Critique my 1/4 time and how to improve!

[289nate]

The part about stock eliminator is true. It's basically all about the 1/8 mile and they sacrifice he back half to tear up the first half with the gear choice. It's ET that wins races! You may wind up picking up mph in the 1/8 while losing mph on the back half. The MPH might stay around the same at the end of the 1/4 mile, but the ET should drop when this happens. You just have to make sure your engine holds onto power and doesn't fall off a cliff or come apart at the higher trap rpm. My combo currently picks up way too much mph on the back half to have a real good ET for the MPH. It's something I need to work on too.

The TKO and T5 based transmissions are street transmissions that should be thought of as a four speed when drag racing. I bet his fifth gear is still synchronized and not faceplated. Mine is that way. All the manual transmissions I know of that use five speeds at the track are clutchless and don't have the huge rpm drop from 4th to 5th. You can't shift into fifth quickly with the TKO/T5 either. Its designed to be a highway cruising gear.

[redliner42]

The part about stock eliminator is true. It's basically all about the 1/8 mile and they sacrifice he back half to tear up the first half with the gear choice. It's ET that wins races! You may wind up picking up mph in the 1/8 while losing mph on the back half. The MPH might stay around the same at the end of the 1/4 mile, but the ET should drop when this happens. You just have to make sure your engine holds onto power and doesn't fall off a cliff or come apart at the higher trap rpm. My combo currently picks up way too much mph on the back half to have a real good ET for the MPH. It's something I need to work on too.

The TKO and T5 based transmissions are street transmissions that should be thought of as a four speed when drag racing. I bet his fifth gear is still synchronized and not faceplated. Mine is that way. All the manual transmissions I know of that use five speeds at the track are clutchless and don't have the huge rpm drop from 4th to 5th. You can't shift into fifth quickly with the TKO/T5 either. Its designed to be a highway cruising gear.

Indeed,the TKO is faceplated in 2,3,4, and with this cam I do not even use 5th. The heads are still gianing in cfm at 1.00 lift,thhe cam is prolly done around 7000 so trappit it 7300- 7400 or so is what I am after. This motor is pullin hard when I pull 4th and is really gittin it at the stripe @ 6000...just run outta track/gear...

[289nate]

The heads are still gianing in cfm at 1.00 lift,thhe cam is prolly done around 7000 so trappit it 7300- 7400 or so is what I am after. This motor is pullin hard when I pull 4th and is really gittin it at the stripe @ 6000...just run outta track/gear...

It really comes down to how well the engine holds onto the power after peak HP as to how much gear you can throw at it. Some engines tank after peak and some hold on for another 1,000 rpm. Stock Eliminator engines probably pretty much flat line for a while after peak HP.

[redliner42]

Update....29.5x 13.5 M/Ts,new valve springs,about a 73lbs. loss in unsprung weight (smaller slicks and new Wilwood disc. all around) how much improvements do you guys think I will see with smaller tires and unsprung weight reduction? 10.91/122.8 w/ 14-32s and drum brakes.

[fdicrasto]

Zero improvement. Just a guess. Phil D.

[redliner]

Zero improvement. Just a guess. Phil D.

So far....10.800@122.56 tis a .11 improvement and I'm just gettin started....

[cab0154]

how far off of coil bind are the valve springs at open? also, can you tell us about the carb? i also think it has too much tire on it. a 28-9 should be more than enough. i would expect it to run more mph.

[redliner]

how far off of coil bind are the valve springs at open? also, can you tell us about the carb? i also think it has too much tire on it. a 28-9 should be more than enough. i would expect it to run more mph.

If I remember right,they are .060 from coil bind. As far as tires,I just went from 14/32s down to 13x 29.5,yer prolly right it could get by with 28s I am sure,I might try some when I wear these out. The carb was built for me 30 years ago by a man by the name of Dave Jamison a local carb guru who (you must see it...) took my stock(progressive ramp style secondary opening) 750 Holley double pumper and inserted small rods perpendicular and above the butterflys ( to quarter the air instead of just halve it as it goes thru venturi)also opens up (I think) the power valve passages to his specs and the power valves front and rear are gutted with his recipe and are wide open...not really a valve at all kinda hard to explain without seeing it. He also drilled out (30 plus years ago remember) the high speed air bleeds a bunch and epoxied inside the main body so as to make the carby two independant 2 barrel carbs. They are ALWAYS jetted and squirted square,and i run the adj. screws about 1/8 of a turn from bottom out.In the 100 degree heat I run size 70 jets and size 35 squirters.I do not pretend to know anything about carbs ( Cause he does and I do what he tells me and it works great!) and I DO KNOW that when I was bracket racing with a glide/brake/crossover delay box, when I put this carby on it turned my car into a killer consistant and deadly racer. Also...instead of having to change jets and squirters every time a cloud blocked the sun I have a set of jets and squirters for spring/fall,and a set for summer! As far as mph,I lost 1.3 mph I presume because of the shorter tire. I am still tuning this combo and am going to put some 72 jets in it as I have bumped the timing up a bit and had already made several changes and well...you know how that goes...oh and it is only trappin about 6500(I think) there is more in this combo...

[redliner]

personally, i think your cam duration is a little too much, you should be leavin the line around 6000 if you can hook

I am not doubting your word Zums just wanna say 5500 launch=1.56 60',6600/1.49,7000/1.456 put the skinnies 3' up and bent the hell outta my license plate....

[greywolf]

I don't think you are overcammed, I would maybe try a 850 carb.
If your crossing the stripe at 6500, a steeper gear (5.13) should shave a tenth or more assuming traction does not become an issue.
And your tune up needs to be optimized, (maybe close already).
I see at 10.60 pass, and at 3300 lbs thats not to bad.

[redliner]

I don't think you are overcammed, I would maybe try a 850 carb.
If your crossing the stripe at 6500, a steeper gear (5.13) should shave a tenth or more assuming traction does not become an issue.
And your tune up needs to be optimized, (maybe close already).
I see at 10.60 pass, and at 3300 lbs thats not to bad.

I am not sure if it was exactly 6500 at the stripe,things happen fast and it looked to be around 6500 ( sorry about my educated guess) however I also failed to mention I wieghed the car and it is now 3150 so I am sure this is where my et reduction came from but there is another fly in the ointment from the 10.91 pass which was run at the tailend of last year....When I first fired up the motor (on its 5th street/dragrace season) I went for a drive and to make a long story short,had a head gasket leak water into #6 cylinder and when I replaced the headgasket there was ZERO hone left in the cylinder and this is along with it already having .006 piston to cylinder wall clearance when fresh soooo I am sure this engine is waaaay down on power. I have not taken a compression test nor put a leakdown guage on it...I bet with a freshenup/new pistons etc this combo would lose at least another tenth....sorry if I have painted a rosy picture I just negelct some things as I have bumped my head alot..... I might try an 850 carb if I can find one to borrow but I would not know where to baseline it....

[randy331]

What did the carb guy do to make sure the power valve circuit isn't going dry on launch?
You mentioned it has that opened up?
At about a 1.50 60' uncovering the secondary jets/power valve becomes a problem and needs addressed.

I'm skeptical of your carb guy. 90% of the time they do more harm than good with the secret mods to carbs.

Randy

[redliner]

What did the carb guy do to make sure the power valve circuit isn't going dry on launch?
You mentioned it has that opened up?
At about a 1.50 60' uncovering the secondary jets/power valve becomes a problem and needs addressed.

I'm skeptical of your carb guy. 90% of the time they do more harm than good with the secret mods to carbs.

Randy

The power valve is no longer a valve but is open. That is a good question I will ask him! I think this guy falls into the 10% you mention tho...