i just got my car (74 firebird) back from getting a new tranny and converter installed. this converter is a custom-built 8" unit that should flash to about 4800 on my current setup. this is the converter that i hope will help me to run in the low 7's (1/8 mile) on my upcoming solid roller setup. it is a totally custom piece with all the bells and whistles, including a steel stator. with the old converter (10", 2500 stall), i had all of the timing (36*) coming in at the advertised stall speed. launching at ~1600~ rpm i was able to pull low 1.70 60 ft. times in good conditions at ~3900~ lbs. race weight. i'm trying to decide where to bring in the timing with this new converter. i'd be interested to hear people's opinions who also have high stall speed converters in their cars. i was thinking of bringing in all the timing at 3000-3500 rpm. my current cam is a comp EE hydraulic flat-tappet with these specs: 230/236 duration at .050, .538/.542 lift on a 110 LSA.

just so you don't think i've gone totally mad by putting this converter in the car now, i am going to a solid roller (262/268, .580/.585, 110) setup this winter. i'm hoping to run in the low 7's at my current weight on ET streets and the stock d-port heads.

thanks in advance for your help.

 

Given where you're flashing to I'm gonna say that it almost doesn't matter what you do. You're still gonna be a full advance when the pedal hits the carpet. You might slow it down to keep it stable at the other end of the curve, however- curb idle speeds (which I'm assuming will be in the 900-100 RPM range with that cam). It's tough to get a decent idle if the centrifugal advance is floating around up and down at durb idle speeds.

 

i talked to the owner of my local speed shop last night. he suggested "locking in" the timing by rotating the distributor 180*. this would give me 36* timing no matter what rpm the engine is turning. anybody had any experience with this method? i have a powermaster starter, so hot starts (as a result of that much initial timing) wouldn't really be a concern.

 

I have the distributor locked out in my 68, with no ill effects. My distributor is an MSD though. I don't know about locking out a stock distributor. Make sure whoever locks out your distributor knows what they are doing, because you don't just rotate the distributor 180. That would just make your engine out of time.

 

my distributor is an MSD pro-billet. can you describe exactly what has to be done to lock out the distributor? i was told to take the gear off the bottom, remove all the weights/pads/springs from the top, then turn the shaft 180* to lock in the advance. this sounds fairly straightforward to me, but if it's more complicated i'd like to know how much expertise is needed before attempting it.

 

I'd just leave it as it is and make a pass. Then just adjust it from there to get your best pass.

The stall converter change shouldn't really affect the optimum place for total ignition advance, unless you start getting some detonation during the launch..then you might have to raise the RPM where the timing is all the way in. When you put the new cam in, you'll have to play with the timing...but I don't think you should have to mess with it just changing the converter.

-Dave C. '97 Z28

 

dave- that's probably what i'll end up doing. hopefully detonation won't be a problem since i run straight 110 all the time. i did get more detailed instructions at the speed shop today, but i'll probably just wait until the cam swap to lock out the distributor.

 

[QUOTE]Originally posted by rumair
my distributor is an MSD pro-billet. can you describe exactly what has to be done to lock out the distributor? i was told to take the gear off the bottom, remove all the weights/pads/springs from the top, then turn the shaft 180* to lock in the advance. this sounds fairly straightforward to me, but if it's more complicated i'd like to know how much expertise is needed before attempting it. [/QUOTE



That sounds about right, you had me wondering in your first post, I just wanted to make sure you weren't gonna throw your timing off . When you pull the gear and all the weights and springs off, there will be a small stud with a nut on it, it also has an advance bushing on the stud. Take the small nut lose, lift the distributor shaft, turn 180*, the put the stud into the small hole in the plate. Put the nut back on and your ready to go. As I said, I have run mine locked out for years,and have no problems. Good luck.