Question : 3.1 installed. Turns over but won't run

[wanako]

I just got a 3.1 (MPFI not 3100) from a 93 Grand Prix to replace my old 2.8 for my '87 Beretta. It's in the car now and plugged back in and everything. It turns over but doesn't start. Battery is fresh. Plugs and wires are fresh. It's on the old 2.8 ECU which shouldn't be any kind of issue because there are 3400 guys running off of the 2.8 ECU. My dad's got the car right now and he says he hears explosions inside the motor but not anything coming out of the exhaust, and the upper intake manifold gets hot even though it doesn't run, just from cranking it. Not like crazy hot but it warms up. He says no metallic or clanking sounds can be heard. I would believe that's a good sign that I installed the pushrods and rockers correctly. At least I would think so. That sounds mad weird to me. Thanks.

[SappySE107]

Sounds like its leaking combustion back up the intake manifold. Did you tear the motor apart before you installed it, or hear it run before? No real way for an intake to get hot on a non running motor other than it is now and exhaust manifold.

[wanako]

I hadn't heard the motor run becuase it came from a warehouse that had running motors from junked cars. I have a 90 day warranty on it. I actually redid the entire top-end and installed new gaskets and timing chain and other misc. parts from my old 2.8 that were in better shape. I used the rockers and pushrods from my 2.8, which I checked were exactly the same size and length and installed them the exact same way they were on the 3.1 when I tore into it. Even if the pushrods were installed the wrong way, wouldn't it make it sound like catastrophic metallic FAIL? My dad says he didn't hear any of that. The heads are the ones that came with the motor, but I saw no problem with the intake valves, which I think would be the only way for combustion to go up to the intake. Thanks, Ben.

[3400-95-Modified]

I asked in your other thread and now I know... you messed with the timing chain. Did you get the timing set correctly?

[wanako]

yup, it was perfect when I installed it. I'm quite sure of it. I took of the cam to relube it and the lifters also.

[Axe_1]

I'm still pretty new to these 60 degree engines, but every GM timing chain set that I ever installed was 180* out when done exactly like the instructions say. I couldn't figure out why so many people had their timing 180* off after an install then I realized that the books tell you to match up the marks on the gears, then rotate a full turn until the marks line up again. They never tell you that you still need to rotate them back so they are both at TDC (top dead center) to be on the #1 piston with both valves closed. I figured that out by watching the rocker arms with the valve cover off. As you rotate the crank the first time you come up to TDC the #1 Intake and exhaust valves are switching positions. The open one will close, the closed one will open. The next time you bring the crank around to TDC both valves will close and stay there for a few degrees. I'd check that before going any further.

Axe

[wanako]

I'm still pretty new to these 60 degree engines, but every GM timing chain set that I ever installed was 180* out when done exactly like the instructions say. I couldn't figure out why so many people had their timing 180* off after an install then I realized that the books tell you to match up the marks on the gears, then rotate a full turn until the marks line up again. They never tell you that you still need to rotate them back so they are both at TDC (top dead center) to be on the #1 piston with both valves closed. I figured that out by watching the rocker arms with the valve cover off. As you rotate the crank the first time you come up to TDC the #1 Intake and exhaust valves are switching positions. The open one will close, the closed one will open. The next time you bring the crank around to TDC both valves will close and stay there for a few degrees. I'd check that before going any further.

Axe

I think you nailed it right on the head sir. I was discussing this with my dad and it actually IS 180* off on the timing. I made a gross miscalculation. When cranking it we felt air rushing OUT of the intake manifold. We're going to reset the timing chain and see if this works. Thanks for the help guys, I'll update this once I find out that was indeed the problem, which I REALLY think it is.

[CNCguy]

If the timing marks were lined up when you installed the timing chain set, the cam timing is correct.

Whether belt, chain or gear driven, the camshaft sprocket is always twice the size of the crank sprocket thus requiring the crank to spin two revolutions for each turn of the cam. The cam timing marks will be 180 degrees off every second revolution of the crankshaft. It has no relevance on a pushrod engine with DIS since it fires each plug every revolution. The only time it matters whether the two marks are 180 out is when you are installing a distributor.

Are you sure the valves aren't adjusted too tight causing compression to leak past the intake valves? I would recheck the valve adjustment and do a compression test.

[3400-95-Modified]

If the timing marks were lined up when you installed the timing chain set, the cam timing is correct.

Whether belt, chain or gear driven, the camshaft sprocket is always twice the size of the crank sprocket thus requiring the crank to spin two revolutions for each turn of the cam. The cam timing marks will be 180 degrees off every second revolution of the crankshaft. It has no relevance on a pushrod engine with DIS since it fires each plug every revolution. The only time it matters whether the two marks are 180 out is when you are installing a distributor.

Are you sure the valves aren't adjusted too tight causing compression to leak past the intake valves? I would recheck the valve adjustment and do a compression test.

Explained the same thing to his post on Bstuff or Beretta.net which ever board it was on.

[wanako]

Jon, you put it on my Bnet thread. thanks guys. We're gonna look this over one more time carefully.

[60dgrzbelow0]

Wan..

When time permits... could you drop us a link to the Beretta thread mentioned by Mr. Pink in your next post? This is very interesting situation and the solution that fixes things will be important to us all. Likewise... we're looking forward to a happy ending to this story...

[Axe_1]

If the timing marks were lined up when you installed the timing chain set, the cam timing is correct.

Whether belt, chain or gear driven, the camshaft sprocket is always twice the size of the crank sprocket thus requiring the crank to spin two revolutions for each turn of the cam. The cam timing marks will be 180 degrees off every second revolution of the crankshaft. It has no relevance on a pushrod engine with DIS since it fires each plug every revolution. The only time it matters whether the two marks are 180 out is when you are installing a distributor.

Are you sure the valves aren't adjusted too tight causing compression to leak past the intake valves? I would recheck the valve adjustment and do a compression test.

Thanks CNCguy! Makes perfect sense to me. That's why I said I'm still new to these engines. I've driven them on and off for years but never really torn into them until now. My first DIS was on an '87 Olds Cierra I bought used in 1990 so I am familiar with the system, even though the books say they weren't available until '88.

Axe

[Axe_1]

Just like mentioned above I would recheck the rockers next. There's nothing like buying a reference manual and having to correct it. I have an extensive collection of Chilton's Manuals, hardback from 1953-2004 I believe, and the rocker arm adjustment method was completely wrong in at least one of them. I had to go through and figure out which valves would be at rest at each point and correct the book so I didn't screw it up the next time I used it.

Axe

[wanako]

thanks for the concern, gentlemen. As soon as I find something or told something of the problem, I'll report it here. Right now my dad has the car about an hour up north, so unfortunately I don't have access to it and can't look at the car myself, as much as I would like to.

Here is the link Mr. Pink and I were referring to:
3.1 Help Thread

[60dgrzbelow0]

Just in case there is any doubt on the two issues of the location of the #1 Cylinder and the proper firing order and spark plug and ICM wiring positions... This is for the 3400 but should still apply here...