Tuning Trouble Tunnel Ram with holley mech. secondaries

Hey guys,

I am having some trouble tuning my tunnel ram setup and was wondering if any of you had some input? The biggest problem/ symptom is when I give it anything over 1/3 throttle from idle it stumbles like crazy, and if i dont take my foot out of it, itll stall out.

if i throw a small rev to get it above 2000 and then punch it, its a neck snapper! The issue is unresponsive to changes in timing and regular idle screw tuning.

I have read elsewhere on the internet that this is a common problem with the holley 450 cfm with mechanical secondaries. (no secondary pump) and i have two of them!

Ive been thinking maybe i need larger jets? or higher idle speed?

My cam's rpm range is from 2500-6800 and my idle speed is set to about 1100 rpm right now. ( it is a four speed)

isky cams calls for 800 cfm carb and 2500 stall converter just for a little f.y.i.

ANY suggestions?

and to keep the thread interesting, Ill post some pictures of the trouble maker too

thanks for your time guys


-Nick-

 

ok i lied. it isnt letting me post pictures. so ill post them tomorrow

 

Sounds like the way my old car acted, i had to change to 50 cc accelerator pumps and the largest spray nozzles i could get. I was getting too much air (all 8 barrels open instantly) and not enough fuel mixed with it.Hope this will help some.

 

oneratfink57, I was going to run the 450's on my TR setup but switched to the double pumpers because of the secondary pump. When talking with Holley they informed me that approx 40 degree is when the secondary throttle blades start to open and without added pump shot it falls flat and that is why the 50cc pump is used. Here is Holleys pump cam lift to throttle position chart http://www.holley.com/data/Products/Technical/PumpCamGraph.pdf You will notice that the brown and yellow cams That come in the 50cc kit http://www.holley.com/20-11.asp not only carry past the 40 degree but still deliver volume. Also here is a vid on accelerator pump tuning kinda basic but a good refresher http://www.youtube.com/watch?v=k-Nx5HEzvlY Each engine has different requirements and when running a TR you my need a bigger squirter (and possibly the "hollow" screw) due to the larger volume size of the TR. Also the TR likes more initial advance 15-20*. The tunning might take a bit but is worth it in the end

 

Thanks for the video 65 imp ss, very informative!

Ill order some 50 cc pumps and see if that does the trick. Ill post up the results tomorrow or thursday depending on when i get the pumps in.

 

what motor? what jets? what squirter size? what exhaust?

 

350 sbc, not sure the jet size they came in the 450s when i bought them. The accel. pumps are 30 cc and i have fender well headers to 2 1/2 inch exhaust to 3 inch bullet race mufflers

 

65 imp ss

The 50cc pumps and the larger cam worked very well, i still have a SLIGHT hesitation probably due to some improper tuning. I am going to adjust the idle screws as well as i can tomorrow afternoon and then maybe up the squirter size if needed. thanks again for the tuning video and the advice

 

Glad to be able to help.

 

here is instructions that came with mine backintheday
then a mag article about dyno test w/450's
other photo just a tease.........

 

sorry could not get scan 450 article to work.........

 

Alright i'll bite, don't leave us hanging on that intake setup (which is sick I might add) give us a little more to go on!
Can you try and rescan 450 dyno test? If not what mag,year,month is article from?

 

bad ass engine. Looks great. Yeah, up squirters too much air makes it hesitate when you open them up.

 

i tried tuning with the idle screws today and still has a slight hesitation but only when I REALLY romp on it. So i guess im upping the squirters tomorrow. i have .031's now. I read somewhere to go up 3 sizes at a time (is this accurate?).that would put me up to .037's.

gasser john, that tunnel ram setup looks fantastic. if you could rescan the 450 dyno test, that would be great.

 

Yea the holley vid suggests going up 3 sizes but you might end up going with the 35's http://www.holley.com/types/Pump Discharge Nozzles.asp or using an index drill bit and enlarging a smaller one. I would just try the 35's and go from there.
And x2 on that 450 dyno info.... or what magazine,year and month was article in????

 

yep i bought the 37;s today and sure enough i went two steps back again. Ill have to try the 35s. Damn those nozzles are expensive...

 

will try dyno test article

 

It's too bad you don't live close by.... I have the Holley accel pump tuning kit... I could have dialed that tunnel ram in for ya..... I'd also hook up a vacuum gage and adjust the screws for the highest idle vacuum readings..

 

I had that problem on my 56 i took a small hand drill and enlarged the squirters I cant remember how much but it was a hole bunch it took care of my problems.

 

spacers made by dashman.com hamb member
made some out of wood years ago added extra rpm...
had ben at dashman make phelonic spacers also....
photo with double spacers is with old geardrive 3barrel...
once you spend some time looking at the tunnel ram with spacers they don't look rite without them........

 

Hey guys.

Whenever i get it to idle properly and rev well from idle (1100) to 2000 which is the rpm range it was hesitating before, the car stalls when the engine is under load (within that rpm range), Any suggestions?

Just a recap. as of right now i have the 50cc accelerator pumps with .037 pump nozzles. I was never able to grab a set of .035 pump nozzles but that was going to be my next step. Oh and also it turns out it was pretty far advanced before, haven't put a timing light on it yet but it seems to be ballpark of where it is supposed to be now.

 

Stupid question/ realization... Its probably because i have 3.07 gears in it now huh?

when i swapped rearends i didnt bother to check what gear ratio it was and when i drove the car i noticed it was relatively lower than what it used to be. Just counted them and it came out to be about 3.07

 

ORF57
As you probably already know you are suffering from a lean condition. Throttle movement is allowing more air than you have allotted fuel for.
You may need to also change the cams on which the pump rides on.
You can also adjust them. Set them up so you have max squirt by this I mean tightening the adjustment so that the pump will produce the biggest and longest squirt. Also set them up so that any ANY throttle movement produces a squirt. Also

 

I had similair problems with my bucket and found playing around with power valves in carbs and giving it as much initial advance as I could get away with made huge difference,