Brain storm a miss wid me!!

[DIRTFUNFAN]

ok street stock motor at 5,600 it busts up have changed everything and i mean everything..
rebuilt the motor
chaged all fuel componets
distributor plugs wires
carb
etc. etc. etc. etc.. any ideas i i am gonna check my valve springs tonight..
runs great then at 5600 rpms it busts out

[raceman17]

Have you had your modulator checked in the distribitor? That sounds like a it may be the problem. Also, have you tried to unplug your tach and see if the problem goes away? What about your fuel pressure. Have you checked that when the motors busting up?

[dirty white boy]

do you run a vacuum advance?? how bout mechanical advance?? how you set your timing?? you got good grounds on motor,heads an dizzy??? got good voltage to dizzy?? sure bout all this???

[DIRTFUNFAN]

ok last night i unplugged the tach and it seems the slightest better might of just been a coincidence.. i hve changed fuel pump and distributors its all good,, what kinda spark pug gap yall run,, this is at 35 but i dont think that would cause it.. drove it down the rd in first gear and it sounded awesome till 5600 started busting out.. i am just assisting somone else when they gave up on this car,, i noticed that the battery is in the back and the ground wire is prolly 14ft long from the back all the way to the block and its not grounded in the back to the chassis rail like i do mine..

[Egoracing]

ok last night i unplugged the tach and it seems the slightest better might of just been a coincidence.. i hve changed fuel pump and distributors its all good,, what kinda spark pug gap yall run,, this is at 35 but i dont think that would cause it.. drove it down the rd in first gear and it sounded awesome till 5600 started busting out.. i am just assisting somone else when they gave up on this car,, i noticed that the battery is in the back and the ground wire is prolly 14ft long from the back all the way to the block and its not grounded in the back to the chassis rail like i do mine..

Running the ground to the engine is 1000% better than EVER grounding it to the chassis as long as the ground wire is large enough.

[stock car driver]

I ground my battery to the chassis right next to the battery, i would add another ground there and to the block. but i doubt thats the issue.

are your plugs fouling when i was way too rich early this year my plugs would fowl after 3 laps i got 5600-5800 max rpm... i had dynoed and had a vac leak in the two piece carb adapter so i was way off on jets. chased it for 4 weeks and basically cost myself a shot at a traveling series title. though I was only 40 pts back before totalling my car two races ago.

jj

[DIRTFUNFAN]

i swear it seem it is in the valve train,,, how high of a rpm are hydralic lifters in a sb chevy good for they are howards lifters... its seems as if it is eithier that or valve springs it seems.. maybe i got some lifter float?

[bushracing67]

make sure the springs are correct for the hydraulic cam, check the rockers and push rods for excessive/unusual wear or damage

[DIRTFUNFAN]

make sure the springs are correct for the hydraulic cam, check the rockers and push rods for excessive/unusual wear or damage

rockers and pushrods are fine, springs were used that i was handed when i put it together i may just call competition products in the morning and order some new springs the cam is 450 lift howards cam it is the 450 lift rule cam any suggestions on spring?

[stock car driver]

you could use a oem gm spring for that low of lift without issue

are the plugs fouled?

[bushracing67]

get em checked, you might have too much spring for the hydraulic lifters

[21 racer]

i got the howards 450 lift cam in my sons car run anti pump up lifters and what they call z28 springs no problems

[dirty white boy]

ok last night i unplugged the tach and it seems the slightest better might of just been a coincidence.. i hve changed fuel pump and distributors its all good,, what kinda spark pug gap yall run,, this is at 35 but i dont think that would cause it.. drove it down the rd in first gear and it sounded awesome till 5600 started busting out.. i am just assisting somone else when they gave up on this car,, i noticed that the battery is in the back and the ground wire is prolly 14ft long from the back all the way to the block and its not grounded in the back to the chassis rail like i do mine..

stock HEI plugs are gaped to 45....id open yours up to lest that much....cables can go bad,corrode in side insulation,an look great but not work...

[merc123]

I had an issue like this. Seemed like a rev limiter at 5300 in mine. Changed everything electrical to include rewire entire car. Had 9 PSI of fuel pressure. Turned out to be plugs. They all looked good though. Start simple, then go more complex.

[ford396]

As raceman 17 mentioned. Have you checked fuel pressure while the engine is breaking up. Could it be a fuel volume issue. To small of a suply line, or a restricted fuel filter. I definitely would suggest keeping it simple at first.