not like the Pertronix kits, nor any Pertronix Hall Effect triggering systems.
I would suggest that you steer clear of these..... but that's just my opinion.


The SBC crankshaft changed in 1986 and became a 1 pc rear main seal engine.
The rear crankshaft flange also changed, so a change to the flywheel became necessary.

Your AQ260 flywheel cover (bellhousing in the auto world) will only accept the 153 tooth ring gear flywheel (the 168 tooth will not work).
Your pre-1986 SBC crankshaft flange is the old style...... so the 153 tooth flywheel is also the old style and will not fit the later SBC crankshaft flange.

You'll need to source a 153 tooth flywheel from a post 1987 Camero car w/ standard transmission.


Be sure to replace the PDS bearings while the engine is out!
You'll need one each industry standard 6206 and 6007 open bearings, and two industry standard 35x62x7mm TCM or Timken seals, and a tube of good quality high pressure bearing grease.
With the transmission removed, this can be done in approx 1 hour, and don't let them tell you differently.

If you miss this oportunity, and if these should fail....., you'll be pulling the engine again.

Also, if the shop removed the flywheel cover with the engine, you'll want to replace the rubber cushion rings and have them do the triangulation alignment adjustment.

If they left the flywheel cover attached to the transom shield, all they need to do is to make sure that the rear engine flange is exactly parallel to the flywheel cover front face.



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What electronic set up would you suggest? I really like this boat and honestly do not like at all the layout of the 85 and newer models so I plan on keeping her as long as possible and updating everything. I was also thinking about putting fuel injection on her.
 
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Chm said:
What electronic set up would you suggest?
I prefer VR (variable reluctor) or even Photo Eye over that of the Pertronix Hall Effect.
And I would never recommend a kit, unless the old distributor is sent in for re-calibration.

I was also thinking about putting fuel injection on her.
Depending on which FI, you may need an EST system. (EST = electronic spark timing)
Click to expand...
 
Affordable fuel injection has a marine injection kit for about probably $1,500 total that comes with an ecm distributor that goes along with the computer for the fuel injection. The shop said that they the complete electronic distributor would be about $500 which is double what I have researched them for. ( I understand them wanting to make a little profit because they are trying to run a business but double is a little excessive) so for the price and it comes with a distributed that is electronically controller with the fuel injection and computer I would think that would be way to go?
 
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