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valve clearence

4K views 30 replies 11 participants last post by  hpete 
#1 ·
I have a 60 over 350 i bought a set of used bowtie phase 2 heads comp xe 268 cam 1.6 full roller rockers. pistons hit valves need help on what to do i have around 600 in heads im trying to stay away from fly cutting pistons
 
#7 ·
It's only the exhaust valve that hits the cam is correct I checked three times I think the heads are zero deck and the blocke was decked .010 but delima is if I have zero clearance now if I get the pistons cut to give me .080 clearence is that to
Much for the pistons I have never seen 488 lift hit pistons but the heads are the in known I was thinking of just pulling the heads back off an selling them an getting a set of dart iron eagles
 
#12 · (Edited)
You want to advance the cam to get the exhaust valves to close sooner. If you want to know how much difference it is going to make, put a dial indicator on the valve end of a rocker, and turn the engine 12 degrees ATDC ( this would be 6 degrees on the cam ) and see how much that brings the rocker up
 
#10 ·
The heads would have had to been milled .100" to get the valves even close to the pistons. Of course then nothing else would fit.

You probably have a three way timing set installed at the wrong position.

I just had a customer, two months ago, with similar problem.. Went thru 16 bent exh valves, eight broken studs and 12 pushrods. Not to mention the gasket sets.

I told him the first time what the problem was. But, customer is always right. Hard headed and stubburn too..
 
#20 ·
Here's what I think is going on as the piston is coming up on
Exhuast stroke the lifter is opening as the piston reaches tdc the valve is fully open I don't think this is correct shouldn't the valve be fully open before tdc I think I got a bad cam
??? Any help please an thanks
 
#27 ·
so i got it fixed it turns out i slipped the timming gear on the wrong way :drunk:got everthing all back togahter adn running its a bit sluggish at low r's anything over 2500 it revs like a chainsaw i was woundring if anyone else is running bowtie heads maybe some pointers thanks
 
#28 ·
Did you install new lifters with the cam? Are you sure you are using the correct lifter for the cam (solid vs. hydraulic)? What about pushrod length? Did you install longer pushrods or did you check valve train geometry to get the correct pushrod lengths? I know these questions probably seem elementary but...................
 
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