looking for some opinions on launch/60ft times

[ky66ss]

ive put together a little 79 malibu for 1/8th mile foot brake bracket racing below i will post all details on car....i have had it to the track 2 weekends in a row the car has done good overall but is lacking in the launch/60ft areas -

details-
approx. 33-3400? full body/interior racing buckets/deleted heater/ac box/removed inner bumper structure
350 .40 over
11.1 compression
aluminum 58cc 210int. runner heads
488/507 lift hyd. flat tappet cam adv.duration .288/.297
1.6 crane full roller rocker arms
performer rpm air gap intake
650cfm double pumper no power valve jetted 76 square
msd billet hei dizzy timing totalled at 37 degrees
powerglide trans w/manual valve body
3800 converter will hold on footbrake at 2500rpm and flashes around 3600rpm
4.56 gears spool with 28/10.0/15 slicks
90/10 shocks on front 50/50 on rear
so far after approx 12 passes the best et was 8.10/60ft 1.78/84.24mph with a most average pass of 8.16/60ft 1.79/83.30mph ihad a lil larger converter in the car first few passes and it ran 8.15/60ft 1.76/83.06mph this converter was a 4000 but wasnt working properly ....it seems to me the car is doing fairly good on topend but the launch is very weak and 60fts are slow compaired to other similar cars i run with ive got a couple that are running almost the same gear /converter running 1.58-1.64 60fts running high 7s in the 1/8th but these cars are running 350th and 400th trannys it seems there is a big debate over 350th/powerglide in bracket cars some are telling me my car is way to heavy for glide and others say i wont see no difference i do know there is a huge low gear difference from my 1.82 glide to the 350th but some say the glide will pick the lost time up from the higher gear mid track when your only making 1 shift instead of 2,,,,from what friends watching the car are saying the car does nothing when coming out of the hole it doesnt seem to me as it starts pulling good until it gets moving im stuck thinking myself its either transmission or fuel? .......i know this car has more in it just looking for insight on what others think open to all opinions......

 

[MPac]

From looking at your engine specs it seems like you have to small of a cam and carb. I would consider giving Mike Jones a call at Jones Cam Designs (704)489-2449 He's one of the best and will take care of you. Really reasonable prices too. I'm trying to remember the RPM Air Gap is a dual plane correct?

It seems like you have to my head for your combination. But if you gave some more detailed info it could really help out. I believe if you kept everything the same on your engine but changed your Carb to a say 750 main body with no choke horn or anything bigger then a 650, Victor Junior intake, and say a http://www.jegs.com/i/Lunati/638/60134/ ... ProductId= or whatever Mike would recommend you would see a better result.

I personally have no experiance with a powerglide, but I do know your not running enough gear for a 1/8 mile powerglide car. I run a TH350 in my car for quarter and 1/8 with a 4.56 gear. Minuimum I would run on a 28 inch tall slick power glide car would be 5.88 depending on what your goal is for trapping RPM.


I believe if you do what I recommend you car should be basement 7's high 6's which would be 10's in the quarter mile. Have you considered running a transbrake? Also on wither or not you should use a glide or 350 is all personal preforance. Swapping rear gears will deffinatly compansate for the weight issue you were talking about. Hope I was able to help.

 

[ky66ss]

bee awhile since ive been able to post back about this .....i swapped back to th350 trans with a faster 60ft but still the same e.t. im thinking of making cam and carb change over the winter im running 1.6 ockers with valvetrain setup with 550 lift spring so with that said you do the math i can go to a .516 lift camshaft at most ive located a couple of cams im considering ones a .515/.515 .300/.300 duration the one im leaning to the most though is a .510/.507 with 296/305 duration ........also planning on have a custom e85 750cfm carb built by mark sullen or horsepower innovations

 

[larryo454]

What is your top rpm of this engine? and your duration @ .050? And if your engine is making good torque you can put the 700r4 first gear in the th350 but you best have the grunt to over come the spread in 1 and 2 gears.

 

[ky66ss]

What is your top rpm of this engine? and your duration @ .050? And if your engine is making good torque you can put the 700r4 first gear in the th350 but you best have the grunt to over come the spread in 1 and 2 gears.

my cam duration now is .235/[email protected] and the motor does its best shifting 5800-6000 rpm ive shifted lower and higher but seems to like it best there it seems to pull good up to about 6500 but it slows it down abit ?

 

[MPac]

Your probably starting to have valves float once your hit 6,500. That's about what hydro tappets are good. Really depends on your spring pressure. For the heads your running you would really benifit from a bigger cam. Which would explain for why your getting slow launchs. With that big of a head is it lazy coming off the line? Any kind of stutter if you stab if from idle? If not try launching from near idle to shock the drivetrain for the most weight transfer. I think you may be leaning out on the top end. When you hit high gear and get near the finsh line does it feel like the power drops? Now if you wanna go REALLY fast consider a HP950 carb .750 lift solid roller and a Super victor intake. 8) Also you said you swapped out the 4,000 stall. What stall are you running now? And what heads are you running?

 

[ky66ss]

Your probably starting to have valves float once your hit 6,500. That's about what hydro tappets are good. Really depends on your spring pressure. For the heads your running you would really benifit from a bigger cam. Which would explain for why your getting slow launchs. With that big of a head is it lazy coming off the line? Any kind of stutter if you stab if from idle? If not try launching from near idle to shock the drivetrain for the most weight transfer. I think you may be leaning out on the top end. When you hit high gear and get near the finsh line does it feel like the power drops? Now if you wanna go REALLY fast consider a HP950 carb .750 lift solid roller and a Super victor intake. 8) Also you said you swapped out the 4,000 stall. What stall are you running now? And what heads are you running?

it seems to like the 5800-6000rpm area for shift point.. the heads are procomp 58cc/210cc that have been cleaned up by a good machinest and had good parts put in them .....the converter is stalling at 2500 on footbrake and flashing at 3600-3800rpms...no stutter or dead spots anywhere from idle to wot and as far as loosing power at the big end it seems to still pull hard but a little slower.....i sent emails to several cam companies asking recommendation on cams told them the story and all specs they have came back with different answers some are saying needing to leave it alone and go with bigger carb(which im planning on regardless when i go to e85) others are saying to see real benifits making it worth swap i need to swap out the whole valvetrain to something in the .550+ area but i was hoping to keep from going that far... if i do i think ill go ahead and swap to hyd. roller in the .600 area..........

 

[MPac]

Your probably starting to have valves float once your hit 6,500. That's about what hydro tappets are good. Really depends on your spring pressure. For the heads your running you would really benifit from a bigger cam. Which would explain for why your getting slow launchs. With that big of a head is it lazy coming off the line? Any kind of stutter if you stab if from idle? If not try launching from near idle to shock the drivetrain for the most weight transfer. I think you may be leaning out on the top end. When you hit high gear and get near the finsh line does it feel like the power drops? Now if you wanna go REALLY fast consider a HP950 carb .750 lift solid roller and a Super victor intake. 8) Also you said you swapped out the 4,000 stall. What stall are you running now? And what heads are you running?

it seems to like the 5800-6000rpm area for shift point.. the heads are procomp 58cc/210cc that have been cleaned up by a good machinest and had good parts put in them .....the converter is stalling at 2500 on footbrake and flashing at 3600-3800rpms...no stutter or dead spots anywhere from idle to wot and as far as loosing power at the big end it seems to still pull hard but a little slower.....i sent emails to several cam companies asking recommendation on cams told them the story and all specs they have came back with different answers some are saying needing to leave it alone and go with bigger carb(which im planning on regardless when i go to e85) others are saying to see real benifits making it worth swap i need to swap out the whole valvetrain to something in the .550+ area but i was hoping to keep from going that far... if i do i think ill go ahead and swap to hyd. roller in the .600 area..........

Well if your dead set on that cam then try like I said leaving from near idle to shock the drive train. Deffinatly go with the .600 roller if you can afford it. Is this a strip only car or even a mostly strip barely street? If so you may be happier going the solid roller route. You will not be dis satisfied. But each cam company will give you a different answer. Ask 10 guys how to make 500 horse and you'll get 10 different answers. Your two best bets would be to call ProComp and see what they reccomend. I myself work for a head company and can tell you that they do alot of R&D on the heads and will deffinatly be able to guide you in what direction to go because they know what kind of cam their heads will like. Or even better would be to call Mike Jones I posted his number in my first post. He will take the time to sit down and go over your combo with you and reccomend the best cam profile for you. He's also one of the best cam grinders in the country. If your still running the same set up next season while your gathering parts try jetting up a little to see if that helps in the top end. Usually what I do is keep jetting it up till I stop picking up MPH. Have you played around with your timing to see if different settings may help? Have you read your plugs after a run but shutting the car down once you cross the finsh line then pulling a plug? That's a good way to help with jetting.

 

[larryo454]

This is my 2c on some of your problems

Your duration a .050 is low that's is one problem you have with slowing down after 6500rpm.That cam is only good for about 6000 then it starts to die off,Your going to need a cam with more duration and a closer lobe Separation.for duration in the upper 250s and the lobe less then 110 something like the cams i put in the post


and this is your cam spec
http://www.summitracing.com/parts/sum-k1107

this is what i use in sbc and even on the street

http://www.ebay.com/itm/3-Solid-Cam-Lif ... 27cbc1bd48

http://www.ebay.com/itm/2-Solid-Cam-Lif ... 1c2bfec45a

http://www.ebay.com/itm/11-Solid-Cam-Li ... 2ec26c8c0a

 

[ky66ss]

Your probably starting to have valves float once your hit 6,500. That's about what hydro tappets are good. Really depends on your spring pressure. For the heads your running you would really benifit from a bigger cam. Which would explain for why your getting slow launchs. With that big of a head is it lazy coming off the line? Any kind of stutter if you stab if from idle? If not try launching from near idle to shock the drivetrain for the most weight transfer. I think you may be leaning out on the top end. When you hit high gear and get near the finsh line does it feel like the power drops? Now if you wanna go REALLY fast consider a HP950 carb .750 lift solid roller and a Super victor intake. 8) Also you said you swapped out the 4,000 stall. What stall are you running now? And what heads are you running?

it seems to like the 5800-6000rpm area for shift point.. the heads are procomp 58cc/210cc that have been cleaned up by a good machinest and had good parts put in them .....the converter is stalling at 2500 on footbrake and flashing at 3600-3800rpms...no stutter or dead spots anywhere from idle to wot and as far as loosing power at the big end it seems to still pull hard but a little slower.....i sent emails to several cam companies asking recommendation on cams told them the story and all specs they have came back with different answers some are saying needing to leave it alone and go with bigger carb(which im planning on regardless when i go to e85) others are saying to see real benifits making it worth swap i need to swap out the whole valvetrain to something in the .550+ area but i was hoping to keep from going that far... if i do i think ill go ahead and swap to hyd. roller in the .600 area..........

Well if your dead set on that cam then try like I said leaving from near idle to shock the drive train. Deffinatly go with the .600 roller if you can afford it. Is this a strip only car or even a mostly strip barely street? If so you may be happier going the solid roller route. You will not be dis satisfied. But each cam company will give you a different answer. Ask 10 guys how to make 500 horse and you'll get 10 different answers. Your two best bets would be to call ProComp and see what they reccomend. I myself work for a head company and can tell you that they do alot of R&D on the heads and will deffinatly be able to guide you in what direction to go because they know what kind of cam their heads will like. Or even better would be to call Mike Jones I posted his number in my first post. He will take the time to sit down and go over your combo with you and reccomend the best cam profile for you. He's also one of the best cam grinders in the country. If your still running the same set up next season while your gathering parts try jetting up a little to see if that helps in the top end. Usually what I do is keep jetting it up till I stop picking up MPH. Have you played around with your timing to see if different settings may help? Have you read your plugs after a run but shutting the car down once you cross the finsh line then pulling a plug? That's a good way to help with jetting.

ive messed with the jets and 77-78 jets seem to be right area ive pulled plugs after a full pass not rich or lean just a clean plug i may call jones and talk to him about a cam for this motor i was on his site he has some very aggressive hyd flat tappet cams that will work with my combo im not gonna do just a basic cam swap unless a knowledgable builder/tech tells me im gonna see very positive results and i might not get that with the under 550 lift im looking at......so again im still talking and asking questions ....as i said im thinking of leaving my combo alone and swapping out the carb im not wanting a bunch 3-4 tenths is what im looking for.