I just reused the original rockers with the right year pushrods
Help! 360 with 302 heads no compression
- Thread starter victa15
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I just reused the original rockers with the right year pushrods
high.rev.trev
Well-Known Member
Yep. But you've still got unexplained lost motion in the timing chain slack: bandaided over by the tensioner , & didn't I see someone or you mention it had originally jumped a tooth ? (Thing have to be in sad shape somewhere for it to do that; like a 70's big or small chev with 1/2 its nylon toothed Camgrar teeth worn off).
You said motor running fine now, but that 120psi cranking pressure is a little on low side all-across - again late valve timing c/o a slack timing chain will cause lower cylinder pressure via late exh valve closing event.
Just my 2 Coins worth
Trev.
I think the issue was the valves sticking. There was a few small dings on the top of the pistons from where the valves hit. But nothing big. The valves were stuck inside the heads with a massive build up of varnish.
nm9stheham
Well-Known Member
Old fuel will varnish the intake valve stems and cause them to stick. But it looks like you had all of them stick to some degree.
As for the chain slack, it IS excessive; I've pulled out a shot /6 timing chain that had that much slack and retarded cam timing by around 4 degrees. But, as said, we don't know the condition of the cam bearings or if the block has been line bored at some time. The cam is retarded (can bee seen in the pix) but it'll run, albeit with less low-mid RPM throttle response. Hey, it's a $300 truck!
As for the chain slack, it IS excessive; I've pulled out a shot /6 timing chain that had that much slack and retarded cam timing by around 4 degrees. But, as said, we don't know the condition of the cam bearings or if the block has been line bored at some time. The cam is retarded (can bee seen in the pix) but it'll run, albeit with less low-mid RPM throttle response. Hey, it's a $300 truck!
I couldnt tell if it had anything done with it. The pistons didnt have any number on the top of them saying of they were .30 or so. But its possible of its been rebuilt in the past. Also i thought it was strange to use a tensioner. I went to a speed shop and the guy pulled out 5 different timing chains for my truck and they were all the same. I talked to a few members on this website and they said they used the tensioner before. It was for the 3.7 v6. The truck seems to run fine right now. But only time will tell
nm9stheham
Well-Known Member
You got your money's worth and more IMHO! And who knows, it could be a faulty block from the factory. Recently, a poster showed up with the back of the block machined in a manner that was not perpendicular to the crank axis, and one guess is that it had been that way since 'birth'.
Edit to add: And I ought to add that with the smaller chambered heads, the higher static CR ought to more than make up for any loss of low end torque due to the retard of cam timing. And retarding will keep it further a way from an possibility of detonation. So... now you can say the retarded cam timing is a 'design feature' LOL
Edit to add: And I ought to add that with the smaller chambered heads, the higher static CR ought to more than make up for any loss of low end torque due to the retard of cam timing. And retarding will keep it further a way from an possibility of detonation. So... now you can say the retarded cam timing is a 'design feature' LOL
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high.rev.trev
Well-Known Member
Agreed...but I'll add to that Can Retard with Slack Chain : You'll get upto 12+ ° of retard with a slack chain if its really slack, it 1 change-1-thing-only rule changed JUST the camchain & the difference in cranking psi comp & off-idle torque increase was nothing short of amazing !.
The can bearings would need to be Oval to cause that much chain slack, same for line boring/honing ( could be a factory lunched block that slipped through, but molars quality control was pretty good on the LA engines).
I'd still be seriously advancing that Can for a little extra effort for the difference between a running eng & a STRONG pulling eng for cost of 1-2 offset MrGasket Keys & few gaskets.
But that's just me.
Trev.
PS while it timed out on me I note someone else agrees & beat me to punchline saying block could've been out since Factory ( great minds thinking alike, as the saying goes).
Boy you sure look to have got a Solid buy for $300 smackers !!
Enjoy !.
Trev.
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