383lt1impala

iTrader: (33)

hello all i am trying to trace down the problem of why my motor won't want to rev past 5500 while going down the road. it revs to 7000 with no problem in neutral or in park but once in gear its a dog when reaching 5000rpm.


when i was getting it dyno tuned the guy mess with the carb a bit. he said quick fuel had it pretty much dead on and only changed out the primary jets to one step bigger. ran and idled better. and when it came to doing to timing on the msd 6010. he noticed i had a timing curve which was high. something like 36* he lowered it to 31 and ran like doodoo. do he put the motor on #1tdc marked the balancer and checked the timing with a light a noticed it was reading about 4-5degrees too high. which would explain why the higher curve ran better i was short on funds then so i didn't have him go in it further. so my question is could it be a sensor issue? which sensor should i switch out? crank or cam? or could it be that the cam degree is off from when it was installed? any help is greatly appreciated. i want to do some research and gain info and do what i can before i take my truck to a shop and have them dig into it

here is the timing curve
20-32* 0-500rpm
32-24* 500-1250rpm
24-29*1250-1900RPM
29-35* 1900-3000rpm
35* from 3000 to infinity.

thats the timing curve i was given or else it wouldn't want to idle and would bog down at lower rpm.


heres a pic of the truck

Pop N Wood

iTrader: (1)

I have seen threads like this in the MSD user forums on their site. The one I seem to remember was the result of a miss aligned crank reluctor wheel. The cam being off a few degrees won't cause this.

Did you do anything to the bottom end?

383lt1impala

iTrader: (33)

Finally some input. And well the bottom end is a stroker 383 I used to run just fine spin at 7500 when it was in the z28 I had. From then to now it's had heads cam and intake. Then swapped in my jeep.

VLS1

No different to old school motors where the keyway can be a couple of degrees off, I wouldn't be surprised if some of the timing variation we are seeing that works for some and not for others, comes down to nothing more than reluctor wheels being a couple of degrees off from factory.

Heck, that might explain why some cars seem to perform better than others of the exact same model when stock?

speedtigger

iTrader: (16)

I have seen a few threads that made me wonder about the accuracy of the MSD's reported timing vs a timing light. One guy claimed his engine ran the best with timing over 40+ degrees. I knew something was up there.

TXsilverado

iTrader: (18)

i'm pretty sure his was a low compression motor on race gas and geared the F out. talking about the square s10?

speedtigger

iTrader: (16)

I can't recall who it was. Maybe.

383lt1impala

iTrader: (33)

Has anyone tried the fast box? I should check out a plCe with a good return policy try it. Before I have someone tear down the motor. I would do it. But u don't have the skillset or time.

Pop N Wood

iTrader: (1)

There was a guy on here just recently who couldn't get the MSD box to work and had to switch to a fast box. Try a search, very recent thread

Violence.z06

iTrader: (3)

Having the same issue on a friends car. breaks up bad at 6500rpm and wont go over. been through just about everything to fix it. We are thinking its the MSD box itself and MSD has no answer for the problem.

383lt1impala

iTrader: (33)

Before 6500 how does it pull? My truck will ight up the tires for a bit once it reaches 5000 that's when the power starts to fade

383lt1impala

iTrader: (33)

this is pedal to the floor on the sand. It wasn't tuned then

Here it is on the dyno.


Many have start issues with their 6010. I don't

dogsballs

ive noticed my rpm chips for 7al3 read/work lower yhan on label

383lt1impala

iTrader: (33)

I'm going to try out a new msd box, harness plug wires to see what's up also new crank and cam sensors

Violence.z06

iTrader: (3)

The car pulls good up until 6500rpm then sputters and pops out the exhaust and noses over. have been through every single piece of the ignition system from the box forward. tried 2 boxes, wires, coils, carb, plugs, msd harness was swapped. problem is still there. cannot find anything in the wiring, fuel is good also.

read around and with the 6010 box its a common issue. so its distributor time.

89gmcs15

iTrader: (7)

What did the dyno show? Can you post your graph. What gears are in it?

383lt1impala

iTrader: (33)

I'll post the graph if I find it. It has 4:11s on 37s

Mine won't go that high in gear nor does it sound like that. Today I put a new cam sensor and box and plugs. Same ole stuff. Let me know how your new set up works for you!

Violence.z06

iTrader: (3)

wont be on my car its on a very good friends car. ill let you know how the new setup works out. i hope is solves the issue.

Pop N Wood

iTrader: (1)

Did you check what the rev limiter setting is? you wouldn't be the first guy who got bit by that one.

Also what valve train/motor combo. Truck valve springs are very weak and will float at high RPM

BTW that truck totally rocks. I would love to have something like that.

383lt1impala

iTrader: (33)

Rev limit is at 7500 and reaches it in neutral or park. Instantly. Ported 806 heads dual valve springs. Stock rockers. Texas speed pushrods ls7 lifters. Ms4 camshaft. And thanks it's been in the family over 23 years and in 24 I grew up riding in it. And now it's mine.