1966 427 425HP Valve Clearances

[Jim D.]

Re: 1966 427 425HP Valve Clearances

I used the lifters that came with the kit. As far as springs go, since I was using 1970 rect. port heads that had the better GM springs, I just replaced the 50+ year old ones with a set of NOS springs.
The next time you talk to Mark, if you can get a word in edgewise, tell him I said "Hi". The last time I talked to him, he was ready to take his car for the maiden voyage.

[Jack C.]

Re: 1966 427 425HP Valve Clearances

I used the lifters that came with the kit. As far as springs go, since I was using 1970 rect. port heads that had the better GM springs, I just replaced the 50+ year old ones with a set of NOS springs.
The next time you talk to Mark, if you can get a word in edgewise, tell him I said "Hi". The last time I talked to him, he was ready to take his car for the maiden voyage.

I see, the kit you mentioned was cam and sealed power lifters. Mark - HA-HAHAHAHA. You need some time when you call him for sure. I'll pass your hello along. Thanks

[Jim D.]

Re: 1966 427 425HP Valve Clearances

Thanks Jack. According to my wife, the same applies to my calls.

[Jack C.]

Re: 1966 427 425HP Valve Clearances

Jack, understood. Main reason I decided to go roller is the ZDDP issue and secondly more power under the curve with a modern grind. The cheapest way to go for sure is flat tappet, and you get vintage idle lope and valve clatter, which I will miss. To me though, well worth the sacrifice.

While saying thanks to all who have provided input and suggestions, I wanted to provide an update with feedback that hopefully will assist others. As it turns out, I was able to find a Sealed Power CS165R on ebay. It is currently at the machine shop to have the oiling groove cut in the rear journal for my 66 block. On Mark Nagy's advice, I ordered the Isky 8005A springs, with Isky VL38 Valve Locks, and Isky 3607ST Spring Retainers. Note that these springs were rated at 135 lbs. seat pressure at a height of 1.875. The 3607ST Spring Retainers add +.060 to the height which should result in in a 111 lb. seat pressure according to Isky specs. I ordered a LSM Racing Products PC-100SLC Valve Spring Seat Pressure Tester to verify the seat pressures and every valve measured 110 - 112 lbs., right on the money. Very happy that the measured pressure matched the rated specs perfectly. At a 400 lbs. per inch compression rate, this should give about 300 lbs. over the nose that I will verify after assembly. These springs are an inner and outer so I can remove the inner springs for cam break in. Also on Mark's recommendation I ordered Lunati lifters, p/n 70984 with the center oiling hole.

Before installing the new springs I checked the seat pressure on the previously installed Comp Bee Hive springs and they measured 170 lbs. on the seat. Clearly why the cam and lifters failed on break in first time around. I'll send in a follow up after all is back together.

[Scott H.]

[Joe L.]

Re: 1966 427 425HP Valve Clearances

I used the lifters with the oil hole in the bottom. My L72 engine rebuild is as stock as I could make it with new internals. 600 miles and doing great. I guess I’ll never know how much difference the extra camshaft oiling makes but I’m glad I used them.

Scott------


If you mean lifters with an oil hole on the camshaft contact surface, NO GM lifters were ever of this design.

[Jack C.]

Re: 1966 427 425HP Valve Clearances

Scott------


If you mean lifters with an oil hole on the camshaft contact surface, NO GM lifters were ever of this design.