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What intake manifold?


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#1 fireforeffect

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Posted 03 August 2020 - 10:15 AM

Searched and didn't find much... asking out loud. My '78 400 WS6 has an aftermarket Edelbrock Performer intake and carb (electric choke) and a hacked up drop base cleaner to accommodate the choke. From the looks of it, both have been on for some time. EGR choke stove (?) was blocked and all the emissions stuff is removed. I'd like to go back to a stock Pontiac aluminum intake (i.e., 1971 H.O. like for sale here: https://www.ebay.com...353.m1438.l9372), but I'm a bit unsure of what carb to use, or what other options are available to me. Are there aftermarket carbs I can use on the H.O. intake, or am I better going w/ a rebuilt Quadrajet w/ electric choke conversion? Or throttle-body EFI? Aftermarket carb w/ a spread-bore adapter? Biggest consideration is I want to keep the shaker and I don't want to affix it to the hood just to keep it. What are my options? I'm not looking to race, but I'd like to optimize available HP and torque I know stock Pontiac parts provide over aftermarket. And where the car was a factory 4spd someone replaced at some point w/ a TH400 AT, just picked up a Super T-10 out of a '79 T/A in good condition. All opinions/insights/advice appreciated... and tracking I'll need to block the exhaust ports the factory cross-over would attach to since it's likely not needed w/ the electric choke or EFI. 


Edited by fireforeffect, 03 August 2020 - 10:20 AM.


#2 Alaskanmutt

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Posted 03 August 2020 - 10:34 AM

Or buy the same part from the same people for 30 less...

https://www.theparts...o-lemans-tempest-h-o-aluminum-intake-manifold-casting-483674/33156

 

How good is it? It is a reproduction


You know you are old when you have to sdcroll to find your birth year.....


#3 fireforeffect

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Posted 04 August 2020 - 03:56 AM

Or buy the same part from the same people for 30 less...

https://www.theparts...o-lemans-tempest-h-o-aluminum-intake-manifold-casting-483674/33156

 

How good is it? It is a reproduction

It's not any cheaper, they charge shipping. 

 

No idea, it's a OER piece. Assume it's manufactured to same standards as original, they depend on their reputation unlike the cheap Chinese ones found on eBay that don't even line up. 



#4 js292

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Posted 04 August 2020 - 10:20 AM

That HO intake isn't going to work unless you fill you heat cross-over ports int he heads.

 

Your performer intake performance wise is on par with the factory intake so your not going to see any improvement there. Nothing wrong with a properly tuned Q-jet, but Holley also makes a 650 spread bore carb that would be a direct bolt on. If you use a spread bore adapter you'll most likely run into fitment issues with your shaker.


Edited by js292, 04 August 2020 - 10:25 AM.

455 Olds, MSD dizzy & 6AL, Edelbrock Performer, Demon 850, Ceramic coated Dougs headers, TH400, 2200 stall, 3:42 10 bolt, Boyd Coddington Rims w/ Nitto 555's


#5 fireforeffect

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Posted 05 August 2020 - 05:02 AM

That HO intake isn't going to work unless you fill you heat cross-over ports int he heads.

 

Your performer intake performance wise is on par with the factory intake so your not going to see any improvement there. Nothing wrong with a properly tuned Q-jet, but Holley also makes a 650 spread bore carb that would be a direct bolt on. If you use a spread bore adapter you'll most likely run into fitment issues with your shaker.

All good info, thx. 

 

If I understand what you said, the HO intake can be run if I block off the exhaust cross-over ports at the head (w/ fabbed plates)? My want is to be absolutely sure, it's what I understood from looking at the whole setup. What else is the cross-over doing for the intake as a system other than providing heat for the choke stove? Tracking the Edelbrock is on par, but I'm just not keen on it and want to go back to a factory intake. The aluminum HO intakes seem the best choice due to weight and factory performance (and looks, hate admitting that) w/ my want to go to Ram Air exhaust manifolds... the only performance gain the long headers that came on the car when I bought it last year provide is rust. I'm not looking for a tire burner, but to be as efficient and strong as can be w/ a mostly stock motor. 


Edited by fireforeffect, 05 August 2020 - 05:12 AM.


#6 js292

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Posted 05 August 2020 - 10:27 AM

All good info, thx. 

 

If I understand what you said, the HO intake can be run if I block off the exhaust cross-over ports at the head (w/ fabbed plates)? My want is to be absolutely sure, it's what I understood from looking at the whole setup. What else is the cross-over doing for the intake as a system other than providing heat for the choke stove? 

You'll have to fab up a block off plates or fill the head heat ports with aluminum. The heat cross-over also helps warm the intake charge in colder climates, I live in the devils armpit in south Texas so I have no need for it. If I remember right the 71 H.O. heads have a taller intake port than standard heads so you'll have a mis-match in ports between the head and intake., but most have a bit of mis-match unless they have been ported to match anyway.

 

If it's just the edelbrock badge you don't like, grind it off and then blast the whole manifold with a aggressive media to give it a cast look.


  • fireforeffect likes this

455 Olds, MSD dizzy & 6AL, Edelbrock Performer, Demon 850, Ceramic coated Dougs headers, TH400, 2200 stall, 3:42 10 bolt, Boyd Coddington Rims w/ Nitto 555's


#7 fireforeffect

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Posted 06 August 2020 - 03:57 AM

The heat cross-over also helps warm the intake charge in colder climates, I live in the devils armpit in south Texas so I have no need for it.

Nailed it, thx. We're in MD right now w/ cold winters and on drier days I'll go out. This seals it for me (no pun intended). 






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