[southside39]

https://www.youtube.com/watch?v=ez8Z...e_gdata_player

I'm at my wits end trying to figure this out. I just changed the cylinder heads on it and finally got everything put back together and I can't get it to fire.
My car is a 1975 Grand Prix with a 400 30 over. The heads it had on before were 96 castings and the heads I just bought from a forum member are ported 62 heads with a lot of work done to them. New mildon valves. Valve seats hardened. Hotchkis 1.65 rocker rollers. Ported to flow 265 intake and 210 exhaust at .500 lift. They were removed from a running engine. My car has a mallory distributor and accel coil on it. The guy said it had a mild cam that he had no specs for. It has a edlebrock performer intake and a holley 830cfm racing carb on it.
I used new felpro gaskets when replacing the top end and I believe I put everything together in the right order. I did an oil change and emptied the radiator and refilled it to complete my work.
When I attempted to start the engine the first time there was a very loud pop that sounded like a gunshot and left my ears ringing. There was a pot of gas in the carb so im not sure if this could have been what caused it or not. Afterwards I waited and tried turning the engine over and the starter was cranking and there was an occasional cylinder firing but it would not turn over. There was also a hissing noise coming from the passenger side of the engine that i could not pinpoint.
I would greatly appreciate any help identifying where I messed up or what could be going wrong with my engine. I really wanna be able to drive my car soon. The following link is a video of the attempted start up. Hopefully someone more knowledgeable than me can hear something going on.

[cdrookie]

sounds like the timing is too far advanced or the battery is weak for one thing, but should still start... start at the basics, timing correct and wired the right way? is it getting gas? check the compression. compression+ fuel+ spark = a running motor unless the timing is wrong.

[MescaBug]

Can be many things...

From what I hear, that battery is weak. You can hear the starter struggling to turn the engine. With a full battery, it should turn a lot faster. Even if this is spark ignition, you need some kind of compression to get things started.

Do something before we go further: jump start from a good and healthy power source, another car with the engine running.

Originally Posted by southside39

There was also a hissing noise coming from the passenger side of the engine that i could not pinpoint.

Vacuum leak.

[2002Z4CSS]

Originally Posted by cdrookie

sounds like the timing is too far advanced or the battery is weak for one thing, but should still start... start at the basics, timing correct and wired the right way? is it getting gas? check the compression. compression+ fuel+ spark = a running motor unless the timing is wrong.

Ditto that!

[Overkillphil]

Did you R/R the distributor for any reason during the head swap?

[fastekibeast]

Originally Posted by Overkillphil

Did you R/R the distributor for any reason during the head swap?

x2

IF you remove the distributor, 180 degrees wrong way??

[southside39]

Originally Posted by Overkillphil

Did you R/R the distributor for any reason during the head swap?

R/R? I took the distributor out and when I put it back in I made sure piston one was at TDC and the rotor was pointed at plug 1.

I also tried a different battery and got nothing. I need to find a compression tester and then I'll do a compression test

[Overkillphil]

Originally Posted by fastekibeast

x2

IF you remove the distributor, 180 degrees wrong way??

Yep, that's where I was headed.



OK, how did you determine TDC?

[southside39]

I couldn't find a piston stop anywhere so I just put a dowel rod in the spark plug hole for piston one and had a buddy slowly turn the bolt on the balancer with a socket wrench until the dowel was at its furthest out point and both valves were closed which should be the top of the compression cycle

[Overkillphil]

Hmmm, you may be 180 degrees out doing it that way. Repeat it and bring up the piston to TDC after the intake valve closes and before the exhaust valve opens. Then, assuming the balancer is on the money just set the mark to '0' rather than playing around with wooden dowels.

Now look at which way your rotor is pointing.

[sts]

The vid speaks a thousand words.

R/R = remove and replace. Actually you did a r&i remove and install not an r&r.

You have been reading too much online tech. Don't waste your time with a compression test.

It's at the top twice on the compression stroke and the exhaust stroke, also meaning the 0 on the balance will be 0 on c-stroke and 0 on the e-stroke.

First, turn the distributor counterclockwise some. If that doesn't solve check to see if it's out 180. I think it's less effort to pull it and install at 180 to check rather than dink with determing which 0 is tdc.

I would be inclined to think it's 180 out. The thing is that bumping the distributor c/c is so easy it isn't a wast of time.

[post toastie]

As long as the cam hasn't been changed and cam timing is correct I would remove number one plug and bump start motor over with thumb plugging #1 until compession stroke pushes thumb off. Then pull the cap to figure out where rotor is pointing on the cap this will be number 1 on the firing order. You may need someone to help you with this. You could also use a compression gauge to help you determine #1 also.

[pont3]

The engine seems to be turning over just fine so I would check fuel delivery. The timing does seem slightly off, but not by much. Also, check your battery cables, especially the negative cable as it seems there may be some resistance in them.

I don't know for sure about the aftermarket intakes, but with the factory intakes, nothing above a '71 will work properly on those heads without some additional work. For instance, a '71 headed engine will require a '71 or older intake to prevent the exhaust leak at the intake/head mating surface.

This may have been addressed in the design of your intake, (I can neither deny nor confirm this), just something else to consider if you haven't already.

Has the engine been cranked enough to get fuel flow to the carb? I did notice the carb linkage moving while you were cranking but not enough to get "first start" on a new engine. Plus, if fuel were there you would have more POPPING, and maybe even a flame or two.

[pont3]

Just re-read your post and you indeed have/had '71 heads as the 96 heads are 1971. So scratch that post.

[PONTIAC LARRY]

dizzie off, 180 out or there abouts previously mentioned. looking for a happy update

No sealing issues with #62's (1969) and Edie Performer.. 65-71 gasket , 72-79 gasket match to year of heads. Performer has small crossover like 72 up head but seals on both heads as long as gasket is right for year of heads.

[southside39]

Out in the garage now. Just tried rotating the distributor 180° and still got nothing. The primaries in he carb are squirtimg but the socondaries aren't so I think the primaries should be enough to get it started. I read somewhere about high compression engines need a stronger starter to crank them over. Since I now have close to 10:1 compression could my starter not be strong enough?

[southside39]

Just tried jumping it with a running car and all I got was a backfire and the carb caught on fire...

[moontower69]

seems like you were 180 off, wad up a paper towel and place it in #1, turn over until it shoots out, then you know your're at TDC....also, 180 off would explain the loud backfire

[PONTIAC LARRY]

other than getting dizzie right also the valve adjustment needs to match the heads if hey have chevy style studs and not bottlenecks be sure and adjust per SBC insructions but still sounds like you are off on distributer. line up zero on balancer TDC and see if your rotor is pointing on or close to #1 terminal.

[southside39]

What should the valve lash be set to? Could that be throwing off the engine if set improperly?

The book How to Rebuild Pontiac V-8s was kinda confusing to me on that topic.