guys i get to make the call on one of two convertor///it is a long story but ill try to get in as short as possible my buddy has a a body buick ive been helping on it we are running at 11.30 in the 1/4 the problem is we started the year at 11.30 and we cant inprove at all ive been saying its the torque convertor so he has borrowed 2 one is a4500 one is a 5000 and he told me to call it ///soHELP PLEASE i feel the 4500 one but his other buddies say the 5000 //they feel the 4500 one will bough it off the line and at each shift drop it out of its power band ill give you as much info as i can and then ask you guys for your input ///#1 it is a SBC/but it is in a great looking skylark /////thats the only downer it is a 400 balanced 10 to 1 com// heads that flow310 with this cam aroller670/674-dur 272 on a 106 lobe installed at 104////we just changed to this cam the old one was a flat tappet and with that cam it dinoed 594 hp at604 lb of torque///the rest of the set up 28 by 9 m/t slicks 390 gear car weight is 3420 w driver///he leaves at 2000/2400 has a ave 60 ft of 1.55 runs 118 mph and as i said 1/4 time is 11.30 sooo we have changed the cam bought new slick bought new shocks install a fuel cell/all new fuel line 3/4 ///b/g elect pump/ have two tricked carbs/one a quick fuel 850 wet we have switched back and forth and it makes no difference weve moved the timing 36 to 38 no difference SO wepulled the trans it is being freshened up/some burnt clutches were found and thurday nite we will put it together but do i go with my gut and the 4500 or not waiting for some input///thanks pete////oops i got the numbers wrong on the cam the right numbers are 640by 645 dur is276 at 50 //the rest is correct //o the other carb is a 850 chuck newton thanks again for input pete
What size are the converters Pete:10", 9", 8"? If they are both the same size and make the 5000 will be looser and will cost you some MPH and ET at the top end. Cheryl
I would be collecting parts of my motor from the track! What RPM does the motor make its power? I would guess that it makes power from 5000 to 7500. Needs more gear. Chevy guys run 4:10, 4:88 and such. I remember running 5:xx gears but I do not think that is done as much now.
to answer both ?? the 5000 is a 9 in the 4500 is a 10 in/////as far as power range we have not dino the eng with this cam but i guess you are about right 5000 up but hes shifting at 7000 so theress not much to work with thanks for the input pete
Without knowing the engine compression, intake manifold, header diameter and length or seeing the cam card here's what I'd do based on building quite a few SBC's for others. IF the mechanicals of the motor can support it, move the shift points to 7500, which is where that cam needs to go to, use the 5000 stall and launch around 3000 off a footbrake. IF it has a transbrake, use the 4500 and leave with the thing stalled maximum. Shift at the same RPM. If raising the shift points isn't an option, use the 4500 and hope for the best. 5000 will be too loose. You'd spend most of your time spinning the converter and not the wheels. God luck.
Personally, I would go with the 10". And you need to up the launch rpm's. I think the gear is a little shallow also but the slicks are short. With the dyno numbers you have, I think your leaving some on the table. Good luck............................
thanks to all who answered this post i thought you deserved an update we diecided to go with the 4500 BUT aswewere ready to bolt it up we found we had no clearance(the conv was pressing on the flywheel)that is a no no so we pulled it a found this conv was for a setup that you use a rear eng support plate SO that forced us to use the 5000/we put it in buttoned it up and went to the track ////the air was good the sun was out the temp was 60 we put the G N carb on and put larger jets in it ran a 1151 car left ok i dont have the slip here sorry but my kid said it didnt run that well so we put the Q F on left the jetting as it was ///it ran a 11.21/ 60ft was 1.52/////and we thought we were on our way the plugs were very white almost no color so we steped it up 3and 3 to 82 and 86 jet size it ran11.28 /60 ft was 1.57 and we quit ////had to get home sweetest day LOL so wehavent made much progress and are still thinking the convertor is to much(he said shiftind at 7000 the tack dropped back to 6000 2to 3 shift ) SO thanks ///o one more thing we are talking of dinoing the eng then going to a conv guy with all the numbers and have one made for this thing all it takes is money right lol thanks guys we didnt solve it but theres always next year pete
