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Tunnel Ram

June 3 2012 at 2:01 PM
  (Login GordMAC)
Member
from IP address 66.186.85.231

Hi guys, I have a chance to pick up a Weiand tunnel ram with a pair of 400 holleys. Is this setup streetable or best used at the strip only. I am running a SVO hydraulic cam, closed chamber heads, I think about 10.5 to 1, 4 speed toploader and 3.73 rear end, Hooker super competion 1 7/8 into 3 1/2 collectors. Mufflers are 3" in and out. The car is not on the road yet, I been moving it around the shop with a 650 edelbrock on an edelbrock 351-4v intake. I love the look of the two fours but don't want to build a dog!

Thanks for the advice!

 
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AuthorReply

James K
(Login 351CRanger)
Member
76.230.66.226

Re: Tunnel Ram

June 4 2012, 8:14 PM 

[linked image]

I'm one of those who used to run a TR on the street and wondered what all the fuss was about. Tuned right, or as right as I could get it, it certainly didn't lack for anything. One of those gigantor UR19 types might lose lotsa torque down low, but my old Offy (and especially the Weiand) did everything better than the typical high rise single plane. If you look around, you might find some magazine articles that show reasonably sized TRs outperforming everything else on the dyno, all around, including useable torque. Where they failed was in efficient use of space. wink.gif The 1992 iteration of my faithful ole Boss 302 certainly had a lot better street manners with the TR, getting something like 18 more ft. lbs. of max torque at almost 500 less RPM (more useable torque all around the tach), and the top-end power was gratifying, to say the least.
Tuned well, I believe you would be quite happy with a Weiand Tunnel-Ram. Maybe I had dumb luck, so YMMV.

A Visigoth explains the sack of Rome: We wanted art, literature...culture! We're sorry we broke some stuff.

 
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(Login tony-can-do)
Member
23.17.112.47

Re: Tunnel Ram

June 4 2012, 9:48 PM 

Same for me,bolted one on with a couple of vacuume linked 600 holleys and just drove.the car,mine is a 4speed car and maybe the might be an advantage but I as well wondered what all the nay Sayers fuss was all about..now trying to get 660's to work for me ont the street that was a pain so I wouldn't recommend that but be sensible on your carb choice and enjoy..

 
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(Login Falcon67)
Member
209.165.224.67

Carbs

June 5 2012, 8:35 AM 

Note that the Holley 390s are vacuum secondary and more forgiving. The Holley 450 list 9776 is a mechanical secondary carb with no back shooters. The 390s would be easier IMHO to tune on the street. If I was going for hot street/strip I'd use a pair of real 650DPs and skip right over the 450s. The other thing I'd watch for is idle circuit tuning - you'll have two idle circuits, both engineered to be the only idle circuit on the motor. I'd recommend a wide band tuning tool to help dial it in if you're serious.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

 
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Mike
(Login 70vert)
Member
63.235.95.162

Theory on TR

June 5 2012, 12:02 PM 

In theory a tunnel ram should improve torque down low, everything else being equal. If you'll notice modern EFI intakes usually have runners closer to a tunnel ram length than that of a low profile single 4 style intake. The longer intake runners get momentum working for you at certain rpm to help fill the cylinders(the longer the length the lower the ideal rpm).

 
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Wayne
(Login fortfun)
Member
67.162.151.23

TR theory

June 5 2012, 3:25 PM 

The reason that TRs are bad down low (and they really are!) is the fuel atomization and especially distributon. All the dyno sheets that show how great they are start at 3000RPM. Which is fine if you have very deep gears (and high stall for an auto), and don't mind shifting a lot to keep the revs up. If you want to be able to lug it down just to cruise around, it doesn't do well.

I am working on some stuff to help out this problem. The fuel distribution is a screwed up mess with any normal TR. You can make it run kind of OK by putting more fuel and timing into it to compensate for the lean cylinders at part throttle, but it drinks gas like crazy and doesn't make good torque until you get it wound up.

 
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(Login Falcon67)
Member
209.165.224.67

I'm considering

June 5 2012, 4:09 PM 

stuffing the ports in mine with some light aluminum tube and using Splash Compound to epoxy the ends at the plenum and head. The regular 4V port will have a lot of volume between the valve and carb. Might not be a big deal with the right attention to detail, but I can see using some sizeable pump shot for running down to the Dairy Queen.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

 
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(Login tony-can-do)
Member
23.17.112.47

Re: I'm considering

June 5 2012, 4:19 PM 

Um yea maybe just try it as is first,I do like your thoughts on the 650 dp and plan to give them a try on mine.

 
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(Login Falcon67)
Member
209.165.224.67

650DPs / Grumpy's notes

June 6 2012, 8:59 AM 

If you look over the Holley spec sheets, you'll note that a 650DP has a smaller venturi than a 600. So I'm thinking the 560DP would provide a little easier tuning and create a smaller signal.

I was glancing at Grumps book "The Chevrolet Racing Engine" last night. Bill sez that his favorite carb for the Pro Stock engine of that time - 330 CID to 350ish - on their heavily reworked Ed TR-1 rams was the List 4224 660 center squirter. He said that the larger carb and dommy made a bit more power on the dyno, but the car was quicker on the track with 660s. He also used "reversion plates" under the carbs to reduce the plenum area seen from the carb flage. Plenum volume was a big tuning tool for him too. His discussion was emphatic that you can only do so much on the dyno and the rest, such as "driveability" had to be sorted at the track. Big power on the dyno did not translate into big ETs without additional work.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

 
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Dan Jones
(Login 74Pantera)
Member
130.76.96.151

Re: Theory on TR

June 6 2012, 12:20 PM 

> the longer the length the lower the ideal rpm

It's more complicated than long runner tunes at low RPM and short runner at
high RPM. Waves travel the length of the intake tract. The frequency of
these waves are a function of the runner length and cross-sectional area.
Note that these waves move within the intake (and exhaust) flow. Depending
upon their direction, they can either aid or hinder flow motion. One
characteristic of a finite amplitude wave is that when it hits an abrupt
area change (such as a runner opening into the plenum in an intake manifold
or a primary pipe ending in a header collector), it will change direction.
So an expansion wave moving up the intake tract will change direction when
it comes to the plenum opening and turn into a compression wave heading
towards the intake valve. By timing (via the valve opening events, intake
runner length and cross-sectional area, header lengths and diameters), the
waves can aid cylinder filling on the intake side and cylinder evacuation
on the exhaust side. The waves tune to harmonic lengths. If the intake
tunes at 4", it will also tune (to a different harmonic) at 8" and 16".
That's what allowed the Pro Stock guy to turn 9500 RPM with a long runner
tunnel ram. They tune to a different harmonic than a street guy with
peak torque at 4000 RPM. Note that each successive harmonic is a weaker
effect than the previous. It's quite possible for a short runner intake
to tune to a lower RPM than a longer one when it tunes to a different harmonic
and is a better match (wave timing) to the rest of the system. The same goes
for the exhaust side. The Pipemax software recognizes this and outputs ideal
header and exhaust lengths as a function of multiple harmonics based upon a
model of the engine. Also note that intake tract tuning applies to WOT.
Closing a butterfly in the intake tract kills the effect.

> A spider type single carburetor single plane manifold will only have as much
> low end torque as the 4 shortest runners allow.

On the dyno, we sometimes see two distinct humps in the torque curve.
It might be the case that one hump corresponds to short runners and
the other corresponds to long runners. The effect is to widen the
curve but knock down the peak. We don't always see that, though.
It's theoretically possible for both the short and long runners to
go into resonance at the exact same RPM but on a different harmonic.
In that case, you'd only see one hump. Of course, it's also possible
that one hump might be driven by the intake tuning and the other by
the exhaust. I hope to learn more when we test IR stack heights.

> If the "400 Holleys" you're referring to are the small Holleys designed for use with tunels rams

I'm not awre of 400 CFM Holleys. I've seen both 390 and 450 CFM
Holleys and there were 400 CFM Carter AFBs that were popular on
small displacement engines with dual quad intakes. I've got a pair
of Carter 400's on a Buick 215 dual quad intake.

I wonder if annular booster carbs with their higher gain boosters
would be a good match on a street tunnel ram.

Dan Jones

 
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(Login gpence)
A1
75.22.50.99

regarding the carbs

June 6 2012, 2:53 PM 

yeah I know there are no 400 Holley carbs.

Decades ago Holley manufactured a small carb specifically for street tunnel rams, it had a special linkage on the secondaries that allowed them to open quickly when they first began opening in order to catch up with the primaries, then once the secondaries caught up the linkage slowed their opening rate down to the rate of the primaries so all 4 butterflies opened at the same rate.

The problem is, I'm having a senior moment, and I can't remember the list number or which size they were, the 390s or 450s or 480s. That's why I referred to them the way I did. But I didn't refer to them as 400s, I referred to them as smaller Holleys. My point is, if the tunnel ram manifold comes with those particular small Holleys, the ones designed for street tunnel rams, that would be a good set-up for the OPs application.

My point was not to create an opportunity for you to correct me, as you have a tendency to do far too often. Internet forum ettiquette is to address the OP's question, not critique other member's replies. Correct?



-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

The Substitute for Cubic Inches is Large Valve Area, Low Friction, a Wide Powerband, and the Right Amount of Crank Arm Leverage!

 
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(Login 74Pantera)
Member
130.76.96.151

Re: regarding the carbs

June 6 2012, 5:03 PM 

> My point was not to create an opportunity for you to correct me, as you have a
> tendency to do far too often.

It wasn't my intention to correct you. I simply noted I'd never heard of a
400 Holley. Whatever else you read into it, was not my intention.

> Internet forum ettiquette is to address the OP's question, not critique other
> member's replies. Correct?

I must have been absent that day.

Dan Jones

 
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(Login gpence)
A1
134.201.253.22

Re: Tunnel Ram

June 5 2012, 6:05 PM 

A spider type single carburetor single plane manifold will only have as much low end torque as the 4 shortest runners allow. With a tunnnel ram you have 8 long - equal length - runners. Its a far better design actually, better torque; the only draw back was their height. Tunnel Ram fuel distribution is controlled by positioning one carb venturi directly over the inlet for each cylinder. In contrast a spider type single carburetor single plane manifold shares a venturi with each pair of corner runners. In either situation, during light throttle operation (when the secondaries are shut) the fuel distribution design is not working optimally, 4 cylinders have to borrow fuel and air from the other 4 cylinders. In other words, the part throttle performance of a tunnel ram is no worse than the part throttle performance of a Torker, Strip Dominator, Funnel Web, etc.

If the "400 Holleys" you're referring to are the small Holleys designed for use with tunels rams, go for it. The small carbs seem to help the part throttle fuel distribution situation. I knew some guys running those set ups, and the tunnel ram was quite streetable with those carbs. As with any Holley from my era, they needed tuning to work well. But once tuned the tunnel rams tooled around town just fine, and kicked arse when you put your foot into it. The 351C 4V heads were designed for large volume long runner manifolds, they perform really well with the tunnel ram.

-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

The Substitute for Cubic Inches is Large Valve Area, Low Friction, a Wide Powerband, and the Right Amount of Crank Arm Leverage!

 
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Steve .k
(Login steve.k)
Member
96.30.200.35

Thats why!

June 5 2012, 6:17 PM 

I think the glidden split dominators cure this problem! While giving a straight shot into intake runner. Expensive option though.

 
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(Login GordMAC)
Member
74.198.87.95

More research to be done

June 13 2012, 1:45 PM 

Thanks for all the input! The current owner is to get me the numbers off the carbs so I can try to identify exactly what they are. I hope they are designed for the TR, that would look pretty horny sticking through the hood of my 61 Falcon!

 
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John
(Login 1964sprint)
Member
71.235.28.99

Holley 390s?

June 13 2012, 2:18 PM 

How about a set of Holley 4160 390cfm carbs on the set-up? I had a spare Boss 302 with a Weiand two-top tunnel ram, single and two four-barrels, and like a D...A.. I sold it all. Run it, it will look great!

 
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mark
(Login ultimatecleveland)
Member
99.181.121.235

tunnel ram

June 13 2012, 5:44 PM 

Someone around here had a stock headed sbc with tunnel ram that ran low 11's with two 500 2barrels.    Sorry chebby story.          

 
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(Login GordMAC)
Member
66.185.192.194

Re: Tunnel Ram

June 22 2012, 7:35 AM 

Hi guys, here is a couple of pics of what I am looking at. I haven't been able to get much info from these numbers. Looks like they are 450cfm but I don't know. Can anyone help me out with what these carbs specs are??

Thanks!

[linked image] [linked image]

 
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(Login Falcon67)
Member
209.165.224.67

List 9776

June 22 2012, 1:11 PM 

Just google it - 450 CFM 4160 style carb, no choke

http://www.jegs.com/i/Holley/510/0-9776/10002/-1

Date code says 3359 - December 19x9 (could be 7, 8, or 9)

Then go here for stock factory specs, see pages pages 13 and 14 for List 9776
http://www.holley.com/data/TechService/Technical/Carb%20Numerical%20Listing.pdf



1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

 
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Gord
(Login GordMAC)
Member
66.185.192.194

Re: List 9776

June 23 2012, 12:09 PM 

OK, thanks everyone, looks like the carbs are 450 cfm, 1999 vintage (according to the seller. Single pumpers, mechanical secondaries.

I need some input as to weather this is too much for the street. 900CFM after all!

My engine is a 71 with flat top pistons (originally a 2v from a Cougar).. Heads are closed chamber 4v, cam is the Ford Motorsports M-6250-A341 cam, .510"/.536" 214/224 {292/302} 4 speed toploader feeding a 8.8 with 3:73 gears. Headers are HH Super Competition, 1 7/8" primary into 3 1/2" collectors. MBRP low restriction exhaust, 3" outlet. Have not weighed the car but it is light, 61 Falcon 2 door. Manual brakes so vacuum is not a major issue. I think my CR is arount 10.5-1.

What do you think? Am I wasting my money?

 
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tinman
(Login tinman351)
Moderators
69.246.218.44

Re: too much?

June 23 2012, 1:04 PM 

excess unused cfm capability is just that, unused

the issue becomes whether the extra venturi size causes an issue for the metering system to read the signal from the engine? if the metering system delivers a proper A/F ratio across your usable rpm range you're golden, but if the carbs can't deliver the right AFR to make power you'll have a stumbling bucket of wet cement connected to your loud pedal

the manual linkages would be nice for a manual trans car, i had vac secs with the lightest springs they would close on their own where i'd've like them to stay open all day. you'll have to learn where the sec's are in the pedal travel and learn what the car will take & when but i see that's do-able

waste of $ or not is up to you but i will say you're gonna like the 8V acceleration happy.gif



there'll be phantoms, there'll be fires on the road... and the white man dancing

 
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tinman
(Login tinman351)
Moderators
69.246.218.44

i had a pair of 1848's

June 22 2012, 12:08 PM 

465 cfm, vacuum secondary just like the universal 1850 600 cfm

there'll be phantoms, there'll be fires on the road... and the white man dancing

 
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Gord
(Login GordMAC)
Member
66.185.192.194

Is 900CFM too much??

June 24 2012, 8:05 AM 

OK, thanks everyone, looks like the carbs are 450 cfm, 1999 vintage (according to the seller. Single pumpers, mechanical secondaries.

I need some input as to weather this is too much for the street. 900CFM after all!

My engine is a 71 with flat top pistons (originally a 2v from a Cougar).. Heads are closed chamber 4v, cam is the Ford Motorsports M-6250-A341 cam, .510"/.536" 214/224 {292/302} 4 speed toploader feeding a 8.8 with 3:73 gears. Headers are HH Super Competition, 1 7/8" primary into 3 1/2" collectors. MBRP low restriction exhaust, 3" outlet. Have not weighed the car but it is light, 61 Falcon 2 door. Manual brakes so vacuum is not a major issue. I think my CR is arount 10.5-1.

What do you think? Am I wasting my money?


 
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bopper
(Login hardbopper)
Member
147.239.118.158

$

June 24 2012, 1:36 PM 

"What do you think? Am I wasting my money?"
Well, yeah, but what the hell...that ship has sailed.
It's always great when you see 2x4s on the street.
b

 
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(Login Falcon67)
Member
209.165.224.67

900CFM

June 25 2012, 8:44 AM 

IMHO - Your cam is so small it's not going to matter. You'll have plenty of cylinder pressure for torque production with 10.5:1 and that tiny cam. Maybe too much.

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

 
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Ryan
(Login boss34)
Member
172.218.208.156

450cfm holley's

June 25 2012, 6:18 PM 

If those are the ones with accelerator pump on the primary only and mechanical secondaries they are junk, you will have nothing but bogging problems. A friend of mine was borrowing my 660 center sqirters on his 418 small block dodge 4 speed, he wantetd to try some carbs without the one to one linkage so he bought a pair of 450 holley's from e-bay, we tied tuning them, differant sqirters, differant cams, staging the pumps.... after a couple of days of frustration driving it on the street and it bogging anytime you tried to accelerate quickly the 660's went back on and the 450's went back to e-bay for the next poor sole.

 
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Miller Mylan
(Login 417strokers)
Member
70.77.16.228

Same here

June 26 2012, 7:18 PM 

I have to agree with Ryan! I have had two friends try the 450 carbs and experiance abog every time the the hammer is hit. One went to a set of 600 vacume the other went 660 center squirters. When the butter flys on the back barrols are open there is no gas to go with the air.

 
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(Login tony-can-do)
Member
23.17.112.47

Re: 450cfm holley's

June 27 2012, 2:55 PM 

Someone correct me if I'm wrong but the 450's are designed for the tunnelram aimed at street use,they are pretty much the same as a Vacuume secondary carb but they tried too eliminate the problems most were having geting the secondarys too open equally or even at all so they got rid off the vacuume equation and made it a mech secondary.

I am running a set of them except in 550 cfm and zero bog but no matter what you read it's 50/50 on them, some love them and other's hate them,I would say if you are getting them at a decent price give them a try especially if it's a street car..

 

:Tony


 
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Gordo
(Login GordMAC)
Member
66.185.192.194

Price$$$

July 2 2012, 4:07 PM 

The asking price is $500, two carbs and the Weiand.

I hate wasting my money and I want to drive this car, not park it at show and shines!

 
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(Login tony-can-do)
Member
23.17.112.47

Re: Price$$$

July 2 2012, 10:11 PM 

Sounds like maybe you should stick with a single 4brl

 
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