Engine and car shakes bad/ misfires on the road after cam swap (CL-12-249-4) 1988 Chevy C1500 aTBI 350

[thebigcar]

Hello everyone, this will be my final update for this project!

I re adjusted my valves with a video from a channel called uncle Tony’s garage

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Linked here^

I also made sure all my plug wires were in order

It ran like a champ. It’s idling way high at 1500 rpm in park (don’t worry I’m fixing tomorrow). What should my target idle be in park on the road etc? I understand I need to adjust the idle screw with the iac in the home position and unplugged?

The engine shakes no more! No more smoke no more shaking gas pedal, all my wacky problems are gone, and my truck is faster then ever as well. Gas mileage also appears to have returned to normal

It doesn’t seem to want to stall either

The idle is way too high and my idle screw cap has already been drilled as I’ve fiddled with this before.

I would like to thank you all once again, I have read every single reply to this thread and done my best to follow everyone’s instructions. If not for this forum I’d be dead in the water

The truck also lightly backfires when accelerating really hard but I can live with it. I figure the computer is still going to need to adjust to the new hardware, I think my timings a little off as well, but these are not the most urgent issues to me.

Thank you!! Runs better then it ever has before

Good job .... Guessing idle speed after performance upgrades is determined by a few factors: cam timing / grind, torque converter stall speed (if auto), flywheel weight (if manual), ignition timing, etc. The factory sets idle speed relatively low for driveability and reliability of moving parts so if you've moved the engine HP / torque band up considerably or have a convertor with more slip then you want to raise the idle about 200-300rpm from factory.

 

[Slade88]

Hey everyone, recently did a cam swap, (Comp CL122494) noticed my truck is now vibrating with my foot slightly on the pedal only at 1100 rpm’s, it doesn’t vibrate at any other speed or in idle. My truck also likes to randomly bog down from 750 to 500 to 0 completey randomly when I take my foot off the pedal at low speeds (under 25). Makes it very scary to drive in neighborhoods, when I see the RPM drop I slightly put my foot on the pedal and that fixes it

Thanks
Slade

 

[Schurkey]

Why start another thread on the same problem that you told us was fixed and the truck...

It ran like a champ. It’s idling way high at 1500 rpm in park (don’t worry I’m fixing tomorrow). What should my target idle be in park on the road etc? I understand I need to adjust the idle screw with the iac in the home position and unplugged?

The engine shakes no more! No more smoke no more shaking gas pedal, all my wacky problems are gone, and my truck is faster then ever as well. Gas mileage also appears to have returned to normal

It doesn’t seem to want to stall either

Engine and car shakes bad/ misfires on the road after cam swap (CL-12-249-4) 1988 Chevy C1500 aTBI 350

Hey everyone, I’ve made a couple posts here about my cam swap I did on my truck. Well I finally got it idling 950 rpm in park with a rough idle, 550 in gear when the truck is hardly in motion and 1000 when the truck is moving very fast down the road with my foot off the gas. Timing is set at...

www.gmt400.com

 

[Slade88]

I didn’t notice it until driving it for a couple days, first time I drove and made that original post I was only gunning the truck with the new power I’ve gained. It took awhile until I could really pinpoint all the new kinks I’ve found

 

[Schurkey]

But all the repair history is in the other thread.

Perhaps a moderator will combine this thread into the other one.

 

[Slade88]

But all the repair history is in the other thread.

Perhaps a moderator will combine this thread into the other one.

Yes indeed, did not know threads could be combined, that sounds good

 

[Slade88]

Just checked, my timing was close to to 0 degrees TDC but not exact maybe a degree or two off, so I got it EXACTLY at 0 degrees TDC with the engine at operating temperature and the timing wire unplugged. Engine still boggs down with you let your foot off the gas under 25 MPH. And the slight vibration still occurs at 1100 rpm

 

[Jroctizzle]

The cam also may not be compatible with your computer, I had a similar issue (loss of power, rough idle, etc.) with a cam as it was a few degrees in duration past what the computer could handle or comprehend.

You could even check out https://harristuning.com/, go through his website as he has a ton of info.

Switched it out for a smaller duration cam and the issues went away. I also put in a new distributor, wires, plugs and spark control module just to make sure there was no issues that would pop up.

Hope you can get it figured out! Nothing worse that having engine issues!