Valve truble

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plymouth1937

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Have some 308 heads that im gona put on my rebuilt 318 they are ported and al the valve job is done in a shop but something is of whid the valves i think that the intake valve is the ones that came whid the heads and the ex valves is from a 360 head whid bigger diameter than stock but the hight of the valves is diferent see photo what to do

20220110_123607.jpg
 
More than likely you have HD truck ex valves in the heads.
As long as the valve heights are pretty even across the tips, and the spring heights/loads are correct, what you’re seeing wouldn't really matter.

If you pull a retainer off the exhaust you can check to see what you have.......the HD valves have two keeper grooves.

If the spring heights aren’t even/correct, then someone should take care of that.
 
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You can see clear as day in the pictures that the stem heights are different . You are going to have to make sure that they are in tolerance for non adjustable rockers if used .
 
Yes your spot on its truck ex valves the valve hight at the tip is not the same in al valves and the valve hight must be shimd
 
In using adjustable rockers so its a bit more forgiving than solid but vhat to do about the diferent valve hight cuting the tip??
 
Its truck int valves 360 ex valve comp cam singel spring whid damper retainer from 360 heads on all valves
 
PRH said:
More than likely you have HD truck ex valves in the heads.
As long as the valve heights are pretty even across the tips, and the spring heights/loads are correct, what you’re seeing wouldn't really matter.

If you pull a retainer off the exhaust you can check to see what you have.......the HD valves have two keeper grooves.

If the spring heights aren’t even/correct, then someone should take care of that.
Click to expand...
How mutch diferens between the tips is axeptebol
 
Put a straight edge across the valves.
If running adjustable rockers, while far from ideal....... personally I’d say if the tips are within about .040, at this stage of the game I’d say “run it”.
I’d prefer to have the springs set up pretty close if possible.

The HD valve and the std valve are very close to each other in OAL(the HD valves are actually .011” shorter).
If the tips are pretty far off each other from intake to exhaust...... that’s more likely related to the seat work(valve job).
From the factory, the tip heights for the HD ex valves are the same as the intakes.
 
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Adjustables on shorter valves is gonna be a very slight difference, your ratio will change slightly. They are all shorter on the exhaust so its not like they are mixed between intake and exhaust. By increasing the adjuster length to tighten up the lash (shorter valve) , you are decreasing the true rocker ratio by thousanths of inch of lift potential. Nothing I'd worry about.
1.54:1 'true' Rocker would equal ~1.438 (all the way down) 1.500 (mid point) 1.560 (adjuster screwed all the way up) EXTREME LIMITS SHOWN..yours will be much smaller
Rocker-arms-207x300.jpg


You can always use lash caps on the exhaust to bring them up to intake height.
 
Ok thanks this is a Street engine so if i shim the springs to the right hight il be ok
 
That's what I call dogshit, in more ways than one. They should have, noticed it/known it, used/switched to pass car valves...or sold you on 11/32 1.94/1.60 +.050 or +.100.
2 diff lengths of push rods and differing geometry between the int/exh.

As they say though.."it'll run" "he'll never know the diff"..and so on..
You went through the trouble to port the heads...unless you ported then to offset the power loss 'aka like to tread water'.. return them.
Fix it now.
 
^^^ THIS RIGHT HERE ^^^ Any shop that cares about what they're doing will keep the valve heights within .010 or less.
 
I haven’t seen any pics of a straight edge across the valves, or been told how much different they actually are.

If the valve lengths are stock, and the tips vary a bunch...... it’s certainly possible that some seat replacement might need to happen to make it truly “correct”.
Is that in the budget?

Might be able to get close with some tip grinding....... of course, how much can you take off before you’ve gone through the hardened part?
 
MOPAROFFICIAL said:
That's what I call dogshit, in more ways than one. They should have, noticed it/known it, used/switched to pass car valves...or sold you on 11/32 1.94/1.60 +.050 or +.100.
2 diff lengths of push rods and differing geometry between the int/exh.

As they say though.."it'll run" "he'll never know the diff"..and so on..
You went through the trouble to port the heads...unless you ported then to offset the power loss 'aka like to tread water'.. return them.
Fix it now.
Click to expand...
Ok thanks for the tip but what to do if it was you?replace the ex valves ?
 
plymouth1937 said:
Ok thanks this is a Street engine so if i shim the springs to the right hight il be ok
Click to expand...
spring height wont change your valve tip height: 1) adjust mechanicals to run, 2) lash cap them to matching height or 3) get matching valves. One of these is free.
 
I see .040 or so
Click to expand...

Which way? Exhaust tips higher?

Which valves do you replace them with that will fix that issue?

The std valves are .011” longer than the HD pieces.

Just to reiterate....... if the exhaust valve tips are “too high”, it’s not caused by having the HD type valves installed....... since they’re actually shorter than the passenger car ex valves(at least according to the SBI valvetrain components catalog).

Easy enough to pull an ex valve out and measure the OAL and see if it’s something oddball, and/or if the valve seat is sunk.
 
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