needing help with launch

Posted By: 65dragnet

needing help with launch - 09/25/11 05:26 PM

Well another wasted weekend trying to get my car to launch. Was a total embarrassment at Monster Mopar. My car is totally lazy off the starting line. I'm at my wits end with it. I've rep laced Msd ign box ,coil, carb torque convertor,went through tranny, two step box, even tried foot braking it and it still won't launch.I know I have probably not gave enough info with my combo for some people to help but this car has had 1.38 60 fts. and now i have 1.58 at best will not spin the tires other than the burnout. Sat. it ran the best at 1.57 60ft 10.34 @ 129.80. I let off the transbrake button and the car drives out like a throttle stop car and then it kicks butt and runs flawlessly through the 1/4 mile no misses pops or anything. I'm beat! ANY HELP APPRECIATED

Posted By: MR_P_BODY

Re: needing help with launch - 09/25/11 06:12 PM

Quote:

Well another wasted weekend trying to get my car to launch. Was a total embarrassment at Monster Mopar. My car is totally lazy off the starting line. I'm at my wits end with it. I've rep laced Msd ign box ,coil, carb torque convertor,went through tranny, two step box, even tried foot braking it and it still won't launch.I know I have probably not gave enough info with my combo for some people to help but this car has had 1.38 60 fts. and now i have 1.58 at best will not spin the tires other than the burnout. Sat. it ran the best at 1.57 60ft 10.34 @ 129.80. I let off the transbrake button and the car drives out like a throttle stop car and then it kicks butt and runs flawlessly through the 1/4 mile no misses pops or anything. I'm beat! ANY HELP APPRECIATED

When did it start the slow launch... did you change
something in the engine... what is the stall on the
converter(when you stall it on the trans brake without
a rev chip)... I had a similar issue when I first
built my car... the stall was WAY TO LOW plus the
valve springs were JUNK so it made no power

Posted By: CHAPPER

Re: needing help with launch - 09/25/11 06:47 PM

Sounds like convertor to me...I spent several $$$ and weeks a few years ago with a problem pretty much like you described. A new convertor fixed the problem.

My car felt like it had a vacuum secondary carb,or, a real slow advancing distributor...which it had neither. Felt like I was chained to the tower till about the 60' marker, then would go fine.

Posted By: Challenger 1

Re: needing help with launch - 09/25/11 07:14 PM

Might try retarding the cam a little.

Posted By: sam64

Re: needing help with launch - 09/25/11 07:44 PM

sounds like when i went to denver the first time,made a 10.90 car an 11.40 car real quick.

Posted By: 65dragnet

Re: needing help with launch - 09/25/11 09:15 PM

Mr P; this all came about when I took my 499 out and replaced it with my known good backup engine,(446c.i.)When freshening this engine I decided to install cam straight up. Big mistake , I did remove two step chip and stalled it against the brake , it wouldn't do 3100 rpms. So I assumed I smoked a convertor. Had the convertor cut open and there was nothing wrong with it. Looked like a new one and by the way this convertor usually stalls 5700 on the brake. Going from there I decided the cam needed to be advanced so I put it back at 4* advanced, where it was originally was.This didn't help either and it still wouldn't stall so I borrowed a convertor and went through tranny just to be sure.Now this convertor will stall 5500 on tranny brake and said now we're getting somewhere. Wrong again! By the way new valve springs too

thanks for your input

Posted By: 65dragnet

Re: needing help with launch - 09/25/11 10:18 PM

Quote:

Might try retarding the cam a little.

Challenger I ,thanks for your reply .I called Comp Cams and ask the Tech people if I should advance the cam timing as to kill a little top end and they agreed I might be in a torque curve problem being this is a pretty big cam for such a small engine. By the way it is290 dur @050 and 650lift , engine is 440 030 over 13.4 cr Indy EZ-1 single plane 950 cfm Quickfuel.

Posted By: 65dragnet

Re: needing help with launch - 09/25/11 10:28 PM

Going to try another MSD distributor next !

Posted By: MR_P_BODY

Re: needing help with launch - 09/25/11 11:23 PM

Quote:

Mr P; this all came about when I took my 499 out and replaced it with my known good backup engine,(446c.i.)When freshening this engine I decided to install cam straight up. Big mistake , I did remove two step chip and stalled it against the brake , it wouldn't do 3100 rpms. So I assumed I smoked a convertor. Had the convertor cut open and there was nothing wrong with it. Looked like a new one and by the way this convertor usually stalls 5700 on the brake. Going from there I decided the cam needed to be advanced so I put it back at 4* advanced, where it was originally was.This didn't help either and it still wouldn't stall so I borrowed a convertor and went through tranny just to be sure.Now this convertor will stall 5500 on tranny brake and said now we're getting somewhere. Wrong again! By the way new valve springs too thanks for your input

Have you done a compression check... it sounds like
a engine issue not making any torque

Posted By: 1_WILD_RT

Re: needing help with launch - 09/26/11 12:53 AM

No help here but thought I'd add some humor... When I first saw your thread title I thought it said "needing help with lunch" & I figured Hey I'm there....

Posted By: 65dragnet

Re: needing help with launch - 09/26/11 12:54 AM

No but I will ! I don't think that's an issue but I can't leave a stone unturned. Thanks Mike ! Engine has fresh stress hone new rings and bearings on freshen up, has 20 passes on it now.

Posted By: 65dragnet

Re: needing help with launch - 09/26/11 12:56 AM

Dang sure don't need help with lunch as fat as I am LOL

Posted By: MR_P_BODY

Re: needing help with launch - 09/26/11 02:23 AM

Quote:

No but I will ! I don't think that's an issue but I can't leave a stone unturned. Thanks Mike ! Engine has fresh stress hone new rings and bearings on freshen up, has 20 passes on it now.

Whats the LSA and what do you have it in at.... and
ARE YOU SURE its at that installed degree... its acting
like its down (alot) on torque... you could have broke
some rings on the install (just a guess) but the
compression test should tell you something..... JMO

Posted By: 65dragnet

Re: needing help with launch - 09/26/11 02:59 AM

Quote:

Quote:

No but I will ! I don't think that's an issue but I can't leave a stone unturned. Thanks Mike ! Engine has fresh stress hone new rings and bearings on freshen up, has 20 passes on it now.

Whats the LSA and what do you have it in at.... and
ARE YOU SURE its at that installed degree... its acting
like its down (alot) on torque... you could have broke
some rings on the install (just a guess) but the
compression test should tell you something..... JMO

108 degreed @ 104 checked it twice . Probably will do a leak down on it this week

Posted By: 65dragnet

Re: needing help with launch - 10/06/11 05:08 AM

Many days have past since my original post and I have finally stumbled onto the problem. I don't have an explaination as to why but , I changed out the transbrake for another , and bingo the launch is back and actually faster. Thanks for the guys who posted and tried to help, I was ready to throw in the towel ! We tested tonight and the car had a best of 10.27 @ 130.71

Posted By: MR_P_BODY

Re: needing help with launch - 10/06/11 05:19 AM

Quote:

Many days have past since my original post and I have finally stumbled onto the problem. I don't have an explaination as to why but , I changed out the transbrake for another , and bingo the launch is back and actually faster. Thanks for the guys who posted and tried to help, I was ready to throw in the towel ! We tested tonight and the car had a best of 10.27 @ 130.71

Thats strange... wonder if it was totally releasing...
did you open up the valve body yet to see whats happening

Posted By: 493_DART

Re: needing help with launch - 10/06/11 09:05 AM

i was going to guess dist. advance.. but a new valve body cured it ?

what was the problem with the 1st VB . or have you sent it back ?

Posted By: B G Racing

Re: needing help with launch - 10/06/11 12:29 PM

This problem could have been caused by pressure bypass or leakage in the valve body causing a delay in the release or apply of band and clutch timing.
We had a similar problem and found a passage broke through on the plate,we used epoxy to patch the area and it work great.

Posted By: 65dragnet

Re: needing help with launch - 10/07/11 02:16 AM

Thanks guys for the replies , I haven't opened it up yet to have a look see. If I find anything I will post, been fighting this no launch problem for a month now. Sure is good to get somewhere finally , a real pita !