VN V8 stumble for a few seconds after rev limiter

[yoda69]

Guys,
Had a look at a VN V8 auto a while back, that after hitting the rev limiter would stumble for a few seconds before settling down and be ok.
Has 24lbers, extractors, 268 cam.
Even when rev'd in idle to the rev limiter and then lift off it would drop back down and still run rough before settling down after a few seconds.
Being only 160baud could not capture anything useful, anybody have any ideas?

The guy is complaining as it dies in the ass when he hits the rev limit in 1st and second.

yoda69

[Jayme]

i was running $12P in my 304 till I sold it the other day... I noticed the same thing, if I let it hit the rev limiter, it loses a bunch of power for a few secs before settling down and going again. never got a chance to get a log of it hapening tho and it doesnt happen in my mates 304 running a similar tune

[Holden202T]

tell him to learn how to drive and shift before the rev limiter

sorry got nothing useful to add

[yoda69]

I agree with Holden 202, but boys will be boys.

I'm wondering about the minimum pulsewidth, maybe the bigger injectors are causing problems if these haven't been adjusted?
I don't have the vehicle or cal at the moment for another look though, was hoping somebody else may have seen it though and found a solution.

yoda69

[Doctor Bob]

its not just a purely mechanical issue is it?
lifters pumping up?
just a thought

[yoda69]

Could very well be, I think the rev limit was raised to about 6000rpm, not sure what else has been done to the motor (high volume/pressure oil pump, etc??)
Would be easy enough to lower it back down to around the factory limit at 5500rpm and see if that helped, and the try 5000rpm as another check if no luck at 5500rpm.

yoda69

[Jayme]

hey I think you ar eonto somehting bob... I dont actually have to hit the limiter, just have to rev it above 5700 to make it lose power.

[Holden202T]

my mates VS 304 happily revs to 6400rpm without having any issues .... its a crow cam but very similar to the 286, it has stock computer ($83) and 30lb injectors with suitable vavle springs.

i know the 30lbers are far from on the limit, and for 6000rpom the 24's SHOULD be enough, but i guess without a good log with duty cycle and such its hard to say.

lifter pump up is the sort of thing that would take a few seconds to recover from, im also wondering, i used to have a similar issue with the 202 when i put the delco on it, it seemed to more run like it had dropped a cylinder though for a few seconds, but it would also do it when i revved it high but not hit the limiter (like holding high revs) .... i always thought it was the camira ignition maybe on the limit or maxed out injectors .... i never really got to the bottom of it before i put the ecotec in its place though.

so far with the 202 in the gemini and the same efi and ignition on it i haven't had any issues .... only difference other than having $12P is its got 80lb injectors .... and higher compression.

probably just rambling, may help

[Doctor Bob]

yep it could well be soft springs allowing the lifters to pump up...

[yoda69]

Spot on Dr Bob.
The revlimit had been set at 6050RPM, dropped it back to 5700RPM which improved things but didn't fix it.
Just got confirmation that with new valve springs it's all good.

yoda69