68notray

Previous owner of my 69 BB car had an engine overhaul done but it looks like everything was left extremely stock, so the single valve springs looked suspicious to me - turns out they were originals, set up at 1.990 instead of 1.880 and had only 55 lbs closed.

So I am replacing them with Comp 925-16 double springs with 111 lbs closed @ 1.900.

After all that my issue is the seals. I've always used umbrellas on big blocks, had a motor once gall all the exhaust valves with positive seals. I like my stems to get SOME oil...Umbrellas won't fit the double springs. So why not use just the original O ring seals at the retainer?

GOSFAST

Not enough spring pressure closed.

Maybe go with Comp's single 911's (1.524" O.D. also) set them up at 1.850" (should be about 140#, better than 111#)?

There is no provision on BB valves for "O" ring seals like the SB's use??

Thanks, Gary in N.Y.

P.S. These springs will at least let you use the OEM style "umbrellas". Not all that crazy about ANY single springs but this will work!

derekderek

I am using comp 911's. Setting up at 1.85. They clear this positive type seal which fits the guide with no modification. I did trim the guide tops about .050 to get me .630 travel so I can run zz502 .540 lift cam. Exhaust valve seals? We don need no steenking exhaust valve seals!

derekderek

How did valves get set up at 1.99? +.100 valves? Or did he take rotators out and not use enough shims? What head casting number? The seal. They call it umbrella, but it is not. https://www.summitracing.com/parts/slp-st-2002

Günther-C3

Take this one, works great:
https://www.summitracing.com/int/parts/cca-515-16

derekderek

Those need the guides machined down to .530.

68notray

Cam is a very mild street grind, flat tappet. I'll look up the specs. Certainly in the rpm range of 1200-4500 so I'm not needing crazy seat/open pressures.

Heads are rotator castings. Rotators replaced with the Comp .300 spacers. I mic 1.990 +/- .010 on all so I'll use shims and -.050 locks to get set up where I want

derekderek

Those Rotator eliminators are supposed to be the same thickness as the rotators that came out. Are you sure you're measuring your valve spring installed height correctly?

68notray

My bad, got SBC on the brain. Correct there is no O ring groove on BBC valve stems.

So - what seals came factory on double spring applications?

BTW my guides measure .625" so nothing is going to fit inside my inner spring. Looks like I'll have to go single spring. Also - according to my books no BBC of this era came with springs over 106# seat pressure.

Yes, I have the tools and know how to measure installed height correctly.

derekderek

A standard umbrella is what I always see on BBC heads. Got some old ones around. I'll get pics and measurements tomorrow. They are kinda snug inside inner springs, but go up and down with the springs. I actually used the seals i posted earlier inside double springs on a set of L29 heads i have in one of my boats. Tight squeeze, but they work. I like these big single springs though. Although boat guys are adamant about double springs. But they have to replace springs every 300 hrs cuz they spend all day at 5k rpm and are scared to death of a spring breaking and leaving the valve in the piston's right-of-way...

68notray

So if my guides are .625" o.d. and my inner springs are .690" i.d. do they make a skinny Viton seal that will fit without machining?