ideal cam shaft charateristics for a tunnel ram

Any advice for selecting a cam shaft to use on a 402bbc set up with a tunnel ram and dual quads?
the 402 is bone stock and runs good and it's what I've got to use in my 55' for probably a couple years until I can get something better.
I've got a tunnel ram of unknown mfg or model with no markings on it that I got off craigslist just to mock things up with (couple picture below).
I've also got two good 450cfm carbs. It's a four speed car with an HEI distributor, an MSD 6AL ignition system and 4.33 gears.
is there an optimal TR for this set up? As mentioned the TR I have now was picked up just to mock things up with...but if it'll work that'd be great!

thanks,

Charlie

 

well you got 450cfmx2 on a BBC. Its CID x MAX RPM divided by 3456.....so 402x (lets say 6500) = 2613000 divided by 3456 = 756 cfm..........call a cam maker and see what they suggest....I've got a buddy who did what your doing, I tried to tell him different, ....tunnel ram big cam headers....it would idle but thats all.....it never ran right...to much carb,cam etc....not enough compression..... it looks cool......

 

Oh I do like the hot rod.....

 

Charlie,

Is the plenum removable on that Tunnel? It sort of resembles an offy with a removable plenum.

If I was looking for a cam shaft to go with it I would be looking for a cam shaft that started working in the 3K range. I would maybe want one with a longish exhaust duration so I could always have a clean charge on my cylinder.

Just my thoughts on the subject I am probably way off.

60srailjob,
I never thought to ask about compression. I would think that the engine in question should be in the 10:1 range stock though.

 

Yeah maybe it does and it wasn't mention......

 

thanks guys, the plenum is removable and I'm thinking with the stock open chamber, oval port heads my compression is in the 9:1 range.
I understand and completely agree that performance wise I'd be better served with a different intake manifold but I've had a picture in my mind for a long time of what this car should look like and it includes a TR.

 

run a different intake till you can hop up the engine....cool car....

 

You can always pick up a bit of compression by changing your head gaskets to steel shim gaskets.

If you get to the point that balls to the walls is what you want out of the big block I have some 660 center squirts that I have been meaning to get rid of a matched pair and a spare.

Not a bad idea, a 2x4 highrise should get the tops of the carbs on that big gaping hole in the hood and aircleaners above that. It would still look good and probably perform better in the long run. May never ever even become a tunnel ram at all.

 

thanks Pork, I have a couple of 660 center squirtes as well but I assumed I'd do better with the smaller carbs and maybe choking down the plenum.
Obviously I'm out of my element here!
Thanks for the comments on the car. I finished the tilt set up on my 55' this last weekend...couple of pics.

 

Way cool man.....

 

Agree a bad big block needs a tunnel ram to look the part. They can be made to work on the street, as long as you can pay at the pump.

As to the cam choice, don't let the race-oriented guys spin your head around with all the duration, lift, LCA, installed centerline specs. Without good heads, more compression, better valves, springs, rocker arms, a longer cam just gives a rump-rump fairgrounds idle. That's not necessarily a bad thing, just makes tuning harder and sucks up yet more fuel.

If it's going to just be a looker at this stage, go with a CompCams Mutha Thumper, or if you're really want to sound bad to the bone, a Big Mutha Thumper and enjoy the ride.

 

The mail box really makes the car. I have grown weary of tri 5 gassers over the years but some of them are pleasent to look at your falls into that catagory.

 

yea everyone should waste money on a poser cam.

I am sorry if you think that we are too advanced for someone building a 402. maybe next time someone asks we should just suggest that they PM you.

 

thanks pork! I think the hood scoop is going to get turned around so the opening is in the back as it looks in my avatar. The reason is I'm going to have to extend the hole in the hood all the way to the fire wall (or darn close to it) so I can get clearance for the carbs and aircleaners. I'm not sure I described that very well.

I actually prefer the scoop as it's set up in the more recent pictures.

 

I deal with Bullet Cams and they can profile you a cam that will work for your BBC with what you have now. Stay away from 660s you will kick yourself for even trying to run them on the street. They are hard to tune for the street major mods. to get them to work. And T/Rs if setup right will get about the same gas mileage as a large carb.

 

Hey thanks Turbo! I'll give them a call!

 

No problem, they are not the only cam company that would help you I just like their cams. And that is either an Offe or a Weiand intake. Good luck and that's a sweet 55!

 

If it where me, I wouldnt go with a long duration cam. Get the valves opened and closed as fast as possible, cuz your gonna loose alot of vacuum with the rise, which will cause a bog when the light turns green.

I am saying this thinking for street application, at the track the rpms will be up so you wont worry about a bog at the start.

You might even install it advanced a little bit depending on the mfg specs.

I always use Comp.

 

I've bought cams from comp cams before and was frustrated with thier technical support, so alternatives suggestions are welcome

 

try Isky

 

my understanding is that TR is intended to smooth out the disruption of fast moving vapors as the valves open and shut...does that sound right? so a quick open/close valve would take advantage of the TR design? Also choking down the plenum would speed up the vapor
making the TR more effective as well on my low compression bbc.

 

http://www.jalopyjournal.com/forum/showthread.php?t=707820&highlight=tunnel+ram Hey!! I have a 302 ford,b-cam(490 lift,280 dur,?) gt40p heads,390 vac secondary carbs. I would think for your set up 600 holley vac secondarys will work better on the street.You have to dial in the primary circuit first(jets) then you dial in the squarters (they make the transfer from idle circuit to primary circuit) then the springs for the vac secondaries. The idle circuit adjust with a vac gauge for the highest reading. then bring the gauge inside while you drive to see what the reading is a cruise speed(55)MAKE SURE ITS NOT AT THE SAME AS YOUR POWER VALVE!,you dont want the power valve to flutter on at highway speeds,(the power valve is to make the transferr from primary circuit to secondary circuit)I drove to a entrance ramp to a highway,pulled over,change one spark plug with a new one,drove at 55 mph for 20 miles to another exit ramp,shut the car off at speed a coasted to a stop, checked the plug, jetted as need(went from a .50 hole to a .68 hole , 2 thousandths at a time,then dialed in the squaters then the vac secondarys. I can't explain things very well(as you can see)but you can make it run great!!It just takes time!! Pete

 

Sometimes making things work well, doing things right, or attempting to address technical issues and the laws of physics, gets in the way of being cool. If coolness factor is the primary concern, and nothing potentially dangerous to others is being undertaken, I guess it doesn't matter to me if the person is doing something they probably shouldn't. All you can do is provide the information. If they want to do otherwise, at least you tried.

 

It favors a Weiand intake to me,,judging by the way the base opens under the top and the shape of the ports.
I would suggest some more compression,,just to do justice to the tunnel ram package,,in the range of 10 to 1 or better. I am predjudice about a tunnel ram,,they work very well when set up and tuned correctly.
They are not nearly as difficult to set up as most people think,,and,,a strong tunnel ram engine needs plenty of carb. The reason being,,at RPM,,,the intake actually "rams" more air and fuel into the cylinders,,making the engine ingest more while the intake valve is open. They do like for a cam range to be about 3 grand or so,,,my grind comes on about 3 and last until 8000 plus,,at least according to the card. The highest I have ever turned it is 7600 according to the Moroso telltale needle. This is a 452 big block Mopar,,two 750's,,and it will scare the living hell out of you.
That being said,,,all engines do run different,,it depends on the combo.
If you want it to run right,,pick the right parts,,otherwise,,like has already been said,,,DON'T BE A POSER.
It is called a Hot Rod for a reason.
Good luck!

Tommy

 

I agree with the "poser" comment. On the other hand I've put so many hours into building this thing that I'm anxious to see it as I've been imagining it.
My plan is to run it with the 402 until I can build up a bbc that will do a TR justice but that could be 2-3 years away...so in the meantime I'll do what I can with what I have. I've thought of buying better heads but that'd be putting lipstick on a pig, and siphon money from the "real" motor.

 

Definitely a Weiand tunnel ram, the flat spot on the lower gives it away. I bet there's a part number on the bottom in the valley area.



I'll have a single quad SBC Weiand tunnel ram for a 350 I'll be using in my 1956 Chevy, I'll be putting the finishing touches on gasket matching/mild street port on a set of heads for it tonight or this weekend.

Two things to think about regarding the HEI: it may not fit runners of the intake; it also may not fit against the firewall. I've been looking for a mag but haven't come up with one yet.

I'm using a mild Summit cam in mine to start off but you've got a big block with 50 more cubes than my engine so I don't think my selection would help you too much. I picked a huge lobe seperation (106) for the lump with relatively mild lift and duration for great throttle response right where the powerband starts. Once I get the turd rolling I'll know how much bigger to go!

FWIW I've been told you have to keep a lot of RPM in a tunnel rammed engine and drive it relatively "hard" compared to milder intakes with shorter runners. Okay by me!

 

that's pretty cool.....I like old speed parts....yeah!

 

Nice! are you running stock heads?

 

Yep, early (1974) 882 castings. They've been called the "best of the worst" smogger SBC heads. The tunnel ram intake I got had already been gasket matched so I had to do the heads and I figured while I had them apart I should clean up the short side radius and around the valve guides.

 

Yea, those 660's are way too big. Carbs that are too big will dump too much fuel in...wanna sell 'em?