anyway to check for a bent valve without removing the head?

urban96

bubb rubb says:"woo woooooo"

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i messed up one of my pushrods pretty good (only about 15 miles on my new motor )

i put a straight edge across the side of all the valves above the springs and they were all even, also measures distance between them and that was the same too... anything else i can do to check without actually removing the head?

 

S

Sicarius428

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All the valves the same height from the head? If one were bent or cocked to one side, it should sit lower than the others.
Kevin

 

CManT1914

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Leakdown test.

 

will1992

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CManT1914 said:

Leakdown test.

Click to expand...

.

 

QDRHRSE

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A regular old compression test would do it. If the valve is bent there is a high probability that the compression in that cylinder would be really low.

 

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JerryDaugherty

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wut is low? i have 145 in all mine cept one i have 135

 

urban96

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that valve is actually sitting a little lower then the rest of em looks like ill be pulling the heads back off and putting on some thicker head gaskets

what thickness would you guys suggest with gt40p heads that have been milled .030?

 

CManT1914

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JerryDaugherty said:

wut is low? i have 145 in all mine cept one i have 135

Click to expand...

145 is normal. I have 140-150 all across mine. You want to have no more than I think 15% difference in between all the cylinders.

 

urban96

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welp, bent the valve for sure... blew air into the spark plug hole and could feel it coming out the intake

 

87MustangGT5.0

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That sucks man, good luck. What do you think caused that valve to bend?

 

CManT1914

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urban96 said:

welp, bent the valve for sure... blew air into the spark plug hole and could feel it coming out the intake

Click to expand...

Dude that really sucks! Sorry to hear that. Some douche mechanic of my friend's came by to look at mine a while back when it was running rough, and he was convinced that I had bent all my valves by tightening the rockers too tight because I didn't have over 200psi compression.

How'd you bend the valve? You just mentioned you messed up a pushrod.

 

urban96

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im not exactly sure yet... i took it out for a small drive and heard what sounded like an exhaust leak and it started running ruff so i got it home figuring maybe the header bolts loostend up

checked all the bolts and were all still tight so i started it up again and heard the ticking under the pass side valve cover and quickly shut it down and pulled the VC and found the #7 pushrod like this

i forgot to check piston to valve clearence before i bolted the heads down but i figured i should be fine running such a mild cam

maybe the lifter got stuck? i mean i wasnt revving the car up or anything, i dont think it went over 3K and all the other rods were fine

i think im gonna run thicker HG's this time tho

 

CManT1914

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urban96 said:

im not exactly sure yet... i took it out for a small drive and heard what sounded like an exhaust leak and it started running ruff so i got it home figuring maybe the header bolts loostend up

checked all the bolts and were all still tight so i started it up again and heard the ticking under the pass side valve cover and quickly shut it down and pulled the VC and found the #7 pushrod like this

i forgot to check piston to valve clearence before i bolted the heads down but i figured i should be fine running such a mild cam

maybe the lifter got stuck? i mean i wasnt revving the car up or anything, i dont think it went over 3K and all the other rods were fine

i think im gonna run thicker HG's this time tho

Click to expand...

HOLY SH IT DUDE!!! WTF?!?! Is that a stock pushrod??

 

Michael Yount

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#14

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Not so fast -- you need to mock it up and measure p to v before you make a decision about the cure. Thicker head gaskets is a BAD choice to solve the problem. First of all, if you had contact just on a test drive (not a missed shift/over rev) then a thicker headgasket isn't gonna buy you enough clearance. More important than that though, a thicker head gasket will ruin your quench dimension and likely make the motor prone to detonation.

Measure first - then decide on the solution. Either less cam, or cut the pistons. But not a thicker head gasket.

With the combo you have, I wouldn't think you'd have p to v problems either. Is it possible you had a rocker fail, or spring bind? Your cranking compression numbers sound ok to me -- that much variation is quite normal. Leak down tests should confirm if a valve is bent or not.

 

CManT1914

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What Michael said makes sense. If the spring binded up, then that might explain why it looks like it's still open (sitting lower) than the rest. Be glad the pushrod took the brunt of the force (from the looks of it anyway) instead of something else. You already did the leakdown right? You mentioned blowing air into the spark plug hole, but that's not all there is too it. I think on an actual leakdown, you blow in a measured amount of air, then compare how much escapes to that measured amount, then you know how bad it is. I could be wrong though, I've never done one.

 

urban96

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i didnt even think of a bound up spring

their new crane valve springs that i had installed when i had the valve job done

 

Michael Yount

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What kind of shape was the rocker in --- the one with the bent pushrod?

 

urban96

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it looked fine but there was like a lip/indent on the tip of the ball on the pushrod where u could see it came out of the cup on the rocker

i cant really get a good pic of it tho

 

urban96

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#19

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pulling the lower intake today to check the lifter out