Last time. The more people you ask about carb size on a tunnel ram the more different answers you get. Im pulling the trigger on the carbs this week. Getting the Holley ultra xp carbs. Talked to Mark Whitener and he suggests 750's. I always take Marks word for anything about carburators, but 750's seem to big. Called Holley and they suggest 600's. i'm thinking 650's.
Holley pro dominator t ram on 410ci sb 13.3:1 with a 7-7500rpm ceiling. 5200 stall and 3300# race weight. i'm more concerned about not over carbing between 5200 and 7500 since that will be the usable range. Thanks

do yourself a favor and take Mark's advice

I ran a pair of 750 double pumpers on a 383 B motor, and once dialed in were deadly accurate. Tunnel rams breathe different than a single 4 intake, and the rpm you are looking to run you will be fine.

I don't know [ Moparts Family Site - Keep it Friendly ] Holley is thinking but I'd be worried the 750's are TOO SMALL. I have a great amout of respect for Mark so I'd have a hard time questioning him either. But at that displacement and RPM the 750's are borderline too small for me.

FWIW I'm making the GIANT ASSumption that when you ordered the cam you specifically bought a cam spec'd for a TR. There are 2 GIANT issues that kill TR's and it ain't over carburation. It's way too much timing. TR's can use 8-10 degress LESS at .050 and run the same RPM. DO NOT OVERCAM A TR.

The second issue is getting the air bleeds and emulsion sorted out. You are doubling the jet area, doubling the bleed area and doubling the emulsion but you did not double the air flow.

If you do those 2 things you will wonder why you did run TR's forever. They make more bottom end, have a flatter TQ curve and make more average HP every single time it is done correctly.

In 1984 I bought my first TR. I personally spent hours on the phone with Ollie Morris (IIRC that was his last name...I'm horrible with names) and he had his own formula to figure out TR carb capacity. He also taught me how to think of airflow in term I can understand. Ollie was an awesome man. His answer was always very simple. If you had a properly sized single 4, and all the dyno numbers looked like they should, then you DOUBLE the CFM rating for a TR. I don't remember the last time I talked to him, but he stood by that every time I questioned him. That always meant that you had enough converter (I run clutches so I never had to worry about a tight converter) the CORRECT gearing and the chassis was sorted out. If you consider that, then you could really find HP in 2 1050's.

Now all the math heads can come in with their formulas and calculations and theories, but they would still be wrong. How do I know? Because in 2015 all the Pro Stock guys would have been stupid. By any math I have ever seen, they are grossly over carburated.

All I can say is I am doing a new engine for my DD/street car and it's the first time I'm not using a TR. I don't want to cut the car up or change it any more than it already is. Otherwise, I would have a fully ported and flowed TR on it, and I'd be running 2 850's. On the street. And Thumprdart would do the carbs.

You should select a pair of carbs. that flow the exact same amount of CFM through both ends of the carbs. Holley 750 DP do, so do 850 D.P. and most Holley 1050 Dominators. The Holley 650 D.P. have different venturi boosters in the rear than in the front, I'm not sure about the 600 D.P.
If I was you and know what I know I wouldn't hesitate a second to buy the Holley 750 D.P. tunnel ram carbs IHTHs

the cam is 267/275@50 .675/.675 on 106. I think the cam may be on the small side for what i'm doing. thanks for that info on t ram and cam size. I am most concerned with going fast in the upper range, but may drive to a car show or two. Do you think it would be drivable enough for that with 750's? maybe 10 mile radius.

well, the holley doen't offer t ram carbs in the ultra xp line, but i'm sure Mark can suggest what they need for IFR, emultion and main jets. looks like 750's may be best.

Absolutely. If you get the issues noted above sorted out, you'll wish all your stuff had a tunnel ram.

BTW, long before it happened, I was told all engines would basically have a TR manifold. Was I was told is correct. Most everything today that is a V-8 layout has a TR on it. They just laid it down to get a hood on it! One of the places that EFI helped (think about the old max wedge crossram stuff).

I think Mark will help me with that(jetting). He's the man.

Then it will idle like a kitty and roar like a lion.

That sounded better in my mind that when I typed it.

Is this thing going on the dyno? I'd love to see the numbers.

You need to remember that the right foot controls the throttle especially on the street
Some things feel so good you just can't help yourself from over doing those things

I would believe two 750's would be good but I would think two 660 Center squirters would work better.

https://www.holley.com/products/fuel_sys...rs/parts/0-4224

So true

LOL! Yes,I agree

Yes, I hear nothing but good about them. The carbs will be poked thru the hood so need to look tough as well and the gray and black ultras xp do that.

Yes going to the Dyno but not with the t ram. I'm taking an 850 and an 1050 dominator.

I for one can't wait.

My combo is near the same and I have two BG 750's on mine and wish I had bought the 850's.

When my 451" DartSport was running in the 10.02 area with a best of 9.96 in good air I had a 1050 Dominator(quicker than smaller carbs I tried) on it. I switched to an M1 TR with two 750 Quickfuel double pumpers and the car ran in the 9.90 range with a best of 9.89 and it even ran 9.90's on hot days.
I loved the tunnel ram and it was more mellow on the street than any single carb I had on it previously.
The only downside was that it drank twice as much fuel.

By the way, I was running the MP 590 purpleshaft.
OhioGTX ran a TR on his big B-body and it went 9.70's with the Comp 650 lift solid cam.