First time post...need a little help. I have an 84 Firebird. The carbed V8 that was in it was blown so I got a new block and rebuilt it. Now my car won't start. I'd like to think of myself as a pretty competent mechanic, but this one's got me stumped. I got a used short block, tossed on my heads, new timing chain, new carb, new distributor. When I go to crank the car...it doesn't exactly sound healthy...not like it used to sound when I cranked it before the rebuild. The y pipe isn't hooked up and when I crank it, it sounds like.."blub blub..blub blub...blub blub". Is this because I don't the have the exhaust hooked up? Second, when I go to crank it, unless I hold the gas pedal to the floor, it spits gas out of the carb vent tube. WTF???? It's a Holley dual inlet, vaccum secondary that's brand new. My first thought was that I had the timing chain 180 out but when I put my hand over the exhaust manifold exit, it did not suck..it blew. What would make my car spit gas through the vent tube?? I cranked it for at least 45 minutes and my spark plugs were bone dry. Shouldn't it have flooded out by now and my plugs soaked?? I know I'm getting spark...I pulled a plug, grounded it on the wheel well, and it fired. So I'm not getting gas. I pulled a valve cover off to make sure my valves were opening and from the looks of it, they were. When I put the timing chain on, I lined up the crank shaft dot at 12 o'clock and the cam shaft dot at 6 o'clock..then spun it over one complete revolution to put it at #1 compression. I don't know what's going on here. Could my intake valve be opening on the exhaust stroke...Is that why it spits gas out the vent tube on the carb?? I'm just guessing now. I've done all the trouble shooting I could. I even called a friend over and he's stumped as well. Can an expert help me out, PLEASE? I'd be eternally grateful. Any more info needed....just post. Thank you.

 

The blub,blub.... etc. is normal for a car with no y-pipe installed. I would at least hook up a y-pipe before trying to start it, just to be safe. With short manifolds, you could take a chance on burning a valve.

Second, your timing chain is installed correctly. You may have your distributor installed 180* out. Do this: pull #1 spark plug, and stuff a wad of tissue paper into the hole, but don't let it go all the way into the cylinder -- you just want to block off the hole.

Now crank the engine over by hand... when the tissue wad pops out, you will be on your compression stroke. Slowly turn the crankshaft until the timing mark on the damper lines up with the mark on the timing cover. You will be at #1 firing position.

Now check the distributor -- see if the rotor is pointing at the #1 spark plug wire terminal. If it is not (it likely is exactly opposite, at # 6) then you need to pull the distributor and relocate the rotor to #1.

I'm a little curious about the gas spitting... ordinarily, when the timing is 180 out, it backfires thru the carb. But I still would check the distributor timing before I went anywhere else. That is one of the most common things to go wrong when assembling an engine.

 

But after cranking the motor over for that long shouldn't my plugs have been soaked with gas? They didn't even smell like gas. I didn't even get so much as a cough from the engine either. It acts like it is starving for gas. ( No surprise if the car is shooting it all up through the carb vent tube.)

 

are you getting fuel out of the squirters when you pump the gas?

 

YESSIR!!

 

If the accel pump is squirting fuel, then your engine should start, unless your intake is blocked (never seen that happen).

Providing, of course, that everything else is right... but clearly you are getting fuel.

Your plugs should not be fuel-soaked unless your engine is flooded.

 

does it spin over strong? the most common problems are distributor way out of time or valve lash wrong.

 

Does anyone know why the carb would be spitting gas through the vent tube when I try to crank it? And wouldn't cranking it for 45 minutes flood it to the point that my plugs are wet?

 

In order for you to soak the plugs, you'd have to flood the engine by constantly pumping the gas pedal, which will keep squirting raw gas down the intake.

Ideally, the fuel is atomized in the venturi, and you get vapor in the combustion chamber. As I said before, I'd expect you to be backfiring thru the carb, but I am not there observing. Based on the info you are providing, I would suggest checking dist. timing before taking any other steps.

 

fuel out the vent tube is high float level or fuel pressure over 8psi

 

Going to do right now...back in a minute.

 

skirkland makes a good point... how did you set your valve lash? If your intake valves are not opening properly, that will starve the engine. However, it is still easier to double-check your distributor timing before you start fooling with valve lash.

 

Floats were set at the factory. I haven't adjusted them. Level looks good on the sight glass. Using my stock fuel pump that came on the motor..didn't switch it, so the fuel pressure should be good. Don't have a gauge to check. But thanks for the info. Could anything else make fuel come out of the vent tube? It only does it when I crank it and the damned thing shoots like a geyser. It doesn't puke gas if I hold my gas pedal to the floor. This is irritating me. Thanks for all the help.

 

to properly diagnose the problem you need to check to fuel pressure 6-7psi is what you want. you could have a bad pump. is it a 2 line or 3 line? the small third line is a return. if the return is blocked the pressure will be too high. if pressure is good you can take the carb back or replace the needle/seat assemblies.

 

Sounds similar to the problem I fought for a week.

Double check your fuel pressure, and ensure that your return line is not kinked, clogged, rusted, etc...

 

If it is really coming out the vent tube, it means that there is too much fuel being delivered to the carb. I have never seen one 'shoot like a geyser' though... and it is curious that flooring the pedal stops the geyser. Do you have the old carb? I think I read that you are using a brand new one. Also, when you say you are using the stock fuel pump, is it the one off your old engine, or the replacement short block? If everything ran OK with your old carb and/or fuel pump, you may want to consider using them.

 

I set the lash by bringing it to TDC #1...adjusting the push rods so I could not spin them with my fingers. Half a turn, adjusted the other ones that were closed. Another half a turn, rechecked. I pulled the valve cover off and it seems like to me that the valves are opening enough so the thing should burp or something when I go to crank it. I haven't gotten so much as a pop or a backfire...which even with my distributor 180 off it should have at least backfired. I'm going to recheck valve lash. But I've set it almost exactly as you said in the earlier post. I need a beer.

The pump is off the old motor. If the needle and seat are clogged, would it stop fuel from being squirted down the venturi? The old carb was a piece of crap...but yes it did run. I've considered putting the old carb back on and seeing if it fires.

 

do you have yuengling? i do. no really how is the oil pressure. maybe the lifters aren't building up.

 

any chance valves are too tight and holding intake valves open causing positive pressure in intake and fuel bowl?if you have a vac. guage should show roughly 3 inches cranking w/a strong battery.

 

Oil pressure is about 50 by the gauge and I'm getting oil through the push rods.

 

Ok guys...this is where I'm at. It's dinner time so...tomorrow I'm going to pull and re-time the distributor, try to crank it. If that doesn't work, I'm going to loosen all the rocker arms and reset the lash. If that doesn't work, I'm taking apart the carb to clean it. If anybody else has any suggestions, please post up. I'm about done with it for the night. I'll let ya'll know how it turns out. Thanks for all the help already. I never expected this much help...this quick.

 

If you don't have any way to check fuel pressure, I would remove the pump and see what happens. If there is fuel in the bowl, and the geyser stops, then you probably are getting too much fuel pressure from the pump.

 

I tried every suggestion that was recommened. Thanks for all the help. Okay, So here is where I'm at: my intake manifold is not sucking, it is blowing. I put my hand over the carb mounting plate and it did not get suction, so WTF is going on here? What would make this happen? Timing chain 180 out? Improperly adjusted valve lash? I also might have mixed my heads up during the reinstallation: driver's and passenger's side got swapped, but the valve layout is identical so it wouldn't matter, right? Help

 

if you didn't get a reverse rotation marine short block or starter i would recheck the timing chain.

 

Ok, I just reset the valve lash and no improvement. It is still blowing through the intake manifold. I laid a rag over it and it blew the rag off.
I am 99.9% sure that I put the timing chain on correctly, would anything else make the manifold do this?

 

Wow... the only thing that makes sense to me is what was previously posted about a reverse rotation engine... which would have a different camshaft. I guess the cam is really all that would be different. Heads can go on either side.

With cam timing 180* out, you would have valves opening at the wrong end of the piston travel, and this often leads to bent valves.

 

Well good thing that I dont have an interference engine or I'd really be screwed.....So the only thing to do now is to check the timing chain position and see if I'm 180* out. Nothing else could be causing this right? Instead of pulling off all my accesories, is there a way to check my valve timing by watching the rocker arms......I COULD HAVE SWORE I PUT THE TIMING CHAIN ON RIGHT!!!!!! I did it with the heads off of the motor. What else could be causing this? Lets say I wired up the starter backwards or something..... When I crank it with the starter, looking at the front of the motor its going clockwise: I spin it over by hand with the ratchet on "tighten" and the starter spins it the same way.
WTH is going on guys? Timing chain put on by lining up the crank dot at 12 and the cam at 6, and the #1 piston was at the top of the bore, installed chain, spun the crank one turn and the marks were both at 12.

 

which way is your rotor turning?is it following sequence on cap?18436572?this will answer your rotational question.if it is and you are absolutely certain about timing marks i would back off all the rockers and see what it does then.

 

IF you set your cam as you stated, it is timed correctly. Direction of rotation is clockwise as you face the engine, so you are correct there.

Where did your camshaft come from? If it was in this used shortblock, where did IT come from?

I don't see how messing up the cam timing would cause reverse intake flow. In order for that to happen, the intake valve has to open on the piston upstroke, and close before it begins the downstroke. The only thing that I can imagine would do that is an incorrect camshaft.

 

Ok, so I loosened all of the intake valves enough so the pushrods would not open them at all, mainly to see if my valves were seating properly and it quit blowing through the intake. So the good news is that the valve seats are good but the bad news is that my cam timing must be way off giving me a ton of overlap. Both the intake and exhaust valves blow air out in pulses, but the intake blows much harder than the exhaust. So logical thinking tells me that my cam is overly advanced or retarded, because the intake valves are opening at the top of the piston's stroke.