Let's Talk Tunnel Rams (Yes again)

[Zack]

5 lbs of pressure is not a magic number either. I am running 6 float bowls on somewhere between 3 and 4 lbs., and as stated in previous posts, too much pressure is one cause of the over rich condition that you were describing.l The carbs need volume, not pressure, but not more volume than can pass through the seat under the needle.

Yes, i am hoping to get the pressure down by installing this regulator. If i can get it down to 4.5 or 5 i will be good. I just could not get it to move after backing the screw out last night. Maybe i didn't go far enough. Will try again tonight.

 

[2old2fast]

When you're adjusting fuel pressure, it can be helpful to have your engine at "fast-idle", even then, it takes a while for the pressure to stabilize.... patience... dave

 

[Zack]

When you're adjusting fuel pressure, it can be helpful to have your engine at "fast-idle", even then, it takes a while for the pressure to stabilize.... patience... dave

Gotcha, thanks Dave.

 

[HomeBrew]

Gotcha, thanks Dave.

Hey Zach, I am new to this place, but I think you are one the right track, testing and eliminating one thing at a time. I have very little experience with afb "style" carbs, but fuel pressure being too high will result in fuel running out if the boosters. Just my 2 cents worth

 

[Zack]

Thanks homebrew and to everyone else as well. She is running better than ever. I got the fuel pressure set at a steady 5lbs and tuned the carbs. The vacuum is running a consistent 15-16 at idle and jumps to 18-20 under acceleration. Right now the exhaust fumes are non existent and it idles perfectly. So, I would say an expert could probably get more out of it but she is running better than ever and i see no other problems with the tuning at this point. Thanks again to all who have offered advise and tips, especially Mike who has been working close by helping me get her tuned.

 

[2old2fast]

Zack, glad you got it sorted out! Care to share w/ the masses what all you did to make things better??

dave

 

[Zack]

Basically just set the F/P at 5lbs. Ran thru the Edelbrock procedure for adjusting the A/F mixture screws, dropped in some fresh plugs, got the vacuum to a consistent 15-16 and left her there. Everything runs great now. I hope to get a video posted this weekend. I plan on getting it out for some drive time tomorrow if the weather holds out.

 

[Zack]

Ben, Got the progressive linkage. However, the rods are too short and would have to have new rods made to reach each carb. Carbs on my TR are further apart than carbs on a low profile quad setup. I guess new rods could be made but that would require a machine shop service and that means more money, LOL. Guess i will stay with my direct linkage as it is working really good at the moment. Thanks for sending it anyway, can't say we didn't try.

 

[RPM]

Hook your vac gauge up, and tweak the timing just a little. See if you can get the vac up another inch or two. Might run even better.

 

[Zack]

Ok, Ron. I will try it. Thanks

 

[Nevadavic]

I’m running a vintage Edelbrock TR1X tunnel ram with two Edelbrock 600 carbs on top. The car was running waaay to rich when I got it; some black smoke. I didn’t want to buy smaller carbs sooo…. after some research on several sites, I decided to take Ted Brown’s sage advice;
Quote from Ted Brown - Oct 30,2010 “…..block off one of the carbs with a plate under it, block the fuel line also, take the bottom butterflies out, now everything can look like it works but no problems anymore, One 4 barrel is plenty... ” Thanks Ted!

I put a plate under the rear carb and blocked the fuel line and just bolted the carburetor on top. Once the intake warms up after several minutes, the car runs good now. It stumbles a little if I mash the pedal but the tunnel ram is worth the “Cool factor.” No more smoke…. One 4 barrel IS plenty!

The engine is a 327 with double hump heads, a mild cam and electronic ignition. Fuel pressure is 5 PSI.

I’m a “cruiser” and the setup suits my style of driving just fine now.

 

[sstock]

I wanted the tunnel ram appearance too, but didn't want to fuss with setting up two carbs, so I went with a Weiand single quad tunnel ram manifold with a Holley 570cfm avenger carb. Im running a bored 283 so even at that it is plenty of carb.

Even though that carb is set up pretty good out of the box, I noticed that it needed more pump shot as soon as I got some warmth in the engine. I pl;an on putting a 14mm bung in the collector and hooking my wideband to it to help get this tuned in. I've seen so many carb setups be from one extreme at an idle to the other at wot. To be perfect- idle, accelerator pump and main metering and finally power valve need to be tuned to get the best economy power and drivability.

 

[Screaming Metal]

As far as I'm concerned, thats the best way to run a Tunnel. That, or run off the front 2 bbl's of the dual quad setup.....essentially running 2-2bbls. Having the rear 2 on both carbs disconnected side-steps alot of problems.
The main thing with a tunnel is over carbing and running in to trouble with weak vac. signals at the carb.
People have trouble running Hilborn injectors on the street, I just don't fight them.....as long as you don't try to idle them at 550 rpm, and try to lug them, your ok.
You gotta have some velocity for these things to work right....

 

[Fort Fun]

Nevadavic - the one-carb scheme would probably work better running off the rear carb. The reason is that the primaries on the rear carb are closer to the center of the manifold, which improves fuel distribution at part throttle. Running off the primaries of the front carb, it is a very long way to the rear cylinders. Probably need a major pump shot size increase too, to get the stumble out.

I have a setup I sell that divides up the one giant plenum into four small plenums, which gets rid of the stumbles and makes a ton of torque even from right off idle. Makes more torque than a dual plane even down low.

 

[Nevadavic]

Hey Fort Fun,
A major pump shot? I moved the lever from the middle hole on the pump to the one on the end of the rod on the Edelbrock carb to increase the volume of the pump which did help some. I'm good with the way it runs.... I'm a cruiser these days and don't have a need to burn rubber out of the hole. ...smiling...

 

[Screaming Metal]

Let me just cover this.... Mike, Ron, and a lot of others here have run Tunnels in past, they know how to tune them and how to set them up. I deal with them fairly regularly, but my bread and butter are blowers.... On any given day, I guess we probably go 20+members running tunnelrams.
Just bare with me, I want to kinda dis-spell a few things here. Tunnel Rams are NOT designed for the street. They ARE a racing intake. You CAN adapt them to the street by using some 'CRUTCHES', things that allow the TR's to function.

A Tunnelram is designed to dump your fuel/air mixture, at speed, directly into the cylinder chamber. Its a falling off the tree limb effect.
I won't go into all the physical laws involved, Mike can do that much better than I can, but these things were not made to idle any less that 1400...just enough to get the car into the staging lanes....and most of the time, they were fouling out plugs unless you had your idle spped of at least 1600...

Now then, Tunnels work best with a mild cam on the street and small carbs. small carbs have small primarys and can keep the velocity up in the intake....

If you gonna run 2-600's or 2-750s on your tunnelram, even after asking our opinions, we have enough other things to do, we don't mind helping anyone get their car straightened out. Thats what we're here for. Bur don't put us thru the song and the dance of helping, then you do whatever you mind is gonna do anyway.
Tunnelrams on the street like these things:
1. Gears to keep the rpms up.
2. Small carbs
3. Mild cams
4. They like a certain amount of timing
5. Don't expect to idle the motor at 550 rpm with the air conditioning on in Drive, and pull away from a redlight on a uphill intersection in 100 degree weather, and smoke the tires....

Tunnelrams at the track LOVE:
1. Keeping the rpms up.
2. Big carbs, with big headers with big valves with big runners that lift way on up there to make Big Power!
3. They want as much timing as a person needs to lead a jet airplane for a person to hit it!


Well, I've got a new computer here folks, and Windows 7 sucks.....it just stops typing sometimes.... anyway....

To run one on the street, you have to run a mild cam and small carbs. There was a really good article over on the NTBA site about tunnel rams, a fewyears back. And theres a ton of info here on the net. Read up on it all....then....ask your questions.....

 

[Screaming Metal]

And the Street Ram, is a redesigned, adopted Animal. Yes, its idle characteristics are different. But at its heart, its still a hi-rpm racing intake.....

 

[Nevadavic]

Great info, Screaming Metal!! Much appreciated....

 

[sstock]

Great truthful read Mr. Screaming. I thought long and hard before I decided and went with my tunnel ram setup. I've played with tunnel rams since the early 70s and they leave alot to be desired when they are used on the street. First of all, I would never run a dual quad setup on the street normally aspirated unless one carb was a dummy, or they were extreemly small carbs. I knew I would be giving up a lot in street trim but decided to minimize the effect by running a single quad small cfm vacuum carb(570cfm), mild cam (224 degree intake), low gears(3.89to1) and a high stall convertor(3200),29" tire and get this a small intake runnered head (165cc)to keep the velocity of the air/fuel charge up. Now keep in mind my road trials have just started with only 5 run cycles or so, but this engine starts on the first hit of the starter and comes up to fast idle on the choke, no stalling or surging. I can say it was a mess at first with the stock jets and squirter, it snapped back through the carb a couple times and egts were too high so I shut her down until I jetted up four sizes on the main jets and 3 sizes on the pump shot. I'm welding a 18mm bung in the exhaust collector and will be using a wideband O2 sensor to dial in the main metering, power valve, secondaries and pump shot. I really think it will be quite livable on the street, but I'm willing to put the time in and play with it too.

 

[ScottRods62]

Has anyone on here run a tunnel ram with a pair of 390 holleys,were setting up one now in one of our buckets,and would a progressice linkage be the way to go?

Thanks,
Scott