MustangFTW

I would bump the idle up a bit and see what happens, my 289 would shake when i was at stop lights since I liked my idle low since it sounded better raising it by 100 rpm fixes most of the time.

If its not that or a misfire I heard a trick from my gramps the other day, crank the car in a dark garage/on a dark night and if you see sparks along your spark plug wires then it's time to replace em.

umfan92

Hey, thanks for the suggestion. My idle is already pretty high. I like the idle to be low as well and it's already too high for my taste. I'm getting a tachometer soon and I will see what it's at currently. I wouldn't want to raise it because that just hides the problem.

And I have tried running the engine in the dark and it looks fine, no sparks. The spark plug wired are relatively new. Thanks though. I appreciate it.

MustangFTW

Once you get that tachometer tell us where your at, a stock 302 should be at 1k give or take a couple hundred rpm, some engines need to run higher to stay smooth, the competitive drag cars with big cams can idle around 3k, imagine that sound D:

Gun Jam

mine idles great at 700 but that's a manual..if its auto then 1000 in park is about money or 750ish in drive

boogerschnot

I allways set it aroud 800 when warm in gear or as low as i can with it running smoothly.

JMD

Is your engine balance right?

If the harmonic balancer, the flywheel, or both are 28 oz balance, (like the car would have come with), they will be wrong for your engine that PROBABLY wants a 50 oz balance flywheel/32 oz harmonic balancer (1982 and newer engines). One or the other of these being wrong will cause a mild shake, both being wrong will cause a shake that is more than mild.

Xring01

"JMD
Is your engine balance right?

If the harmonic balancer, the flywheel, or both are 28 oz balance, (like the car would have come with), they will be wrong for your engine that PROBABLY wants a 50 oz balance flywheel/32 oz harmonic balancer (1982 and newer engines). One or the other of these being wrong will cause a mild shake, both being wrong will cause a shake that is more than mild. "

JMD, your comments confuse me... how can a 32oz balancer work with a 50oz flywheel...

Not to high jack this thread... but we might be on to something hear... My engine built to 1985 GT Mustang specs,,, but is does have a 50oz Balancer and Flywheel... Does a Roller Cam engine have to have a 28oz balancer and flywheel.?

1slow67

No it does not, I have a late model 5.0 as well and run a 50oz balancer and flywheel. I have no problems with it and this is my 2nd late model 5.0.

umfan92

Ok well I'm not going to reply to every comment individually but I'll try to cover everything.

I have a T5 transmission. I would like the idle to be around 800 but I'm pretty sure it's higher than that. I bought the tachometer today. It's garbage. It said my RPM was at 130. Then I tried it on a Volkswagon Golf and I revved the engine and held it at 2000 and it told me it was at 500. So I'm returning that. I need to get another one so I'm still not sure what my idle is at right now.

Also, I bought the harmonic balancer from Summit 3 weeks ago. I specifically made sure it was a 50 oz. imbalance. The flywheel came with the transmission and is a 1986 Mustang flywheel that we pulled out of my dad's 1986 Mustang, which had a 5.0 in it.

I hope I answered all the questions. Could the distributor be doing this? I pulled the cap off today and there was a lot of moisture in it. I'm not sure why. What could be making it shake like that?

MustangFTW

There shouldn't be any moisture. Make sure you set the tach to the proper number of cylinders, there's usually a switch with 4/6/8 options.