TB2

iTrader: (1)

Ok, I took my bird to the track last weekend. It seems to be come on strong after about 50-60 ft, but seems really flat coming out of the hole. I ran a 12.9 @ 113 mph, with a 2.0 60ft. time. It doesn't seem to bog, or pop, it's just a slug coming out of the hole. Nothing violent at all. I think most of my problems are in my accelerator pumps setup. I'm running a 800cfm mechanical secondary holley. Right now it's got a 30cc up front, and a 50cc rear. Is it normal to run [2] 50cc pumps? I'm also thinking of getting rid of the back power valve. Let me know what you think.
Oh yea, it's an 84 T/A, 3100lbs, with an early LT1 short block with World products ported sportsman heads, a CS XE294H-10 Comp cam, Hooker Super Comps with 3" duals, turbo 400 with a 3500 stall, Moser 9" with a 4.10, on a 9" slick

bluegrassz

iTrader: (3)

Did you spin any off the line?

How tall are the slicks? How much psi?

If you dont already have them, get some LCA relocation brackets. Remove or unhook the front sway bar. Air the front tires up to around 40 psi for better roll out.

Were is the rpm's when you leave the line? Are you holding the rpms, or just stabbing it off the line. What rpm is the converter flashing to?

TB2

iTrader: (1)

Not even close to any wheel spin off the line. pressure in the slicks is at 14lbs. It has relocation brackets. I tryed both foot braking it, and just stabbing it. Stabbing from an idle produced much better reults. I'm not sure what the convertor is flashed.

xpndbl3

iTrader: (5)

I doubt it's the pump shot without any bog off the line. What is your timing and do you flash the converter? You may want more stall with that cam as well. Perhaps try a slightly bigger squirter up front if you're paranoid about it and see what happens, but to me it looks like a converter issue or spinning and you don't know it. 2.0 60' is a street tire launch not a slick launch.

TB2

iTrader: (1)

I'm not sure what you mean by flashing the converter. Please explain. If I remember right, the timing is set at 35 total advance. It sure doesn't seem like I'm getting any wheel spin. I'd hope that I would realize it. But I will say that I don't have a lot of experience running on slicks. Below is a vid from that day. You can see how it just kinda pulls out, and then comes on late. Oh yea, and it's a 28" tall slick.

http://media.putfile.com/race1-78-17

bluegrassz

iTrader: (3)

You should be ok with the th400/4.10/28" tire combo. Try bumping the timing to 38-40*.

Have you tried changing the LCA angles with the relocation brackets?

What intake are you running? any carb spacers?

DCOWBOYS1975

What are the LCA relocation brackets?

bluegrassz

iTrader: (3)

Here is a link. http://www.spohn.net/?action=product&pid=1017

They weld to the rear end housing were the lower control arms bolt up to the rear. They correct the angle on lowered cars. They work good on stock ride hight also.

TB2

iTrader: (1)

The lower control arms are set to the lowest setting with no wheel hop. The intake is a weiand team G with a 1" phelonic spacer. I'll try bumping the timing up, but I'm not sure 3deg will make that much difference. Also, I swapped the rear mains from 76 to 82 and picked up 4 mph, but didn't do anything to the 60ft. time.

DCOWBOYS1975

Thank You!!!

Trey

bluegrassz

iTrader: (3)

You would be suprised what bumping the timming can do. I picked up .15 in the 1/4 going from 38* to 40*.

You also might try removing the carb spacer. It may be robbing you of some torque off the line.

Im also wondering if you have enough converter also. What brand is it?

Check out my times with MPH in my sig. You should be in the low 12's or high 11's with that MPH.
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Your welcome.

TB2

iTrader: (1)

Im also wondering if you have enough converter also. What brand is it?

Check out my times with MPH in my sig. You should be in the low 12's or high 11's with that MPH.
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I agree, it could be the converter. It's a ******* 9" converter. How do I flash the converter??? Is that the point that it locks up??? And I agree I should be low 12's to high 11's if I can get this thing to come out of the hole right. There's a lot of power on the big end. Its still pulling really strong as I go through the traps. I'm also wondering though if the Accelerator pumps could be expended by the time I launch. They seem to hit right off of idle right away. I changed the cam on the primary trying to get it to come in later, but it didn't seem to make much difference.

DCOWBOYS1975

Thank You!!!

Trey

bluegrassz

iTrader: (3)

You really cant find the true stall rpm of a converter, but you can get close.
Try having a friend ride with you to watch the tach. Take the car out on the highway. Keep the trans in drive and be at a low speed. Go WOT and have your friend watch the tach. It should jump to a hi rpm and stay there till the car catches up. This should be close to what the converter is flashing to. You can also try going WOT off idle. That is flashing the converter off the line.

Also are you clearing the carb out after the burnout so its not loading?

You may need a 3800-4000 converter.

TB2

iTrader: (1)

I geuss this sight doesn't like the word red neck. It's a red neck converter.

TB2

iTrader: (1)

Ok, here is what I need to know:

1] Right now it has a 30cc Accelerator pump up front, and a 50cc rear. I'm considering running 2 50cc pumps. Is it normal to run [2] 50cc pumps?

2] I'm also thinking of getting rid of the back power valve. Is anybody running without it, if so how is it working.


I know I'm not spinning, and I'm going to check the flash on the converter today, and I'm going to try bumping up the timing to see what that does. I appreciate the suggestions, but I'm still fairly confident that most of my problems are carb related. I just have not had a lot of experience with holleys, and am looking for some direction on some carb setups that work, and understand why. If these were Webers, I'd know what to do. Thanks for all your help guys.

xpndbl3

iTrader: (5)

you don't need more pump shot, it's only there to help a bog, then there is no more shot. Since you're not experiencing one, there is no magic in adding more fuel. Getting rid of the back power valve is up to you, you would have to jet up 8-10 jet sizes in the rear to compensate for it being gone.

bluegrassz

iTrader: (3)

I have done tried the pv blockoff. I found it best to just use the correct one instead of having to rejet.

What is you vaccum at idle in gear?

I still think it is in the timing or converter. I have been helping a friend with the same problem. His car wouldnt 60 ft like it use to. He changed the timing and the converter at the same time. The carb was not changed at all. His 60's went from 1.65 to 1.90's and 2.00's.

He has yet to change the timing back and has the same converter that I get 1.63 60ft out of.

Try the timing and see what you get.

TB2

iTrader: (1)

Ok, I tried seeing what the converter flashes at. It seems to be about 3500rpm. I'm not going to be able to get back to the track for a couple of weeks. On street tires the motor launches hard and the rpm's come right up. Of course I have to back pedal it the whole time trying to get the tires to stick. I think I'm going to put the Slicks back on it, and try launching it from the entrance ramp by my house a couple times and see if I can figure out whats happening. I understand that the timing can help it, but I'm only a couple degrees from what your suggesting. I'm having a hard time believing 2 or 3 degrees is going to give me 3 or 4 tenths at 60 ft. The suspension shouldn't make much difference until I start losing traction. So if all the accelerator pumps are doing is keeping it from bogging, then I agree they should be fine. The way it's coming on strong on the big end, I know I'm not running out of fuel, but I did pick up 4 mph with a jet change. If you have any more suggestions let me know. Maybe I need more than a 3500 stall? But even so, I would think that 3500 would get me a better 60ft than that!
Thanks for your help.

cp87GTA

If you don't have a pop back thru the carb when you stab it, then It's probably getting enough fuel on the pump shot. Does it have a puff of black smoke when you stab it? If it does , you have too much pump shot. If you have too much, it'll take it a little time to recover. Is this a street car, or a race car? I'd personally remove the rear power valve and tune the carb. But if it's a street car it'll take some doing. I have both power valves removed on my race car. The car will 60 ft better if you bump the timming and lean the pump shot. Lean the pump shot untill you get a pop back thru the carb then fatten it up till it goes away. You may have to change the weights and springs in the dist to get the timming the engine needs to get a decent 60 fter out of it. If the car leaves hard with street tires, spinning, then you can get it to replicate with some tunning. My comp cam like a lot of timming, over 40*, and mine is all in when I leave the line.

Andy316

have you solved the probleme yet and what was it?

TB2

iTrader: (1)

I've been working on it, but I have not been able to get back to the track yet. I bought a jet kit, power valve plug, and adjusted the timing. Putting a new roof on my house this weekend. Then i'll be back to the track for test and tune. I've got a list of things I'm going to try. Some good suggestions from some guys on here, and some I've been thinking of trying. And then see which ones help, or at least point me in a direction. I'll give an update when I get back from the track.

mw66nova

iTrader: (13)

i'm +1 for more timing before spending more money. it's free and easy and will yeild immediate results!

TB2

iTrader: (1)

I agree, timing is one of the first things I'm going to try. I also found last time I was at the track, that I gained 4mph with a jet change, so I know there's some room there to experiment. I also inherently rush when I'm staging, so I want to make sure that after my burnout, I need to put it in nuetral, and clean it out good before staging. As well as trying to foot braking it at different rpms, and see what it likes better. I also want to play with the accelerator pumps. From the info that I've gotten from here, my idea that they are too lean may be wrong, and may actually be too rich. So I've got quite a few things to try, and well see what helps, and what doesnt. I appreciate the help guys. If you have any other ideas let me know. And I'll give you an update as soon as I can get back from the track.

bluegrassz

iTrader: (3)

Yeah, let us know how things go.

Oh yeah, Put 40psi in you front tires for better roll out. Think about how hard it is to push a car with low tires.

Andy316

keep us posted. Hope you figure it out.

TB2

iTrader: (1)

Ok, I finally got back to the Track! I improved from my last time out of 12.9 to a 12.7, with a 1.9 60ft, at 115mph. I tried bumping up the timing, first to 40, then 42. That got me the best improvement. I also tried leaning out the accellerator pumps. It didn't gain anything noticable, but it didn't lose anything either. I bumped up the secondary mains. I checked to make sure that I don't have any wheel spin at launch. I tried launching at different rpm without much difference.
I'm convinced that I need a bigger stall to fix this. I also had a chance to go back through my old paperwork. The stall I have is rated @ 3000, not 3500 like I thought. The motor seems to run really good. There's no bog coming out of the hole. The motor really starts to pull hard above 4000. I also changed the rev chip from 6600 to 6800. The motor is still pulling hard at that, but with a stock bottom end, i'm getting nervous about going much higher. The car is very consistant. Even with the changes I was making, my et never changed more than .1 all day.
I think a new, higher stall converter is in my very near future. Any recomendations on what stall speed I should get? I was thinking around 4200-4500. The car does see some limited street use.

Andy316

i would suggest edge converters. let them custom make one for you. I hope you get this thing nailed down. Sounds like you have the power to make a high 11 low 12 run if you could get the car out of the hole.

bluegrassz

iTrader: (3)

Check out www.ptcrace.com

They will custom make a converter for your car. They are resonably priced and stand behind there product.

With the right stall, you should get some 1.60's or 1.50's 60 ft times.

Last time at the track I ran 12.16 at 110.55 mph with a 1.63 60 ft. With your 115 mph you should be in the high to mid 11's. That is if you are not spinning.