Can't quite get it running

[lukecp]

I can't seem to get my truck to run after swapping heads. I have got the motor fully assembled back together, and i tried to start it a few times. First, it backfired a little bit, so i thought i got the distributor in wrong. So, i put the #1 cylinder at TDC on the compression stroke, and set up the distributor so that the rotor was directly under the #1 spark plug wire terminal. I then tired to start the truck, and it backfired pretty bad again. However, it backfired almost as soon as i turned the key over, where before it was taking it several revolutions to back fire.

I have checked the firing order, and it is fine. I know the truck is getting gas (i can see it in the fuel filter, and i can hear it squirt down the carb if i operate the throttle), and i doubt my coil or module are at fault since they worked just fine before i tore it apart.

This leads me to believe i have adjusted the valves too tight, since it was my first time adjusting them. I tightned them down until i couldn't move the pushrod up and down, and then went another 3/4 turn. Should i try to adjust them again, but not quite as tight?

I really want to hear the truck run again, i haven't drove it in a week and i am sick of running around in a minivan all the time

[Blue_71]

your too far advanced on the timing!!!! lol, and on how to adjust valves, you grab the push rod and spin it untill its got alot of drag on it and its hard to turn, than i do 1/2 turn more. then when i get it running finish adjusting.

[Blue_71]

btw-- to reatrd the timing, turn the dist counter clockwise

[lukecp]

I just went and backed it off a bit...still no luck.

Are you sure i'm giving it too much advance? If the rotor is right under the #1 terminal when the #1 piston is a TDC on the compression stroke, wouldn't that mean the timing is set at 0 degrees?

[Blue_71]

mine backfires when you advance it to far while your trying to start it... other then that i dont know what could make it backfire.. how are you checking to make sure your at TDC number 1 comp stroke? when you but the dist back in, are you putting the #1 wire on top of where the rotor button is pointing?

[lukecp]

I check for TDC by putting a little ball of saran wrap in the spark plug hole for the #1 cylinder, and then rotating the engine by turning the fan. When the ball of saran wrap shoots out, i continue turning it until the mark on the balancer is even with the "0" mark on the timing tab.

Yes, i am also putting the #1 wire right on top of the rotor's position, when #1 is at TDC........

[Blue_71]

i dunno then man, timing to far advanced is the only thing ive ever had backfiring from

[love it loud]

when you set the rotor at the #1 spark plug terminal, make sure it's static timed at about 12 deg. btdc!

[lukecp]

Thankfully, the search function is working again, and i found this:

http://67-72chevytrucks.com/vboard/s...justing+valves

Looks like this guy had the exact same problem i do. I think i will just go and re-adjust the valves tomorrow, but i will tightnen them down until i feel a slight drag while turning the pushrod, instead of no up-down movement in the pushrod, and then go 3/4 of a turn tighter. I think i will static time it to about 8 degrees advanced....i'm not sure how the motor will run on 91 octane gas yet, lol.

Thanks for all the help!

[Class of 69]

yellow....that adjustment procedure is for new install without oil in the lifters!! Your engine had been run...so you should have only tightened them until there was no play. I, personally ,about here would only tighten them to remove play, and attempt to start it. It may clatter badly from loose push rods, but you should really adjust them while it's running anyway. To check the timing, hook up your timing light, and watch for the flash WHILE turning it over...I have timed many engines on the starter motor before the engine ever ran, that way, you can eliminate timing as a problem. It may not be exact once the engine starts, but it will be very close.

[jef5150]

i dont think you adjusted them in the right sequence ,you can " ONLY " adjust the #1,3,4,8 exhaust,and the #1,2,5,7 intake at tdc #1piston,,,thats it ,,,"THEN" rotate 1 revolution of the crank to 0 on dampner ,this is #6piston firing position adjust#2,5,6,7 exhaust ,and #3,4,6,8 intake,,,,,,fix your distribor and i bet it starts...

[ZOOMY]

You may have the distributor 180 degrees out of time. Watch the intake rocker for #1 cylinder. Rotate the crank until the TDC mark comes up AFTER the #1 intake closes. Then drop the distributor in keeping in mind it might not go all the way in if the oil pump slot isn't exactly lined up.