New engine with dyno time and a couple minutes on the hose.

What causes a seal to break like this? I have 2 that are broken. Did I use the wrong seal? I got them from the machine shop that did the valve work.

The lift is only .585/.612 and there's plenty of spring left.

Jack,
Are those stock retainers ? If so, there is a good chance that the retainer is hitting the seal at max lift on the camshaft. I will have to check on a head at the shop in the morning to be certain, but I am almost certain with that much lift you need to either use an aftermarket retainer or machine the valve guide down for more clearance. We normally machine the guide for a positive type valve stem seal anyway.

By the way, depending on the camshaft, that single spring is probably marginal. I think almost every cam I have seen with that much lift calls for a double spring.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Thanks Bill, The shop that did my valves is pretty much a stocker only shop so I imagine they gave me whatever they had on the shelf.

I was just looking online for umbrella seals for high lift cams... maybe?

The springs are from an Isky triple spring set. A person at Isky told me not to use the inner (blue) spring and just use the 2 outside springs. The middle spring is flat so you can't see it very well.

Oops, looks like dual spring with damper. I remember good spring pressures at the valve shop... and we got good rpm's at the dyno (6000 with peak hp at 5300).

Can I change these seals without removing the heads? I read it can be done by rotating to compression stroke and rigging an air compressor to a compression gauge. It said 50 lbs keeps them pretty much glued to the head?

I would have to agree with Bill... the retainers are hitting the seals at max lift.

If the inner had a blue stripe, and the outer has an orange stripe, it sounds like an Isky 8005A. If that's the case, I'd put the inners back in... the outers alone are probably not enough spring. The flat part you're referring to is not a spring, it's a damper. I'd say you're going to have to have the valve guides machined to gain the proper retainer to seal clearance, so I'd take the heads to a good shop who can machine the guides and check/set up your springs for proper seat and nose pressure.

Really no such thing If you dont want to pull the heads, your best bet would be to get a set of aftermarket retainers that fit your springs, yet are not as "deep" as the stock ones in the center. If I have a minute I will take a look to see which numbers we have been using.

The best thing though would be to pull the heads, have the guides cut for a positive seal and then have them properly set up by a shop that knows performance work.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

I AGREE WITH BILL,REMOVE THE HEADS,HAVE GUIDES CUT FOR PC SEALS,AND YOU R GOOD TO GO.

I am really suprised you weren't going into valve float on the dyno without the inner spring. Your basically running the 805 OD. It's the same spring as that of the 8005A without the inner. I'm not sure without looking it up however I would think that cam would need near 140 seat and 425 open. You should definately look into recommended spgs though. I remember the 8005A were used often on solid hyd. however had multiple uses as well. Because of the common solid use I wonder if the shop said to use just the outer considering it was for a hyd. set up unless your using a solid roller tight lash set up.?


8005-A Dual w/ Damper 1.005
1.530 .730
1.110 135 Lbs.
@1.875" 395 Lbs.
@1.225" .650"


805-DO Outer w/ Damper 1.530 1.110 120 Lbs.
@1.875" 290 Lbs.
@1.350" .525"



Not sure what Cam grind you have however this is for the 139011/168731 Crane cam. This came off their cam card.

Spring Requirements: Triple Dual Outer Inner
Part Number 99896
Loads Closed 150 LBS @ 1.900 or 1 29/32
Open 454 LBS @ 1.310

The cam is the Isky RR-275/284 hyd roller w/1.8 rockers. I'll call them again today to see if a different guys gives me a different story

Here's a graph from the dyno numbers at 32 and 34 degree timing.

There is something going on at the end that didn't look too good to me. Could that be signs of valve float? The dyno guys didn't even blink and I didn't worry about it much because I'll prop for 5300-5400 rpm. It sounded perfect all the way through (to me).