I have a 650 Barry Grant Speed Demon carb on my engine(350 ci) that performs flawlessly......I switched the camshaft to one that has duration of (.050 lift)242 intake, 248 exhaust(.530 lift) and also installed a single plane manifold.....
The problem I have is that he car will not idle........the techs at Grant told me the Speed Demon carb will not atomize the fuel properly with a cam of that duration and suggested that I get a Mighty Demon carb that is designed to work with long duration cams.......I just hate to spend $500 for a new carb.....is there anything I can do to rework the one I have to make it work?????
I had a GM "ZZZ" cam in the car and was able to get the car into the 11.20 zone.....gotta get into the 10's....that's why I switched.....but as usual.....one thing touches another=$$$$$$$$$$$$$$$$$$
As usual.....Thanks
Ken :cool:
http://www.chevelles.com/showroom/SS396Convert/nova.jpg

are you on the power valves at idle? for the past few weeks ive been dealing fuel distibution problems all over a 4 hole spacer.

I still have the Stock Power Valve that came in the carb in it (6.5???)......I did a vacuum check and at 1000 rpm I had 9" vacuum and stumbling at 700 rpm it had about 5".....
Thanks
Ken
:cool: :cool: :cool:
http://www.chevelles.com/showroom/SS396Convert/nova.jpg

i went to 3.5s on mine and it helped a bunch. i had about 7" in gear. with the 6.5s it was gaging me

Originally posted by SS396 Convert:
I still have the Stock Power Valve that came in the carb in it (6.5???)......I did a vacuum check and at 1000 rpm I had 9" vacuum and stumbling at 700 rpm it had about 5".....
Thanks
Ken
:cool: :cool: :cool:
http://www.chevelles.com/showroom/SS396Convert/nova.jpg Your power valve is rated too high. Subtract 2.5 from the lowest steady vac reading in gear and go with that PV. With your cam I would suspect that your engine would like a 4.5" PV.

My 383 with 248* cam likes the 4.5" PV. A 6.5 will occasionally start to open at idle and cause an over-rich condition.

Also, going to a single plane intake will probably make your optimal jet size increase. I had to go up 2 sizes with a Holley when I went from dual plane to single plane. This won't effect your idle though, only WOT.

posted 11-01-2003 07:19 AM
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quote:
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Originally posted by SS396 Convert:
I still have the Stock Power Valve that came in the carb in it (6.5???)......I did a vacuum check and at 1000 rpm I had 9" vacuum and stumbling at 700 rpm it had about 5".....
Thanks
Ken

http://www.chevelles.com/showroom/SS396Convert/nova.jpg
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Your power valve is rated too high. Subtract 2.5 from the lowest steady vac reading in gear and go with that PV. With your cam I would suspect that your engine would like a 4.5" PV.

My 383 with 248* cam likes the 4.5" PV. A 6.5 will occasionally start to open at idle and cause an over-rich condition.

Thanks.......I'll try changing the power valves.........sounds like you have a well thought out balanced combo in your car graemlins/beers.gif

Ken

graemlins/thumbsup.gif
http://www.chevelles.com/showroom/SS396Convert/nova.jpg

posted 11-01-2003 07:19 AM
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quote:
--------------------------------------------------------------------------------
Originally posted by SS396 Convert:
I still have the Stock Power Valve that came in the carb in it (6.5???)......I did a vacuum check and at 1000 rpm I had 9" vacuum and stumbling at 700 rpm it had about 5".....
Thanks
Ken

http://www.chevelles.com/showroom/SS396Convert/nova.jpg
--------------------------------------------------------------------------------

Your power valve is rated too high. Subtract 2.5 from the lowest steady vac reading in gear and go with that PV. With your cam I would suspect that your engine would like a 4.5" PV.

My 383 with 248* cam likes the 4.5" PV. A 6.5 will occasionally start to open at idle and cause an over-rich condition.

Thanks.......I'll try changing the power valves.........sounds like you have a well thought out balanced combo in your car graemlins/beers.gif

Ken

graemlins/thumbsup.gif
http://www.chevelles.com/showroom/SS396Convert/nova.jpg