I've been having a strange problem with valve seals on my Edelbrock heads. They keep popping off!!. I should mention that I am not using the valve seals that originally came with the Edelbrock heads, as I changed to a dual spring setup and the Edelbrock seals were too large in diameter...they hit the springs.

I am now using a stock GM type Viton seal, on both the Intake and Exhaust. Problem is...I believe that they are made for a slightly larger guide O.D. than what the Edelbrock heads have. Seem to be fine on the street...but every time I run a Track day ( Road racing ) they start popping off.

Obvious answer is to use Positive type PC seals....but I have had bad luck with these in the past. Can anyone recommend a good brand or type to use? Anyone know of a brand that uses a metal outer shell like the Imports use? Those, I know, fit the guides very, very tight.

 

Measure the guide diameter. I can't recall for sure, but I think it's .530" on those heads; measure to be sure.

Comp and Crane, and I believe also Manley and Crower, have Teflon seals. In Comp, they're part # 501 for that guide OD and the usual valve stem diameter.

 

they're undersize... so you'll need the smaller aftermarket seals.

im having good luck with the comp cams teflon ones.

 

Went to my Machine shop this afternoon and found just what I was looking for. GM "Vortec" valve seals. These are designed for a .530" guide and have an outer metal shell just like the Imports. Detroit\Corteco #10293. ( Edit. Disregard. Vortec seals are .550" id to fit a .560" guide )

The seals that we were using before was a standard Detroit seal for GM vehicles from the early eigties and up. Viton rubber construction. Now these are fairly flexible and in fact fit from .530" to .560" guides. Therein lies the problem.

Talked to my engine builder and we came to the same conclusion.

When I run track days the oil gets stinking hot. I don't have an oil cooler, since track days are an occassional thing ( Although one will be added if I don't sell the car). Last race I saw water temps of 235 degrees. ( 110 degrees ambient temp )...so my oil temp was probably pushing 280 degrees ( No oil temp guage. To be added ). No problem for the oil as I run Mobile 1. However, we think that the valve seals got so hot that the rubber softened and off they came.

The Vortec seals should solve that problem. The Vortec seals have exactly what I'm looking for. Viton\Nitryl sealing lip with a metal shell. That should do the job.

I don't like the white Teflon seals. Have had trouble with them before. So has the machine shop...and he builds hundreds of engines a year....but thanks for the suggestion.

Edit: Update. The Vortec seals do NOT work. ID turns out to be .550". Machinest had an oddball seal in his stock. NO listing for any metal clad seal with stem dia of 11\32" and .530" guide that we can find. Going to try the Teflon seals.