1974 K5 Blazer New member, wierd problem
drewski120
10-22-2008, 02:19 AM
Well i am a new member so first let me say hey to everyone!
Then on the truck, i own a 1974 k5 Blazer...has a 350 bored over to a 383
Brand new Quadrajet 4 barrel carb on it...750 Cfm electric choke
Has from what i can tell(reccently bought this vehicle so im not sure) what looks like a Cadillac radiator in it, a lil smaller than what came stock in this vehicle im pretty sure and the previous owner seems to have compensated for this using 2 electric cooling fans...however the original crank fan isnt on the vehicle either.
Ive been tinkering ever since i bought it, it had a new ignition on it MSD, good from what i can tell...i checked and replaced the plugs and plug wires...checked and replaced the starter and starter solenoid.
Then i slapped a new battery in it, also ran new battery cables...and now to the problem....
It never ran what i would call "solid" first 30 mins of running it ran good...but after that you had to baby it a bit...thought it might just need a carb adjustment but i have adjusted and adjusted and it still doesnt seem to wanna stay running after it has been for 30 mins or so...i dont know what else to try and would really appriciate any advice at all, thanks everyone!
Sorry for double posting wasnt sure where to put it!
Then on the truck, i own a 1974 k5 Blazer...has a 350 bored over to a 383
Brand new Quadrajet 4 barrel carb on it...750 Cfm electric choke
Has from what i can tell(reccently bought this vehicle so im not sure) what looks like a Cadillac radiator in it, a lil smaller than what came stock in this vehicle im pretty sure and the previous owner seems to have compensated for this using 2 electric cooling fans...however the original crank fan isnt on the vehicle either.
Ive been tinkering ever since i bought it, it had a new ignition on it MSD, good from what i can tell...i checked and replaced the plugs and plug wires...checked and replaced the starter and starter solenoid.
Then i slapped a new battery in it, also ran new battery cables...and now to the problem....
It never ran what i would call "solid" first 30 mins of running it ran good...but after that you had to baby it a bit...thought it might just need a carb adjustment but i have adjusted and adjusted and it still doesnt seem to wanna stay running after it has been for 30 mins or so...i dont know what else to try and would really appriciate any advice at all, thanks everyone!
Sorry for double posting wasnt sure where to put it!
Blue Bowtie
10-26-2008, 11:57 AM
The overbore and additional stroke of the 383 is likely going to require re-jetting the carb, as well as a different set of secondary metering rods and the rod hanger. This should tune the carb for the 30-some extra cubic inches the engine now has. Even though the vacuum produced by the engine should help to compensate somewhat automatically, there will be a need for additional fuel at WOT and just off idle. That is why different engines have carburetors jetted differently.
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