Acceleration Question

[AZCOWBO]

I waited until 7:01 this morning before firing up the "Billet-T", to appease my neighbors. I cruised around town for about 45 min. What a kick!

My question is, keeping in mind, that I have a 327 punched out .030 with domed pistons, Weiand Ram intake with a pair of Demon Jr. 525s, Mallory dist., high-performance mech. fuel pump, 540 cam, 2200 Stall converter, and a 2.88 diff., so until I change it to a 3.73, I shift into 2nd. very quickly upon takeoff.

We digitally set the timing and it is right on, and tuned in the Demon Jr. 525s. The motor runs perfect upon gradual acceleration, but if I punch it just the slightest, it stalls out, as if I immediately turned off the ignition. Any suggestions?

Ron

 

[Francis Blake]

That's a lot of carb for a 327 if they both open at the same time my guess is your loseing vacum. This will be interesting to know when you get it worked out.

 

[donsrods]

I had a similar problem when I got my T running, it would hesitate badly if I stabbed it then take off. Bumped the timing up and set the accelerator pump to shoot more in and it went away.

Don

 

[RPM]

You said the timing is right on. Right on what? Factory specs won't work with that motor, it will want a lot of timing and with domed pistons . It will probably want racing gas. I would think 18-20 deg of initial timing and about 36-40 total timing all in by about 2500 rpm. Then if you still have a bog you will need a lot of pump shot.

 

[one finger john]

The thing is that the Demons are small enough and your cam (if I remember hearing it on a video) healthy enough and they are in and on a relatively small engine, the change to lower gears makes sense. Actually the only answer. The 327 doesn't have the bottom end to pull away smoothly.
Having said that, the part where you have to get into 2nd gear quickly is a bit troubling. Does it need a trans shift adjustment? Does the trans have sufficient vacuum to operate? Could this be a vacuum problem?
Also I echo what RPM has said, although I would run a max of 12 degrees initial w/24 in the dist. for a total of 36 degrees (never more total advance). See engines/drive train, the recent thread on Roosters pinging problem and how I would check and set the ignition.
Also, and this could be the real problem, do the carbs have vacuum secondaries? Are they opening up too quickly? To isolate, run on the primaries only. Block the secondaries and get the primaries sorted out first. Then whatever spring you have in the vacuum secondaries, put in a heavier one (actually two, dual carb). And tune from there. Car Craft recently had a good article on tuning a tunnel ram for the street and the NTBA site in their tech section has useful info.

If you think you're having fun now, just wait til you get 3.73's in it.

Warning ! - 3.73's might make carb./ignition problem worse !

Get it smoothed out first and THEN change gears.

And if all else fails, contact a known professional in your area and invest in the proper repairs.


John

 

[Ted Brown]

Nothing wrong with the gears you have now... Sounds like the tranny needs adjustment, or hold it in gear till you want it to shift,,, CRS forgot which trans you have? a 400?

 

[AZCOWBO]

I have a 1963 T-350 out of the orginal Corvette the motor came from. I adjusted the low range for longer duration. I need to change out to a ratchet shifter, as my current one has only P-R-N-D and no way to lock it into low. When I am setting still and reving the motor everything works fine. It is when I punch it on the street when it falters. Keeping in mind it is in 2nd. or 3rd. under load with the 2.88. At 45MPH, I am turning approx. 1700-1800 rpms. Gradual acceleration is not a problem.

 

[speedkills502]

If you don't have any rich problems. I would rich up the primary at the accelerator pump just like Don said. This is a common problem with tunnel rams if it helps but still has a slight flat spot go to 50cc pumps in the primaries.