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Old 10-06-2013, 07:55 PM
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72 Nova 350

Hi Folks, A few months ago I purchased a 72 Nova with a 350 supposedly bored 30 over. The engine has a tunnel ram with 2 Holley 450s' that run really rich no matter what we do. Unfortunately I do not know the crank or cam size. I think something is not matched up. I am no mechanic, but I can do most external stuff. Also, I was thinking about swapping the motor for a 383 stroker crate motor with 400+ horsepower. Any suggestions?

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Old 10-06-2013, 08:08 PM
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I miss my 72 Nova
As you already know without knowing the cu in, whats in there, who built it, and all the other important stuff, it's all a guess and will probably never be what you want unless you start over...

It happen to me last year with something I bought, motor looked amazing, ran amazing, had amazing hi end parts, but it was just to dam slow for me so I sold it. I've been kicking myself in the butt for a yr for not putting a 396 sbc in it. You can get a 396 sbc thats basically 500/500 for just a tad over 5K Brand New from Jegs. Hell I lost more than that when I sold mine
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Old 10-06-2013, 10:19 PM
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full tune up time
carbs come off and apart,see whats nside.
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Old 10-07-2013, 05:31 AM
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Thanks guys, yesterday we installed an Edelbrock dual plane intake with a Proform 750. The engine ran much better but still has a slight exhaust backfire when its first fired up. Even when it warms up there is a slight backfire and stall from 0-full throttle. Also, nowhere near the power of the tunnel ram, even when the TR was running crappy. The TR would fall on its face from 0-full throttle every time.

We tried rebuilding the carbs on the TR before the swap, and we still couldn't get it dialed in. New plugs, wires, etc. Maybe I should try a new distributer. The motor is 355 ci, but no idea of cam size.
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Old 10-07-2013, 06:32 AM
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You really should have an idea of the cam specs, static CR, etc before attempting to tune. My guess is that you either have a vacuum leak, very lean carb and weak pump shot, and/or improper ignition curve and initial timing.
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Old 10-07-2013, 10:00 AM
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does that mean you have a cheap T.R. for sale with a couple free carbs?
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Old 10-07-2013, 04:07 PM
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most of the issues with tunnel rams result from the wrong ignition timing curve.
Those 450cfm tiny carbs are not well suited to a tunnel ram if you actually want to make power.

Tunnel rams like a lot lot lot of initial spark advance at idle.
We're talking 24 +deg at idle.
A stock distributor needs to be modified to allow this.
If the cam is big then just lock out the distributor timing curve alto gether.
set the locked timing at 34-36deg BTDC.
Now reset the carbs for correct throttle angle at idle and reset the idle mixture screws for best idle vacuum and idle quality.
Those 450's are junk on a tunnel ram for serious real power.
Get some 650 or 750 edelbrocks or some 650-750 holley double pumpers
Or get the real deal 660cfm centersquiter holley carbs.

If you reinstall the tunnel ram with decent carbs and fix the ignition tune up problems ( spark plugs/ wires, cap/ rotor) and correct the ignition timing curve you can get the power back and it will perform very well on the street.
But don't expet max performance from the 450cfm carbs.
They are not a good carb set for a tunnel ram at all.

You can and will get great results both power and drivability, with a tunnel ram. But not when using those carbs on it.
You will never really get it right with those carbs.
The tunnel ram is not the problem. Its the carbs.
and the distributor advance curve set up.

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Old 10-07-2013, 04:28 PM
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Does this car have a stock low stall torque converter?
That is going to be a issue.
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Old 10-09-2013, 05:37 AM
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Thanks for the response, after digging a little more I found the distributer has already been changed. The springs and weights are already gone and it has a small bolt locking the thing where the springs hook up. we used a gauge to find the vacuum on the carbs and all we could get from it was around 5lbs. we set the timing to 45 degrees. It seems to run alot better but the torque is still crappy. It wont light them up like it should, and still sluggish from 0-full throttle. I really want to buy another carb for the tunnel ram and see what happens.
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Old 10-09-2013, 05:39 AM
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Oh, and the converter is a 3200 stall
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Old 10-09-2013, 06:36 AM
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45 is too much timing.You will need to varify the timing marks on the balancer.
post a video of the car,it might help.
re slugish? is that with the T.R. or new w/e you put on?
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Old 10-10-2013, 10:25 AM
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I agree with F'Bird88 on his comment pertaining to the 450 Holleys on a TR. I have them on my 327 with a TR, and I spent a lot of time tuning and changing things to get them to run well. The biggest problem they have is they are mechanical secondaries, but have no accelerator pumps on the secondaries!
If you check your engine vacuum, you might find it's low enough that the power valves are opening at idle, and you need to go much smaller to make the Holleys not run rich at idle.
After changing power valves, jets, accelerator pumps, nozzles, accelerator cams, etc., I have mine working great. But I bought two 600cfm Holley vacuum secondary carbs to use on my BBC TR engine, and simply bolted them on and they run perfect out of the box. Only change I plan for them is rejetting them to get the mix a little richer, as they run lean with my headers open at the drags.
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Old 10-10-2013, 03:55 PM
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Vinnie its swapped out to the Victor Jr intake with a pro form 750, both brand new. We fooled with the timing and we just cant seem to get it right. Maybe I should purchase a new distributer.
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Old 10-10-2013, 05:08 PM
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Quote:
Originally Posted by Spalding 72 Nova View Post
Vinnie its swapped out to the Victor Jr intake with a pro form 750, both brand new. We fooled with the timing and we just cant seem to get it right. Maybe I should purchase a new distributer.
Before you buy anything, verify TDC on your balancer.
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Old 10-10-2013, 08:01 PM
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I use a Victor Jr intake,I dont recommend them unless you have a hot engine and like higher RPM,and or a larger engine.
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