598 SLUG
 

THIS MOTOR WONT GO OVER 6800 AT THE LIGHTS,, ALL NEW.BEST OF EVERY THING.1150 CARB..850 LIFT CAM.287-309- DURATION @.050.110 C/L.14./1 COMP. BRODEX HEADS,365 PORTS.356 LBS SPRINGS.3200 LB CAR 55 CHEVY.. 1.23 60 FOOT.. 8.65 @1000 FOOT. 9.43 @141MPH, ET?? 4.10 GEAR.. 4.56 GEAR.. CARB SPACER. MSD 7AL. NOT CRANK TRIGGER.. YOU CAN PUT 50 DEG. TIMING OR 36 DEG TIMING CAR RUNS THE SAME. PLUGS LOOK GREAT. GROUND SHOWS NO HEAT AT ALL!!POWER GLIDE. 29.5 TALL TIRE. :cry:

May be too much cam for the heads, i know of an identical situation about 3 yrs ago. 598" Brodix 2 extra heads, tunnel ram with 2 1150's almost the same cam, in a 2600 lb Vega. Thr car would not run less than 5.70's in the 1/8 mi, it would run 5.30's with 400 shot of nitrous. Heads were ported but wouldn't flow over 370 cfm. He has since torn it down and going with another combination. Another problem he had was it had 2 1/8" headers with 4" collectors.
These are just my opinion of what was wrong with the Vaga motor and may not be your problems.

Zip.

What brand of 1150 is it? Have you tried jetting up? You might be running out of fuel at the stripe. You also might want to try a 1250 if you could borrow one that you know works.

598 SLUG
 

I DO HAVE 1/78 HEADERS!!MAY BE IT?? THANKS

598 SLUG
 

I HAVE NEVER TRIED ANY BIGGER CARB THAN 1150.PLUGS LOOK NICE .. MAY BE RICH ..

I would say those headers are choking it. Change those and see what it does. Then try a 1250, bet it picks up.

I'm going through this same scenario w/ a 598 right now, just won't run the MPH that it should. Biggest problem is the heads, mine has BB2Xtras CNC on it and they just won't support an engine of this CI. I'm agonizing over the Headhunters or the 3Xtra CNC right now. HH's will require new shaft rockers, intake and maybe pistons. I'm running nearly the same cam as you, and all the builders I have talked to said it's too big for the heads, but would work with better heads. You should pick up some w/ better headers, but it's still choked off with the heads. I don't have the coin for the headhunters right now but who knows later on............good luck to you! 8) JB

What he said............

I have more questions to ask, you say it wont go high in the lights, how about at the shift, what are you shifting it at ? If its going over 6800 at the shift ... I'll need some converter info. Stall, Size and such.

598
 

HI SHIFTS AT 6800. CONVERTOR IS 5500 NITROS.

598
 

THANKS.. MY HEADS ARE NOT +2 CNC

I would be looking at the converter. Put a tighter one in and you will go faster. Hope this helps you

i'd be looking at a converter also .. but no way would it be a tighter converter then he has.


Rapptor
I'd do this, go out and see if it shifts @ 7000, if it does you just about guarntee that converter is your issue @ the stripe. A 5500 nitrous converter, should be very tight, do you no the actual stall flash and fallback rpm after shift ?

598
 

THANKS WILL TRY A NEW CONVERTOR

598
 

NO I DONT KNOW RPM CHANGE AT SHIFT. I THINK IT IS ABOUT 500 RPM TIRES CHIRP ..

The 141 is close (down a couple) for the ET, the 1.23 60' should be 9.30 area, but I can attribute that to the small diameter headers.

My personal opinion is the engine just isn't making the power due to some component mismatch.

Might want to find a chassis dyno before you start throwing money at it.

You need to figure out the stall of the converter. Its one of the most important things on a race car. i hate doing it this way but take 2 step chip out and put it on the transbrake somewhere and check the stall.

598 slug
 

A less harsh way to check stall is get it going about 30 mph in high gear, let off and then mat it and see where the tach goes instantly. You can also use your playback tach or record on your delay box if it has a max RPM function. If it spins the tires, do a burn out and try again.

Old school but might still work today.

Re: 598
 

I SHIFTED THE CAR AT 7200. FELL BACK TO 6900.

Re: 598
 

well that tells ya everything IMO
it'll go 7200 at the shift with no issues, it'll do it at the finish line.
Someone missed major on that 5500 nitrous converter if the fallback is 6900. Thats very loose for that heavy car. You should look for something around 6000 fallback. You can get away with that in a light dragster/door car but not @ 3200. Typically a 5500 nitrous conv will be very tight,unless it was made for much less hp/trq to start with.

I guess my only question would be: Where did you go to test on a Tuesday?

598
 

PALM BEACH MOTOR SPORTS PARK.I LIVE NEXT TO IT.. LOL

I wouldn't get anything done if I lived next door to a track I could run on during the week.

That MPH must be with the 4.56's?
With my calculations your conveter only has 3% slippage with 4.56's or -7% with 4.11's :?
somthing's amiss?
let us know what you find.
Good luck,
cam67152

598
 

HI THANKS FOR REPLY.. 4.11 0R 4.56 SAME MPH. 9.41 ET OR 9.46 ET.