I just recently went a installed new head, intake, exhaust manifold gaskets, And now it wont start for anything. everything is torqued to specs, and hooked up just how it was. I reset valve lash to what the manual says ( tighten untill no play, then 3/4 turn more).

When i try to start it, it backfires and shoots up through the carb, now there is oil all inside of it. What could possibly have went wrong?


The engine is a 305 sb, 2bbl carb

I hate the Chevy technique of no play then 3/4 turn. Invariably you will get the valve lash to tight. Try Re-adjusting your valves again, and make sure when you are checking for the "no play" that you are moving the rocker end to end and not side to side. Try a 1/2 turn and see if this does not help.

I always set the valves loose for the initial start, the 1/2 turn advice is good. I'll go that far when I adjust them on older motors. The best bet is to do them when the engine is running.

For your backfire issue, your distributor might be 180 degrees out. A common thing that everyone does at least once or more often.

Bob

I noticed when I looked at the inside of the cap that the rotor peice is in the #1 position, but the cap was slightly turned so it was one postion back, could the cap being twisted make a differance?

http://www.classiccarauto.com/impala/how_to/install_distributor.shtml

This link should help you out. Before I take out a distributor I make a mark on the distributor and intake manifold with a tire crayon. If it started before it was out and it goes back the same way, it should start again. The vacuum advance is a good reference point to use.

Yours I believe is 180 degrees out and all you have to do is rotate the engine once, bring the #1 cylinder up to TDC and drop the distributor in.

You might also be a tooth off on the gear, the spiral cut makes it impossible to drop straight down, so you have to back it off a bit when you drop it in. This is where the match marks come in handy.

Also back off on the rocker nuts a 1/4 turn. It may be a bit nosiy but that can be adjusted while it runs, after it is warmed up.

To do the adjustment, back off each rocker nut in turn until it clacks loudly, tighten it slowly until the noise goes away, this is the zero point. Tighten it a 1/4 turn, wait for the lifter to pump up and the motor settles out, do another 1/4 turn, let it settle again and go to the next one.

I'm not a big believer in the 3/4 turn, but as long as it results in a smooth idling motor and the parts are all new, try it. If the result is a motor that shakes, then you probably have a too tight valve and it will eventually burn the valve(s).

Bob