I changed from Dynomax headers to Hooker Competition with Jet-Hot coating this year on my '69 350-350 efi engine.With-in 20 miles of road time they started dulling.After a call to Jet-Hot,they indicated that the block must be really hot and they would recoat them for me under warranty.They also indicated that they can not continously do this so I have to find a way to cool the block.The car is used only for showing in the summer month's and I'm running an electric fan with a shroud.The block is stock with Edelbrock Performer RPM Heads,Cam, and Pro-Flo Fuel injection.I appreciate any and all suggestions-thanks in advance-John. :confused:

I would guess that the problem isn't in your cooling system as much as in your state of tune. A lean A/F mixture can cause excessively hot exhaust temps., which can affect the finish of the coating. I'd make sure that is squared away before sending them in. Another culprit could be retarded ignition timing or retarded cam timing.

I don't think it's the block temp causing the problem. It's the exhaust temps, not enough timing or too lean could be causes for the excessive heat.