See https://www.thirdgen.org/techbb2/sho...threadid=72443 for the original.

The local speed shop only had PVs going to 7.5, so I picked one of those up and put it in. Definate improvement on that flat spot when increasing throttle from either idle or cruise. Makes me think the 8.5 would be even better.

One of these days I'll mount the vacuum gage and check cruise vacuum per the Holley website recommendations for mild cams. I'm sure my idle vacuum is low because of the altitude here.

For those who don't want to read the previous post or the Holley website: for a racing cam, pick the power valve 2" below your idle vacuum: i.e., if you have 8" Hg vacuum at idle, get a 5.5 PV; for milder street cams, pick the PV 2" below your typical cruise vacuum.

 

Hi,
I took the 6.5 out of my 4160 / 600 and put in a 2 stage, Holley # 125-206. Partial enrichment occurs at 12.5" with full at 5.5". Combined with a weaker secondary spring and more agressive pump cam' this improved my low and mid' end acceleration but still maintained economy.
Now it should be noted that I'm still using the stock camshaft combined with an Edelbrok Performer intake, strip-chip and 160F cooling. You'd be surprised, though, at the difference it's made from stock!
I still think that 600CFM's is just a little much at WOT but hope to take up the 'slack' with a good exhaust, headers and 1.6 rockers.
Great board guys... A fabulous way to spent some hours! Regards...

 

I'm glad to hear you got the problem taken care of. Who would have though the holley was leaner in the primaries than the qjet?
I was reading some stuff over at the second gen site on tunning holleys a few days back and they had some interesting information about over compensating one part to fix a problem with another. I'll post the link it, might contain some usefull tips for us all.
SSC


Link: http://www.nastyz28.com/perftune.html#carbtrouble