A cross post from V-8 Buick - I modded a spare manifold and tried it out... pretty good results but still workign out the bugs. Any advice from here is appreciated too!
http://www.v8buick.com/showthread.php?t=209741Thanks, Rhett
Re: doctors orders
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I bolted on my "Doc Mod" intake yesterday on my bone stock 65 Gran Sport and with no tuning took it out for a few runs this morning, as timed by my G-Tech meter.
Nearest I can tell with only 4 runs under my belt, the manifold is good for .2 tenths. First run was 15.5, with mucho wheelspin on cold tires. Next two were both 15.1, one with no wheelspin but plenty of bog, the next with some wheelspin but shifting manually. Next run I matched my prior best run of 14.9, hzed the tires and shifting manually.
I was surprised that the mod didnt kill torque like I thought it would, but does feel stronger on the top end.
The one dissapointment is that it created a huge off-throttle flat spot. I get the whole "change in venturi effect" thing, and I'll admit I havent tuned for optimum vacuum yet either. But on a square bore manifold, this carb (AFB at factory settings) had immediate throttle response. It almost feels like the secondaries are dumping open too soon, but with out permanent mods I dont think I can change that on an AFB. I could try jetting/rod changes, I assume to go richer but I'm just guessing. One other aspect is it was 54 degrees out, and I put blocked heat riser gaskets in when I did the intake, but I let the car warm up thouroghly, and the choke was fully open.
Anybody have any advice? The car still runs very strong but obviously has more in it.
Thanks, Rhett