Thread: tunnel ram question

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hey guys i am currently building a pickup and am going to put a sbc 283 in it. i am not really knowledgable about tunnel rams but my dad has a tunnel ram with 2 4brl holley 600cfm carbs(i think...i'll have to look to make sure)on it. could i put this set up on the 283 and have it run ok or would it be way too much for it? i know how to make linkage on the carbs where it will only use the 1st carb til you lay into it and it will start using the 2nd one. also would make my gas mileage super horrible? i'm not goin to be racing or anything but just like the look...and i have one in hand. thanks for any info.

thanks,
Jeremy

With a small motor, a fairly heavy vehicle and street gears, a tunnel ram is a nightmare to tune. Low end torque goes away, and the power band is 3500 RPM to 7500 or so. Also, you probably have three times the carburation that a street 283 can take. I know people who have done it "for the look," and never got it to run right. This is especially true on an otherwise unmodified engine. If you don't have the cam, compression and gears to run the RPMs necessary to get into the power band, that setup will give you worse performance and worse mileage than a nice single 4-bbl.

On the other side of the coin, I see tunnel rams everywhere I go. If you're open to experimenting, and you have one in hand, go for it. Just be prepared for a LOT of issues and less than optimal performance.

Just a few thoughts from the been there/done that crowd.

thanks for your advice...what about one of those adapters that you put on a dual quad tunnel rams so you can use a single 4 barrel carb? if i did go with that tunnel ram what size carb would be best for that setup?

thanks,
jeremy

there is no true way to give a carb size recomendation without having the cam specs and compression ratio and also, if running a manual or automatic, the torque converter specs, with rear end gear ratio. you will have to build that 283 pretty stout to get a 2x4 bbl set up to run without a lot of tuning issues, but it can and has been done by alot of people. so dont rule it out if that is what you want. pictured is a basic holley carb size chart, i personally think this chart is a little undersized, but it is always better in being low than high in carb selection.

thanks for your input guys. still up for some helpful comments to help me make my decision. i have a mild cam for it...not sure what the number is off the top of my head though. i'm not planning on driving it all the time when i get it done...mainly because of gas prices to income ratio lol...tryin to make it through college and support my hobbie at the same time so probably just a weekend cruizer so i guess it is mainly for the look...tunnel rams look so sweet!

thanks,
jeremy

Originally Posted by jeremy_e87

thanks for your input guys. still up for some helpful comments to help me make my decision. i have a mild cam for it...not sure what the number is off the top of my head though. i'm not planning on driving it all the time when i get it done...mainly because of gas prices to income ratio lol...tryin to make it through college and support my hobbie at the same time so probably just a weekend cruizer so i guess it is mainly for the look...tunnel rams look so sweet!

thanks,
jeremy

As the previous owner of a tunnel ram on a small block street engine, I cannot urge you enough to forget it. It may look cool, but it will perform badly on the street. A tunnel ram is meant to perform between 3500 and 8500 rpm. That is what they are designed to do. So you would be expecting it to perform out of its intended range. I had no bottom end response, and it would not start really coming on until about 4000 rpm and my redline was 6000 rpm. That is only a 2000 rpm band. Do yourself a huge favor and go with a low profile dual quad or three deuce set up if you want multiple carbs. You will like the performance much better and still have a visually cool engine. The Beach Boys had a song on their Little Deuce Coupe album called No Go Showboat, and that is what plays in my head when I see a tunnel ram on a street rod or street machine. LOL!

Save the tunnel ram for a light car with a high winding engine some day. As others have said, they can be made to run but even if you do get the tune correct on the carb or carbs the manifold itself only lends itself to high rpm operation. Preferably with a 4 speed and tall gears so you can keep it in that 4,000 to 8,500 rpm range.....