What rear gears are you running. If it is anything like 3.08's, once you get tires spin, forget it. Add some weight to the trunk?? I have never run Nittos or drag radials, but folks tell me that DR's are harder to hook with a stick. I run Hoosiers and they grab OK, in fact I even spun the rim on one of them last weekend.

Hey, how do you like the Tremec? Can you speed shift that thing at the track?

 

I have 3.42s. I know its harder to hook up with the manual and drag radials but 4th gen guys are doing it left and right and getting 1.6 60ft times with Nittos and the t-56.

I love the Tremec. I could speed shift it fairly easy(2-3 would be tough with the stock shifter tho)but I have no rev-limiter so I lay off the speed-shifting for now. Its pretty smooth and real nice to have 5th gear on the highway. Really only have good things to say about it...people complain about the gear spread(which they have fixed apparently with the new tremecs) but I find it to be fine.

 

3.42's should not be that bad. What size Nittos are we talking about here? You could add weight to the rear. Not as bad as it may sound. 100 pounds is huge for traction and people cringe at it, but it would only slow you down a tenth of a second. But,....if it helps you hook, you will knock the 60' times down and then eventually run quicker.
Light rear + leaf springs + stock suspension + stick shift = lousy traction.
It is a posi, right?

 

What air pressure are you running ?

BTW, I know how frustrating it is, I'm running mid 13s @ 106 mph, with a 396 4 speed car.

 

Hopefully the Cal-tracs will help. I think it's a combination of things, and I'm unfamiliar with your suspension, but seems that you might be shocking the leafs and they can't take it.

You running at Leicester?

 

Just a thought, you are saying you bog at any RPM below 3000? You say you are running a 650DP. By that I am assuming 650 double-pumper w/ mechanical secondaries. That is (IMHO) too much carb for the rest of your engine set-up. Everyone seems to think that they must run a double pumper to go fast, but it's just not true. You could stick on a vac secondary carb, and let the engine decide when to give you more air and fuel. This would allow you to launch at lower RPM and possibly not spin the tires. Lots and lots of stock class drag racers run vacuum secondaries because they have to, and they run very well and extremely consistent or they don't win.

 

I second the vacuum carb...you can either have 650 cfm as soon as you floor it and might not need it,or you can have 750 cfm gradually induced with the vacuum carb and get it as the motor requires

 

Thanks for all the replies guys!

Epistuff- They are 275 Nittos, not huge but good enough to be able to hook up. I was actually thinking about throwing the street tires and rims in the trunk as you suggested for extra wieght...might have to try that next time.

Thad- I'm running air pressure from 22-18.

427L88- Yep Leicester. Probably gonna be there alot this summer, gonna try every week or so for weds bracket racing or friday test and tune. For 10 Bucks to race, espically when you can get alot of runs in this time of year before the 150+ ricers start showin up you can't beat it!

tpshea and mr. four speed- Thanks for just assuring me that some of my thoughts were right. I was thinking the Double Pumper was too much. I have a 3310-2 750 Vacuum Secondary carb I think I'm gonna put on it. Hopefully that will help cure the problem(and put my wallet at ease with gas bills). What do you suggest for initial jetting, considering this is a street/strip car and I want to see decent milaege with gas at 2.35 a gallon!

 

72 primary jets are stock in a 3310..go for a lighter secondary spring too..

 

Yeah I would ditch the DP. Had a similar problem with my 67 Camaro. Also, the Nitto's are a tough tire and WILL take lower PSI without shredding. You can probably safely run 16psi but no lower.

 

ALLSHOWNOGO I have Nitto 555R and ran a 13.2, another member ran 12.00 flat another 12.1 but you MUST heat them up! You should burn out for bout 8 seconds then gradually let off brakes until you HEAR your tires scratch then, and only then, are they ready to hook. I ran 14.2 at 104 then 14.88's until I properly heated the tires which took more than a second of my time, but my 60 foot times where in the 2.3 plus times! If you are just smoking them then you will over heat then producing a light oil film on the top. I have seen big blocks, stout small blocks, and supercharged engine (04 cobra's) run Nitto 555R and they flat out hook for the street tires they are.

 

Good luck. That sure sounds like it could be an easy 13 second car if you can get it to hook up and get rid of the bog. Personally, I would love it if I can get mine into the 14's, I have to get the d**n thing running, or it's gonna kill me (if wife doesn't first). Next winter is going to see a M-20 and either 3.55's or 3.73's going in, so next summer will be even better.

 

tpshea & mr 4 spd, sorry if this is a dumb question, but on the vacuum carb how well do they work on the street compared to the pumper carb? The only experience I have is with it on my 4 stroke dirt bike where the rpm's control the amount of fuel flow. It lacks a whole bunch of responsiveness compared to a pumper carb. I'm sure on the strip you're at 3-4000 rpms but what about 8-900 rpm at a stop light? Not that we would be mashing the gas pedal at a stop light , just curious for my build.

 

Well, my brother launches somewhere above 5800rpm with 3.73s and an M21. I have seen him bog it off the line with lower tire pressure. When it hooks, it hooks, and if you don't have the torque to overcome it, you are going to bog.

Have you tried launching at a higher RPM with lower tire pressure? I have been surprised at what half a pound of pressure either way will do to traction. I think we have run as low as 17lbs.

It might be that you need to get it to where it just barely slips coming off the line to keep the revs going until it's out of the hole.

Oh, and to 70elc,
The vacuum secondary carbs are fine on the street. In fact, that is their intended application: hot street cars. You only get as much carb as you need when you need it.

 

70ECam,

I wouldn't run anything but a vacuum secondary on a street car. I think you have to decide what the cars primary purpose is going to be. Mechanical carbs are great for engines that can rev real fast, or that are going to start out at higher RPM levels and can use the massive influx of air and gas. But for lower RPMs, or engines/drivetrains that aren't built to rev quickly, you are feeding the engine before it is needing fed. I have never tried this myself, and am not sure it's even possible, but I read somewhere once that you could disable the mechanical secondaries on a mechanical 4-bbl and get a good idea of if the carb is causing a bog due to too much too fast. Has anyone else ever heard of this or done it?