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.

 

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

 

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.

 

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

 

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

 

whats the pressures on your springs? Seat and open?

 

What rocker arms are you using?

Shane

 

yella terra rockers,135 closed,375 open.

 

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

 

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

 

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

 

anybody else,running out of ideas.

 

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

 

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

 

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

Shane

 

good luck!

 

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

 

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.

 

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.

 

So what was this issue, float?