Valve To Piston Calculator

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bobscuda67

bobscuda67

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Hey everyone! Is there a valve to piston calculator online? I had my distance recorded with my Hughes cam but I switched to a Comp cam this year and in my haste I forgot to check the distance with the new cam before I put it all together. I really don't want to tear it apart and use clay to check it.
It's a XE274H cam with .236 degrees of Ex. duration @.050 and I'm quite sure it will be fine but I just want to be sure.
I did measure it at TDC with a valve drop to the relief with the head gasket is .380 on the intake and .310 on the exhaust.
 
There is no such thing. To many variables. The way you measured will not work. What was the lift of the old one and the new one?
 
valve to piston clearance needs to be checked during the overlap period of the camshaft...where it exhaust valve is closing the intake is opening...that is where the pistons and valves are their closest..

you can remove no. 1 intake and exhaust springs..and but light valve checking springs on number 1 cylinder...set up a dial dictator on the intake valve and turn engine over by hand ..and check valve to piston clearance every 2 degrees thru the cam over lap period....repeat the same on the exhaust
 
The lift on the old cam was .558 on the Ex. and .522 on the In.
The new cam has a Ex. lift of.523 and a In. lift of .520.
From what I understand it's not the lift but the duration that makes the valve closer to the piston. And it's closer on the exhaust than the intake.
I turned it by hand and it didn't touch, but that doesn't mean it's not to close.
 
yes...duration....Lobe Centerline...Lobe Separation...whether the cam is advance...straight up or retarded will change the P to V clearance..

what pistons do you have..flat tops?...dished.....valve reliefs ???
 
About the only thing you can do at this point is check it the way 70aarcuda suggested.
Most people assume valve clearance is checked at TDC. But that is not the way to do it.
 
According to the comp catalog.

For 106 and 110 ICL
Intake lobe lift at TDC is .080 and .066
Exhaust lobe lift at TDC is .085 and .072

Multiply those by your rocker ratio depending on ICL.

My guess, you'll be OK. The closest point is usually a bit before TDC, say 15*. The cam has a duration at .050 of 230 and 236. Duration at .200 is 143 and 144. Using some brain dead extrapolation. Going from .050 to .200 lift it lifts about .0034 and .0032 per degree for intake and exhaust. .0034*15 = .0517 .0032*15 = .048 Add that to the intake .080 for .1317 *1.5 rocker = 1.9755 and on exh, .085 + .048 = .133 * 1.5 = 1.995.

Consider the piston is further in the bore, so that needs to reduce the change. 340 stroke 3.31*15/180 = .276 360stroke 3.58*15/180 = .298

340
.310-.197+.276 = .389
.320-.199+.276 = .397

I had a small roller that was mid 230's and .580 lift 106 ICL and it had in excess of .300 clearance with KB107's.

I'll guess you have a long way to go before tagging anything. Best to check the way Tony suggests using a checking spring to remove all doubt.
 
crackedback said:
According to the comp catalog.

For 106 and 110 ICL
Intake lobe lift at TDC is .080 and .066
Exhaust lobe lift at TDC is .085 and .072

Multiply those by your rocker ratio depending on ICL.

My guess, you'll be OK. The closest point is usually a bit before TDC. The cam has a duration at .050 of 230 and 236. Duration at .200 is 143 and 144. Using some brain dead extrapolation. Going from .050 to .200 lift it lifts about .0034 and .0032 per degree for intake and exhaust. .0034*15 = .0517 .0032*15 = .048 Add that to the intake .080 for .1317 *1.5 rocker = 1.9755 and on exh, .085 + .048 = .133 * 1.5 = 1.995.

Consider the piston is further in the bore, so that needs to reduce the change. 340 stroke 3.31*15/180 = .276 360stroke 3.58*15/180 = .298

340
.310-.197+.276 = .389
.320-.199+.276 = .397

I'll guess you have a long way to go before tagging anything. Best to check the way Tony suggests using a checking spring to remove all doubt.
Click to expand...
Damn,now you gave me a headache!
 
Sorry I watched the Science guy this morning and was feeling "smartish" LOL
 
Thanks guys. But I should have mentioned that I have a 3.58 stroke and 1.6 rockers. Pistons are dished with a zero deck. That will make it a little tighter.
 
crackedback said:
Sorry I watched the Science guy this morning and was feeling "smartish" LOL
Click to expand...

OR,you could find some teflon type string packing, put it in thru the spark plug hole, and roll the engine over. the teflon is soft enough to smash if you don`t have enough clearance. we used to use 50/50 lead type solder on them yrs ago, it even worked w/o bending the valves. if it smashes down between the valve and piston, u can mike it w/ a certain degree of accuracy, but not 100%. will tell u if u need to be worried or not. just an idea, might give u peace of mind---------bob
 
crackedback said:
According to the comp catalog.

For 106 and 110 ICL
Intake lobe lift at TDC is .080 and .066
Exhaust lobe lift at TDC is .085 and .072

Multiply those by your rocker ratio depending on ICL.

My guess, you'll be OK. The closest point is usually a bit before TDC, say 15*. The cam has a duration at .050 of 230 and 236. Duration at .200 is 143 and 144. Using some brain dead extrapolation. Going from .050 to .200 lift it lifts about .0034 and .0032 per degree for intake and exhaust. .0034*15 = .0517 .0032*15 = .048 Add that to the intake .080 for .1317 *1.5 rocker = 1.9755 and on exh, .085 + .048 = .133 * 1.5 = 1.995.

Consider the piston is further in the bore, so that needs to reduce the change. 340 stroke 3.31*15/180 = .276 360stroke 3.58*15/180 = .298

340
.310-.197+.276 = .389
.320-.199+.276 = .397

I had a small roller that was mid 230's and .580 lift 106 ICL and it had in excess of .300 clearance with KB107's.

I'll guess you have a long way to go before tagging anything. Best to check the way Tony suggests using a checking spring to remove all doubt.
Click to expand...

Very nice!
 
Duh, pay no attention to the intake side, it's barely starting to open. The exhaust side is the side that matters in this case.
 
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