i was helping my brother get his new motor hooked up last night when all was complete an he was tryin to fire it it was acting as if it wanted to light then boom fire shot out of the carb im thinking timeing but we ran out of time as it was late what do you guys think i have had this problem before well kinda the motor was running in my case this motor is just plain wicked an ive heard that makes it more tricky any help would be appreciated thanks

 

definatly the timing. get a timing light and you'll be good.

 

this is where it gets funny what do you think to much advance or retard i have been thinking about it and tell you the trueth im not sure an dont remember from my past experience other then i had to pull the distributor

 

I'm not sure what the timing should be at. I'd just adjust it until the engine runs steady then see where I'm at. If it's a stock engine you should be able to look up the timing.

 

I'd guess its retarted. Try somewhere around 8* BTDC with the vacuum plugged. It should be close.

 

so if you are guessing retarded that means the distuto needs to be moved counter clock wise correct

 

you guys are over reacting a little you should rewind some, i've had a back fire through carb when the plug wires were crossed, just check the wires firing order is 18436572 and the driver side cylinders are odds and passenger side is evens just make sure you have the no. 1 cylinder on TDC of the compression stroke. check that before you fool with the timing onless you know its perfect.

 

... and when you put it back in you put it in 180 degrees off.

Take it back out, turn it 180 degrees, try again.

 

i'm gonna have to agree with them.. i had the same problem and after sorting plug wires, it was a simple turn of the dist. cap to get everything right. depending on your calibrated ear, you can usually just go for a smooth sound to get it close enough.

 

it has to be really retarded to get that to happen... pretyt much your sparking befor the intake valves close ... before you pull the distributor though, check your firing order... then to make it even easier just so its not more tearing into it flip the plugs around 180 just so you dont have to hassel with keep on flipping the dist... you will tell right away if its flipped but im guessing thats it... usually when wires are crossed you will get a mixture of carb back fires and exhaust back fires... its a fun little moneky to track down and you end up moving the distributor so much you wont even know once you got it right... just put it in factory position and make sure the wires are right, then swap wires 180 if that works you know the dist needs to be swapped 180... even a crazy cam setup will usually sputter a little bit on factory timing settings... it will getyou close atleast

 

yeah this is pretty much what i was thinking when i put the distributor in though both valves were closed an the timing mark was at tdc i thought if it were out 180 the timing mark would be on bottom an not line up am i confused my brothers at school tonight so i got a few hours to deside i cant wait to put the timing light on it we were running out of time last night as morning was rolling around an zeon light was fried got the bulb cant wait till firing something about it just makes my heart race even know this time its not mine the feeling is the same i finished mine a little over a month ago sweet i wish i could do it everyday

 

haha i know the feeling of getting one of these f body projects to fire up after days of work. i agree that it would be great to experience this everyday, however, hopefully it will only be necessary once! good luck to you in your timing adventures..

 

The Timing Mark will show TDC when #1 or #6 is at TDC. My guess is you are 180 out with the distributor.

 

recent update i have continued with tryin to get this timing issue figured out i thought about the same thing as you guys that it was 180 out so i flipped the distributor 180 wow big boom out the exaust then nothing so i put the timeing light on it an had my son crank it it way out the only # on the balancer i see is 270 degree mark an thats a couple inchs off to be honest i feelin a little confused at this point what am i doin wrong im settin distri per # 1 being at top dead center timing marks line up both valves closed

 

is this a roller, hyd. or solid cam?
1. big backfire out the exhaust generally means over-retarded timing (if the firing order is right)
2. big backfire out the intake generally means over-advanced timing
3. you may have adjusted a valve(s) too tight and it's not closing completly

 

thanks the valve adjust may be a issue when i first put these in i thought they were not right so i readjusted them now that they are pumped up could very well not be closeing completely that and resetting the distrib. so basically just start for scratch going over everything for the 100th time. thanks for the ideas keep you posted on the progress

 

Exactly. Like you mentioned, you should be at #1 TDC compression, aka both valves closed, 0 degrees on timing marker, and if you pull the plug and back it up a little, and crank it past, you should feel a poof of air out #1. That will verify you're at the correct point. Once you get to 0 degrees, verified TDC compression at #1, turn the motor, say with a breaker bar on the balancer center-bolt, until you get to your base timing reading, say 8 or 10 degrees BTDC, I forget what your stock timing is. But then turn the distributor so that the rotor lines up as close as you can to #1 on the cap. Lock it down and you can fine tune from there but your timing should be within +/- 2 degrees or so, enough to get it started.

And yes yes yes recheck all the valves, those will cause big issues. Also look for major vacuum leaks and crossed wires. Verify you have the correct firing order for your engine and camshaft.

 

tonight i solved a good part of the timing issue i was haveing with backfiring. my next ? involves a different part of the timeing being valve timing. in the past ive destroyed a cam by not having this correct. so here is what i didi took each cylinder to top dead center tighteneach one till movement an slopp were gone slightly tight then gave each one 3/4 a turn and tightened down is this correct or am i missing something? do i need to repeat this process now that the motor is runnig or is this correct an continue with cam break in?

 

You want to set the valves with the lifter contacting the base of the cam, you don't want the lifter to be on the lobe of the cam at all. I usually set the valves by waiting for the valve to close, then give the motor a half turn, then adjust that valve. You can also set them with the motor running by backing off the nut until you hear the rocker start to "clack" then tighten up the nut 1/2 turn or so. Its messy this way, but works well.

 

ok i set the valves up off the base of the cam my ? is now that the motor is running an the lifters are pumped up do i need to repeat this process for setting the valves?