Tunnel Ram Power Band?

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JGC403

JGC403

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I am building a 383 and would like to run a Tunnel Ram. What is the RPM operating range for the manifold, or what would be a good cam to run with it?

Engine is a 383 bored 30 over, stock stroke, 440 length rods, domed pistons with 1/16", 1/16", 3/16" ring set, 10.5:1 compression ratio, 906 head ported with Mopar templates, all backed by a 4 speed.

Its going into a street car.
 
For the most part, i'd try and discourage you from doing it. But if your going for the visual, and I have to admit they are cool, you'll need to get the total combination just right to have a pleasurable car to street drive.

Carb size, which I would stay in the 450/500cfm range, your torque converter stall speed and rear gear will make or break the combo. As far as cam selection, if you have a true 10.5 compression with iron heads, you'll need to thread the needle with intake duration and the intake closing point to have decent vacuum and not too much dynamic compression that doesn't allow the use of regulation pump fuel.

Any more info you can provide will do nothing but help us give you some good feedback.
 
OldmanRick said:
For the most part, i'd try and discourage you from doing it. But if your going for the visual, and I have to admit they are cool, you'll need to get the total combination just right to have a pleasurable car to street drive.

Carb size, which I would stay in the 450/500cfm range, your torque converter stall speed and rear gear will make or break the combo. As far as cam selection, if you have a true 10.5 compression with iron heads, you'll need to thread the needle with intake duration and the intake closing point to have decent vacuum and not too much dynamic compression that doesn't allow the use of regulation pump fuel.

Any more info you can provide will do nothing but help us give you some good feedback.
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Don't have to worry about a torque converter. Its a 4 speed manual trans behind this engine.

What other info do you need?

I'm toying with the idea of having fuel injection bungs welded in to convert the manifold to fuel injection. Not sure on that yet.

I can still lower the compression a bit if need be, but I think I can get away with over 10:1 using pump gas.
 
JGC403 said:
Don't have to worry about a torque converter. Its a 4 speed manual trans behind this engine.

What other info do you need?

I'm toying with the idea of having fuel injection bungs welded in to convert the manifold to fuel injection. Not sure on that yet.

I can still lower the compression a bit if need be, but I think I can get away with over 10:1 using pump gas.
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If you turn the intake into a dry one it by going efi it very well may change things as far as what rpm range the intake will like. Reason I am thinking this is because damn near every efi manifold out there is a single plane.....and they all will produce power down low if the motor is built correctly.
 
JGC403 said:
all backed by a 4 speed.
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Oops! My bad.

I wouldn't lower the comp. I was just thinking about a cam choice that will give you enough cylinder pressure to still allow you to use pump fuel and also make some power upstairs where the tunnel ram will be the happiest (4000/6000). As far as gearing, i'd like to see 3.55's at least.

I'll think on it some and get back when I have something more to offer. I do like what your doing though. It's all about having fun and looking cool...:D.
 
If I remember correctly,tunnel rams USED to be just for drag racing !Did not run efficiently on the street.But they've developed a new tunnel ram with the pots under the carbs were a totally different shape to change the streetabilty charecteristics !
 
OldmanRick said:
Oops! My bad.

I wouldn't lower the comp. I was just thinking about a cam choice that will give you enough cylinder pressure to still allow you to use pump fuel and also make some power upstairs where the tunnel ram will be the happiest (4000/6000). As far as gearing, i'd like to see 3.55's at least.
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Yes, I'm using a rear with 3.55 gears.
 
JGC403 I kind of want one on my 273 65 Cuda after seeing a tunnel ram Ford 260 build :)
 
Somethin like this is what you're lookin for.

http://www.ebay.com/itm/Offenhauser...Parts_Accessories&hash=item53f5ec6bdf&vxp=mtr

Look how long the runners are in the bottom half. That equals GOBS of bottom end torque. Weiand also made one with long runners similar to that. Whether you go with single or dual top, that's what you're lookin for. Long runners. PM 340 8BBL up there. His stuff runs like a ***** in church and he has a very mild engine. Don't listen to people who say "don't do it". They don't know squat.

If Edelbrock ever made a "Street Tunnel Ram" for the 383, that would be the one to get, but I don't think they ever made one. I could be wrong. I've never seen one anyway. I would look for the Offenhauser first, then the Weiand. Either of those would work well.

Here's an example of what NOT to get.

http://www.ebay.com/itm/Weiand-1995...Parts_Accessories&hash=item5d3211730b&vxp=mtr

I know it's a small block version, but look how short the runners are on the bottom half. Also look how much plenum volume there is. You're gonna need a LOT of carburetor anf a LOT of RPM to make that work. NOt good for the street.

Here is a good example of what you WANT.

http://www.ebay.com/itm/Weiand-1987...Parts_Accessories&hash=item2ebbb4385c&vxp=mtr

Although it's for an RB, Weiand made this for the B engine, too. Se ehow long the runners are in that bottom half? Look also at the plenum volume. Small. That means you can run pretty small carburetors and still have a strong signal. The long runners make for great bottom end torque. The B engine version of that has been discontinued for a number of years but they popup on ebay from time to time. If you can score the Offy, do it, but the Weiand will probably pop up first. Good luck.
 
In that article they used a cam with duration of 239/247 @ 0.050", .573"/.597" lift and 110LSA. I think this one and the one suggested above might be a little to hot.

What do you guys think of a Hughes hydraulic roller with 222/228 duration @ .050" 0.51"/0.51 lift and 110LSA that or 218/228 @0.050" 0.51"/0.51 lift 110LSA. ("Sweet Spot" is between 2500-6400 for both cams) Depending on the intake to exhaust flow ratio is, would select the cam between these two.
 
yeah put a cam in there with about 240-250 at .050 and 3.55:1 or better gears and you will have a hardhitting bigblock for sure. try to find a tunnelram with fairly long runners. add a pair of 500cfm carbs they usualy work pretty darn good right out of the box.
a good friend runs a 383csb with edelbrock heads with just a touch up and about that camsize,3000 rpm stall converter and 3.73 gears in a malibu and it ran 11.50s in the quarter while being a very reliable smokemachine on the street. dont listen to all those people that says tunnelrams dont work on the street,they flatout works
 
That's too much cam for a street bound 383 with a tunnel ram. You want a good vacuum signal for decent idle quality. Talk to 340 8BBL up there. His cam is mild and his runs like gangbusters. I think he's runnin the magical crane 222/234 @ .050 hyd grind.
 
JGC403 said:
In that article they used a cam with duration of 239/247 @ 0.050", .573"/.597" lift and 110LSA. I think this one and the one suggested above might be a little to hot.

What do you guys think of a Hughes hydraulic roller with 222/228 duration @ .050" 0.51"/0.51 lift and 110LSA that or 218/228 @0.050" 0.51"/0.51 lift 110LSA. ("Sweet Spot" is between 2500-6400 for both cams) Depending on the intake to exhaust flow ratio is, would select the cam between these two.
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if i could afford to run a hyd. roller id have gone that route.both those cams look decent to me.small carbs and a good timing cure with lots of initial will help.
 
I runing a 440 punched to 496 590 purple cam full ported 440 source heads 2800 to 3200 torque convertor it stalls at 3500 at the track.The torque curve is 3500 to 7000.Im running two 600 eddys and drive it every were.Turns 11.0 still tuning changing to 456 /88s to high.O i run off both carbs all the time.Its fun to drive
 
with a true 10.5:1 compresionratio and ironheads that engine will need some duration to keep the cylinderpresure at a sane level and stay out of detonation. thats one of the reasons i would put some cam in that 383,another reason is that i think it will idle fine.

im running a 242/248 at .050 solid roller in a 340 and i dont consider the idle being a problem fairly stable in gear at about 800rpm with an autotransmission,cant see it being a problem with a manual trans car.
 
Well, it's not really the duration. It does need some, but it's how late the intake valve closes. Close it later and you bleed off pressure. Close it sooner and cylinder pressure goes up. A long duration might not necessarily close the intake valve late enough. It all depends on the event timing.
 
Hot Rod Mag just did an article on tunnel rams. End result was it showed high RPm power increases but also showed it didn't hurt the lower and mid range numbers.

Personally I only want to deal with one carb and find the tunnel ram to be more about looks. If you want it though it can be done.
 
340 8BBL said:
its all in the tune......
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Very true.....if you can not figure it out find someone who can. An old neighbor of mine had raced with a tunnel ram on and off for years. Local hot rodder had a street car with a BBC with a tunnel ram. Was a complete pig. My friend spent a weekend or so changing the cam, tweaking both valve & ignition timing and going thru the carbs. When he was done the car ran fantastic. Would idle without loading up. Pulled like a train....the tickets he got from no hood and the height of it made him pull it off......
 
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