3/4ths Good ie missing

audiocontr · Post by **audiocontr** » Thu Jun 24, 2010 9:12 pm

yup, compression check and valves adjusted.

milesdzyn · Post by **milesdzyn** » Thu Jun 24, 2010 9:56 pm

I had the same problem a while back but with the #2 cylinder. I too went with the Air - Fuel - Spark theory of solving the problem, with no joy. Someone on this forum suggested that I may have a vacuum leak; sure enough I had a leak at the head inlet seal. Put in a new gasket and everything was fine.

Grab the front carb and see if it wiggles.

Miles

Erik712m · Post by **Erik712m** » Thu Jun 24, 2010 10:44 pm

Easy way to look for vacuum leak is spray brake clean around the carbs. The engine will want to stall

Boelt63A · Post by **Boelt63A** » Fri Jun 25, 2010 6:55 am

Carbs are nice and snug, I have taken to giving them a wiggle almost everytime I take the dogbox off. I'll try the brake clean trick though.

At this point I am on the edge of my mechanical abilities.

How do I check compression and if it is bad, how do I go about fixing it? Rings? Seems like a big driveway job to me!

Thanks

audiocontr · Post by **audiocontr** » Fri Jun 25, 2010 7:14 am

Grab a compression gauge from Sears, remove spark plugs, unplug coil (so you dont shock yourself), screw in the gauge, open up the carbs all the way and crank it 5 times. Record the number on the gauge. Do this for all 4 cyls.

Put the plugs back in and start it up. Expect it to smoke from all the fuel you just pumped in.

There should be a lot of posts on the forum explaining how to do it.

Boelt63A · Post by **Boelt63A** » Fri Jun 25, 2010 10:05 am

Thanks

M Wehrman · Post by **M Wehrman** » Fri Jun 25, 2010 11:25 am

===== Grab a compression gauge from Sears,====

Or Harbor Freight!

Jim LaGuardia · Post by **Jim LaGuardia** » Fri Jun 25, 2010 4:19 pm

If you find low compression in any cylinders, adjust the valves for that cylinder and test again.
At least 75% of trucks with a low cylinder that I have checked, had a tight exhaust or intake valve.
When the engine warms up, the miss gets worse due to metal expansion, resulting in less rocker arm clearance , and the valve not fully seating.

pinzinator · Post by **pinzinator** » Sat Jun 26, 2010 7:45 am

Jim, what would you consider normal compression- around 120 PSI? Also, would you consider the acceptable variance between cylinders- around 10%?

Boelt63A · Post by **Boelt63A** » Wed Jun 30, 2010 2:35 am

Well the truck is running great!! Kudos to Pinz Pete!! My "new" Dist cap must have been out of spec or something cause it was BAD!!

I changed the cap and she runs like a top!!

Thanks to all for the suggestions and help!!

Chuck

Pinzgauer Pete · Post by **Pinzgauer Pete** » Wed Jun 30, 2010 7:36 am

I am glad to be of service...it is indeed a tough job to diagnose a problematic vehicle without actually seeing it, a series of tests could be done in a matter of minutes that would isolate the issue and make it easier to figure out when you have the vehicle in front of you. I give you credit for having the patience to try the different solutions offered, and arrive at the solution to your problem all the while learning valuable diagnostic skills to help in a quick resolution the next time a problem arises.