Vic Edelbrock really did alot of work getting their streetable TunnelRam together....it works great. I've got several friends that run theirs, no problems. Wieand has a pretty good one also, not to knock Vic's stuff.
Yes, a progressive linkage is the way to go, theres alot of folks from both camps here....you give me that 388 and that tunnel with a progressive linkage and have the guy in the next lane, same setup, dumping all barrels on a straight linkgage.... I'll make him load his motor up or redlight every time!
It works, plane and simply like dumping all your barrels on a 4 bbl. carb. Your engine is a glorified air pump. But. it works on a vaccuum on the intake side. If you dump too much air volumn into that intake, its gonna stall. The only way around this is to bring the RPM's up enough so the motor won't stall out. That is fine on a race car....but it's costly, unnerving and dangerous on the street.
The progressive linkage is like your 4 bbl. carb with vaccuum secondaries. you run on your first 2, then when your motor can take it, you step on it and the rear 2 tilt. Its really over-simplified, the way I'm telling it....but you get the idea.
Back in 77 to 87, I had a 60's shoebox Nova, Tilt fiberglass nose, straight axle under the front, 2 dr., roolbar, the whole 9 yards. I has a tunnelram on a 283 with a dirttrack rollercam in it. It had the best of everything in it. I drove it everyday on the street. My mom and dad would go off on vacation every year, and I'd pull the motor and I had another shortblock, I'd just change them out. Same came same bores same steel cranks....I'd just swap the block cause I'd have new mains, new rings, pump. For the first 2 years....I dreaded coming away from the redlight, cause I'd have to feather the clutch. Really and truely, my rings and mains weren't bad, but my clutch was usually almost completely fried.
I saw a car built buy these folks up north, I had a tunnelram on it, and it idled decent. I got to looking at their throttle setup. And it worked. I set out on making my own, and for the street, it works. When I put that linkage on...I didn't have enough carb and all to feed the 12.5 to 1 compression, and the .750" of valvelift I was running. My throttle response was no longer crisp like a race car. That got me to thinking and studying.
IWent down to a smaller cam grind, then I pulled my heads and went to the open chambered heads. I didn't need pop up pistons, I had those, so I went with the bugger chamers to lower my overall compression ratio. My car got faster, and it was more consistant. Instead of running high 11's on one pass to high 12's the next pass....they got consistant...about 11.85's to 11.50's run after run.
Now, I'm not gonna beat that dead horse agian, the progressive linkage is the way to go. On the closed intakes that doesn't have a balance chamber between the sets of 4 cylinders....you can't run a progressive linkage or you'll starve part of your motor. I ran the early tr tunnels....they weren't known for their low end. Todays intakes have more lowend though.
When you run a tunnel on the street, you have to match the parts. Tunnels are best run on the small carbs and with a smaller camshaft. On my motors, I run the variable bleed lifters...so you can have a little more cam when the oil pressure makes the lifters go into full lift above 2000rpm's. The Idle of these are extremely dependent on carbs and cam.
Its not hard to tune these, you can't just go changing stuff around willy-nilly, you've gotta match your parts. A street tunnelram has more low end than a race tunnelram. A street tunnel will idle down to 650 to 850 rpms, a race tunnel will fall on its face below 1000-1250 rpm. A street tunnel will have a powerband from 2200/2500-7000 and make good power. the whole way. A race tunnel will start at about 3800, start pulling hard around 5000, and all hell breaks loose about 6500+ till about 9500 or so. Two completely different animals that look the same on the outside but are completely different on the inside. Its all in the interior volumns, lengths, radius's and runner lengths/ heights.
There's alot of folks here running them, I run one on my 2nd motor in my old 55 gasser, it has a stroked 454 with 2 780's. Though this next year, I'm gonna build that one into a blown gasser with the Hilborn injectors. Anyway....theres alot of folks here running them and there is alot of info here. And theres a good bit over at the Jalopy Journal and at the NTBA site as well.
