Tried the accelerometer on my 03 infinitti sedan (auto) and the 72 coupe today (383) three speed auto. First time I've ran the 383 over 100.

about 68 degrees, country road far from everything. Did a few 0-60 runs and then I got in two 1/4 mile runs.

Alot of tire spin I need to work on. 18" 275's on the back. O.K. enough foreplay.

best 1/4 mile (out of two)

60ft 2.18
330ft 5.88
0-60 5.23
0-100 12.63
1/8 8.85 at 83.1
1000ft 11.4
1/4 13.6 at 102.7

My best run out of three for 0-60 was 5.0 flat (tire spin).

By the way, Inf G35 sedan auto 0-60 was 6.5.

 

383 Info. --------------------------------------------------------------------------------
By the way. 383- 770 Holley Street Avenger, Edelbrock Perfomer RPM manifold, I am not numbers to post for my cam but I have them. ADV INT 272 INT and 272 EXH/ .050 Dur-216 INT and 216 exh. 4340 crank. world class heads. TH400 and B&M holeshot 2400 stall speed.

How can I get better results? (besides trying to reduce wheelspin).

 

I like to see people trying new things.

With what you have, Get a LM1 air fuel ratio meter or some other vendor. To really dial it in. You have to work with timing and the carb to better what you have.

 

thanks and I will do a little homework on suppliers.

My third attempt at the 1/4 was cut short as the engine started to cut out at high RPM's. Does this make any sense after two o.k runs?

 

That is strange about the engine cutting out, what type of ignition do you run? Also, we have never had a tire spin problem, and have about the same setup as you. We are only running about 430 HP, MSD ignition. We bark the tires at gear changes, but never spin off the line.

 

Nice looking coupe..... love those wheels
But you have a big gap in the wheel wells..... What is the overall diameter of your wheel/tyre combo ? A smaller diameter will increase wheel spin issues.

You have a 383 with a good strong low end torque output based on that cam spec and the performer manifold, and the resultant tyre spin issues.... You may be down on torque at the upper rpm, hence not gaining much if you rev out to redline. Do you have a dyno output of your motor..... You may gain a better time if you change up a little earlier to keep the motor in its maximum torque range.

Get better grip and you'll definitely bring down the times....
What diff gearing do you have?

Using an accellerometer requires a flat (level) track / road.
They are also prone to errors if not zeroed correctly at the start....

Tyre grip at a track is much better than any road surface, so 2.18s 60' should come down and wheel spin should be less of a problem.
Else get some M/T ET street radials..... I believe there is an 18" available now.

There might be some others who can suggest tuning tweaks..... eg cam timing could be altered to shift the torque peak to slightly higher rpm...

Good effort on first attempt though.
I have only just fired up my new 383, and need to get a few miles on it before I also do a few runs.

cheers
tom

 

Bigger cam, more like 230 duration @ .005, might give up some low end torq (sounds like you can spare some) but will more than make up for it up top @6000 rpm's. Should still have very good street manners in a 383.

Other than that, practise leaving without spinning the tires

 

I"d check your timing and carb settings. What does your timing curve look like? If you can get a LM-1 that would be great, or you could take your car to a chassis dyno that has a wide band A/F meter.

Have you ever considered dropping the TH400 and going with a modified TH350. They can be built to take the abuse and don't suck up as much HP.

 

Thanks for the replies. The Th400 was just built with a shift kit so changing trannies at this point is not an option. Have not made it to the dyno yet so I do not have the torque curve. I will be making the trip shortly.

 

Took the accelerometer to the track. (Texas Motorplex). I was very interested in the traction that everyone had spoken about vs. street. My best 0-60 time on the beltronic accelerometer on the street was 5.0, my best reading on the track was 4.7 (beltronic). my 1/4 time read by the track mngmt system was 13.0 while the belltronic read 13.35 with a reading of 4.7 0-60 and 12.8 0-100mph. I was a little dissapointed in the not so accurate results and I intend to call belltronic tomorrow to see what the differnece could be.

I have a TH400, even with my first time out I was able to pull 1.97 60' time. I will say I had a blast being able to launch without tire spin (almost no tire spin, something I am still working on).

 

Hey chanc... I live pretty close to Plano, over in Lantana off of 407 near Flour Mound.

Anyway...I also have a 383 (spec's below) and hoping to hit the Denton 1/8th track soon... I would expect you to run better at Denton they prep the track there really well, several of my friends run there with great results.

Also like someone said get a LM1 and fine tune everything. I have one and it has worked wonders for me. You will be able to tune the crap out of your car and better than any dyno shop can unless you know the owner of a dyno.

We will have to hit the Denton track with a few others soon.

 

Can you send the website for the LM1.

Sent you a PM.

 

13.0 on street tires is pretty good. What rear gear do you have? I chopped about 5 tenths off my best et going from 3.08 to 3.73. I don't always hook up too well off the line. 12.90 is my best.

 

Sent EM to Verizon address

 

If it took 12.8-seconds to reach 100 MPH, and you covered the 1320' in 13-flat, I'd assume your trap-speed wasn't much over 101 or 102 MPH?

If-so, with 3.55 gears, 27"-tall tires (a guess? ), and a non-locking THM400, I'd guess you to be trapping about 5000 RPM:
you could throw more rear-gearing (3.90s ) at the car, so it'd be turning approx 5500 RPM at the same MPH, allowing the car to 'use-up' all of it's power & RPM potential in the quarter-mile.....
it might pick-up another .1-seconds of ET, making it a solid 12-second machine!

 

Right on the money with RPM's. The 13 second run was at a top speed of 106. Is it easier moving towards different gears or swapping out heads and manifold?

 

By the way, how much additional horsepower do I need to go from a 13.0 second car to a low 12.0 car. (all else equal)?

Dyno-300 RWH and 347Tourqe

 

I doubt swapping heads & manifold will improve top-end power much, with such a short (216* @ .050" lift? ) cam:
gears will help the car's performance at all RPM levels, but going from 3.55s to 3.73s is hard to justify, because it is such a small change.....
if all-out Low-ET is the goal, 4.11s would be better, and put the RPM near 5800 at your current trap-speed MPH.

ET is a function of effeciently-applying ALL of your available power to the track via traction, gearing, chassis, and TQ-multpilication, while MPH shows how-much power you are making at that point in time:
you ran 13s at 106, yet I regularly run 12-eighties at 105 (I have 4.11s, 28" slicks, and an 8"/4500 stall converter ) because my car possibly 'works' better than yours.

ET is about 'time', so work-on getting the 60' times as-quick as you can:
for every .1 you can improve the 60', the ET will generally-improve another .1 down-track.....

You'll need to run about 111-113 (minimum, more with less gearing or converter ) to reach 12-flat, so figure-out what kind of power that requires, then gear the car to hit that speed at max RPM in High Gear

P.S.: to answer your question directly, I saw a mid-'70s C3 with a stock ZZ502, THM400, 3.90s and 28" slicks walk off fthe line, then run 12.003 @ 112, while another C3, this one with a high-compression, high-winding 468" BBC, 4-speed, 4.11s, and similar slicks run 12-teens @ 116:
a tenth quicker while being 4 MPH slower.....

 

I love these threads, I am in the same situation with trying to squeeze more out of my 383. I'm running 12.8 @ 104 the last time I went to the track and it matched my accelerometer dead on. I have the Escort G-Timer GT-2. I just ordered my LM-1 and it should be here tomorrow so I will be able to fine tune my carb. Now I have MT ET street drag radials as opposed to the street tires, waiting on skinny front wheels so I can put the small tires on, a NEW 3000 stall converter from a 3500 that might have been slipping, and better front springs for better weight transfer when the front lifts up. (I cut too many coils off of the other ones I had). I'm also running a modified TH350 w/ 3:70 gears.

The LM-1 should help better tune the carb for topend performance via changing out jets. And then dialing in the timing to match. Although I have a solid lifter cam, I STILL can't make good torque above 5300 rpm. Right now I'm second guessing the cam specs that came in the engine that I got from the seller, he built it some time ago and had to remember what they were. I have a feeling he was just trying to get rid of it and faked the funk with the specs as a selling point. Now my next thing to do after tuning with the LM-1 is check where the cam timing is at, -4, 0, or +4. Supposedly my cams specs are 248/248 dur and 525 lift which should be around the 1500-6500 rpm range according to some magazine ads, but that ain't happening.

Good luck with any changes and don't forget to update us with any improvments. I'll be watching this thread! Check my sig for more complete specs on my setup.