Tunnel Ram on Street?

Discussion in 'Small Block Mopar Engine' started by gzig5, Aug 10, 2018.

  1. gzig5

    gzig5 FABO Gold Member FABO Gold Member

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    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?
     
  2. Jimacuda

    Jimacuda Well-Known Member

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    Spend you go-fast $`s elsewhere.
    Tunnels are just "look at me" for street use.
    Dual plane is much more streetable IMO.
     
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    • diymirage

      diymirage HP@idle > hondaHP@redline FABO Gold Member

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      best low end response would be a stroker kit
       
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      • el5dart

        el5dart Well-Known Member

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        i had a tunnel ram with w2 econo heads on my barracuda. it ran good but bogged a little on the low end. and it sucked when it started raining
         
      • Garry in AZ

        Garry in AZ Building a 9 second Valiant FABO Gold Member

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        The tunnel ram manifolds are designed to work better at higher RPM, usually 3500 or so and up. Not a good choice for a street car, and never a good choice for low RPM use.
         
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        • yellow rose

          yellow rose Doctor of Thinkology.

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          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 ass everywhere on everything else.
           
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          • nm9stheham

            nm9stheham Well-Known Member

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            So is the reason to not go small on the carbs to make sure you don't choke right right down on the better flow that the TR can afford? (I get the carb tuning and the air flow in each venturi...)

            Is the smaller duration because the flow overall can be better, with less pressure drop, and thus the fill is just automatically better?

            Tnx for posting BTW.
             
          • yellow rose

            yellow rose Doctor of Thinkology.

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            Exactly. When the carb or carbs are too small, they tend to go dead rich and it's hard to correct.

            Exactly. Overall flow in terms of flow numbers, but more importantly flow QUALITY is better. So you need less cam timing to keep the RPM the same. And the TR will make amazing low end torque while not giving up anything on top. If you don't reduce the seat timing, the bottom end goes to hell, and you have to spin the guts out of it to get the power back. That is an over cammed issue and not an intake issue.

            Look at modern EFI intakes. They are nothing more than laid down tunnel rams. You can't do that with wet flow like a carb, but dry flow with EFI makes it possible.

            Like I said...I have a perfectly good TR under the bench in the shop. If my car didn't have the factory Raisin Bran hood, that beeeeeeeeotch would be on my car.
             
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            • Garry in AZ

              Garry in AZ Building a 9 second Valiant FABO Gold Member

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              Interesting information. I learned something today. Thanks!
               
            • Gdub310

              Gdub310 FABO Gold Member FABO Gold Member

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              Can confirm. Huge mistake, it was a total dog but looked tough.
               
            • gzig5

              gzig5 FABO Gold Member FABO Gold Member

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              This was my understanding and the reason I was considering it. I could have the brand new in the box TR intake and a hood already cut for a TR for $350. Sounds like it could be a booger to tune so I will think on it some more.
               
            • yellow rose

              yellow rose Doctor of Thinkology.

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              It won't be difficult to tune if you get the correct cam and get the carbs set up by a pro.

              Those who say they are a dog didn't do it correctly.
               
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              • Divenut

                Divenut Well-Known Member

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                Tunnel rams definitely look awesome! And while I understand tuning for the street can be tricky, I have seen, and been in, some very quick tunnel ram equipped cars that would absolutely get it off the line. Looking forward to seeing what you ultimately go with gzig5.

                Be well,
                Pat
                 
              • 72Dart6pack

                72Dart6pack Harder Better Faster Stronger.

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                Tunnel ram it. Go Big! Or go Home. Oh look another 4bbl with a chrome Air Cleaner. You need to make a statement.
                :thumbsup:
                 
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                • gzig5

                  gzig5 FABO Gold Member FABO Gold Member

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                  Y'all are a bunch of enablers....
                  :lol:
                   
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                  • 72Dart6pack

                    72Dart6pack Harder Better Faster Stronger.

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                    Who? Us? Naw! :)
                     
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                    • nm9stheham

                      nm9stheham Well-Known Member

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                      FWIW... the only car to ever beat me in the old days in street racing in Chambersburg PA was a tunnel rammed '56 Chevy with a nice 327..... he had a fight on his hands but had the top end in the end. The 440's and all else never could keep ahead of my 351C after I hit 2nd. Man, that was fun LOL... looking back I can't believe we weren't all put in prison!

                      The .050" duration on that 351C cam was 190/200....on a 114 LSA... really... I am looking at the cam card now. Torker Intake, just a 600 cfm Holley VS, 1-7/8" headers w/ 18" collectors, 10.3 SCR, 8.3 DCR, quench, and the good breathing of the 351C heads. Maybe that shows what is being illustrated.... set up the whole package to make things breathe and then set the cam to maintain your torque band wide.

                      Bet I coulda beat that tunnel-rammed Chevy with a bigger carb... dang. But I also bet I would be hard-pressed against the improved parts you can get so easily today.
                       
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                      • replicaracer43

                        replicaracer43 Old school member

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                        A properly tuned tunnel ram will make more power EVERYWHERE in the rpm band, if the proper cam and carb setup is used like yellow rose suggested
                         
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                        • replicaracer43

                          replicaracer43 Old school member

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                          But keep in mind, I daily drive a duster with a 410 stroker equipped with a edelbrock str-12 crossram, with dual fitech throttle body's, so I aint scared of tuning.
                           
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                          • diymirage

                            diymirage HP@idle > hondaHP@redline FABO Gold Member

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                            19 posts and no pictures?
                             
                          • 72Dart6pack

                            72Dart6pack Harder Better Faster Stronger.

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                            This is just a bench racing post. That's why there are no Pics.
                             
                          • jas0162

                            jas0162 Well-Known Member

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                            My experience with a tunnel ram intake is very positive, it made a marked improvement on my bracket car- but I don't think street driving with one would be good unless you lived someplace with no rain, sleet, or snow. I wouldn't want all the bug guts on my carb either.
                             
                          • 1Fast340

                            1Fast340 Well-Known Member

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                            Sure is worth trying a tunnelram,just get a good combo of parts and tune it right.

                            Dont know how tall the MP tunnelrams are but i ran a Eddy tunnelram on the street and it fit under the sixpackscoop on my 73 duster with a couple 2x?" aircleaners that just rubbed alitle on the underside of the scoop,ran with a couple of 750 proforms that in my opinion where to large for the combo but those saying that tunnelrams only work at high rpm and are useless on the street are clueless,its all in the combination of parts and having the knowledge to make them work together,if i did i again on a good stockstroke street 340 i would probably go for a pair of 500cfm edelbrock carbs,600-650cfm 4150 Holleys or the legendary 660 centersquirters.


                            Stay away from those crappy holley mechanical secondary carbs with no secondary accpump.

                            For what its worth a friend ran a pair of 500CFM edelbrocks on his tunnelramed XR280R cammed Eddy RPM headed 383 chevy and those where good enough right out of the box to push his very nice 65 Malibu into the 11:50s with just 3.73:1 gears and a 3000rpm converter shifting at 6000rpm The thing was easy to start cold and warm very nice to drive and the thing was an absolute animal when asked to.

                            Here comes a pic of my old tunnelramed 11:1 compression solidrollercamed daily driven 340 while i was puting it togheter. I used to have a pic of the carbs under the scoop aswell but i cant seem to find it.

                            tr 014.jpg

                            Oh and yes i ran it with PB and PS,the ps pump did not seem to appreciate the rpm over tim but that could probably be sorted with different pulleys and the PB was not always happy in very slow stop and go trafic but it doesnt realy mather and it was never realy a problem, either a vacumcan,vacumpump or a smaller cam would have taken care of it but it was ok since there usualy isnt much need for all that assist anyway at low speeds and at higherspeeds there are plenty of vacum for the brakes anyway,this did not change due to the TR it was the same with other intakemanifolds aswell.
                             
                            Last edited: Aug 11, 2018
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                            • matthon

                              matthon Well-Known Member

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                              I run a TR for years on a 383 4 speed.
                              First with 390 vacuum secondaries, always ran rich, but ran very well with a slight hesitation at initial throttle.
                              Switched to 600s, ran better and seemed faster.
                              Switched to dual quad FiTech, very happy with how tunable it is from the driver's seat.

                              It has a thumper cam, and I always thought a custom one from a knowledgeable cam grinder would make a huge difference.

                              Can you get a custom cam from a manufacturer, or is that something done in a machine shop?

                              20180617_144433.jpg
                               
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                              • Cope

                                Cope Well-Known Member

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                                20180811_101902_zpsqf4jeona.jpg

                                20180808_124651_zpsjmt2mxb1.jpg

                                Here's mine, 360, 11-1, 4.88s, (street car) :)
                                Not running yet but will be running soon and destroying folks stoplight to stoplight....

                                There's a few guys here running dam quick with em. Check out my thread on them in the racers section. Some good advice and ideas there.
                                 
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