torque converter question

[dawnovsky]

Hi,

I am still investigating my new built driving conditions.
As a reminder, i have a 250-2v head (w/ oversized exhaust valves) over a 200 block, with C4, 350 holley, duraspark and CI headers.
since installation of new cam (clay smith H-264/110 0.480 in./0.480ex. lift)
with 16° advance, i am able to set the engine to perform smoothly and idle perfectly, but the engine die when in drive. i have to advance the ignition about 10 more degrees to keep her from dying in drive.
engine revvs good, no pinging, but seems to lack a bit of power when driving.
A V8 friend of mine as well as someone from the forum (Xtasy if i remember well) mentions it might needs a bigger torque converter.
to be honnest, as i 'm french (we are not really keen on autotransmission in europe) i don't understand shi** about auto transmission.

will it worth the money and time to swap the converter ?
If yes, what model will suit the application best (daily driver, strictly steet use)?

clearly i have inverstigated many other option before concidering the torque converter. My V8 fellow mustang owner who is a pro mechanic and engine builder mention the converter right away after trying to tune the car for 15 minutes.
in another hand he was surprise to seen the engine performs good without pinging with a really high initial advance.

thanks in advance for advices and answer.

 

[JackFish]

I have the 264/274/112 cam with a C4 and it functions pretty good.
My converter was tweaked to about 2200rpm, but I don't think that's your problem.
It has usually been recommended here to go with a 112 lobe center with an automatic transmission.
Have you hooked up a vacuum gauge, and what kind of readings are you getting?

 

[80broncoman]

Are you useing the stock ignition timing specs on your engine?? If so forget those numbers, as your engine is no longer stock.
As long as you don't have any preignition or detonation you are fine to turn up the base timing.

 

[JackFish]

But then your idle rpm goes up.
Which now requires more carb tuning.

 

[dawnovsky]

I have a vacuum reading of about 13-15. this is kind of low, but with that cam is could be normal.
I undestand that non stock engine require different setting on ignition.
What would be a good ignition advance on such a setting.
IMO around 25 (with is what i have) of initial seem like a lot.

 

[jahearne]

Your vacuum reading appears normal for you cam, like you said. What is your idle speed? An automatic requires higher idle speed than a manual transmission. You may have to set you idle speed to 800 rpm or higher with a stock torque converter. I'm running 274 degree 112 lobe seperation cam with a stock converter and 750 rpm idle speed. If this doesn't work I would suspect your carburator needs attention. Holley's are great due to their infinite tunablitly but a 350 out of the box may be too big for 200. I use an Autolite 1.08, which is 287 CFMs on a 250 six cylinder. http://classicinlines.com/autolitecarbs.asp

Good luck,

 

[dawnovsky]

hi,
thanks for the answer .
350 might me too much for a stock 200, but with a 250-2v head installed over it seems to be one of the best option.
car works good with 25 or so initial advance ..
when set lower, engine die on drive ...

 

[jahearne]

I'm running a bigger engine and more aggressive cam with a smaller carb and I get great results. I honestly don't think your stalling is related to the torque converter. When you exhausted all other option, I suggest you take another look at your carb to make sure it is functioning properly.

 

[dawnovsky]

Hi again,

I am just thinking of it now after driving the car for a few miles today.
it seems to run rich despite the fact mixture was set almost to min.
I would now suspect a to big power valve.
My carb is a new holley 350 out of the box. IIRW it came with a 75 power valve. it might need something smaller (55 may be).
As my idle vacuum is about 13-14 the carb might be in between idle and power circuit most of the time while at idle. It would explain the rich mixture andthe hard to tune situation.

 

[FalconSedanDelivery]

What is your Vacuum ( IN GEAR ) ?

 

[dawnovsky]

idle vacuum on drive is about 8-9 in/hg
engine really seem to be to rich on idle and then rev fine once out of idle. (run better with vacuum open (leak) and smoke dark on idle)
once of idle engine rev perfectly.
i would suspect a inappropriate carb power valve

 

[Gene Fiore]

idle vacuum on drive is about 8-9 in/hg

I wouldn't use anything higher than a 65 power valve then.