Valve Guide Seals for Big Block

[Clem Z.]

Re: Valve Guide Seals for Big Block

Larry------



Then GM's description of the 12371061 kit is incorrect.They describe it as containing 16 of the GM #3970627. However, as I pointed out before, GM #3970627 is NOT a valve spring. It's the part number of a KIT that includes the valve spring + retainer. I'm sure the spring, by itself, has its own part number. But, it was never published because it's an internal number and has no SERVICE relevance since its not available separately in SERVICE.

For example, GM #12368082 is a rocker arm KIT. It contains a GM #3959182 rocker arm, a GM #12338047 rocker ball, and GM #3896648 nut.

GM #12368085 is a rocker arm unit which contains 16 of the above referenced GM #12368082 rocker arm kits. I purchased one of these units quite some time ago. It was a box which contained 16 individual GM boxes with the 12368082 part number on them.

i would order 1 3970627 and see what you get

[Joe L.]

Re: Valve Guide Seals for Big Block

Here's a pic (thumbnail below) out of that 1971 BB Chev book, which shows 3998265. I notice that the OD of the valve guide is NOT machined -- I missed that before .

Joe --- yes, # 3866612 is stamped in black ink on the paper back of those two packs of 16 rubber seals shown in my pic of post #7. Amazing how soft they are, after 40 years.

Wayne-----


I don't think the seal being installed in that picture is from the 3998265 kit. I'm not sure, but I'll have to dig out one of my 3998265 kits. I don't know when I'll be brave enough to do that, though.

IF the seal shown is a seal from the 3998265 kit, then GM later replaced it with a plain old umbrella seal because that's what the GM #460527 is. It seems quite strange to me that they would go from the umbrella seal (the 3866612) to a positive seal (the 3998265 if it actually is a positive seal as shown in the photo) and then back to an umbrella seal (the 460527). Actually, the seal which is integral to retainers supplied with the 3970627 kit is also a form of an umbrella seal.

As far as the positive seal in the photo being installed on a non-machined valve guide boss, the valve guide boss IS machined; all Chevrolet V-8 valve guide bosses are machined on the OD. It's just that it is not machined down to a reduced OD to accommodate the seal. These positive seals are available to fit several different valve guide boss OD's. It's just that in some cases, notably small blocks, the OD of the positive seal to fit a non reduced diameter valve guide boss would not fit within the size valve spring used. Big block springs are, of course, larger and may accommodate a positive seal big enough to fit on a non-reduced diameter valve guide boss. Still, I don't think the seal shown in the photo is a GM piece.

[Clem Z.]

Re: Valve Guide Seals for Big Block

Wayne-----


I don't think the seal being installed in that picture is from the 3998265 kit. I'm not sure, but I'll have to dig out one of my 3998265 kits. I don't know when I'll be brave enough to do that, though.

IF the seal shown is a seal from the 3998265 kit, then GM later replaced it with a plain old umbrella seal because that's what the GM #460527 is. It seems quite strange to me that they would go from the umbrella seal (the 3866612) to a positive seal (the 3998265 if it actually is a positive seal as shown in the photo) and then back to an umbrella seal (the 460527). Actually, the seal which is integral to retainers supplied with the 3970627 kit is also a form of an umbrella seal.

As far as the positive seal in the photo being installed on a non-machined valve guide boss, the valve guide boss IS machined; all Chevrolet V-8 valve guide bosses are machined on the OD. It's just that it is not machined down to a reduced OD to accommodate the seal. These positive seals are available to fit several different valve guide boss OD's. It's just that in some cases, notably small blocks, the OD of the positive seal to fit a non reduced diameter valve guide boss would not fit within the size valve spring used. Big block springs are, of course, larger and may accommodate a positive seal big enough to fit on a non-reduced diameter valve guide boss. Still, I don't think the seal shown in the photo is a GM piece.

the metal bodied seal shown in the picture like i have are after market and they fit a BBC valve without machining. i have not seen that type seal for over 40 years. they only had a thin rubber disk type seal on the top and i am not sure how long they would last in a street driven car. i used them on drag race engines which do not see many miles. the best type of positive seal is the perfect circle all teflon one with the metal band around the out side of the guide part and a wound spring around the valve stem part of the seal

[Joe L.]

Re: Valve Guide Seals for Big Block

the metal bodied seal shown in the picture like i have are after market and they fit a BBC valve without machining. i have not seen that type seal for over 40 years. they only had a thin rubber disk type seal on the top and i am not sure how long they would last in a street driven car. i used them on drag race engines which do not see many miles. the best type of positive seal is the perfect circle all teflon one with the metal band around the out side of the guide part and a wound spring around the valve stem part of the seal

clem------

...well, 40 years ago would put it just about the time the 3998265 was released. So, maybe these are those seals. It will have to await my digging out one of the 3998265 kits I have. I'm leaving for Los Angeles tomorrow morning for my aunt's funeral next Monday so I can't get to it for awhile.

[Larry T.]

Re: Valve Guide Seals for Big Block

i would order 1 3970627 and see what you get

Went to the dealer to order one 3970627, they told me it was discontinued. They looked up the #12371061 kit in the computer and it indicated that the retainer and seal that were required, and sold seperately. What would be a good aftermarket alternative if I did not want to spend the $500+ required for GM parts?