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71chevelle
New User
Jul 18, 2009, 3:12 AM
Post #1 of 8
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71 Chevelle has no power
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Just installed a 350 crate motor and a TH350 trans with all the fluff, e.g.
headers, high rise intake, 750 edelbrock, 50K volt ignition etc. Engine will
rev up like it should to 6K rpms in park and neutral. But in gear it will not
go over 2K rpms - just bogs down and stalls out??? Did check timing and
it advances with rpms. Any ideas??? thanks
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 18, 2009, 6:09 AM
Post #2 of 8
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Re: 71 Chevelle has no power
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Are you getting any backfires or anything?
What is your base timing?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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71chevelle
New User
Jul 18, 2009, 7:35 AM
Post #3 of 8
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Re: 71 Chevelle has no power
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When I rev it up in park or neutral - no backfire.
In gear, it will backfire if I try to give it fast
acceleration and then it dies out.
.
timing is set at 8 degrees advanced
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 18, 2009, 8:30 AM
Post #4 of 8
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Re: 71 Chevelle has no power
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It sounds like the secondary ignition is brealing down under load. That could be a bad coil, coil wire, dist cap or rotor.
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Loren Champlain Sr
Veteran
/ Moderator
Jul 21, 2009, 1:48 PM
Post #5 of 8
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Re: 71 Chevelle has no power
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71Chevelle; 750cfm is too much for a stock 350, in my opinion.  Should be around 600, maybe 650cfm. Try disconnecting the vacuum advance to see if it makes any difference. Those distributors were famous for the centrifugal advances to 'freeze up'. Also, the pickup coils would break down under advance.
Loren
SW Washington
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71chevelle
New User
Jul 25, 2009, 7:28 AM
Post #6 of 8
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Re: 71 Chevelle has no power
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This is the 350/350hp crate motor, w/high rise intake and headers
should be around 380hp. Has new electronic 50k volt ignition.
This 750 Edelbrock has the smaller "economy" jets. The carburetor
is new but I did have to replace the accelerator pump. Hope this
helps.
thanks
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Loren Champlain Sr
Veteran
/ Moderator
Jul 26, 2009, 12:05 PM
Post #7 of 8
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Re: 71 Chevelle has no power
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71Chevelle; I noticed Hammer asked you what the base timing is set at? What about advance curves? Centrifugal and vacuum. I'm still leaning towards carburetion, though. Does this 50k distributor have a vacuum advance? Voltage output doesn't mean squat if it isn't getting the voltage to the plugs at the correct time. Just a sales gimmick, IMO. A stock, HEI distributor will put out 35-40K which is more than sufficient.
I've had much larger (455 cu. in, 400hp) engines that didn't need 750cfm. And, those 'economizer' jets may be shooting you in the foot? A gas analyzer would help greatly in determining what's going on. If it's 'starving' for fuel or 'overfueling'.
Loren
SW Washington
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 26, 2009, 12:17 PM
Post #8 of 8
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Re: 71 Chevelle has no power
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That 750 shouldn't be a problem. I ran one on a 340 small block and once it was set up right, I could hole shot about anything.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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