May 2012 Chevy High Performance Q&A

Richard’s at it Again

Kevin McClelland Mar 22, 2012 0 Comment(s)

You said you have your ground cable running from the battery to the rear bumpstop bracket. This may be a great ground for the unibody, but there is no ground path to the front subframe that the engine is grounded to by your four-gauge cable. Your problem is likely that there is no ground from the main body to the front subframe. The subframe is mounted to the unibody by four rubber isolators that will prevent the engine from having a ground path to the battery. Another clue is that everything worked just fine until you relocated the battery. The Powermaster alternator didn’t have an issue keeping up with all your power accessories until the relocation. Again, we like to see a ground cable running from the battery directly to the rear of the transmission case, to eliminate any ground path issues with battery relocation. Don’t remove your current ground going to the unibody, just add one to the engine or trans.

Running one cable should take care of your problem. Since you have the car finished in four-gauge, try adding a four-gauge ground up the car to your powerplant. It’s worth a try to see if your gremlins go away. Good luck, and let us know how it turns out.

Little Leaks

I have a set of AFR 180 aluminum heads for my ’66 Nova. After bending a rod and thinking is was my fault, I rebuilt the engine with a new rod and piston. I noticed that after a few weeks there was antifreeze underneath the car. Thinking I had a cracked block, I took the block to a friend, an engine builder. He could not find a crack in the block. He checked the brand-new heads and found one leaked through the intake port. I sent them back to Air Flow after marking the head where the leak was located. Their testing could not re-create the leak. The owner had the heads coated inside the water jackets. This will be the third time I have put the engine together and I am afraid these may leak a month or a year down the road. Should I put the engine together and trust this sealer or should I just get a new set of heads? Thank you for your advice.

Gerry Clark
Via email

Sand casting is an art. Anyone who has been involved with pouring cylinder heads or intake manifolds knows it is virtually impossible to pour a perfect part. Air Flow Research goes to great lengths to re-create perfect parts every time.

We have a few questions: What pressure did your machinist apply to the water jackets to create the leak in the inlet port, and did AFR use the same pressure? Usually, when doing a pressure test you will use what would be considered maximum operating pressure. This would be what the radiator cap relief is at plus some headroom. You wouldn’t want to put more than 30 psi of pressure in the water jackets.

We’ve had good experiences and not-so-good experiences with water jacket sealers. Usually, a latex-type sealer is used, which is a thick liquid poured into the water jackets. Plates are installed on the deck surface, covering the water ports on the intake flange. The cylinder head is rotated around to ensure that the sealer has reached all surfaces of the water jacket. Then air pressure is applied to the water jackets to impregnate the sealer into whatever porosity is in the water jackets. After the air pressure has forced in the sealer, the plates are removed and the excess sealer is drained. Then the head is baked in an oven to cure the sealer.


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