topcat572

Im running a swing arm with a long stroke 572, 3.89 rear, 1.80 trans, 33.5 tire,4500 stall. I know this is consertave, but doing 1/8 mile seat time now. Ran 5.31 @128 with 1.18 shorts. Still have 1 inch of throttle left. QUESTION? How far below the actual stall do you set the chip for hardest launch? Thanks, lot of smart people on here.TC

hammertime

Every combo reacts different, I've had some that liked 100 below stall and some that are 2500rpms below on the launch. What kind of car is this in ? 4500 stall seems very low to me for this combo.

topcat572

David thanks 4 the reply, see u on here a lot.Its a worthy swing arm. Have been running a 4400 chip. Wasnt a lot of time to test everything. Yes conserative, crashed the 27 wheelstanding roadster twice. Came back with the new digger.Just working our way back,thanks TC

hammertime

I understand, I was thinking when you said swingarm you were talking about a dragster. I've found on all my bbc stuff in my cars that 4000-4600 launch works very well for being consistent yet fast. I think you combo would be a lot more consistent with a higher stall convertor. I now run a 6800 stall spragless and launch at 4400. If you need any other info on anything feel free to PM me.

shawnp

Wow. That stall is way off. My guess is 6200-6800 would be a better place for you. Is it an 8 inch or 9 inch convertor. Sounds like you are driving right thru that convertor. What carb, cam, etc. We launch our swingarm at 4400-4600. It is a 548 with a 5800 stall single 1050 alky carb. It runs short time of 1.16 and runs 5.0's 4.90's with a 6600 shift. Where you shifting at?

3dracing

I,ve got a mullis 4-link my daughter drives, same size motor 34.5 tire 4.30 gear we launch at 4800 and have 1.09 60'.


Steve

topcat572

''thanks again, i knew the stall is too low. this is a 4.5 x4.5 572 12 yr old shafiroff combonation. dart funnelram with a book 1150.dart 360 with super mod porting. cam is a c rane 791/731 with intake 297@50 and 310@50 on the ex.He recommended a 5500 stall. I ordered a bte 9'' with the 4500 stall because i didnt want the violence we had in the old car just starting out. max rpm for this combo is 7000. i dont understand how you can run a 6400 or up converter on a 7000 motor. i know yall know yall stuff, yhats why im here. also, were still on 3/4 throttle, but are ready to turn it loose as he gets a little more seat time. i also went with the 3.89 for the 4.5 stroke because most of the 4.25 stroke guys seem to run the 4.11?

topcat572

shifting at 6400, didnt play with that yet.

hammertime

IMO your motor all out in a worthy (which is light) should go 4.8's easily. I may have went with the 4.11 gear just to get it in the powerband. when you are ready to turn it loose I would shift it @ 7000-7200, and get a 6000-6200 stall spragless convertor 9" and your good to go.

shawnp

I agree with Dave except on the spragless convertor. Have not been a big fan of them but I know Dave has had exceptional luck with his. To each there own. I think the gear is a little much as well and suggest the 4.11 gear.

The cam that is in our 555 is a Reher Morrison uses. It is an Erson custom ground cam. Duartion is 284/298 and lift is 808/765 at 112 center. It will be a 7/4 swap set up. Your cam could be a little bigger but is a decent application.

Your heads may want to see a little more RPM to work the motor. I am sure Dave is suggesting more RPM at the shift point for this reason. Even at 7000-7200 that is conservative for that head. What size header are you running? I would think the 2 3/8" should be what is on it.