Hey, I could really use some help here. I have a '68 Mustang with a c9 block 429 w/ c8ve heads. Rebuilt c-6 trans. Edelbrock 750 carb, performer intake, splitfire plugs, accel coil, very small air-cleaner. Stock fuel lines (originally a 289), and an apparently stock fuel pump. Open exhaust pipes dump after crossover beneath passenger compartment (Dig the fumes, man).
When I started she had what i believe was original carb in bad shape, and stock coil. She ran very poorly, seeming to starve for fuel at random and would bog upon the first blip of the accelerator. I changed the coil to the accel and carb to the 750 edelbrock 1411 with electric choke and she fired up fine, but I couldnt get the revs to drop despite fully lean choke, and idlemix screws turned 1/2 turn from full lean. Some dieseling also. I took her to a respected local 'stang shop and had them set timing and check compression. They said the # 7 and 8 cylinders are below 30psi compression and that this is a complete rebuild job. I drove her home about 1and 1/2 miles and she sputtered and snorted and died a few times on the (invigorating!) drive home. Then she dieseled for a good 5 seconds before turning off.
Heres my major point of confusion: This car did run before and seemed strong when she wasnt bogging. I will try some Engine Restore or similar stuff to try to restore compression, but what is the real deal here? Could some gaskets be loose that would affect this? The open headers? The carb being improperly tuned/Too much carb? Any help or commentary would be appreciated before I go crazy looking to rebuild the whole dang thing, which I cant really afford right now! I may be in denial, but there must be something else I can do? Right? Thanks.

 

Well it sounds like you do have a few problems. You said the local shop checked your compression. What method did they use to isolate the compression loss? First thing I would do is pull all the spark plugs and look at the tops of all the pistons. If #7 & 8 aren't holding PSI you might have a hole or really worn piston rings. Just use a flash light and eye ball the piston tops. Now comes the fun part of figuring out if it is the rings or the valves. If you squirt oil in the cylinder and the PSI goes up bad rings, no change then it is your valve train. Let us know what your results are before we dig any farther into it then we need too. Local shops love to tell you that you need a new engine so they can get ahold of your cash or worse engine block.

 

Thanks for the reply- I havent been able to contact the mechanic at the shop- I think its closed for holiday(?) Anyway, no return phone call yet. I will try the oil trick, etc on Monday when I get in. Ill update you then.

 

I try to do most things myself, but some projects I feel like I cant tackle or dont have the right tools and a car goes to a mechanic.....I listen very carefully to what they say is wrong and then put that together in my head with the symptoms Im aware of, and then do what you just did, run it by my friends at FTE (251,000 brains are always better than one, no matter how knowledgeable) be careful here......good luck