need new pistons....
03-04-2007, 05:00 AM
#1
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need new pistons....
I need new pistons for my 1985 mustang gt, but they cant be just any pistons. The pistons must work with this setup. gt40p heads, raising stock compression to around 10.5/1, and be notched to clear this camshaft.....
286°286°0.542"0.542"224°224°
What piston would you recomend?
286°286°0.542"0.542"224°224°
What piston would you recomend?
03-04-2007, 12:37 PM
#5
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RE: need new pistons....
Those are a small valve inline head. 10.5:1 is going to be a flattop piston. That cam is not big nor radical. I'd be surprised if you could find ANY aftermarket flattop piston that wouldn't clear that setup.
Bang for the buck, I'd order a set of Probe pistons from www.fordstrokers.com.
Bang for the buck, I'd order a set of Probe pistons from www.fordstrokers.com.
03-04-2007, 01:10 PM
#6
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RE: need new pistons....
^^^The guy at the site referenced above knows his stuff.
The duration is fairly mild in your cam 224*
Duration is what causes most p/v clearance issues, as the valve should be closed by TDC anyway.
the only way to know for sure if it will clear is to mock it up and crank the motor over by hand, with some clay on the piston top.
Probe pistons do have some pretty decent valve reliefs. I would guess they would work well.
jason
The duration is fairly mild in your cam 224*
Duration is what causes most p/v clearance issues, as the valve should be closed by TDC anyway.
the only way to know for sure if it will clear is to mock it up and crank the motor over by hand, with some clay on the piston top.
Probe pistons do have some pretty decent valve reliefs. I would guess they would work well.
jason
03-04-2007, 01:44 PM
#8
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RE: need new pistons....
WTF 
, a probe piston is usally relieved with atleast a 2.15-2.30 cutter and the depth is substantial as most of the pistons offer the first ring land down atleast .250 thou. That cam is of no worry in regards to PTV clearance and if there is an issue, you got something way out of wack.
, a probe piston is usally relieved with atleast a 2.15-2.30 cutter and the depth is substantial as most of the pistons offer the first ring land down atleast .250 thou. That cam is of no worry in regards to PTV clearance and if there is an issue, you got something way out of wack.
03-04-2007, 02:16 PM
#9
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RE: need new pistons....
Been here before. Here's whats up. First offI'm assuming this is a306 cid engine were talkin about??? Anyhow,you dont really want to resort to domed piston if you can help it...a flat top design is way more efficient although the dome wouldnt have to be that big. Either way, the best way to do this would be to have your heads milled 0.030" and then have your block deck milled 0.016"this should allow the piston to sit .005" above the deck using a probe, JE, or most other flat top 5.0 pistons with similar compression height. All this will result in
10.04: 1compression ratio (with a flat top piston and a .040" head gasket)
.035" Quench distance
Approx. 58 cc combustion chambers
and somewhere between a 7.6 and 7.7 : 1 Dynamic compression ratio
As long as you didnt get crazy with the timing 32-34 total adv. it should run just fine on 91 and quite possibly 89 octane. Of course you could crank it up a couple and run some 104 and make a few more ponies.
Any questions?
10.04: 1compression ratio (with a flat top piston and a .040" head gasket)
.035" Quench distance
Approx. 58 cc combustion chambers
and somewhere between a 7.6 and 7.7 : 1 Dynamic compression ratio
As long as you didnt get crazy with the timing 32-34 total adv. it should run just fine on 91 and quite possibly 89 octane. Of course you could crank it up a couple and run some 104 and make a few more ponies.
Any questions?
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