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tunnel ram question: plenum divider

Posted By: hemienvy

tunnel ram question: plenum divider - 09/02/19 12:48 AM

Normally you have 2 carbs, a big open plenum, and 8 hungry intake ports.

What if you divided the plenum in half front to back, so the front carb feeds only 1-2-3-4, and the rear carb feeds only 5-6-7-8 ??

Big block firing order is 1-8-4-3-6-5-7-2.

Could you get away with a smaller plenum and maybe better transient throttle response ?

I can see darn well that when #1 intake valve opens, it certainly does not pull from the secondary venturies of the rear carb.
Posted By: jcc

Re: tunnel ram question: plenum divider - 09/02/19 01:21 AM

bump

I haven't a clue, but I thought the "big" plenum worked to soften the intake pulses, making it easier on the carbs metering stuff.
Posted By: 2boltmain

Re: tunnel ram question: plenum divider - 09/02/19 11:55 AM

Keep in mind when talking Weiand tunnel ram and 440 mopar the tunnel ram already performs well as is and defies logic.(logic being that a T Ram on a street engine is a slug under 4000rpm) On this forum many times its been discussed how well the Weiand T ram works from a mild 440 to an all out race only race 440. One member here ran/runs one on his 440 pickup truck and said it was great.
Posted By: Hot 340

Re: tunnel ram question: plenum divider - 09/02/19 02:51 PM

Originally Posted by hemienvy
Normally you have 2 carbs, a big open plenum, and 8 hungry intake ports.

What if you divided the plenum in half front to back, so the front carb feeds only 1-2-3-4, and the rear carb feeds only 5-6-7-8 ??

Big block firing order is 1-8-4-3-6-5-7-2.

Could you get away with a smaller plenum and maybe better transient throttle response ?

I can see darn well that when #1 intake valve opens, it certainly does not pull from the secondary venturies of the rear carb.

What are you trying to achieve? What it you are trying to fix?

A couple of rules I use for rams that has worked for me and others i know..

1. No vacuum carbs
2.no used carbs
3.go twice as big on cfm as the old hot rod mags from the 80's told you (too small equals lazy engine all rpms)
4. Dont take advice from the guy who says they dont work because he obviously cant do the job.
5. Custom carbs from a GOOD shop are a plus
Posted By: modelmakerinc

Re: tunnel ram question: plenum divider - 09/02/19 06:06 PM

On my mild 440 auto, street car I used two 1" 4 hole phenolic spacers to add signal to the carbs and used 1:1 not progressive linkage. Car ran better than with a single four both around town and on the track.

Love the Weiand TR.

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Posted By: 70HemiGTX

Re: tunnel ram question: plenum divider - 09/03/19 01:51 AM

I have had Holley 600's vac. sec., 750 vac. sec., Carter 625's (actual Max Wedge carbs), but now have a set of old Holley 660 Center squirters that have been reworked to like 690's. They are by far the best running set I have had on. More lower end response and the top end is unreal. They are on a Weiand tunnel ram that has only been port matched top to bottom and port matched to the heads. Also running just old cast iron heads.

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Posted By: polyspheric

Re: tunnel ram question: plenum divider - 09/03/19 01:24 PM

Has anyone ever seen a comparison of TR (for the same engine) by plenum volume alone?
Like tape the runner entries shut and fill it with water up to the flange?
Jenkins used a wooden stuffer on the floor of a pro stock SBC 45 years ago - the box was to big.
Posted By: 67Satty

Re: tunnel ram question: plenum divider - 09/03/19 04:24 PM

Originally Posted by 70HemiGTX
I have had Holley 600's vac. sec., 750 vac. sec., Carter 625's (actual Max Wedge carbs), but now have a set of old Holley 660 Center squirters that have been reworked to like 690's. They are by far the best running set I have had on. More lower end response and the top end is unreal. They are on a Weiand tunnel ram that has only been port matched top to bottom and port matched to the heads. Also running just old cast iron heads.


Holley was blowing out the now-discontinued 660s for about $235 brand-new from their online store not long ago. I shouldn't have listened to the nay-sayers just bought a couple when I had the chance.
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