HELP with 440 Dual Quad Tunnel Ram

Im starting to put together A 440 Dual 450 mechanical secondary Holleys double pumpers on a Weiand Hi Rise Tunnel Ram, and an Intake .507 Lift & .284 duration cam with Automatic 3 speed 727 with a 2800 stall, In a C Body 1968 Plymouth Fury weighing in at about 2 tons. Anyone know how this is going to act or any issues in going to run into? I'm also putting on 1 3/4 headers to 3 in collector to 3 in out the back through a set of super 10s. Only thing is I may not be able to change yet is the 2.76 rear end on the peg legged rear. Any and all responses with be greatly appreciated thank you!

I wouldn't run the 450's. Dual 650's minimum. Wait for other opinions though.

Compression?
I ran a tunnel ram,ran great.
Agree on more carb.
Might consider a little more cam depending on other components.

personally I would go less cam. that fury is heavy. small tube headers and a smaller cam would be your best bet. I think 450s would be fine, if your just cruising it.

Weiand makes a great tunnel ram, but I wouldn't use carbs with mechanical secondaries on that heavy car and those gears. I'd suggest 600 carbs with vacuum secondaries, if not you're looking for a bogging engine when you get on the go pedal.

Why is it the guys with the motors that could use a tunnel ram use a large singal four barrel and the guys that sould be useing a 750 want to use a tunnel ram?

You need a cam with 280@.050 + duration, 5000 stall converter, 4.88 gears and a lite car.

The 450 CFM carbs are a good choice BUT mechanical secondaries are not. Go with 2 450's with vacuum secondaries.

I've run vacuum secondary 600's and I think the 450's would be a much better choice.

Small blocks that rev high and fast like bigger carbs and mechanical secondaries - lumbering big blocks do not!

People suggesting BIG carbs consider this ... opening the primaries on twin 650's is like opening the throttle on a dominator - the off-idle response will be terrible.

I bought the engine trans combo as is with some specs on the cam and knowing it has 2800 stall, supposedly I was told its all blue printed but I don't know. He said it should be 9:1 compression it's a 1971 440. Also doing some research I was seeing that the 450's work better If they are double pumpers, I don't know never messed with tunnel ram set up. Also low on the funds so changing parts is not very easy option haha. I may be able to get a 4.10 for the rear if that will help the throttle responsiveness at all.

Also thanks for the responses everyone!

I think it's 9:1, that's what the cam requires too so giving its supposedly blue printed I hope it all matches right haha.

What makes the mechanical secondaries such an infamous choice? I keep see this same response to other people's tunnel ram questions. Makes me wish I was able to choose the carbs haha.

I don't mean to be a poop about the tunnel ram, in truth aways thought it would be fun, and back in the 70s I had a freand with one on a 440 that worked pretty good.

And back in the 70s to get 650 hp from a 440 you would have needed a tunnel ram but not today, a 950 or 1050 Holley and a M1 or Eldelbrock will get you there.

So the old tunnel ram is definitely OLD SCHOOL COOL and will Make power if you have the parts under it but be slug and no fun at all if you can't make it work!
Otherwise you can put dog collar around each stack you have on the carbs.

With the mechanical secondaries, once you floor it all the throttle blades open right up, you lose air velocity and vacuum signal to the carbs and they don't meter fuel properly, worse at low rpm. A higher stall converter and a lighter car with steeper rear gear help offset this problem.

The 440 weiand hi rise tunnel ram is a great intake, works much better on a 440 than on most other engine platforms. It will run great once it's all dialed in and on a 440 those intakes make for a nice driving car, however as stated, you should consider selling those mechanical secondary carbs.

Would a 4.10 rear help counteract some of that or just try to change the carbs?

"mechanical" secondaries mean they're controlled with the pedal. Vacuum secondaries are controlled by manifold vacuum so they kick in when the engine tells them too.

Either route needs some fine tuning but generally the vacuum secondaries will give you better cruising.

At a minimum, it is the last you could do, your going to need more gear.

I have dual 500 AFB's, B-Body runs like the wind.

The mech sec 450 Holley #9776 is not a double pumper The lean tip in has to be covered by the single pri acc pump. These may be hard to tune on a tunnel ram that often needs a big acc shot.

For a heavy C body, I'd run a pair of (in order of preference)
500 Edelbrock AVS with dual quad calibration #1804
390 vac sec Holley #8007
600 vac sec Holley #1850

I'm also in the 500AVS or 600 VS camp.

I never really liked the 450 single pumpers.

Myself...... I'd probably try and hunt down a couple of clean used slightly older 1850 Holleys, since I don't really care for the new version with the non-adjustable floats.
I just can't imagine spending $300+ each for a pair of those.

I'd probably step up to the QFT 1857 instead, but then you're at over $750 for the pair.
About the same $$$ as a pair of new AVS's.


Obviously if you already have the 450's..... I'd try it and see how they work.

Really their not double pumpers? It's nearly the first thing on the box they're sitting in, in gray bold "double pumpers" but I could be wrong, I'm not sure cause it is the #9776. Can you send pictures on here?

add pics thru the "file manager" below the text box

Don't check the box, check your carbs. If they have accelerator pumps in the front & rear bowls they're double pumpers.

Considering all options I may try to sell the 450's and get the vacuum 600's. What's the best one to get given my circumstances?

Gotcha alright didn't even open the boxes yet haha.

Looks like it's a single then. Yeah I guess I best start going the vacuum route then. Thank you saved me from a lot of headache later haha.

Your 450 carbs are made for multiple carb applications but they're not a good choice with your convertor, car weight and gears. A better choice would be an 1850 600 as listed above.

Just got the 2 Holley vacuum 600's for a nice price. Thanks everyone for your input!

Start familiarizing yourself with holley tuning. I wouldn't expect to plop them on and have them run perfect right out of the box.

Go to this site and get these guys to help you.

Amazing what they will tell you.

http://racingfuelsystems.myfunforum.org/

What kinda power you think I'd get out of this set up? I was looking and it seems like it's around 500 horse but not sure, anyone have a better idea?

Thanks will do!

You won't know how much power the motor will make until you run it I have made 430 HP with a mild 440 stock 446 C.I. iron headed pump gas street motor with a six pack on a DTS engine dyno. I have also made 535 HP with a 451 C.I. 440( .055 over bore) motor with ported big valve pump gas iron heads and a lot bigger solid lifter camshaft with a single 850 Holey D.P. carb.
Cam timing, jetting, exhaust system and a bunch of other things end up helping or hurting how much power a motor can make
I've seen 80 HP loss and gain by changing the cam timing(going from 5 degrees advanced to two degrees retarded) on a engine dyno test
The 4.10 gears in that car will make you wonder were all the power came from
Drive it first with the 2.76 and then the 4.10

Not to mention how much more of a hassle it will be to tune the Holleys compared to a set of Edelbrocks.

The Holleys will have to be removed and the fuel drained to get the bowls off for jet and metering plate changes.
Edelbrock metering rods are swapped easy enough and will only need the top off for jet changes.

If those are stock heads on there, I don't think you'll be far over 400hp. 430 sounds about right with good carb tuning, good cam and ignition timing.

I'm not sure all I know is they're ported and polished. Didn't the factory high performance 440s make 410 at the flywheel? Seems like all this for 20 more horse is kinda low haha.

Edit: Removed my valve cover the other day and it looks like it's the 346 head.

If the heads would really be killing it that much anyone have any suggestions for a set of heads that would work well with my build? With in a mildly reasonable price if possible haha,
The number of 500 ponies is where I'd like to ideally be at.

Start with what you got and then see if your happy or not If not, fix it
Every body wants what they think they want, until they find out what they thought was good was too much
Ask any Hellcat driver

The Weiand tunnel ram allows you to mount the carbs sideways to facilitate bowl removal.

Back in the 70's I ran a 440 in a 64 Fury wagon with a tunnel ram with 2 - 750 double pumper Holley carbs, I did run a 4 speed with 4.88 gears. I didn't have a problem on the street or the track but one thing I do remember is spark plugs only lasted a week and twisted off a lot of u-joints.

Good advice cab, definitely run what you brung before tearing it apart.

Furious, when someone says heads have been ported and polished, that means nothing unless they provide a flow sheet. Enough flow for 500hp usually involves considerably porting, and oversized valves, or aftermarket heads.

Gotcha I'll just have to dyno it once it's all said and done. I don't know what was done and I don't think I can unless I start tearing things apart. The only facts I have is that it's got the the Weiand triple Bug catcher air scoop, 1987-Weiand high rise Tunnel Ram, Dual 600 Vacuum Holleys, 21-225-4 Comp Cam, 1 3/4 headers to 3 in collector, 3 in H pipe exhaust to flowmaster super 10, compression probably around 9:1 assuming stock, and evidence that head work was done on 346 1971 heads (double springs and the port and polish, but as stated no flow sheet.) we'll have to wait and see how she takes it.

I wouldn't expect miracles. I would learn to tune the carbs, put in a good advance curve in the distributor and educate yourself on tweaking the combination. I wouldn't expect more than 350-400HP at the flywheel but run it and upgrade it down the road as you become bored with it.

My only concerns is with a 2 ton car I don't think 350-400 hp will do much for it haha.

Edit: But to be fair it could be perfect, so we'll just have to wait and see.

You're probably only 200lbs heavier than a 68 B-body, so .2 slower in the 1/4 mile. Not the end of the world.

Probably closer to 500 lbs haha, but gotcha like I said well set it all up and see how it is and if I can dyno it it's a bonus.

Thanks for your input and thanks to everyone else who helped me on here too it's been a big help!