would street tires cause...

Posted By: Mr.Yuck

would street tires cause... - 02/20/12 04:30 PM

a stumble? I posted a while back about a slight pause in the carbs. I though it might be do to the weather (cold). Well I drove the car Sat (57*) and it's still there. Seems to come on right when the PV opens (4.5PV) Of course this is at 10-20 and stomping it. I wonder if the lack of traction wings the motor up quicker opening the outboards faster? or maybe not quick enough. I can try a dead stomp w/ the radials for oblivious reasons.
Only reason I ask is I was watching the vac gauge yesterday and as soon as it drops below 5 on a heavy foot it has the hiccup. Still was nice to put a few miles on the car.

Posted By: BSB67

Re: would street tires cause... - 02/21/12 01:43 AM

Quote:

I wonder if the lack of traction wings the motor up quicker opening the outboards faster?

Yes, this can be the reason. This can also happen if you hammer the throttle from a roll starting at an rpm above the converter stall rpm. The signal that the carbs get at the track under WOT from a dead stop with traction is different than on the street from a roll or tires spinning. It becomes more pronounced (i.e. more hesitation on the street) the heavier the car, the taller the gear, and the tighter the converter.

This might not be what is going on with your car, but I will say this with certainty, only adjust the outboard carb opening rates AT THE TRACK.

Posted By: Mr.Yuck

Re: would street tires cause... - 02/21/12 02:16 AM

Quote:

Quote:

I wonder if the lack of traction wings the motor up quicker opening the outboards faster?

Yes, this can be the reason. This can also happen if you hammer the throttle from a roll starting at an rpm above the converter stall rpm. The signal that the carbs get at the track under WOT from a dead stop with traction is different than on the street from a roll or tires spinning. It becomes more pronounced (i.e. more hesitation on the street) the heavier the car, the taller the gear, and the tighter the converter.

This might not be what is going on with your car, but I will say this with certainty, only adjust the outboard carb opening rates AT THE TRACK.

yeah I wasn't going to mess with them unless I had issues at the track. so far they've run just fine there. Heay?? about 38-3900lbs 3.91's and 3800 stall.

Posted By: Cab_Burge

Re: would street tires cause... - 02/21/12 03:12 AM

You might want to use a heavier,slower opening, spring on the outboards for street driving, maybe change back them at the track to see which set 60 fts. the best

Posted By: Mr.Yuck

Re: would street tires cause... - 02/21/12 03:17 AM

Quote:

You might want to use a heavier,slower opening, spring on the outboards for street driving, maybe change back them at the track to see which set 60 fts. the best

I have the purples in now. Not to worried about the street.

Posted By: Dodgem

Re: would street tires cause... - 02/21/12 07:32 PM

My guess is you need a higher number PV Dabeast2 just went from a 4.5 to a 7.5 and got rid of his hickup. maybe a 6.5 so you get the power enrichment circit working in time to have the fuel needed there in time!

Posted By: Mr.Yuck

Re: would street tires cause... - 02/21/12 07:40 PM

Quote:

My guess is you need a higher number PV Dabeast2 just went from a 4.5 to a 7.5 and got rid of his hickup. maybe a 6.5 so you get the power enrichment circit working in time to have the fuel needed there in time!

I had the 4.5's in last season and had no issues. This is really the 1st time I've used anything but the hoosiers on the car. All of the "testing" was done w/ the drag radials. Didn't have any issues at the track, but I do have an assortment of jets, PVs squirters and springs I bring with me.

Posted By: 572charger

Re: would street tires cause... - 02/21/12 11:38 PM

i ran heaver springs on the street and taped off the kill bleeds at the track so they would open up instantly !! back in 1986 ihad a stock 6 pack on a 590 cammd 30 over 440 that would run 11.30sin a 3800 lb charger !!!! i would crush any car on the street with the 6 pack in the 80s

Posted By: Mr.Yuck

Re: would street tires cause... - 02/22/12 01:18 AM

Quote:

i ran heaver springs on the street and taped off the kill bleeds at the track so they would open up instantly !! back in 1986 ihad a stock 6 pack on a 590 cammd 30 over 440 that would run 11.30sin a 3800 lb charger !!!! i would crush any car on the street with the 6 pack in the 80s

I'm not crushing anything with these tires... 590 is a good cam. I have a 588 solid roller and a stock 6-pack.

Posted By: lewtot184

Re: would street tires cause... - 02/22/12 02:35 AM

reading thru some of these replys. my experience has been a cold intake and cooler temps, including 50's, will cause a flat spot on kickdown, but probably not from a standing start. the cold intake has a denser charge and will create a lean condition on initial opening of the end carbs. i wouldn't get lost in it as long as you know fuel pressure and float level are correct.