Valve stem seal questions

[1969Fstback 58]

I have the original 302 and it smokes a ton on start up and burns oil.  I started changing the valve stem seals over the weekend.  I pulled of the intake valve one and compared it to what I ordered.  The one I pulled off the car has a inner diameter of 3/4 on the base and 5/8 inch tall and fits horribly.  No doubt the wrong ones.  The exhaust valve had even a different size.  IT has a base ID of closer to 7/8 and was only 3/8 tall where as the ones I ordered that fit well have a 5/8 ID at base and 1/2 inch tall.

I received my cylinder leakage tester today.  I am going to check all the cylinders then do a compression test on all after I get it all back together.  My question is, other than on start up, how or what other issues would having valve stem seals that far off cause? Would it cause oil to be burnt while driving vs just on start up?

My gut tells me that the old motor is probably just pretty worn and I will find that out with the leak down tests and or compression tests.  The plan would be to figure out this summer what I want to do motor wise then pull it beginning of next fall. 

 

thanks

[barnett468 418]

bad valve guide seals and bad valve guides will not cause it to smoke a ton.

can you post a photo of the seals?

the orig ones were the "umbrella" type

 

[1969Fstback 58]

Yep umbrella.  One on right is the new one and fits the crown on the head perfectly, the middle is old off the intake, one on left is old off exhaust valve. 

[1969_Mach1 333]

Bad valve seals and/or guides will cause a puff a oil smoke on start up.  That was a big problem when I worked as a GM tech and they merely used square cut O-ring type valve seals on small block V8's.  We swapped a lot of them out for umbrella or positive type seals.  Why don't you try positive type seals like these,  https://www.summitracing.com/parts/fms-m-6571-a50/overview/ They are soft and pliable, work better than umbrella seals, and not rigid like the Teflon seals. 

[1969Fstback 58]

I just went out did a leakage test on the passenger side. Granted it was cold and I know it makes a difference,  however, at 80 psi input front 2 were mid 30s. Plugs black. 3rd back plug looked good and it was holding 75 out of 80. The back cylinder was 60 out of 80 and plug was not as black as front 2, but blacker then the 3rd.  So, I guess that tells me all I need to know unless someone much wiser tells me heating it up would make that much difference in the front 2?

[1969Fstback 58]

And the air was escaping up through the head where the oil drains back down to the pan. None from exhaust, nor carb, nor radiator. I had all the rockers off so I know the valves were closed.

[barnett468 418]

10 minutes ago, 1969Fstback said:

I just went out did a leakage test on the passenger side. Granted it was cold and I know it makes a difference,  however, at 80 psi input front 2 were mid 30s. Plugs black. 3rd back plug looked good and it was holding 75 out of 80. The back cylinder was 60 out of 80 and plug was not as black as front 2, but blacker then the 3rd.  So, I guess that tells me all I need to know unless someone much wiser tells me heating it up would make that much difference in the front 2?

I like to do a regular compression test as well, but as I mentioned, bad seals and guides will not make a ton of smoke as you describe it.

Those seals are all basic stock types with the longest one providing the best shield from oil getting on the valves unless you use ones that push over the valve guides.