engine still runs lean - Team Camaro Tech
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post #1 of 11 (permalink) Old Jul 21st, 09, 03:30 PM Thread Starter
 
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Unhappy engine still runs lean

this seems to be an ongoing project for almost 2 seasons.
i have a 350 sbc with AFR 195cc heads 65cc chambers, i re-camed the engine about 2 weeks ago with a new Comp Cams solid flat tappet 510in/522ex 226in/232ex, im using a Edelbrock RPM air gap intake with a 650 holley DP. its a 9:1 compression motor and i have 35* advance at 3000 RPM (hei setup).

drivetrain: th350 w/ 3000 stall, 4.10 gears

this has been a very frusterating project, for the life of me i cannot get this engine to run richer. if i free rev the engine and idle it i could pull out perfect looking plugs a good golden brown color, but the second i drive the car and put it under and load or just cruise around i pull out grey white plugs, indicating that it needs more fuel. the funny thing is that i have went from a 72main /80 secondary on my 650 all the way up to a 80 main/ 90 sec. it dosent seem to have any affect on the way the plugs look. the fuel pressure is fine all the way up runs around 6psi. i would think by now i should be pulling out black plugs but i dont seem to be anywhere close.
there are no vac leaks either...
what could i possibly be missing, ive never had this much troubble tuning a small block this simple
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post #2 of 11 (permalink) Old Jul 21st, 09, 03:46 PM
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Re: engine still runs lean

what vacum are you pulling at idle?
your power valve might be wrong.
or you can swing by and 2 heads are better than one?
where ya located in CT?


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post #3 of 11 (permalink) Old Jul 21st, 09, 05:48 PM
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Re: engine still runs lean

Dose it feel like its running lean at cruise and under a load... Something like a real crackling sound from the exhaust at that time and is your float level up to snuff. Someone had told me recently that its harder to read a plug now a days because of the fuel we run now a days, so white or off white might not be as lean as you think. I'm no expert but kinda in the same boat and i have a AFR meter and still see lean looking plugs.

One more thing that i think can run the carb a little goofy is a PCV may run the carb on the lean side.

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post #4 of 11 (permalink) Old Jul 21st, 09, 06:20 PM Thread Starter
 
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Re: engine still runs lean

dawg im located in east haddam ct,

it seems to run lean crusing and under load , basicaly thru the whole RPM range even WOT, i have a steady idle around 700 Rpm and have 12-13 inches or manifold vac. and i do get a slight crackling thru the exhaust even under small amounts of load. and float level is right up in the middle of the sight glass if not even higher
is it possible that something in the bottom end of the engine could be doing this?

thanks
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post #5 of 11 (permalink) Old Jul 22nd, 09, 05:29 AM
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Re: engine still runs lean

Really can't go by plug readings these days due to the additives in the fuel and such. The carbs are suppose to run leaner at cruise until the PV opens. I bet your OK.

You can try 4 sizes richer main jets. Just reset the mixtures and go. See if you feel anything. But, you will have to deal with a richer cruise.....which it may or may not need.

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post #6 of 11 (permalink) Old Jul 22nd, 09, 05:38 AM
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Re: engine still runs lean

richen it up or youll blow the motor,its better to run alil rich than to lean..why can you adjust the mixture or change the jet size??thats true what skeeter 55 said check your pcv valve!!
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post #7 of 11 (permalink) Old Jul 22nd, 09, 07:53 AM Thread Starter
 
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Re: engine still runs lean

ive tried without PCV and w/ PCV valve , both run the same unfortunately.
i guess i could try jetting at WOT and keep going up and see if i feel a diff.

but again, could this have anything to do with the bottom end of the engine?
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post #8 of 11 (permalink) Old Jul 22nd, 09, 08:04 AM
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Re: engine still runs lean

Quote:
Originally Posted by monstersk8 View Post
could this have anything to do with the bottom end of the engine?
I can't see how it could.Check for vac. leaks.Around the base of the carb. and manifold to heads.What exhaust do you have on the car?A restricted exhaust can make a car act lean by causing backpressure and raising exhaust temp.Has the car been sitting?I have seen rats fill a muffler up with crap and clog it up.

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post #9 of 11 (permalink) Old Jul 22nd, 09, 08:07 AM
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Re: engine still runs lean

What plugs are you running and what heat range are they? What temp is the engine running? Are your headers glowing or discoloring? Is there any surging at steady cruise speed?

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post #10 of 11 (permalink) Old Jul 22nd, 09, 08:07 AM
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Re: engine still runs lean

Time for a dyno tune....
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post #11 of 11 (permalink) Old Jul 22nd, 09, 08:54 AM
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Re: engine still runs lean

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Originally Posted by Vegas69 View Post
Time for a dyno tune....
This would be the quickest way and you will be able to get some sleep. I spent 4-6 weeks trying to figure out if i was lean or rich (love that Innovate ARF meeter). Everything mentioned above is great info and should all be done.

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