Author Topic: Big Block Cross-Ram intake  (Read 3091 times)

crossboss

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Big Block Cross-Ram intake
« on: December 12, 2018, 04:57:48 PM »
Boys,
Hope I'm not repeating an old topic...Did Chevy (or aftermarket) make a Big Block Cross-Ram intake?
Just another T/A fanatic. A new project in the works.

camaroboy68ss

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Re: Big Block Cross-Ram intake
« Reply #1 on: December 12, 2018, 06:37:54 PM »
The aftermarket made them, I know that edelbrock had had the side by side cross ram. Though i dont think any aftermarket company made a GM style cross ram for a big block. Then to my knowledge Chevy never did it. As NASCAR had banned multi carb set ups in the late 50's/early 60's and then with the big AMA ban of 63 there wasn't a need for a cross ram setup for a big block as Chevy at that point was not "actively" in racing.
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bcmiller

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Re: Big Block Cross-Ram intake
« Reply #2 on: December 13, 2018, 06:23:49 PM »
No cross rams for big blocks that I am aware of, but tunnel rams - of course.

Look back at old drag racing photos with big blocks. Inline - not offset - carbs were the thing. Find some old photos of Grumpy or Dick Harrell.

Cross rams look impressive visually but can be hard to tune and generally are not street friendly. Yes I know there are guys that run them. It’s been proven on the dyno that with a little 302, a single 800 cfm or larger carb will perform as good or better than a cross ram setup.

My experience with multiple carb setups has mostly been on the old W motor Chevy 409s and Fords with over 460 cubic inches. And the Fords were in jet boats, not cars.
« Last Edit: December 13, 2018, 11:54:00 PM by bcmiller »
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
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crossboss

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Re: Big Block Cross-Ram intake
« Reply #3 on: December 13, 2018, 09:12:55 PM »
Thanks boys for the info. My plan was to build a Big Block with a Cross-Ram for a potential T/A type of car. And yes, I am very familiar with tuning a Cross-Ram intake, as I used to own a T/A Boss 302 with the 'Cross-Boss' intake and Autolite Inline carb for street and vintage racing. Anyways, maybe a Weber set up on the Big Block might be a better way to go?
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maroman

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Re: Big Block Cross-Ram intake
« Reply #4 on: December 13, 2018, 10:02:53 PM »
It would look better too.
Doug  '67 RS/SS 396 auto I know the car since new

crossboss

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Re: Big Block Cross-Ram intake
« Reply #5 on: December 13, 2018, 10:23:57 PM »
Yep, can't argue with that statement. Webers DO look cool on anything!
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PHAT69AMX

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Re: Big Block Cross-Ram intake
« Reply #6 on: December 13, 2018, 11:38:35 PM »
A retired GM Engineer that was directly involved in the mid to late 60's tells me
the original "intent" was to see how much if any HorsePower some of the then available
aftermarket "CrossRam" Intake(s) for Big Block Chevy would make...
They started with one that had 2 Individual plenums and it did NOT work well due to pulses...
So in doing development at GM by a GM Engineer on a Chevrolet Big Block with a Crossram
it was found the larger the common plenum area the better, ending up with a large single plenum
but with the horizontal tuned length individual runners on the floor of the plenum...
Having tuned length intake runners was key for power... and
a single large common plenum to "manage" the pulses without disturbing carburetor fuel air distribution.
-BUT- no "desired" application was identified for use on the Big Block Chevy...
Can Am "went" all Injection to achieve tuned runner length and required no plenum, not carburetion...
So... the "learnings" and "development" done by GM Engineering on the Big Block Chevy
for an under-hood tuned length runner common plenum carburetion Intake manifold was "re-applied"
for the Small Block 302 Camaro Z-28 Trans Am Racing CrossRam, where there was an "application".
There may have been aftermarket Big Block Chevrolet CrossRam Intakes produced,
but in testing done by GM Engineering none were found to be actual "functional" power producers...

crossboss

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Re: Big Block Cross-Ram intake
« Reply #7 on: December 14, 2018, 12:15:52 AM »
A retired GM Engineer that was directly involved in the mid to late 60's tells me
the original "intent" was to see how much if any HorsePower some of the then available
aftermarket "CrossRam" Intake(s) for Big Block Chevy would make...
They started with one that had 2 Individual plenums and it did NOT work well due to pulses...
So in doing development at GM by a GM Engineer on a Chevrolet Big Block with a Crossram
it was found the larger the common plenum area the better, ending up with a large single plenum
but with the horizontal tuned length individual runners on the floor of the plenum...
Having tuned length intake runners was key for power... and
a single large common plenum to "manage" the pulses without disturbing carburetor fuel air distribution.
-BUT- no "desired" application was identified for use on the Big Block Chevy...
Can Am "went" all Injection to achieve tuned runner length and required no plenum, not carburetion...
So... the "learnings" and "development" done by GM Engineering on the Big Block Chevy
for an under-hood tuned length runner common plenum carburetion Intake manifold was "re-applied"
for the Small Block 302 Camaro Z-28 Trans Am Racing CrossRam, where there was an "application".
There may have been aftermarket Big Block Chevrolet CrossRam Intakes produced,
but in testing done by GM Engineering none were found to be actual "functional" power producers...



Mopar had excellent results with their Cross Ram manifolds, as did Ford. That said, When I ran the Cross-Boss intake and Inline carb with the large port heads on a little Boss 302 along with the factory experimental T/A camshaft, low end torque is well... as you can image, non existent. Idle quality will need to be high to maintain some velocity with that big plenum, long runners, and huge ports. I also did some internal 'modifications' on the plenum by removing the bumps and sharp edges to help maintain port to port consistency, and from fuel puddling. Also, off idle pump shot will need to be at its max to avoid any lean/bogs. Lastly, it was defiantly a learning curve no doubt. Some tuning was a hit or miss, and eventually I found the sweet spot and it worked well.
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PHAT69AMX

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Re: Big Block Cross-Ram intake
« Reply #8 on: December 14, 2018, 01:01:45 AM »
Agree, they can make power, but understanding is ( not that I "know" ) that a large single common plenum
it what it takes to make a CrossRam "work" as the 426 Hemi, and others had.
Having to fit beneath a closed stock hood was a "design driving limitation" imposed by sanctioning rules.
Unaware of if there was a large single common plenum CrossRam produced for the Big Block Chevy.
It is my hope to avoid sounding as if "I know"...  Simply an enthusiast intrigued by and interesting question.
Was just sharing what information had came up during a discussion with a retired Engineer.

bcmiller

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Re: Big Block Cross-Ram intake
« Reply #9 on: December 14, 2018, 01:42:41 AM »
Trust me, if it was possible to make a big block effectively generate good power with a cross ram - it would have already been done.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

crossboss

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Re: Big Block Cross-Ram intake
« Reply #10 on: December 14, 2018, 03:31:10 PM »
Agree, they can make power, but understanding is ( not that I "know" ) that a large single common plenum
it what it takes to make a CrossRam "work" as the 426 Hemi, and others had.
Having to fit beneath a closed stock hood was a "design driving limitation" imposed by sanctioning rules.
Unaware of if there was a large single common plenum CrossRam produced for the Big Block Chevy.
It is my hope to avoid sounding as if "I know"...  Simply an enthusiast intrigued by and interesting question.
Was just sharing what information had came up during a discussion with a retired Engineer.



Absolutely correct. The 'under the hood' limitations were the issues with Cross Ram intakes. Air and fuel does not like to travel sideways to the intake port. I appreciate everyones input! Never the less, too bad there were never really any good Big Block Chevy Ram-Box type of intakes….that would have been a neat set up on an L-88 road racer!
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crossboss

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Re: Big Block Cross-Ram intake
« Reply #11 on: December 20, 2018, 03:30:18 PM »
Boys,
Apparently, the only one I could find was the older Edelbrock X-C96 Cross-Ram for a Big Block.
Click on pics to enlarge.

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crossboss

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Re: Big Block Cross-Ram intake
« Reply #12 on: December 20, 2018, 03:31:06 PM »
Bottom view.
Click on pic to enlarge.

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Kelley W King

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Re: Big Block Cross-Ram intake
« Reply #13 on: December 20, 2018, 04:09:37 PM »
In my opinion it would take a lot of velocity to make that intake work.
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crossboss

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Re: Big Block Cross-Ram intake
« Reply #14 on: December 20, 2018, 07:59:35 PM »
In my opinion it would take a lot of velocity to make that intake work.




You are correct. Re-read my experience with the 'Cross-Boss' intake. To achieve some velocity, a high idle is required.
Just another T/A fanatic. A new project in the works.

 

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