r572cobra

Im having problems with the car at the track,not pulling in third gear and miss firing.took it to the dyno,power is taking a dive around 5800,both with nos and na.motor 383,ls6 heads,comp cam,248/615 lift,114,patriot valve springs,fp was no lower than 58 psi,plugs looked good.dyno guy said it may be a broken valve spring,motor used to rev to 7000,with no problem.any ideas.

Darkman

iTrader: (2)

Sounds like valve float. Assuming the plugs look okay - pull the valve covers and look at/test the springs/pushrods/etc.

r572cobra

I asked the dyno guy if it was valve float,but he said,it did look like on the on the computer,would a broken spring cause it,motor only has 5k on it.

r572cobra

all the springs looked okay,did a commpression test,every cyl. around 180.pulled 2 springs and goint to have them tested.

r572cobra

pulled all the spring,they checked good,i entered pinks on nov.20th,anybody have any ideas.

TurboBuick6

iTrader: (2)

whats the pressures on your springs? Seat and open?

XtraCajunSS

iTrader: (2)

What rocker arms are you using?

Shane

r572cobra

yella terra rockers,135 closed,375 open.

XtraCajunSS

iTrader: (2)

You don't have enough spring for Yella Terras with XE-R lobes. I'd put stock rockers back on it. You're problem should remedy itself.

Shane

r572cobra

i understand what you are saying,but the motor never had this problem,used to rev to 7k.no problem.

Whiteaw57

iTrader: (2)

Is that due to the extra weight of the yella terras? sorry if thats a dumb question i just feel like i had a lightbulb moment here

r572cobra

anybody else,running out of ideas.

XtraCajunSS

iTrader: (2)

Those springs are done.

Yes, it is due to the extra weight of the Yella Terras.

I know for a fact you don't have enough spring pressure for your setup.

Shane

r572cobra

I order the extremes,should be here today,i dont have the stock rockers anymore.

XtraCajunSS

iTrader: (2)

They should get you another season. Check them often. They will not last long in your application.

Shane

Whiteaw57

iTrader: (2)

good luck!

r572cobra

thanks,for all the help.should have it back together tonight,hope that fixes it.

TurboBuick6

iTrader: (2)

Hopefully that cures your problems. Make sure you install to correct coil bind. I dont know what partiot recomends but I would say about .060 from coil bind.

r572cobra

did a couple of second gear pulls last night on the highway,felt putty good,pick up 2 inches of vacumm,at idle cant figure that one out.

masterz28

iTrader: (8)

So what was this issue, float?