Posted on: September 26, 2016

by Dave Lawler in the January 1982 RootesReview:

Elnore’s “Orange Blossom Special” missed its first United this year because of a failure of the valve train the night before leaving for Savannah. I have been fighting the resolution of the problem since October and I thought it would be worthwhile to cover the details this way, so that YOU don’t go through the same thing.

At the basic core of the problem is an original bad design of the single spring arrangement used in the very late model Alpine heads; in our case, it was a head from a 1970 GT.

I found out about the bad design when I was forced to go through the design procedure in order to find an alternate somewhat near the original specifications. This is when I found that a well designed spring should have at least one more coil to keep the stress level low enough to be considered within acceptable limits.

The shop rebuilding our head had placed .060 shims under the springs in an effort to raise the seating force to somewhere near specifications. This small amount of dimensional change pushed the springs almost instant catastrophic failure.

In looking for alternates, I found several. The best alternative was a Volkswagen spring. However, I ran into a problem with the extra coil. This caused the fully compressed state of the spring to be so marginal that I was afraid that slight changes of dimensions, due to temperature or rpm, would cause the springs to coil-bind. This would result in a broken rocker arm or a bent push rod. Bob Pennell ran into this type of failure with Vega springs, and I now suspect this was the culprit.

I had the choice of machining the pocket deeper in the head with the possibility of running into a water jacket or of converting the head to the older Series V retainer and keeper arrangement. I took the coward’s way out and made the change.

Additionally, I now needed new stem seals which are available normally only in full head-set gaskets to be purchased at its attendant-price. I found a U.S.-made alternate, which can be purchased from most hydraulic parts distributors. The commercial part number is Parker Seal Corporation #2-109-Viton. The military part number is A M83248/1-109-NIL-R-248-TY1.

In either case, along with the size being important, the compound, Viton, a poly acrylic, must be used or it will not hold up under the temperature conditions. You may have to wait a few days for them since most suppliers do not have a complete stock of sizes of seals in this compound.

Incidentally the price should be about 60-cents each in quantities of 10 to about 28-cents each in quantities of 100. I mention this only because I had one distributor try to charge me $2 each for them!

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