1984 Intake Manifold Options
Thread Starter
Heel & Toe
Joined: Feb 2025
Posts: 15
Likes: 2
1984 Intake Manifold Options
I am new to the C4 community. I am wanting to swap out the crossfire system. I have read that the original intake didn't breath well not allowing the two tbi's to perform at optimum level. I have read that Renegade produced an option that worked well if you could find one machined right, but finding one is not easy. I have thought about porting as an option, but wondered if there was a dual intake manifold option that would work and would allow me to keep using the stock tbi. I've seen some dual manifolds by Edelbrock. I was thinking I could find an adaptor plate to make it work. I've thought about carb swapping, but if i could fine a manifold that would keep it mostly stock and ecu & ignition stock it would lessen any issues. Any help would be greatly appreciated.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
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From: New Jersey
You could potentially make something like an offenhauser cross ram work if you fabricate a custom top plate... but the results probably wouldn't be great. For ease of swap, using a ported stock intake would be the best bet. You could convert to a later TBI intake and use a standard 2 bbl tbi on the system too as that would mostly be bolt and go. Not sure on the hood clearance with either option...
Thread Starter
Heel & Toe
Joined: Feb 2025
Posts: 15
Likes: 2
You could potentially make something like an offenhauser cross ram work if you fabricate a custom top plate... but the results probably wouldn't be great. For ease of swap, using a ported stock intake would be the best bet. You could convert to a later TBI intake and use a standard 2 bbl tbi on the system too as that would mostly be bolt and go. Not sure on the hood clearance with either option...
I agree. I've seen a lot of mixed reviews for the Offy. Do you have a later TBI intake that you recommend i look at. I also found a 3 bolt TBI to 4 BBL adaptor that would work with Holley or Eddlebrock. This is one I've found. https://www.ebay.com/itm/304983739299 Here is one intake that I saw that was dual. I know I would still have to address linkage issues. Do you think with this plate it opens other options. Hood clearance I'm not too worried about. Body work is not a problem. Im mainly thinking about trying to keep the other pieces stock to lessen the troubleshooting. If I did get it this one ported. Is there a recommendation for this process if I take it in?
I've seen a lot of people go either way for the results.
Melting Slicks
Joined: May 2002
Posts: 2,263
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From: Muskogee OK
Cruise-In VI Veteran
If you aren't going the offy x ram route, you'd be performance and trou troubleshooting ahead by throwing the vortec heads and intake on it for the 7.4 dual TBI pod
Burning Brakes
Joined: Sep 2017
Posts: 941
Likes: 169
I am new to the C4 community. I am wanting to swap out the crossfire system. I have read that the original intake didn't breath well not allowing the two tbi's to perform at optimum level. I have read that Renegade produced an option that worked well if you could find one machined right, but finding one is not easy. I have thought about porting as an option, but wondered if there was a dual intake manifold option that would work and would allow me to keep using the stock tbi. I've seen some dual manifolds by Edelbrock. I was thinking I could find an adaptor plate to make it work. I've thought about carb swapping, but if i could fine a manifold that would keep it mostly stock and ecu & ignition stock it would lessen any issues. Any help would be greatly appreciated.
Thread Starter
Heel & Toe
Joined: Feb 2025
Posts: 15
Likes: 2
did you reused the stock TBI? Going from 2 to 1 TBI seems like it wouldn’t work well with stock but I know the stock could handle more than original intake. How was the performance following your swap?
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Thread Starter
Heel & Toe
Joined: Feb 2025
Posts: 15
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how easy is it to swap heads and intake? Have you done this? What year did you pull this off of and what other specific adjustments have to be made to make this work? Did this have any effect on ignition, ecu, torque converter?
Pro
Joined: Mar 2024
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From: Northern California
Burning Brakes
Joined: Sep 2017
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what I'm saying is the exhaust is also bad. headers are pinched at collector. 1.5" header tubing should flow 160cfm, but the tube is choked down to a small cross section that at best flows 114cfm. stock heads with stock cam flow 135cfm.
stock manifold flows 140-155cfm. stock head with stock cam flows 180cfm. mildly ported stock manifold can flow 190cfm.
this picture of intake opening at head shows how much smaller port opening is compared to head port opening. that thickness only goes for .75".
the intake port is that small size the entire length of the runner and wall thicknesses are about .25".
stock manifold flows 140-155cfm. stock head with stock cam flows 180cfm. mildly ported stock manifold can flow 190cfm.
this picture of intake opening at head shows how much smaller port opening is compared to head port opening. that thickness only goes for .75".
the intake port is that small size the entire length of the runner and wall thicknesses are about .25".
Melting Slicks
Joined: Dec 2009
Posts: 2,237
Likes: 286
Melting Slicks
Joined: Dec 2009
Posts: 2,237
Likes: 286