I plan to get a buddy to machine a 1" spacer for me (I was thinking of a phenolic one but the dust is an issue). Talking to Indy, they didn't see an improvement on a 572 (1/2" spacer) until over 7200 rpm. Pretty sure the 580 we have starts tailing off there anyway (Best shift seems to be around 6800). I do think it will help on the 655 though. I might just go ahead and try it my self in phenolic to see what occurs.
I didn't want to, but also I think I'm gonna strip down the induction, give everything a clean and set it all up on the bench before it goes back on the engine just to eliminate any possible issues as it's been standing over a year. We're house hunting at the moment so racing is taking a bit of a back seat but we should out at the start of Sept for a day of testing, then 4 days of racing. Should get plenty of passes if the weathers good so plenty of data and tuning up

PS out of interest what was the issue you spotted ?

Last edited by Tig; 08/03/22 01:43 PM.

'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03