Vacuum question!

Thx for all your answers!
I think i figured the vacuum thing out! I looked more at the advertised duration than at the @.050. And then also that the idle rpm is so high, i tested to lower it to about 700-800rpm and the vac. dropped to 4-5 ipm! :)

moper said

Those numbers are fine for a 4" arm. I'd expect to see a slightly less number with a better carb. 750 is just plain too small for a long stroke like that. In "std" Holley cfms, I'd say at least an 850 on it, in Demon, Avenger Holley, or "wet flowed" the number should be 800 or larger. The cam is mild, but perfect IMO. If the heads were milled for the open chamber, the 38° number may be ok. If the smaller chambers are run with pump gas (at least the 10% ethanol and 92-93 ocvtane numbers we have over here) and properly designed quench, the low 30s will be the highest you need. A recent big block with Indy SRs likes a max of 28° total. I had to make a bushing for the MSD for that...lol. Like Dave said...you want max pressure at about 20° after TDC in crank degrees. Lower octanes burn faster.

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Would there be a performance gain worth the money to go with a Demon 800-850 ?
Would there be any big performance gain in switching the cam for something more agressive like Hughes HTL4652AS ? Or would that sacrifice alot of streetability? I dont find it annoying to ride with the cam i have today, is there a big change to switch to something more aggressive ? :)
And also how much gain is to ride with a mechanical cam vs. a hydralic! I read different opinions every where!?

I dont know the ethanol mix in our fuel but i think its about 10%! But i always go with Shell 99 octane and add octane booster! And it seems to like higher timing! I just ordered a MSD Billet dist. instead of my Chrysler dist! Its going to be fun to test :)