HEMI rebuild

Last year I pulled the 540 cid HEMI out of the Coronet to find the excessive oil consumption. I’m glad I did. I had used a well known shop for the build. For some reason, my engine must have been worked on only on Mondays after a long weekend! They had built several engines for magazines, and friends. I expected professional results. Instead I had the following:

The block was delivered already bored and honed for the 4032 alloy Diamond coated pistons. It appeared as though the shop didn’t like the tight clearance that Diamond recommends for these pistons and so the bores were opened up to TWICE the recommended clearance. To make matters worse, the tools used did not provide the proper finish. Indeed, much of the wall surface showed NO crosshatch!

I had pre assembled the engine (new parts) and determined that the deck needed to be cut .040” Instead it had been cut .090” causing witness marks where the pistons had been contacting the heads!

The valve to guide clearance was as much as .007” vs .0015”. This shop either didn’t posses measuring instruments or didn’t know how to use them! I found out after the fact that they didn’t own torque plates for a HEMI. They evidently didn't have the correct honing stones for a Mega Block either!


The list goes on. Had I not pulled the engine, it would have had a short life.

After talking to several people I chose Bob Meyer at Performance Automotive in Greenville TN. Bob worked on Allen Johnson’s Pro Stock engines. He not only had a torque plate but a fixture to properly locate the bore center for honing!

Bob corrected all the problems and sent me these photos. He also ported the MP heads. I can’t wait to see the results on his Dyno in the near future!

Been there. Had a very well-known Mopar SS racer in SoCal do my Hemi, which is still fine.
Years later, had him do my SB race motor.
Found problems even before the install, took it back.
A few easy passes, boom.
Post-mortem showed lots of problems, poor work...
Like valve reliefs machined through the piston crown...

I think anyone that has been around these cars long enough has had issues like this. I had an engine builder that had built several terrific engines for me really screw up a 408 Stroker for me. Never would get a good ring seal, blowing smoke, it almost hydrolocked from all the oil in the cylinders. Was a bad finish on the cylinder walls. So basic. I even took it back to the builder, so he did it again....still was not right. Finally, several aggravating months later, and removing the engine again, I had success from another builder. Cylinder wall finish was all that was really found wrong.

It turns my stomach to read when this happens. I also feel these shops should be outed for their shoddy work.

Yes this is true. I am not naming the shop as I feel this will take care of itself. My car is very well known in the area. The shop is question is very well known, word will spread and business will be lost or fail without my help!

Been there, feel your pain....

100 years ago, a famous MoPar racer and author had a famous shop build him a B stroker engine, for a car to be raced immediately. He assumed that everything had been checked...

The crank would not make a full revolution.

I did my own assembly, but the machine work was done by a local machine shop, I think I will have one problem with a rod bushing, I may have to tear the engine down and hone it out if there is a problem. We also didnt put valve seals on the exhausts, I think that may also be a problem...Time will tell if I screwed the pooch on my 572 hemi...I feel your pain. Tim

That sucks, I'm glad it's getting fixed. And your car is gorgeous!

Thanks and your car is impressively fast for a true street car! Driving the car is what I enjoy, but having a car that you can really drive that also runs deep into the 10s is like having your cake and eating it too!

I honestly think some builders should be forced to have malpractice insurance.

Hemi ragtop...hope it works out better for you this time!

astjp2...FWIW, I haven't run exhaust valve seals on my hemi for a long time w/ no issues. I know every setup is different though.

Nice to hear all the issues were found and are being fixed. You should be set for a long time afterwards!