rpm not changing [Archive] - Racingjunk Forums

smokinsmallblock

01-19-2011, 02:29 PM

i have put 3 sets of gears in my truck 4.86 5.14 an 5.43 the rpm is the same wit all 3 when i go through the trap 6700rpm.

TopspeedLowet

01-19-2011, 02:36 PM

Do you happen to use a RPM chip in your ignition? near 6700rpm.
Are your valve springs regulating your top rpm?
Bruce

BEAST477

01-19-2011, 05:09 PM

Give some more detailed specs on your truck.

superstreeter

01-19-2011, 05:28 PM

Part of that could all be in the convertor.....

smokinsmallblock

01-19-2011, 05:36 PM

yes 1 have a 7200 chip in it. its a 434 dart pro 1 heads it runs 590's all day, have a 670 645 cam in it. shift it at 6700rpm. 6000 coverter. car weight is 2450 wit a power glide

JEFF69Z28

01-20-2011, 03:24 AM

TO MUCH CONVERTER?

curtisreed

01-20-2011, 03:46 AM

I don't think the converter is really out of line. With a 434 small block it needs a lot of cylinder head though. Could it be out of flow limiting rpm? Couple of questions though. How are you getting the rpm reading, data recorder? Did your MPH change?

Curtis

smokinsmallblock

01-20-2011, 04:12 AM

i sent my heads to steve schmitz. got the open up. i went from 6.20's to 5.90's. yes the mph did change wit the 5.43 only went 6.00's wit them but the same rpm. only 109mph. avg. mhp is 113

smokinsmallblock

01-20-2011, 04:15 AM

i get my rpm data from my play back tach

TopspeedLowet

01-20-2011, 04:58 AM

i get my rpm data from my play back tach

you have a ignition problem limiting your rpm or something in that area. Change that chip to another one you have like the 8000 rpm one that came with your ignition. If you can not get past 6700 rpm in first gear either............. STOP and THINK for a minuet, then look again at the ignition.
Bruce

hammertime

01-20-2011, 05:00 AM

yes 1 have a 7200 chip in it. its a 434 dart pro 1 heads it runs 590's all day, have a 670 645 cam in it. shift it at 6700rpm. 6000 coverter. car weight is 2450 wit a power glide

. What is your stall that you checked, at the launch, after the shift fallback and if you've checked in the garage what is it ?

What high side chip do you run ?

TopspeedLowet

01-20-2011, 05:03 AM

yes 1 have a 7200 chip in it. its a 434 dart pro 1 heads it runs 590's all day, have a 670 645 cam in it. shift it at 6700rpm. 6000 coverter. car weight is 2450 wit a power glide

6000 converter, is this something you checked or thats what they told you it would be ?

If you changed the gear and seen no change, it all leads to the converter. What is your stall that you checked, at the launch, after the shift fallback and if you've checked in the garage what is it ?

How in the heck can a loose or tight converter possibly limit the top rpm?
The speed is diminishing with gear changes and the rpm the same?
Bruce

smokinsmallblock

01-20-2011, 08:00 AM

yes it can go past 6700rpm in first gear. i shift around that area, steve said i need to shift around 7000rpm but it slows up. if i take my trans break chip out and go on the converter it goes to 5900rpm. my shift lite comes on bout half track wit the 3 gears. heres my number mabe i can explain a little better 5404551035

fast75vega

01-20-2011, 06:16 PM

could you be running out of fuel on the top end..... which could be limiting your rpm........ :wink: thats alot of gear changes for it not to change ur rpm though the traps

hammertime

01-20-2011, 06:27 PM

TopspeedLowet

01-21-2011, 03:15 AM

If he were driving thru the converter with a given gear, then his MPH would not have diminished with higher numerical ratios and his rpm would have to increase at the finish line and through out the pass,.......... unless the car was not moving and you were doing a stall test.
I got a feeling that we do not have all the information we need to accurately diagnose this persons car set up problems or problem.

I would suggest that this guy talk this over with Steve Schmidt further and see if something else in the engine combination is relenting or unhappy with the new port job?
Best of luck solving you issue
Bruce

itsabird

01-21-2011, 05:23 AM

Just out of curiosity, what size tire or you running?

smokinsmallblock

01-21-2011, 03:50 PM

tire size is 14 32. ok let me ask yall this question. i ran 5.92 at 6700rpm wit the 514 in the 1/8th, in the 1/4 mile i ran a 9.54 at about 7300rpm. do that add up?

maxpower671

01-21-2011, 04:36 PM

tire size is 14 32. ok let me ask yall this question. i ran 5.92 at 6700rpm wit the 514 in the 1/8th, in the 1/4 mile i ran a 9.54 at about 7300rpm. do that add up?

NO. you should be at least .20 seconds quicker...???

itsabird

01-21-2011, 04:52 PM

I am starting to think along the same line as fastvega, fuel problem, a little lean, did you retune your carb after the port work, and what was the 1/4 mph on that pass?

fast75vega

01-22-2011, 07:20 AM

I am starting to think along the same line as fastvega, fuel problem, a little lean, did you retune your carb after the port work, and what was the 1/4 mph on that pass?

i thinking either not enough air(dirty air filter) which is making it run rich or its starving for fuel on the top end... :) i've had both happen to me and it sounds the same :wink:

smokinsmallblock

01-24-2011, 04:49 AM

i have a 1050 carb. on it. 92 jet square. plugs stay black. sometimes i run wit no hood on so i think its gettin enough air

fast75vega

01-24-2011, 05:00 AM

i have a 1050 carb. on it. 92 jet square. plugs stay black. sometimes i run wit no hood on so i think its gettin enough air

if the plugs are staying black..... def sounds like ur running rich then :wink:

either too much fuel or not enough air.......try running it with out the air cleaner for a pass or two and see what it does :wink:

smokinsmallblock

01-24-2011, 05:27 AM

i dont have an air cleaner on it at all. i have jetted it down to 90's but no change

itsabird

01-24-2011, 08:09 AM

Sorry just getting back, cable has been down. it could be rich at idle and the main circuit still lean. what size idle air bleeds, also high speed bleeds, is it a 3 or 2 curcuit carb?

smokinsmallblock

01-26-2011, 05:07 AM

i dont know the answer to the carb question, but i have took the 1050carb off an put a 950 carb on it and it response alot better an sounds crisper. but the 60ft an et stay the same with both carbs

shawnp

01-26-2011, 05:27 AM

What ignition box are you running? I had this happen with a brand new, out of the box 7al3 from MSD.

smokinsmallblock

01-26-2011, 05:29 AM

i have an 6al

fast75vega

01-26-2011, 05:31 AM

i dont know the answer to the carb question, but i have took the 1050carb off an put a 950 carb on it and it response alot better an sounds crisper. but the 60ft an et stay the same with both carbs

i would figure that your 60' would be.... but did you notice a diff. on the big end :?

shawnp

01-26-2011, 07:35 AM

So this has been a combo that has been together and worked fine with no previous problems? If so, what have you changed besides the gear?

SABOT7

01-26-2011, 10:57 AM

Someone posted ealirer that your 1/8th time should be .2 faster. I have always used the 1/4 time divided by 1.59 and got really close. For instance, your 9.54 divided by 1.59 comes out to 6 flat for the 1/8th. Not exact but pretty close. Anyway, when you change the gears, does the 6700 happen sooner on the track the previous higher (lower numerical) gears? Something else to check also if you are using an autometer tach with the adjustable shift light dial, is that it is working correctly. I had a similar issure using the adjustable shift light and some how it was overriding the shift pill in my two step. Last things I would check is valve spring seat and open pressure and also make sure that the timing and floats are set correctly.

smokinsmallblock

01-26-2011, 06:59 PM

the combo has been together for 2 yrs. my problem came when i tried differant gears, thats when i found out sumthing wrong

shawnp

01-27-2011, 05:32 AM

I would be looking at possibly 2 things if you have tried jetting, timing and settng the car back up to the original working combo. I would swap out ignition boxes and I would swap out MSD RPM modules (2-step or shift box). You may have a bad MSD chip. Sounds more in some of the electronics vs the motor.

smokinsmallblock

02-01-2011, 05:18 AM

another thing i for got to add i run 112 racing fuel is that enough?

fast75vega

02-01-2011, 06:22 AM

another thing i for got to add i run 112 racing fuel is that enough?

thats all i run :wink: but cause my brother in law is twisting my arm and the price of gas is suppose to go though the roof.... i might be switching to alky soon :)