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edelbrock 750 on 350 having hesitation

13K views 30 replies 12 participants last post by  91chevyss 
#1 ·
hi everyone i have 91 chevy tbi engine that i switched to carb and its in a 91 silverado. I had the motor rebuilt a few years ago it was bored .060 over due the rod bearing overlaping, the cam has .488 lift, it also has electric water pump and fans, edelbrock shorty headers, edelbrock torker intake, edelbrock 1407 750 with spacer, and a holley regulator set at about 5-5.5 psi. also an accel coil in cap hei with msd wires. once i first got it running it wouldnt rev past 2500-3000 rpms got that fixed by changing module in dist. i took down the road and to town a few times and by normal driving i guess you could say light throttle it would be hesitate or bog down not sure but if you stomp on it wouldnt be as bad and it will also rev fine in park well i fixed most of the problem by relizing the choke wasnt all the way open "about half way" lol new to carb. also when i had the revving up problem i thought the carb was to big and was getting to much gas so i took out the .113 prim and .107 secs and put in .101 and .95 and that was all i changed and i still have them in there, but im still having the hesitation or bog cant really tell and it does it the most right when im creeping up around 2000 rpms. it smells like it could be running rich and theres also a little wetness around the pump at the top of the carb. one other thing my wife was behind me one day when i got on it and she said it had llke this burnt smell but no smoke came out. any help would be greatly appreciated.
 
#27 ·
just looked at the page you sent in the commet "centerline", the calibration kit for the 1406 with .101 uses .073 x .047 which is the same rod thats in the carb now but was wondering why the 1407 with .101 use a .065 x .037. thanks again for the help.
 
#29 ·
i finally found the problem, well i purchased the spring kit and installed the yellow spring and it made it worse, although it was shorter than the one i pulled out it was also stiffer. so i tried the blue springs even worse. it was just popping and bogging down starting at around 2000 rpms. the next day i pulled all the spark plugs out a about half were a tan color and a couple plugs were two tone white on side and tan on the other. so i figured it wasnt getting enough gas, but it didnt make since because it seem to run better on the lowest hole on the accel pump even though it was still popping and bogging down. so today i pulled the top of the carb off to make sure the jets werent clogged and i got to looking at the jet holes and the size of the rod through each jet, the .101 with the rod through it didnt look very big. so i switch the jets around. i took the .095 out of the secs and put the .101 in place and put .107 in the prims. and checked the floats and then i put everything back together. i also put my stock springs back in which where identical to the orange springs (mine were plain, guess they lost their color). well i cranked it and it ran even worse come to find out i mixed up the #6 and #8 wires when i checked the plugs, switched them back and fired it up and it ran like brand new lol, took it down the road with out any popping and bogging, but it did have a little hesistation when i stepped on it so i moved the linkage to the middle hole and that fixed that. so now its running 100 times better and im guessing the rod was to big for the .101 jets. im still gonna check the vac advance and get the timing set correctly. thanks everyone for all the help.
 
#30 · (Edited)
Hey freakin seuss.

Baseline the carb back to STOCK SETTINGS! Step up springs to suit the vacuum at idle and for tip in of the enrichment circuit (it's in the manual).

Set the timing correctly- be sure the total doesn't exceed 36 degrees.

Run it (you'll love it) and check the plugs to see what- if anything- needs to be done w/the carb settings.
 
#31 ·
so do i need to put the .113 jets back in? i was trying to save a little gas but the .107 with the 7147 rod could give me worse mileage not sure. where exactly do i hook up to get a reading for the stepup spring to use? I misplaced the manual, but i found one online and it still doesnt make since lol. is it suppose to give a reading low enough to equal the hg on the spring at idle? as far as timing i need to get a tab for the cover because im using the aftermarket chrome cover and it didnt come with one.
 
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