L31 crate engine issues

[Jrainman]

Just installed a new GM L31 crate engine in my 68 , number 2 cylinder is not firing , I have installed 3 hei distributors one used and 2 new .

when I first started the engine both number 2 and 3 where not firing , replaced spark plugs with another set of new plugs changed out distirbutor with another new distibutor .
fuel is present on spark plug but not firing ,the raw unburnt fuel is firing (exploding) in that side of the exhaus as loud pops. all other cylinders are firing , re timed engine 4 times to verify , right now it seems to like 12 deg BTDC . also 2 new sets of spark plug wires were used , I am running a very lean A/F about 14.1 at idle as of now this is a new fresh install only thing used is the battery that has 13,2 volts across and when running 14.2 volts across. engine starts good but does have a small amount of pre ingnition when shut down that I am relating to the unburt fuel from #2 cylinder.


this is driving me crazy is there a special type of distibutor that needs to used other then the drive gear has to be compatable with a roller cam (melonized drive gear)

[geezer#99]

More info!
Is it a new crate engine?
What intake?
What carb?

[PGSigns]

Have you done a compression check? It may have a valve over adjusted. Did you adjust the valves? It is rally easy to test the ignition to see if the plug is firing and the wire is good. Shove a plug in the wire and ground it to the engine ans have some one spin the motor over. Did you put the correct melonized gear on the distributors you are swapping in?
Jimmy

[Jrainman]

Thanks for chimming in Guys , figured out my problem yesterday right after I posted my issues ,I relized the question I asked had the answer , somtimes you have to write it down and read it .

I feel stupid, but as I asked the ditributor question in my original post about is there any special disributor that needs to be used other then the melonized gear , Bingo the light in my head went off as I read back my post to myself

I was using the 96 and up 5.7 firing order and not the 95 and down firing order for a 350 as I should have been using on this 97 -2000 Vortec engine because I was using the old style Gen 1 Hei distributor with requires the the early gen 1 firing order

95 and earlier 1,8,4,3,6,5,7,2
96-and up 1,8,2,4,6,5,3,7

[Marv D]

Hu????
I don't see any way you could fire 2, 4, 6 in sequence

Not to rub salt in a wound, but just to clarify a couple things,,,
The SBC is all 1843562 unless it's a reverse rotation marine motor, or has a '7-4 swap' (or a 7-4 / 2-3 swap) custom cam. The CAM dictates the F.O. in a 90° V-8

The LS 'is' a 7-4 swap like the furds FO patern 18726543, (except the furd 351 and 400 odd ball) (With the LS7 is a 7-4 / 2-3 swap)

If you re-number the ford cylinders like a 'real' motor (GM) and start with the second in their FO it's a 18436572, or a few furds are 7/4 swap and 18736542

Anyways point is,, because you have two pistons at TDC at the exact same time, you have PAIRS of cylinders that have to remain 180° apart in the FO (360 crank),, paired as 1 & 6, 2 & 3, 4 & 7, and 5 & 8.. You can swap those cylinders as firing in the first revolution or second (with a cam change) ,, but you can't 'move' them around in the FO without redesigning the crankshaft

[Bigdav160]

I think he is looking at the cap/wire orientation where the vortec has odd down one side and evens down the other side.

[Jrainman]

Originally Posted by Bigdav160

I think he is looking at the cap/wire orientation where the vortec has odd down one side and evens down the other side.

Yes Bigdav is correct, that is excactly what I did I was following the cap orientation in the chilton manual for a 96 and up cap , if you own a 96- and up manual you will see it clearly shows in there pictorial the engine and corasponding distributor cap 18246537 firing order . On a side note engine is running very well and I am happy with the L31 crate engine and rebuilt 200 4 R transmission.

[PGSigns]

Yup 18436572 is it.
Jimmy

[Captainfab]

As already stated. The firing order on a L31 Vortec 350 is still 18436572. The L31 Vortec distributor cap is designed such that the odd cylinders are on one side and the even on the other side corresponding to the cylinders on that side of the engine