Need a second opinion on pushrods length
10-10-2014, 09:33 AM
#1
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Need a second opinion on pushrods length Originally here was the setup:
224r cam
241 heads milled
Cometic .030 gaskets
Harland sharp roller rockers 1.7s
I measured for and installed a set of 7.300 pushrods. Went about 15-20k with no issues or noise at all
Now I have changed two things:
Cam is now a BTR stage 3 231/242 .617"/.592" 112+2
Head gaskets are gm mls gaskets supposedly .052 thick
Now measuring the pushrods I came up with a 7.4
So my question is does this sound accurate? Seems like a big jump from what I was running. If I came up with a 7.35 I'd roll with it and not think twice. To me it says that I've measured wrong at some point unless the base circle is causing the difference. I was either wrong when I measured for the 7.3 or now I'm wrong measuring the 7.4
224r cam
241 heads milled
Cometic .030 gaskets
Harland sharp roller rockers 1.7s
I measured for and installed a set of 7.300 pushrods. Went about 15-20k with no issues or noise at all
Now I have changed two things:
Cam is now a BTR stage 3 231/242 .617"/.592" 112+2
Head gaskets are gm mls gaskets supposedly .052 thick
Now measuring the pushrods I came up with a 7.4
So my question is does this sound accurate? Seems like a big jump from what I was running. If I came up with a 7.35 I'd roll with it and not think twice. To me it says that I've measured wrong at some point unless the base circle is causing the difference. I was either wrong when I measured for the 7.3 or now I'm wrong measuring the 7.4
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10-17-2014, 10:34 AM
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Stock lifters. The first go around I ran the smaller gaskets for more compression. My head guy thought it would help get the most of of the cam and the little bit of port work he did. Seemed to work it went 11.20 na before I ran into other issues that had me chasing my tail and fighting for traction.
The short block was stock at that time. I was close but on the safe side of piston to valve. I'm not very experienced so as far as quench, and where the piston was in the bore I'm really not sure.
I'll dig into it this weekend and remeasure. I saw the difference and just stopped there to gather more info.
The short block was stock at that time. I was close but on the safe side of piston to valve. I'm not very experienced so as far as quench, and where the piston was in the bore I'm really not sure.
I'll dig into it this weekend and remeasure. I saw the difference and just stopped there to gather more info.
Last edited by 1320Chicken; 10-17-2014 at 10:40 AM.
10-17-2014, 10:54 AM
#9
The quench area has nothing to do with PtV... since stock pistons generally come out of the bore .006" you only had .024" clearance between the piston and the head itself... not the valve. That's very tight. Glad a piston didn't touch and shatter.
The minimum is really around .035" piston to head clearance on a street motor and .030" for a race motor. That gives you a good tight quench and gives you room for when the aluminum expands...
Sounds like your head guy is a SBC dude. A .030" gasket there does help with compression as the pistons can be in the hole .020" or so with SBCs. Even milling the head to get zero deck, you end up with a tight, but allowable .030" quench.
The minimum is really around .035" piston to head clearance on a street motor and .030" for a race motor. That gives you a good tight quench and gives you room for when the aluminum expands...
Sounds like your head guy is a SBC dude. A .030" gasket there does help with compression as the pistons can be in the hole .020" or so with SBCs. Even milling the head to get zero deck, you end up with a tight, but allowable .030" quench.