Bbc Timing ?????

[Freakonaleash]

OK this is going to sound stupid but what does backfireing tthrough the carbs?? I thought it ment the timing was to retarted. So i advanced it and it still does it. this is a fresh rebuild and I'm trying to fire it for the first time. thanks
Tom

[396_Z]

Are you sure your not 180* off?

[Freakonaleash]

IT was the first time i tryed to fire it so i changed it and now it fires but won't stay running and backfires thuough the top.??? I'm stumped!!! thanks
Tom

[wideopen545]

sounds like your 180 out

[Havasu Hangin']

Plug wire switched?
Cam timing?

[Infomaniac]

One or more cylinders?
Exhaust valve not opening will do the same thing.

[Infomaniac]

PM me your phone number if you do not get it going.
I will call you back and we can go over the basics tomorrow.

[Freakonaleash]

thanks info i will do that i'm going to double check every thing and i will let you know what i found. thank you
Tom

[Racing Ray]

Since you already fired it up with it out 180* you most likely already experienced backfiring, this can blow out power valves on Holly's if that is what your using might check for that.

[BGMAN203]

sounds like your either 180 out, have exhaust valves not opening, or your 1 tooth off in the dist gear, and its not advanced enough.

[SERIOUS ISSUES]

just a thought if you are running hydrolic lifters. when they pump up the valves are not closing all the way. loosen them a little. if they are mechanical I am a little stumped unless wires are wrong or mechanical timing is off. my .02

[BGMAN203]

Did you figure it out??? Kinda interested to see what the prob was???

[HOSS]

Are you running with a Lunati? Maybe you got a Ford cam and I got a Chevy.
Seriously, do a quick visual on the springs to see if one is broken. Make SURE a plug wire is not crossed. Re check timing for distributor. Last thing to check would be pulling timing cover. I don`t think your 180 out. I did that my first cam change on a 305 in my ElCo back 20+ years ago. 180 out makes a bomb. Blew off my mufflers.

[DansBlown73Nordic]

Hoss, lmao you blew the mufflers OFF....You come from a long line of disasters.....;)

[HOSS]

Yeah, like I said if it can happen it will and to me. But these disasters are all part of the learning curve. I`m just on the low end of it.

[Freakonaleash]

Well i got it fired up and running its just a mother to start it runs like a raped ape now my problem is i can't get it to idel at less then a 1000 rpm so setting base timeing is a little hard. sorry to take so long in getting back to everyone. 60hr of work leaves no time to play with the toy. thanks for all the feedback. The cam is a comp cam 292h-10. .550 lift and 292 duration 110.0 separation
thanks
tom

[skeepwerkzaz]

Who set up the cam? Could be that if everything else is set up right (plug wires, distributor, etc. and it barely idles, the cam could be a tooth off, or the harmonic balancer is shot (elastomer)and giving you an erroneous timing indication. I have dealt with both of these problems on a bbc. You could also have a monster vacuum leak. You aren't by any chance running a square port intake on oval port heads are you??????/
Skeep

[Hotcrusader76]

Originally posted by Freakonaleash
OK this is going to sound stupid but what does backfireing tthrough the carbs?? I thought it ment the timing was to retarted. So i advanced it and it still does it. this is a fresh rebuild and I'm trying to fire it for the first time. thanks
Tom
Some advice given to me one day :D
Go back to "square one" (Now this is assuming everything on the engine is good operational condition, IE camshaft isn't flat, good valvetrain, and you don't have a dead cylinder.)
Find Top Dead Center (on compression stroke utilizing your finger in the number one cylinder hole as an indicator of the compression after TDC) and marking the harmonic dampner, take all of your wires off the engine and reconnect them utilizing the correct fireing order (trust me...take them off and put them back on again), then drop your distributer in on number one.
Prime your system and check your fuel pressure. Should be around 6.5-7 psi. Also check your float levels on the carburetors. If your pressure is high then your boosters will drip causing a hard to start rich condition, not enough pressure will cause it to die or not even start when hot. Nonetheless keep it simple and check all of the basics.
Once everything is checked and inspected for correct pressures give her a turn and she should ignite first or second kick. It worked for me...:D
Note- If your valve lash is too tight then you will not compress the mixture and therefore you will redirect the pressure upward pass the intake valve through the intake while the spark is igniting it. This is depicted as a large orange flame that seems to flash with the revolution of the engine:D with the assistance of the engine starter through the carburetors. Not the sort of dynamics were trying to envision here.

[Freakonaleash]

Hey TY
The carbs look great and i had a little bit of a prolbem with the float level was a little high but nothing i couldn't handle. the thing runs grate fires firest time i try to start it now but it just won't idel. i was able the break in the cam but i haven't had time to try anything elce sence. hopefully i will get to this weekend. I will try to e-mail you some pic as soon as i can.
Tom

[Fiat48]

Pull the valve covers, turn the engine over and watch the valve action. Make sure the cam made break in without going flat. Then continue investigation.