Thread: Measuring for coil bind/guide interference?

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I am installing a cam kit in a motor that uses 'top hat' type seals on the intake valves.They are stock replacement seals like the originals that came on the heads and I've never put a higher lift cam in a motor that used these. They look like they sit pretty high and I want to measure to check clearance.Here's what I have,hyd.cam 465/488 lift,1.5 roller-tip rocker with long slot,k-motion spring that says good up to .500" lift with coil bind @ 1.050",375#@1.150 open,stock length pushrods.I think I will have a good safty margin but having never rebuilt a motor with these type seals I would rather measure.Will I be ok or will I need a telescoping mic,dial indicator,to measure or can I put it together and use a feeler gauge or calipers? When the spring says,"good up to 500 lift" does that include using 'top hat' seals?

"When the spring says,"good up to 500 lift" does that include using 'top hat' seals?"

No, the spring has no idea what seal you're using. All it knows it that with the spring at installed height (you have that figure from the mfg), you can compress the spring 0.500" from there before you start getting coil bind.

I assume you're talking about "umbrella" type seals that look like an upside down bucket that ride on the valve stem and fit down over the valve guide.

Beg, borrow or steal a set of snap gauges. With the head on the bench so that the valve will go into the guide sideways, slide in a valve and push a seal down on the stem and over the guide. Get some thick grease and apply liberally to a retainer and a set of keepers. Without the spring, assemble the retainer and keepers onto the valve stem with lots of grease to hold them together on there. Get a buddy to help you if necessary. With the valve on its seat, snap gauge the distance from where the spring will sit under the retainer to the spring seat in the head. Write down that distance. Now open the valve as far as it will go until the bottom of the retainer is against the seal. Don't force it. Now snap gauge that distance and write it down. Subtract the 2 numbers you wrote down and that is the valve lift you have to play with before you have seal interference.

P.S. forgot to say, you'll need a dial caliper to measure the distance on the snap gauges.

Thanks Techinspector1. Sounds good,I figured that with a mild cam I would be safe but I'll do this check,sounds very logical.By 'top hat' I was talking about the type intake seals that have the two metal rings,one at top,one at bottom.Come to think about it tophat was probably the slang used to describe the seal you mentioned.Mine look more like the 1800's style Russian hat,but colored blue

Measured and have .484 from open to closed. And since my cam tech card says 465 in.lift,488 ex.lift at valve (if this is acuate actual lift) I will possibly have some interference. These seals are original factory type.Can I use a different type seal (shorter) that will seal good without looking like the 'bug sprayer' truck? Don't want to machine for different seals,anyone give some advice?

There are a couple of ways to do this.

Not Recommended:
Sink the valve on its seat a little to move the spring mounting surface on the bottom of the retainer further away from the head. Use shims between the spring mounting surface of the retainer and head to establish correct spring installed height.

Recommended but expensive: (new valves)
Use a little longer valve to move the spring mounting surface on the bottom of the retainer further away from the head. Use shims between the spring mounting surface of the retainer and head to establish correct spring installed height.

Recommended and not so expensive: (new retainers)
Consult with the cam grinder who furnished your cam to supply new retainers which will move the spring mounting surface on the bottom of the retainer and the center part of the retainer which will interfere with the seal further away from the head. Use shims between the spring mounting surface of the retainer and head to establish correct spring installed height.

Thanks Tech.,guess I'll pay Mr. Coughlin's store another visit yet,his place is popular this time of the year, and stronger retainers with more clearance sounds good,thanks again.

all you have to do is spot face the seal with a seal cutter this will move the seal down on the head and take some of your guide a way. no big deal it is done all the time. i have done it many times

Pat Mccarthy,I know machine shops do that but what would I use to cut the lower step on the guide boss? While on the subject I have to ask another question.What function does the lower part of the retainer serve? I can understand that it may add strength but it doesn't come in contact with the locks,my locks are.175 up the valve and with the locks and retainer sloped(angled) down,there is no way the locks will go there,if locks break or give way they go out the top(unless the retainer would break). Of course there is the off-set locks that will give you .050 retainer clearance I could use or shorter retainers.

the bottom of the retainer is for added steel or titanium make it stronger to help stop pull thru or spilting the retianer . the step your are talking about get cut with the seal cutting tool . you can just call me pat. why do you want to play with the keeper? if they setup at 1.750 they are fine cut the seal down ?you can cut some off the bottom of the retainer and have done some of this but why? cut the seal down if you go to a higher set up. like longer valves +.050 keepers or retainers on the spring you lose your seat psi on your spring

Pat,the guide cutters that comp cams and others sell to cut the guide boss down to use 2-3 spring set-up, does it also cut guide boss height or are you talking about another cutter? If another,who sells it?

seal cutter for 530 or 500 for the seals is is the most used. but there is more sizes it will chamfer the top faces of the and will cut down the guide and faces the bottom were the seal stops look at goodson www.goodson.com they sell spot facers this is what i use and then cut for the seals it gose faster this way but the seal cutter will do it to .it has alot to do with how much you have to wack off the tops

Thanks Pat,I appreciate your help!

ok good luck

Geez Pat, I dont know what happened, but thanks for covering for me. My brain must have locked up....I didnt even mention the simplest fix first. After doin this stuff for over 50 years, I must be goin senile.

Sorry Shevy