Originally Posted by 91chevyss
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.
first pull the carb off after you run it around the block and it is warmed up...see if there is a puddle of fuel under the carb at the bottom of the intake. If this is the problem, your carb is too big....down size to a 600cfm carb.
Next check to see that the vacuum hoses are in new condition to the distributor and that infact the vacuum advance is working...Simple method is to suck on the hose to the advance unit and hold your tip of the tongue on it for a time to see if it moves, as well as hold vacuum....insure all vacuum lines are in good condition and are in the right place...a vacuum leak will do the same thing, if it is cracked, but not seen...idle will be erratic also, or higher than normal and shifting may, or may not work as it should.
Did you pull the distributor, when you did the intake manifold? If you did, then make sure you did it at TDC....To find this correctly, pull the #1 plug out and spin the motor by hand and wait until finger is blown off the cylinder head than take a look at the dampner and put it on the timing mark dead center, then pull the cap off and check to see that the rotator is pointing to #1 cylinder....\
I think if you do these things, you will find your problem...
Lastly, insure fuel pressure is there from the pump and that your pressure reading really is 5-5.5psi.
Good luck and I think the 600cfm will work better for you,