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dave350v8 08-13-2012 09:08 PM

piston to valve clearance
 
Hi everyone,
Im in the middle of swapping my camel hump heads to some new aluminium heads, Im keeping the magnum 280(480/480) cam, do you think I will have any piston to valve clearance issues with installing the new heads?

The camel humps had 1.94/1.5 valves the new heads 2.02/1.6 valves.
The pistons are flat tops with 4 valve reliefs.
I wish I had checked with clay before torqueing heads down!

Thanks in advance

68NovaSS 08-13-2012 09:27 PM

You could check gross clearance from the top, bring the piston to TDC, get an in-car valve spring compressor, (cheap on the "Fix It" display at parts houses) remove the keeper and spring, and see how far the valve drops before hitting the piston, do the math with your cam spec card for actual lift at the valve if you changed rocker ratios. My guess is with .480 lift and valve reliefs, you won't have any problems.

dave350v8 08-14-2012 08:39 AM

Thanks for that, im still running standard ratio rockers,but now rollers.
Its looks like I will be ok then! If I end up taking heads off to clearance the pushrod holes then I will check with some clay,just in a rush to get it done,got 2 weeks before I take it down the strip...

67-4-fun 08-14-2012 12:05 PM

if the block has never been deck or heads milled down, mostly likely as mention you should have no issues.. i would go as far to guess you will have over .200 clearence which is well acceptable.. just my thoughts anyway

Huneycutt 08-14-2012 12:15 PM

You should definitely check it manually like was already recommended. Exhaust valve at 10 degrees BTDC and the intake at 10 degrees ATDC. Even if it is a pain, it's a lot better than fixing all the damage that comes with a broken valve.

dave350v8 08-14-2012 03:08 PM

Thanks guys,first class as usual,cant wait to try new heads out!

bigdog7373 08-14-2012 03:58 PM

Quote:

Originally Posted by dave350v8 (Post 1582689)
Thanks for that, im still running standard ratio rockers,but now rollers.
Its looks like I will be ok then! If I end up taking heads off to clearance the pushrod holes then I will check with some clay,just in a rush to get it done,got 2 weeks before I take it down the strip...

Don't rush too much, that's how you make mistakes. Good luck with your build:thumbup:

dave350v8 08-14-2012 04:07 PM

Quote:

Originally Posted by bigdog7373 (Post 1582763)
Don't rush too much, that's how you make mistakes. Good luck with your build:thumbup:

Thanks for that, finally been able to afford some "decent" heads, I should read installation notes first, I suppose we all learn by mistakes..

bigdog7373 08-14-2012 04:21 PM

Heads make or break the engine! What's the engine in?

cobalt327 08-14-2012 06:59 PM

Quote:

Originally Posted by dave350v8 (Post 1582767)
Thanks for that, finally been able to afford some "decent" heads, I should read installation notes first, I suppose we all learn by mistakes..

Piston to valve, while being very important, is only one of the valve train points that should be checked. The correct pushrod length should be high on your list of priorities- the p-rod length sets the valve train geometry.

The new heads should have plenty of clearance at the pushrod hole in the head; they're made to be used w/screw in studs and guide plates.

Good luck.

dave350v8 08-15-2012 09:50 AM

Quote:

Originally Posted by cobalt327 (Post 1582815)
Piston to valve, while being very important, is only one of the valve train points that should be checked. The correct pushrod length should be high on your list of priorities- the p-rod length sets the valve train geometry.

The new heads should have plenty of clearance at the pushrod hole in the head; they're made to be used w/screw in studs and guide plates.

Good luck.

Thanks for the link,very good read!


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