This gets frustrating, I have to get the lower gears in the rearend. The difference between 3/30 and 9/8 is a different transmission and larger tires. Went from a TH400 to a TH350 for the transmission. For the tires, went from 225/70 to 275/60. I think that I should be in the 13's so easily since I am running at 103 MPH. It just takes so long to get going, my 60' times have also suffered with the larger tires going from low 2.2's to mid 2.4's.

3/30/01 - 14.331 - 99.07
3/30/01 - 14.231 - 99.58
9/8/01 - 14.370 - 101.14
9/22/01 - 14.546 - 102.27
9/22/01 - 14.358 - 103.48
9/22/01 - 14.273 - 103.73

 

Those 60' times are horrible. Get those down and 13s is no problem. Or get a higher stall - I got a 2700 stall and the 60' are no problem :cheers:

 

You need to get that 60 foot time down a little. The car is just not hooking up very well. A converter or gears will help but then traction is going to be a problem. It is a matter of practice with street tires. I average a 2.1 60 foot time. I have got a 2.0 but that is rare.

 

I am not spinning my tires at all. I just have NO low end and the 3.08 gears don't help anything. I am brake loading the torque converter just the same as I have always done. You all are right, the key is going to a higher stall. I forgot that when I swapped transmissions, I put the stock stall converter back in instead of the 2500 I had in. That definately makes up the difference on the 60' times. I dread pulling the transmission again to change that out.

 

MPH is largely a function of horsepower- gaining over 4 MPH makes me wonder if you made any engine mods or tuned it up since March....or maybe the TH350 is sapping less than the TH400 did. As for gearing I agree- if the 1/4 mile is a priority you'll like lower gears. I went kinda moderate w/ mine- went from 2.73s :U to 3.55s and am very happy. I added a B&M 2400 converter. Again, I kept it moderate so that my highway cruise RPM would allow the converter to fully engage to avoid the excess heat that results from slippage, which will kill the trans.

 

In stock form, aren't the 350 and 400 both 2.48, 1.48 and 1? The new tires also hurt your ET. They are .6 in taller. You might want to try a 245/60. It is possible to run 8 sec at 80 mph or 16 at 150. The speed is a seperate set of beams at the end of the track and has nothing to do with ET.

 

Sounds like you need some distributor tuning. It may be that your carb is a bit too big for good off-the-line response, if not just too big, as well. Easy way to check the carb size is to make one pass at WOT through the traps (make sure the butterflies are opening all the way) and one pass with a slight lift off the gas about 200 feet from the traps. Do this a couple of time and if you find the second pass being quicker then the first you can bet your carb is too big for the motor.

Also… are you flashing the converter or bringing it up to stall speed at the launch?

 

Ok, you just went past my knowledge level. Remember I am rookie. What is Distributor tuning? I have a MSD 6a and the only thing I have ever done is get my adjustable timing light, set it to 36 degrees, rev it a little and adjust the distributor to make the marks line up. Is there something else I need to be doing?
As far as the Carb goes, I have a Carter AFB 750 and it doesn't have the butterfly on top, it was removed before I got it. The problem I had originally is that it didn't open all the way, I think I have fixed that because my times are much better now. I think that the carb is not set up right though. I need to get a book or something on how to tune it with different size whatevers that go in it but I really am out of my leauge when it comes to that.
For the torque converter, I press the brake at the line, and rev my engine until the car feels like it is going to start moving then keep it at that RPM until the last yellow and I take off like a turtle.
Tuning - My car is in a constant state of tuning, this could also be a reason for the variation of times and MPH flux. I feel like as I learn more the better I can tune the car. I read something here and run out and try it on my car and I feel like all of these little baby steps are working me towards my low 13 sec car that I know I have. The biggest problem I have right now is my rocker arm nuts keep loosening up. I have to retighten them at least every 300 miles ( about 2 tanks of gas ). I just went out and bought new locking nuts and it seems to not have made any difference and they will loosen up to the point where the rocker arms come off of the push rods. The other issue with this is that some of the nuts are really really really tight and some are really loose. I thought that it was a defect of the nuts that were on there but it is the same with the new ones that I put on also, the ones that were tight are still really tight and the ones that are loose are still really loose. I guess it is a defect in the studs that come out of the heads which suck as they are only about 6 months old and I have been having the same problem the whole time with them.

 

Man, you got a bunch of stuff going on! Just as advice, I'd check the rocker problem first. You didn't mention cam, so I'll assume relatively mild with no coil bind. Either the studs are pulling out of the heads (I would think one would have fallen out by now), or you need some positive lock nuts. These are taller and have a set screw in the center that locks against the stud after you have it adjusted. Cheap insurance against valve adjusment change.

As for the timing, I don't quite get your description, but I'd check to see what kind of vacuum you had at the advance first (assuming it isn't a full mechanical advance distributor). If it is direct (you can feel vacuum from the hose at idle), switch it to ported (so that you feel the vacuum as you rev it up). Play with the timing so that you ge just a slight ping on pump gas (fully warmed up under hard acceleration) and back it of a couple of degrees. This is assuming the mechanical weights in the top of the distributor are stock and working. This will affect street gas mileage, so you might want to switch it back when you're done, but I doubt it! The butterflies that were mentioned by Banshee 63 are the lower ones in the carb itself. With the engine OFF, have a helper give it full throttle and hold it. Look down the primary and secondary bores and see if the plates are wide open. You would be surprised how many I've seen with floor mats and carpet crammed under the pedal, restricting full travel! The problem with this is, it should now spin the tires off the line, which kills 60 ft times! :yesnod: I guess it would be a start...

Mess with the jetting last. AFB's have a great jetting system, that basically requires their "track pack" of jets and metering rods. It is an assortment of jets and rods, that can be changed on the car, between rounds.

I hope some of this helps. It can get a bit more technical, but it's a start. Hammer down!

Hans

 

I have the Edelbrock performer RPM cam 7102.

From the Edelbrock website.
Duration at .006 Lift: Intake 308° Exhaust 318° Centerlines
Duration at .050 Lift: Intake 234° Exhaust 244° Lobe Separation: 112°
Lift at cam: Intake .325 Exhaust .340 Intake Centerline: 107°
Lift at valve: Intake .488 Exhaust .510
Timing at .050 lift: Open Close
Intake 10° BTDC 44° ABDC
Exhaust 59° BBDC 5° ATDC

My distributor is a MSD tach drive distributor. I haven't played with anything under the cap and have actually never taken the cap off of it. Sounds like something to check out. The way I set my timing is to hook up my timing light, set it to 36 degrees advance, rev the engine and turn the distributor until the lines line up on the harmonic balencer and the guide on the engine. I will try the move up my timing till it pings approach and see what effects that has on everything. As far as gas mileage goes, it sucks now anyway (around 8 mpg) so that doesn't really concern me. AH HA! I understand what you are saying about the butterflies now, I will also check that when I get home. Thanks for the advice on the locking nuts for my rocker arms, I will see if can find some of those. Another question on that also, if I never got the nuts tight enough in the first place, would it be easier for them to back off? The way that I have adjusted them after trying many different ways posted here is to take off the valve covers, check to see if any are loose, if so, tighten to zero lash plus 1/4 turn, bump engine, keep checking, keep bumping .... The downfall to this is that when I am done, the car barely idles. Regardless of which method I use to set the valve lash, it always barely idles and I start just loosening up and tightening different rocker arms until it idles smoothly again.

 

My engine setup is almost identical to this. I decided to go with this setup for the very reason is that it should put out big numbers and so far it hasn't :cry . I have the same heads, intake, cam, similar carb, same compression pistions, same ignition, my bore is +.040, I have headers, 2 1/2 inch exaust. I just don't have the knowledge to "TUNE" this dang thing. But, I am getting closer! Baby steps...
http://www.edelbrock.com/automotive/7101pp.html

 

Just a guess. It looks like a pretty big cam with that and the auto and 3.08's I 'm sure it takes it awhile to get "on the pipe" and old moto cross term for being in the power ban. I am guessing it is just like a car I had that would come out slow and not even spin the tires and eventualy wind up going down the track? Hope you find tha cause of the valve problem. With 103mph top end you make the power to get 13's. I think you deffinatley need more gear. I guess a stall would help also and the two together would be just right and a ton of fun :D

 

Valve adjust 101. Covers off engine off. Bump the engine over (I use a starter button with the ignition disabled) and adjust the exhaust valve when the intake just closes on the same cylinder (180 degrees before the exhaust will start to open again), then adjust the intake valve when the exhaust just starts to crack open on the same cylinder. Move on to the next cylinder and repeat. There may be a few cams or engine configurations that call for a different technique, but I've used this for years on V-8's.

I may have miss understood on the distributor. Does it have vacuum advance or is full electronic? I'm not familiar with the MSD systems (Old fartitis!).

Hans

 

INMYBLOOD is absolutely right on this as well. Low gears (I always liked 370's for combination street/strip) and a 2800-3000 stall converter would work right now. Good luck.

Hans

 

A quick and dirty way to keep the rocker arm nuts from backing off is to double nut them. Get them adjusted and put a second nut on there and
tighten it down locking the first one in place.

 

I just did the math. Going for 8 seconds at 80mph will get you as far as 0.18mls. Which means for making an 8sec 80mph pass you'll have to run about 120mph at the start line and then hit the brakes :D

 

It sounds like I am adjusting my valves the same way as you. Should it make a difference in the idle of the car it the rocker arms are tightend correctly? By that I mean, suppose the rocker arms are perfectly tightend and the engine is idleing, then you loosen all of the rocker arms by 1/4 turn, should the idle increase/stay the same/decrease? Just wondering if I need to increase the idle on my carb after adjusting the rocker arms.

 

Sounds like a good idea, thanks.

 

If your within the adjustment range of the hydraulic lifter (which is usually quite a bit), Idle quality should not change, other than momentarily. I have had sets of anti pump-up lifters that were VERY sensitive to adjustment. They liked to be barely into the adjustment range, say 1/8 to 1/4 turn. Also, I have had problem engines come to me that had very high oil pressure that would pump up the lifters. Weak springs that have no seat pressure, either due to excessive seat grinding , lack of shims, or loss of tension, (generally due to old age or very high lift) can also cause them to run wierd. If you push on the valve end of the rocker by hand, it should take a pretty good shove to actuate the valve, even with stock springs. Anormal stock spring will have 70-80 lbs. of seat pressure installed. If seat pressure is a little low, a 65-80 lb. high press. oil pump WILL mess you up. I run 90-110 lbs of seat pressure in my 7000 rpm BOSS 302 and have run hydraulics successfully. I don't know what other types of mods you have in your engine, but it sounds like it's minor adjustments that are needed.

Hans

 

Norris, was just here and I should have gave them to him. But all R-Rockers come with center allen locking nuts. Problem is solved. No, double nuts.

All you really need is a higher stall convertor. So you can get into the power range faster. Norris ask me about my 3000 stall - I told him that without a big oil cooler and lower gears I would not recomend it without a lockup switch.