Exhaust Port Question?
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From: Bremerton, WA
Exhaust Port Question? I have been searching everywhere to try and find the difference in exhaust ports between the new Warhawk LS7x/C5R, LS7/L92, and the standard LS1. Mainly to try and figure out if headers made for an LS1 will work with LS7 or LS7x (which has C5R style exhaust ports) heads. Any input or pictures would be extremely helpful...Thanks
LS7 Headers On the GM LS7 heads, the bolt pattern is the same as the standard Gen III pattern.
There is, however, a difference in the port sizes, with the LS7 being the larger. It's also a D port like the 243 casting.
LS1 headers would be ok if they are 1 7/8", but I wouldn't use the 1 3/4" on the LS7 heads. Kook's can put the LS7 D flanges on their 1 7/8" headers if you want.
As far as gaskets, you have two choices if you're going to run D port headers, the GM 12594171 or the Percy's 8027A.
If you still need some pics, PM me and I should be able to get them to you today.
There is, however, a difference in the port sizes, with the LS7 being the larger. It's also a D port like the 243 casting.
LS1 headers would be ok if they are 1 7/8", but I wouldn't use the 1 3/4" on the LS7 heads. Kook's can put the LS7 D flanges on their 1 7/8" headers if you want.
As far as gaskets, you have two choices if you're going to run D port headers, the GM 12594171 or the Percy's 8027A.
If you still need some pics, PM me and I should be able to get them to you today.
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TECH Enthusiast
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From: Bremerton, WA
Thanks scatillac, that is what I was thinking about the LS7/L92 heads, but I'm still wondering about the Warhawk LS7x heads which I have been told by World Products have C5R style exhaust ports. Do C5R heads require custom headers?
John B.....are you running the LS7 gasket with your headers or the LS1/LS2 stock gasket?I have a LS7 right now with Kooks 1 7/8 headers on it and was waundering how much power I'm loosing with the LS1 header on it versus the D-port LS7 header.Traver
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John B,
Since my engine is still on the dolly, I checked my heads again last night and the GM 12558673 (round port Gen III) gaskets overhang into the exhaust ports on each head. In several of these (using ARP exhaust studs) it's almost .055-.060, mostly on the sides of the port. These gaskets matched up with both Pacesetter and ASM 1 3/4" headers. (I have a leftover new set of truck Pacesetters that I also checked again last)
Is there another GM gasket that I'm not familiar with? That could very well be part of my information gap (especially large for an old SBC guy).
My heads are a recent purchase (late February) from SDPC. I wonder if they've changed the CNC program for the heads? I don't know how to decipher the batch/serial number etched on the heads for date/batch run info.
Although 1 3/4" are available for my car, I bought the 1 7/8" because of the engine displacement (and a lot of experience with very large Gen I SBCs
), state of tune and there were also no penalties (fitment issues/chassis proximity) with the larger tubes.
Since my engine is still on the dolly, I checked my heads again last night and the GM 12558673 (round port Gen III) gaskets overhang into the exhaust ports on each head. In several of these (using ARP exhaust studs) it's almost .055-.060, mostly on the sides of the port. These gaskets matched up with both Pacesetter and ASM 1 3/4" headers. (I have a leftover new set of truck Pacesetters that I also checked again last)
Is there another GM gasket that I'm not familiar with? That could very well be part of my information gap (especially large for an old SBC guy).
My heads are a recent purchase (late February) from SDPC. I wonder if they've changed the CNC program for the heads? I don't know how to decipher the batch/serial number etched on the heads for date/batch run info.
Although 1 3/4" are available for my car, I bought the 1 7/8" because of the engine displacement (and a lot of experience with very large Gen I SBCs
), state of tune and there were also no penalties (fitment issues/chassis proximity) with the larger tubes. LS1 Tech Stories
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Verdad Gallardo Headers I've been looking into this header issue and like the post above says, I believe that the round port headers with the LS1 style gasket is quite a resistance on the D-Port heads of the LS7.The question is just how much?!I waunder how much power I'm leaving on the table.Also,I could be gaining some down low torque but loosing out on the top end.Anybody else have any thoughts on this? 
Traver
Traver 