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compression test

N

Namvet

New Member
Ran a compression test on a 302 and the numbers were 145, 146, 149, and the rest were 155. I actually think the three lower numbers were higher than that but I believe the gauge wasn't sealed up the way it should have been.
I am going to put in a 20W-50 oil today and see if the grey smoke disappears.
I think those numbers were pretty good. If anybody thinks otherwise please let me know.
I also put on a new PCV valve and the idle speed dropped right down to almost stalling. Could someone explain that to me. Thanks
 
Old PCV valve was not functioning and now the new one is. It does pull vacuum thru it so that could make a difference. Might want to re-adjust the mixture too.
 
Just took it out for a ride. Cleaned the plugs, regapped them to .060, and put the 20W 50 oil in. Ran great, no more smoke. What should I expect from a 302 running about 185-190 degrees at about 900- 1000 rpm idle and 2000 rpm on the road. I am getting 25 idle and not quite 30 running. Runs just over 50 on cold start.
Thanks
God watchover the soldiers
 
Oil pressure sounds normal. Compression numbers are, IMO, indicative of a decent ring/valve seal, moderate compression and a mild/OEM camshaft. If you want further information, a leakdown test and oil content analysis can assist. Everything sounds nominal to me. Drive it.
 
Thanks for the replies. One more question. I have a 650 Holley in this thing. A little big but like I said it runs fine. Adjusted the idle speed but the idle mixture screws seem to do very little unless I open them up very wide. Could the Holley be too big? If it ain't broke don't fix it but I have wondered what having too big a carburetor would affect.
 
If the throttle plates are opened up to far to get the idle speed correct, you could be past the range for the idle circuit to be effective. I would set the mixture screws at the 2 turns out and see if you can bring the idle speed down. Then fine tune a bit on the mixture screws a bit more.

Other than that, you might check to see if the carb is leaking fuel anywhere internally.

Just some ideas.....
 
I've run as big as 800's on 289's with no adverse effects on idle. Properly adjusted, even with racing cams, you can get a steady idle only a couple hundred rpm above OEM. Try screwing the screws all the way in (gently touching the seat), then backing off 2 turns, then starting the engine and turning each one in 1/4 turn at a time until the idle deteriorates, then back out to the smoothest idle; then reset idle speed and adjust one more time for quality. I usually do a final adjustment for an automatic in drive (wheels chocked, parking brake set) just for fine-tuning.

How is the idle quality right now? What does your vacuum gauge read in gear (presuming automatic)? Out of gear?
 
It idles great, I do not have a vacuum meter but I think I will get one to check. I will do as you suggest and post what is going on.
My son is coming back from Afghanistan tomorrow. I think he has been there five times and to Iraq 4 times. Army Ranger. He does shorter tours than regular Army but it is usually four or five months here and then four or five months there.
Thanks
 
Glad to read your son is coming home safe. Obviously, your priorities are with him now. Keep us posted on your progress as achieved. Good luck.
 
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