Thread: shift point problem

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I have a '67 chevy impala w/ a 327 and a powerglide that is basically stock but with a edlbrk performer intake/650 cfm 4bbl,msd billet hei and headers.I recently put some header insulation wrap on and it made it to where the car is shifting at about 3200 rpm.The car runs like a top besides this.Looking for suggestions.

the shift point problem started immediately after I put the header wrap on.The 327 is a stock rebuild (not sure what you mean by "setup").I have read that the insulation may increase manifold vacuum if that helps.

You must have knocked something out of kilter when installing the wrap. Heat retention in the headers won't affect shift points. Check linkage, vacuum lines, etc.

Originally posted by R Pope
You must have knocked something out of kilter when installing the wrap. Heat retention in the headers won't affect shift points. Check linkage, vacuum lines, etc.

I'll second that. I'll bet you accidentally knocked off your vacuum line that goes to your tranny vacuum modulator........ assuming a GM tranny is similar to my Ford C6, in that they use a vacuum modulator to shift If everything is hooked up, look for cracks in the vacuum line.

Makes sense,I'll have to inspect it a little closer.Thanks.