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Old 07-24-2008, 11:27 PM
MadHippo MadHippo is offline
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Join Date: Nov 2002
Location: Oakland, California
Posts: 95
Default 428 stumble and dyno question

Here is the setup in my 67 GTO convertible.

428 stock rods and crank. .30 over.
#62 heads
1.65 rollers
comp cams xe268h
edelbrock 750 and performer manifold
1 5/8" headers.
PYPES 3" exhaust w/ X pipe
MSD billet distributor set 12 degrees btdc
muncie 4 speed

The car pulls like crazy from around 1500 to about 4000 rpms. The problem is that it has a stumble from the line. If i keep the rpms up before letting off the clutch, its fine. If i take off really really slow, its fine. If I take off normally, it stumbles/bogs, almost to the point of stalling. The guys at the dyno think that it may be a carb/cam combo problem. Also, the HP seems to fall off fairly early if you look at the dyno sheet.

Please have a look and throw me some suggestions if you have some.

thanks,

matt
Attached Files
File Type: pdf Dyno.pdf (18.5 KB, 109 views)