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slmorissette

Engine Shakes roughly at Idle

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Hello 02 Experts.

I recently had my head done. I reassembled the vehicle the same way I took apart. The car is timed correctly, I've checked all areas of common vacuum leaks, found one. fixed it. (intake nozzle). My engine still at 800 rpm shakes more than it did before the head work. I have a new weber 32/36 dgev carb. Factory jetting.

I guess my question is what could make this happen?

Do I need better jets as per CD Jetting perscription? Or should I look for more possible vacuum leaks?

Any suggestions would be herlpful!

Thanks

Shawn

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Have you checked the motor mounts? It can idle smooth and still shake if the mounts are bad.

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I think your problem is the "factory jetting" is this the jetting from webber or from bmw?

If you just bought a 32/36 and threw it on there, chances are thats your problem and the jettings off.

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I bought a 32/36 and slapped it on the 72 and it ran like...well, perhaps best left unsaid, but you get my point. I figured I'd do CD's suggested jetting and I have to say I noticed an immediate improvement. Given the success that many have found with it, I would say it is definitely a solid starting point for any of us with a 32/36 who haven't spent a bunch of time fooling around with a bazillion jet combinations.

I have an AEM UEGO A/F gauge I want to put on the 72 to see how it is doing at various loads. One of these days!

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....AND BEFORE you go deep with c.d. 's jetting -

I would REALLY, REALLY! use a timing light first,

to set the "BALL " mark in the inspection hole

@ 1,500 RPM (remove vacuum hose if your distributor has

one during the check). Then adjust the idle mixture,

and idle speed at 800 RPM (+/- 50 RPM)

till you optain the smoothest idle.

Check your valve clearances lately ? COLD ??

SET TO 0.006" ...0.008"

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Guest Anonymous

Double check your intake manifold gaskets (spray carb cleaner on each one especially the lower part). I had cyl #4 bottom of the gasket leaking {I wasn't careful enough installing the manifold) and tried everything prior to that simple check.

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CD,

This is one of those "up in the air" issues, I have a Tii distributor, I recently set the timing to the steel ball at 2200, (Tii recommendation by book) should I use standard carb settings??? I have purchased all components to install the prescription, just wanted to be sure.

I runs great otherwise, just idiling is rough.

So 1500rpm or 2200??

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Oh and btw this is factory weber settings on the carb. I sprayed carb cleaner everywhere, it varies very little, not enought to make me rip the intake off. I may just need to install lock washers on the manifold bolts.

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Guest Anonymous

Double check your intake manifold gaskets (spray carb cleaner on each one especially the lower part). I had cyl #4 bottom of the gasket leaking {I wasn't careful enough installing the manifold) and tried everything prior to that simple check.

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Ok, I just reset the timing at running temp to the steel ball @ 1500 rpm, and adjudted the mixture screw accordingly. Could it possibly be a spark issue? I'll check the plugs and wires next. Vacuum gauge reads 20lbs at idle, steady needle, for the most part.

Just trying to get it running decent, been a long road.

Thanks everyone!

I'm looking for a head? Thats possibly in running condition. If anyone knows of one please keep me posted.

smorissette@tampabay.rr.com

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I was having a very similar issue with my 2002. I also am running the factory Weber setting on my 32/36. I checked for vacuum leaks and found none, and also checked the timing. It wasnt until I installed my AEM UEGO wideband O2 meter last week that I realized my car was running VERY lean at idle. I now have the idle at between 900 and 1000 RPMs and The fuel ratio at about 12.5 to 13.0, which is alittle rich, but my 2002 likes it that way.

Good luck.

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WOW !!! I AM IMPRESSED with you using a vacuum gauge,

and 20 is a good reading - and if you adjust to the highest vacuum

reading at 800 rpm - you'll be spot on with air/fuel mixture without

having a probe/exhaust tester in the tail pipe.

Vacuum gauge is the poor man's exhaust gas tester

and your valve adjustments are set to what ?

new plugs ?

got points ? dwell is very important .

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