Valve Guide Seals for Big Block

[Larry T.]

I started my day with plans to change my valve guide seals from positive stop teflon to an umbrella style. I got derailed but finally got to it and the non-OEM seals I bought would not fit. Too large in diameter. I have what I believe are 3970627 valve springs. The new seals probably would have fit fine on the original single spring.

I prefer not to buy a new spring kit that has the seals and everything included because these springs have only about 3500 miles on them. What is my best choice?

Thanks.

[Michael G.]

Re: Valve Guide Seals for Big Block

Larry,

Just curious as when I had my bb engine built choose to use positive stop style seals as opposed to umbrella seals. Why the switch to umbrella?

[Joe L.]

Re: Valve Guide Seals for Big Block

I started my day with plans to change my valve guide seals from positive stop teflon to an umbrella style. I got derailed but finally got to it and the non-OEM seals I bought would not fit. Too large in diameter. I have what I believe are 3970627 valve springs. The new seals probably would have fit fine on the original single spring.

I prefer not to buy a new spring kit that has the seals and everything included because these springs have only about 3500 miles on them. What is my best choice?

Thanks.

Larry------


The GM #3970627 was a KIT which included a valve spring assembly and a valve CAP (retainer) which included an integral umbrella seal. Assuming you actually do have the springs included in the 3970627 kit and that someone has previously replaced the caps that were supplied with those springs, you can obtain the cap/umbrella seal separately under GM #3964264. The problem is that these things GM list for about 15 bucks each and you, of course, need 16 of them. But, who said it was going to be cheap?

[Wayne M.]

Re: Valve Guide Seals for Big Block

...you can obtain the cap/umbrella seal separately under GM #3964264. The problem is that these things GM list for about 15 bucks each and you, of course, need 16 of them. But, who said it was going to be cheap?

Joe, Larry -- I have two NOS (circa 1969 ?) upper engine kits (pic of one below). They each have a package of 16 valve seals (black rubber, will post a pic later). the part # on the seal package is 3866612. You can see the 16 seals listed on the kit menu.

[Clem Z.]

Re: Valve Guide Seals for Big Block

if they are black rubber they are not viton and they will get hard and fall apart from the oil and heat.

[Michael G.]

Re: Valve Guide Seals for Big Block

Anyone care to offer up opinion of positive stop seal as compared to the umbrella seal? Pro/con? My researched indicated the PS seal had advantages over the umbrella seal.

[Wayne M.]

Re: Valve Guide Seals for Big Block

Here's the pics of the 16-seal packages in the upper engine rebuild kits Gr 0.289, # 3917955 & 3957990. Also a pic from How to Hotrod BB Chev's showing difference in GM springs available around 1971.

[Larry T.]

Re: Valve Guide Seals for Big Block

I started my day with plans to change my valve guide seals from positive stop teflon to an umbrella style. I got derailed but finally got to it and the non-OEM seals I bought would not fit. Too large in diameter. I have what I believe are 3970627 valve springs. The new seals probably would have fit fine on the original single spring.

I prefer not to buy a new spring kit that has the seals and everything included because these springs have only about 3500 miles on them. What is my best choice?

Thanks.

Attached are pictures of my springs, etc. The valve seal is about .630 in diameter. The ID of the spring is about .6875. These are not OEM springs, correct? They actually have three springs, an inner, outer and a flat center spring. OEM do not have the outer spring from what I have seen. If these are non-OEM as I believe, and I change to the OEM 3970627 do I leave the shims in place? Any other thoughts?

Thanks.

[Clem Z.]

Re: Valve Guide Seals for Big Block

Attached are pictures of my springs, etc. The valve seal is about .630 in diameter. The ID of the spring is about .6875. These are not OEM springs, correct? They actually have three springs, an inner, outer and a flat center spring. OEM do not have the outer spring from what I have seen. If these are non-OEM as I believe, and I change to the OEM 3970627 do I leave the shims in place? Any other thoughts?

Thanks.

i would not change to umbrella seals and the springs you have are some after market or maybe L-88 springs. i would not use them before checking them for installed on the seat pressure. if you change to the GM springs you should check the installed height and it should be 1.880 or 1-7/8"

[Larry T.]

Re: Valve Guide Seals for Big Block

a pic from How to Hotrod BB Chev's showing difference in GM springs available around 1971.

Attached are pictures of my springs, etc. The valve seal is about .630 in diameter. The ID of the spring is about .6875. These are not OEM springs, correct? They actually have three springs, an inner, outer and a flat center spring. OEM do not have the outer spring from what I have seen. If these are non-OEM as I believe, and I change to the OEM 3970627 do I leave the shims in place? Any other thoughts?

Thanks.

For a moment I thought I may have the L-88/ZL-1 springs referenced in the picture from Wayne. But mine have an OD of 1.50, bigger than any of the ones referneced in the article from Wayne.

[Clem Z.]

Re: Valve Guide Seals for Big Block

For a moment I thought I may have the L-88/ZL-1 springs referenced in the picture from Wayne. But mine have an OD of 1.50, bigger than any of the ones referneced in the article from Wayne.

i just measured a L-88 spring and it is 1.480 dia

[Clem Z.]

Re: Valve Guide Seals for Big Block

is there any paint stripes on the spring ??

[Larry T.]

Re: Valve Guide Seals for Big Block

No paint visible. But maybe these are L-88 springs. My cheap micrometer measures in 16ths. But again, no paint so maybe aftermarket.

[Larry T.]

Re: Valve Guide Seals for Big Block

Anyone care to offer up opinion of positive stop seal as compared to the umbrella seal? Pro/con? My researched indicated the PS seal had advantages over the umbrella seal.

I am far from an expert, but what I have read is that with the less than ideal top end oiling quality of the BBC that the umbrellas are better, although the positive stop seems to be the favotite for the SBC. A couple of guys have had my same problem with excess oil usage and changed from positive stop and made a great difference. Others already had umbrellas and did not have my problem. Maybe I am getting ahead of myself, but I want to get some immediate results.

[Clem Z.]

Re: Valve Guide Seals for Big Block

I am far from an expert, but what I have read is that with the less than ideal top end oiling quality of the BBC that the umbrellas are better, although the positive stop seems to be the favotite for the SBC. A couple of guys have had my same problem with excess oil usage and changed from positive stop and made a great difference. Others already had umbrellas and did not have my problem. Maybe I am getting ahead of myself, but I want to get some immediate results.

before installing the umbrella type make sure the guides have not been redone with any spiral type guide liners as these will a have continues path for oil to be sucked down the intake guide. if your engines has original type piddle valve lifters you are getting plenty of oil to the top end.