need mechanically inclined people inside

[nino]

my problem: only under WOT when i hit 5000 rpms my car stutters for a second, drops the rpms, drives like poopoo for a minute, then resumes normal driving. happens only at the track, being that is the only place i hit 5000 rpm under WOT. the rest of the time the car seems to be fine.
at first people thought it was a misfire. 12 plugs and wires later i dont think it is.
what i was told today (and in my lack of knowledge in mechanical engineering, i am a little lost at words) is that only at high rpms (5000 cosistently) a valve is staying open and then closes shortly afterwards. he said something about some preload being too high and causing the valve to stay open. he said that maybe adjustable rocker arms or shims might fix that problem. i dont know if we have adj. rocker arms or shims for our cars.
is there any insight you might be able to share with me on this? it would truly be appreciated.
thanks for everything,

nino sandoval

[slacker69]

did u get the valve spring upgrade on your heads if not maybe at that load you are floating the valves untill it comes off that cam spot. But all this still wouldnt explain why u are smokeing at idel unless u also burnt up and exshuast valve or piston ring

[pgriffith]

I dont see anywhere in his post it says he is smoking at idle. Nino do you have troubles at idle too? If so what does it do?

[nino]

slacker69 has seen my car and felt the problem man to car. yes my car smokes more than a cheech and chong movie, but i think that is just a bad valve seal. its the 5000 rpm whammie that is keeping me from the track though. this is what tom wrote me. not i do not have autotap.
Nino,
Thats possible I guess but it can be verified by taking some
measurements of
the pushrod as you tighten the rocker arms.

You can also use an adjustable pushrod length checker to measure exact
required length based on the change in cam base circle and the head
milling.

You have an AutoTap correct? Why don't you set it up to log:

rpm
throttle position
maf flow rate
all four O2 sensors
long term fuel trims both banks
short term fuel trims both banks
fuel pressure
ign timing

then you can look at what if any changes occur at 5000rpm.

Do you that you have adequate fuel pressure/flow up top?

Rocker arms. We've been trying to get some adjustable roller rockers for
the
GM3800 like we have for the 3.8 Ford. One manufacturuer even bought some
aluminum stock to produce some prototypes with the offset valve tip, but
the
general manager told the production guy to stop work on them because of
some
issue with another rocker company. I don't know if it will be resolved
or
not.

I'm sorry to hear about your problems. Look first at using your
diagnostics
and have required pushrod length measured with an adjustable checker to
see
exactly where you are. If your pushrods are slightly long causing
excessive
preload, you could use shims to raise the pedestal.

[Magnus]

Do you have a MAF T+ hooked up?

[nino]

yes i got the stiffer valve springs and yes the maft+ is hooked up but it is set as base settings for now. the only time i have changed them was at the track, where i saw no improvement. but it was an aweful day to race- extremely hot on a hot engine only able to get an embarrasing 14.9 at best that day.

[slacker69]

do u have stock pushrods, if so why dont you get the comp cams pushrods they are like 99 bucks and are chrome moly and suppose to be nice and i need to buy auto tap so we can fix your car just havent had the money you know how it is but i promise you we will fix your car.

[Magnus]

Unplug the MAF T+ completely.. use the timing bypass plug as well.. I had a similar problem due to excessive knock retard and the MAF T+.. Without the MAF T+ I was good to go however with the MAF T+ my car would go crazy at WOT around 5K rpm's.

[nino]

<blockquote>quote:</font><hr> Unplug the MAF T+ completely.. use the timing bypass plug as well.. <hr></blockquote>
i am a little lost here. unplug it but use what? do you mean keep what is spliced but lose the thing in the maf? please tell more.

[Magnus]

Completely remove the MAF T+ from the car.. Use the little black bypass plug they gave you on the 2 ignition wires.

[slacker69]

hey magnus if this does make that problem stop then what do we do. I mean of course we need to reinstall the maft+ but what do we do different that will stop the stumbling at around 5000 rpms.