Tunnel Ram on Street?
Are those tunnel rams going to give the best low end response on a street driven motor with a couple of small carbs.? I'm looking into some W2 heads for my 340 and may be able to get a Mopar dual tunnel ram to go with them. Wouldn't be a max effort cam, need to be streetable with an automatic and PS/PB. Probably would go with a solid lifter. Should be a 10:1 engine if it's still got the original 1970 pistons, yet to be verified. Worth trying the tunnel or stick with a lower profile single or dual plane?
There are three reasons why tunnel Rams don't work correctly. When they do, they make more bottom end, more mid and more top than any other intake manifold there is. The biggest set back for guys like me is I have a hood I don't want to screw up and I don't want to take it off and store it. If it wasn't what it is, I'd have a tunnel ram on my car. I've been using them since 1984.
The number one reason tunnel ram fails to live up to the look is cam timing. I can't stress this enough. The TR will need LESS seat timing. By a fair margin. Don't use an off the shelf cam. Call a cam grinder that will give you a cam ground for your combination. You'd be surprised how small in duration a cam can be with a TR. If you don't get the correct cam, the power curve will be very peaky. You will give up bottom and mid range and you'll have to RPM the engine higher to make the same power. This isn't the manifolds problem. It's entirely a camshaft problem.
The number two reason a TR fails to live up to the look is carb selection. There is never EVER a reason to run a vacuum secondary carb on a TR. I don't like a VS carb for anything, but for a TR it's a big NO NO. They used to make very small TR carbs that had an accelerator pump on the primaries and mechanical secondaries with no accelerator pump. It was so small it didn't need a secondary pump. They are worthless. The smallest carb to use is a pair of 650 double pumpers. This would have to be a very low RPM, low output engine or even those carbs are too small. As an example, I did the port work on a set of heads and an Edelbrock cross ram for a SBM. I spent a ton of time on the intake, and we had a 1 inch spacer made up to lift the entire top up 1 inch. The customer wanted nothing bigger than 650's on it so it's what he got. It made good power, but on the dyno it was down on power. It needed a pair of 750's and if he wanted to mess with it, we could have most likely used carbs that could flow 1000 CFM each.
The third reason things go sideways on TR engines is carb tuning. Think about what has happened. You have doubled the venturi's, doubled the jet area, needle and seat area, doubled the idle feed area and the emulsion area, and doubled the air bleed area, but you didn't double the air flow. What you end up with is essentially an unrunable mess. You can't possibly pull enough jet out without killing power on transition. If you jet for WOT it will be lean in transition. It will be slobbery rich rich at idle and cruise because you have again, doubled the jet area without doubling flow.
Unless you are very estute in carb tuning, as in understating emulsion, bleed area to jet size etc. you need to have your carbs set up by a pro who is familiar with carburetor calibration. The payoff is well worth the money, in that simple jet changes and a few other things the end user can do will make the carb tunable. I prefer Dominic of Thumpr carbs, who is here on FABO a little bit but is easier to reach on moparts. Also, Mark Whitner is great with carbs and knows what he's doing. Both down the work themselves and both answer the phone so you talk to the guy doing the work.
If you get the correct cam, buy the right carbs and get them tuned, your TR will kick *** everywhere on everything else.
