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| Mac Winter 76XB351GS |
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Gday,
Im planning to add a set of em185 Pavtek heads, Pavtek 3V intake, hyd lifters, roller rockers, custom Crow cam (size?), and most likely a 750 carb to my 351 clevo. At the moment I have extractors going into a twin 2inch system which has a nice note but is very tame. Im after a nice lumpy sound and bark but not deafening. Gotta keep transport at happy. I have been quoted $490 for a twin 2.5" xtractor back system with one str8thru muffler either side. Is 2.5 going to be too big and loose too much backpressure? Would I be better going with 2.25? Thanx.
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| XR9UTE |
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With that combo a 2 1/2" twin would be the minimum.
Dummy fit your headers first because they are likely to need modification on a Pre-XE Falcon which has a very small gearbox crossmember as opposed to your double hump type. In fact you may find a modified or custom crossmember is in order for your XB..rather than modify the headers? I used 4V 1 3/4" 4 into 1 Pacemakers on my XE with no clearance problems purely because of what I've mentioned. Cheers, Pete. |
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| Warlock |
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i run twin 2 1/2 inch exhaust goes well but its a bit loud tested at 112db lol
_________________ WINNER: |
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| Mac Winter 76XB351GS |
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Ok cool, theres no trouble with headers as Ive already got them on there, just upgrading the piping. Twin 2.5 it is then!
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| ltd351T |
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the 3V's will move the pipes up .400, you may need to bend them down.
If using on street alot, but still wanting good flow, I'd run twin 2 1/2 from extractors into twin 3" hooker aerochamber mufflers and then twin 3" over the diff, it will flow plenty, but still retain ground clearance and better street manners than twin 3's will. The twin 3 may make more peak tho. Hooker aerochambers are only 110$ each and are a non-packed muffler so they don't rot. |
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| XR9UTE |
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{USERNAME} wrote: the 3V's will move the pipes up .400, you may need to bend them down.
If using on street alot, but still wanting good flow, I'd run twin 2 1/2 from extractors into twin 3" hooker aerochamber mufflers and then twin 3" over the diff, it will flow plenty, but still retain ground clearance and better street manners than twin 3's will. The twin 3 may make more peak tho. Hooker aerochambers are only 110$ each and are a non-packed muffler so they don't rot. What he said. But then I also already said that... BTW I was running the 2 1/2" twin with no tailpipes but got threatened by the pork with a yellow. He said some s**t about it being legal on utes that were NOT based on passenger cars...I humoured him and got away without the yellow. Anyway I made some tailpipes now and it's wayyy quieter. Can't notice a drop off in power but then it's only got a mild 51w now. Are you running the 185's ltd351T? Cheers, Pete. |
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| Mac Winter 76XB351GS |
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I kinda forgot about this thread.... Because the exhaust ports are .400" higher will the extractors I have now still bolt up or will they bolt up but not line up with the current exhaust system? If so what do I need to bend?
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| XR9UTE |
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You need to buy 4V type headers not 2V ones because the exhaust ports get covered up by the header flange with 2V type headers. Rather than bend the headers I would modify your gearbox crossmember or fab a new one to suit.
Pete. |
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| Mac Winter 76XB351GS |
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Ah ok....would it be possible to take metal off the header flange so they dont cover up the ports?
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| XR9UTE |
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Nope....you'll hit air.
Pete. |
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| master_jawa |
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Hey dude,
I finally checked out those Pavtek systems you've been telling me about for months and they seem alright, but I'll look into them a bit more. It's a pity they're bare heads. Anyways I've decided against getting this ESP and have decided to just spend all my cash on the coupe. Cya round dude. Oh, and come n see what I can do about some prices on your exhaust system. |
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| brenx |
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You can use the 2V extractors on the 185's. I run 2V ones on the 218's
 It's far easier to just ve 4V extractors though. Some with 1 7/8" primaries.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| Mac Winter 76XB351GS |
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Ah thats ok then, atleast I'll be able to get her all together at home then drive it down with the 2V headers on to get a set of new 4V headers fitted. Now Iv just gotta save for all the goodies.....
Has anyone had any issues fitting the Pavtek 185 heads or is it a direct replacement job? Id like to be able to just bolt everything together and not have to stress about making everything fit.
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| brenx |
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You shouldn't have any issues as CHI has changed the exhaust face to prevent issues. Fortunately I live around 1.5 hours from CHI and have spent quite a lot of time in the CHI factory. I'd dare say around 3mths in 2005. Don't plan to spend that much time there this year but we'll see.
_________________ XB Fairmont sedan 11.07@123.02mph |
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