Where to start...Tunnel Ram T Bucket...

Ok, I've posted pics of the car before but never asked for advise on tuning it.

1923 fad T, 1964 300hp 327, Comp Cams 12-242-2 (.477 intake / .480 exhaust) (268 / 280 duration), Weiand Tunnel Ram, dual Holley 450s vacuum secondaries, stock double hump heads, long tube tee bucket headers, old style distributor with new electronic internals.

Carbs are set up with 57 mains, 5.5 power valves, 21 squirters and yellow secondary springs. The carbs are vintage mid 1960s. They were fully refurbished by Joe Bunatic in Collinsville, IL when I got them.

It will foul a number 4 NGK v-power spark plug in about 5 outings. Transmission is stock powerglide, stock converter. It made 11 pounds of vacuum at idle in gear.

I just want to clean it up drive wise, it bogs and sputters and fouls plugs etc.

Any help appreciated.

Regards,
Bill Wilson

 

Hey!!! Don,t know if this would help,my set up on a 302 ford with gt40p heads,b-303 cam,pertronics distributor,limefire headers,5-speed stick,3:55 rear,in a 32 glass coupe(2600 lbs)weiand tunnel ram with 2 390 holleys ,#67(.068 hole)in rear carb-#66(.066 hole in front carb) seems the front carb feeds the front 4 cylinders and back carb does the back,6.5 power valve,purple spring,#28 squirter,10 degrees timing at idle-34 advanced, idle mixture screws 3/4 out, stock secondary plate #134-34. search VIDEO of my coupe on this site. I think our motors are close in specs,the stick helps alot,never fowled plugs yet(knock on wood) runs great. Pete

 

I had similar problems with a similar setup. The tunnel rams are great for wide open throttle but can suffer over carburation at idle. They tend to "pool fuel" at low rpm. If she blows black smoke under early heavy acceleration, I would look at dropping to 390 cfm carbs or dropping my jet size. Even then, sometimes the
street manners are not so good. Like everything in the GoFast world, there are trade offs.

 

You might try a much looser converter(higher stall speed).This will get the engine closer to the RPM range that the Tunnel Ram would like, quicker.

 

Hey Bill!! I reread your post and the one thing that stuck out was that your vacuum reading at idle in gear was 11,my vacuum at idle out of gear is 20. put the vacuum gauge inside the car with you and go for a drive on the highway(55 mph)check your reading,if it is down to around 5.5 then your power valve may be fluttering open and dumping fuel in(power valve should only open when you lean into the throttle and make the transition from primary circuit to secondary circuit) it does the same job as the squirter does when making the transition from idle circuit to primary circuit.My vacuum at 55 is 14 pounds then I jump on it and it goes down below 6.5 thats my powervalve. The primary circuit is the most important(jets) for street tuning,get the jets rights then tune the rest(squirter, power valve,secondary spring) Highway driving will get your jets to where they need to be(it takes time) Pete

 

Question: Would modifying the plenum by adding extention tube/tubes from the bottom to the top,effectively bypasing the plenum all together and make longer runners or smaller plenum help?

 

Pete, and all that have replied, thanks.

OK, as I recall the vacuum was a bit higher than 11 when I checked it. Holley recommended halving the powervalve to the vacuum reading thus the 5.5 valves installed. The idle needle screws are out as much as needed to allow it to start without giving it gas and smoothly idle. I did not degree the cam when I installed it and the base timing is around 12* I think, (I need to recheck it). The floats were set properly as well.

Could the metering plates simply be too rich? I can get the numbers for them later. Like I mentioned Joe set up these carbs. They were mid 1960s set up for a low rise 289 Ford dual quad Mustang intake. All the jetting and everything was set up that way (that's what he told me). They don't have any vacuum ports AT ALL on the base plates. When I took the vacuum reading I had to put a 1-inch spacer plate under the front carb and then start it. The engine could be pulling way more vacuum than I measured that way I suppose. The only thing I have changed from Joe's set up was the powervalves. They were at 8.5s.

I like your idea of incremental increasing the jets and squirter sizes via drilling and noting increases in the performance/driveability. However, if it already appears rich then what?

As an aside the secondaries have never opened, holding it in first and romping on it they never even budge. Springs way too strong I suspect.

Your thoughts?

Regards,
Bill Wilson
Lee's Summit, MO
The Turnover 'T'

 

Dump the tunnel, or get your RPMs up. I would dump the tunnel for the sake of better street wise and gas wise.

 

How many turns out are the idle screws at this point, and how much initial timing? Sorry, I see 12 degrees already.

 

just for starters that cam aint very big.those heads may need to be worked and a looser converter.ive run the old 1850s on a ram with no problems on the street.been doing it for over 30 yrs.if the engine is.i dont remember compression ratings for that engine, but all of mine were over 10.5 -1.everyone of mine would idle at around 800 rpms and wouldnt bog as i jabbed the go pedal. but on one engine i did have to run 390s. i dont rememeber why i did it though.any way if you havent fiqured out what to do, ill go out to the old shop filing cabinet and see if i cant find the build sheet on one of them.

 

Smaller carbs will be a big help. PIX! How deep is the plenum? Rear gears?

 

Before I even try to tune it any further, I would swap the converter out for a typical "2800 stall" 11" converter. As others have said, this is not a MONDO cam, but that converter is putting too much load on it when its idling in gear.
Once you get a proper converter, back the idle speed screws off completely, then turn them back in until they JUST make contact with the lever,then go about 1 1/2 turns, NO MORE. Then try a little more initial, maybe 2/4 degrees more. Now set the mixture screws.
At this point, if it wont idle cleanly without turning the idle speed screws in farther, I would look at the ifr's being too large for your combination. Block the idle air bleeds (the outer ones) with your finger, this will give you a good indicator if the idle mixture is too rich or not. Keep in mind, the idle mixture screws DO NOT adjust the air/fuel ratio of the idle emulsion, only the total quantity of emulsion entering the venturis at idle. the actual AFR of the emulsion is strictly a function of the area of the IFR relative to the area of the air bleed.

The manifold vacuum reading you have is lower than I would expect with that cam in a 327. I suspect, the converter change in conjunction with a tad more initial, and getting the throttle plates back into the transfer slots will cure your problem, but if it doesnt, you might have to look at messing with the IFR's, or drilling holes in the throttle plates. Both do the same thing, but reducing the size of the IFR's is getting right at the source of the issue, the holes in the throttle plates are more of a "band-aid". If you get to that point, you can decide which way you want to address it then.

After all this, and the idle is cleaned up, then and only then, if its still bogging at sudden WOT, I would start enlarging the shooters and pink #330 pump cams.

 

Dump the Holleys and put two Edelbrock 500's on it. I am running a similar setup, 331 stroker, aluminum heads, X303 cam, etc, but with a lowriser 2 x 4 manifold and two Edelbrock 600's. Also am using the NGK F4 plugs and they burn the right shade and last for at least a year (I only change them when I want to race it).

Maybe the tunnel ram is causing some issues (I hate them on the street) but I think the carbs may be more of a problem than the manifold.

Don

 

Hey Bill!! did you get a chance to drive at highway speeds to see what your vac # is(just to see that your powervalve is not fluttering open). I was told that the higher the carbs on the manifold the richer the carb needs to be(stock 390 jets are #51-.050 hole,I,m now at #67-.068 hole for the rear carb and #66-.066 hole for the front)I tuned my with the heavest spring in the secondary's so they would not open just to get the jets right then the rest fell into place. I got on the entrance ramp on the highway, stopped,put one new plug then drove at 55 mph for 20 miles to a exit ramp,shut off the engine in neutral and coasted to a stop(checked the plug,went home jeted the carbs and repeated until I got color) Making sure your vac is above your powervalve # so your only driving on the primary circuit.

 

install a hot ignition system

msd. will solve most of your trouble............

 

The metering plates are only going to be of concern if you can pull enough vacumm to open the secondaries.

Most of the time on a tunnel ram I like to run a locked secondary (like the 660 centert squirter uses) or a mechanical secondary at the very least. My experience with a tunnel ram is that it is hard to make enough vacumm to open a vac secondary.

The idle vac divided by 2 for your poewer valve is just a starting place. You may well go up or down .5 easily on them before you get dialed. I would loose the metering plate as well, either get yourself a cheaper plate or drill your metering plate to accept a standard jet. You can replace the metering plate with a cheater plate for about the same price as a new metering plate.

If you are fouling your plugs you may need to think about 2 things 1 is that you are jetteed too fat and the other is that you need to loose the gimic plugs and go to a stadard plug that is gapped properly for your ignition.

 

And the part that the MSD doesn't solve can be gotten rid of by ditching the tunnel ram.

Bob

 

Lots of good advice here.
my 2 cents is change out the converter first. At least a 2500-2800 stall if not more.
With the cam and tunnel ram, it's going to be soggy down low. Also Ts are too light for a stock converter. How many RPMs do you loose from N to D?
Then when you aren't bogging the motor down, give it 12-15 degrees BTDC.
After that, get the idle so it's fairly happy. If you can find a gas analyzer near by, it will be a help. A dyno with one even better.

 

x2. I forgot, add that to what I said above. As far as ditching the tunnel ram, yea, if your some half-assed, whiny mommas boy who is completely incapable of rudimentary tuning, then I would agree with that advice. Otherwise, theres no reason whatsoever you cant make a tunnel ram and holleys work on this combo. If I had thought that you WERE some half-assed, whiny mommas boy who is completely incapable of rudimentary tuning, I wouldn't have wasted my time posting on this thread...

 

Priceless! Another thing is that the Edelbrock - Carter Weber carbs have the general benfit of a simpler design and the "no gaskets below the fuel line" BS (for guys that drive slow enough that the fuel sits level in the bowl at all times) there is only so much you can do with metering tubes and spring swaps. Unless you are doing something really trick with one of these you'll never have the same options to dial in an intake such as a tunnel ram as you do with a Holley.

 

oh yeah i forgot. or ot nova runs a tunnelram with 2 600 edelbrocks now. they run good but we cant dial them in like we could with the old holleys. damn i forgot all about that.

 

Follow Falcongeorge's advice:
"Before I even try to tune it any further, I would swap the converter out for a typical "2800 stall" 11" converter. As others have said, this is not a MONDO cam, but that converter is putting too much load on it when its idling in gear.
Once you get a proper converter, back the idle speed screws off completely, then turn them back in until they JUST make contact with the lever,then go about 1 1/2 turns, NO MORE. Then try a little more initial, maybe 2/4 degrees more. Now set the mixture screws.
"
And:
"The manifold vacuum reading you have is lower than I would expect with that cam in a 327. I suspect, the converter change in conjunction with a tad more initial, and getting the throttle plates back into the transfer slots will cure your problem"

I betcha you've got the idle screws (not the mixture screws) open too far. OR a huge vacuum leak.
Ralph

 

Keep the tunnel ram they will work if you tune for it. One of the best suggestions I heard was changing to the 2800 stall converter, it will definitely help. About two years ago Hot Rod mag did a really good article about tuning a setup just like yours, try doing a search on their website, once u get those carbs dialed in you will be loving that converter, it will transform that car! If you haven't driven a light car with a loose converter and a steep rear gear you haven't really experienced a kick in the pants!

 

I'm not sure if you are serious or being sarcastic here. I never said it was impossible to make a given engine run well with an Edelbrock-Carter-Weber or any carb for that matter just that you have more available options with a Holley four barrel in this sort of tuning adventure to give the engine what it needs.

 

on youtube in car gopro video

Model A vs. Henry J Eagle Field 2012


2x4 660 holleys//327

 

nothing better than a tunnel ram on a t bucket.holley power valves are sensitive to damage from backfires and so on.look into it.if your vacuum is at 11 at idle,split that number.being 5.5 cfm per carb you are opening your power valves at idle.try adjusting your timing at idle by best vacuum reading first and recheck ,then get smaller number pvalves.a little at a time.

 

Try properly setting the idle mixture and either replace the holleys or tear them apart and block off the power valves. You probably backfired up through the carbs at one time and ruptured the diaphragm on one or both.

Scott

 

The only time I recommend blocking the power valves on a holley/tunnel-ram combo is if you are running the carbs sideways ie dual double pumpers.

 

I had a 289 with a tunnel ram and 2 holleys on it 13 years ago ... never could get it off the line right. Real weak until it hit 3000 rpm then it came alive! I was just a broke kid and never could afford a higher stall converter, so I would do 3500 rpm then drop it in gear... Didn't work to bad... I ended up swapping tops of the tunnel ram for the single plane... that helped quite a bit.

 

Hi!! Good point about the power valves being damaged with a backfire,If the are leaking then they are dumping raw fuel when driving on the primary circuit(fouling plugs)the new carbs have blow out protection and you have older units. Pete