Thread: Very confused-chronic timing event

Tweet

Good Morning,

Sorry for the length of the post. Thanks for everyone's help thus far. It's been a slow process as I tend to travel too much and the wife has a list of "honey-do's" a mile long every weekend. I'm sure most of you understand the lack of wrench time.

I've been building an SBC that consisted of a couple of odd parts that were discussed here:

http://www.clubhotrod.com/forums/showthread.php?t=26594

I'm still struggling with the timing and was hoping someone could shed some light on this. The backfiring, through the exhaust, has continued so i dumped the fuel injection and went to a carb. Backfiring continued. Next, I went after the ignition. Everything was already new: MSD 6A, Blaster 2 and a billet distributor. Swapped the reluctor, pick-up, rotor, cap and plugs. seperated wires, isolated power and ground aalong with trigger wires, etc... No joy.

Pulled the engine and went through it checking to make sure the cam didn't flat-lobe, heads/valves were ok, etc... Everything checked out and re-assembled (lined up crank and cam dots and rotated to #1 top dead center)and put it back in. Still backfiring. Pulled plug wires hoping to isolate a specific cylinder with no success. It seems as though there is raw fuel dumping into the exhaust, sporadically, and lighting up when it hits air.

I went over to the salvage yard where I got the block/tranny and was talking to the guys. I'm there a lot and they shed some light on the origin of the engine. It was in a service truck owned by the local power utility and was being run on propane. I can't find where I wrote down the casting number off the block and I can't get to it installed in the Jeep.

A few questions I have:

-Was propane a factory option on a Gen 1 Block ?
-If so, was the firing order set up differently ?
-Given the wierd nature of the heads and intake, could it be a 18246537
firing order as per '96 and up (taken from a Haynes Manual I found) ?
-Is there a way to determine if the crank is set-up for a different firing order
short of pulling the block ?
-Will engine damage occur if I change the firing order on the distributor to
18246537 and start the engine ?

I'm really stumped on this one. Specs are as follows:

-Stock bore and stroke
-Heads-casting number 10147898
-Valves 1.72" Intake, 1.50" Exhaust 76 CC Chambers
-Cam-Hyd, flat tappet, Intake .420, Exhaust .443. Duration 270, 280 I/E
-Compression Ratio (If my math is correct) 9.013
-Edelbrock Performer RPM Manifold
-Edelbrock 650 Carb
-Fuel pressure at idle 6lbs. Mixture seems good
-SM465 Tranny to Dana 300 Transfer Case
-Initial timing at 8*(although it is bouncing all over the place) with an additional 24* in by 3000 RPM. (32*total)
-Mallory adjustable fuel pressure regulator with return line (3/8" in and out)
-

This has to be something very simple as it is, clearly, a timing event. I feel like the cam and crank are out of synch meaning, valve timinmg and crank stroke aren't where they're supposed to be, when they're supposed to be there. I'm out of ideas. What am I missing ??

Any and all input is gratefully accepted. I'm willing to test/check just about anything at this point. Thanks in advance for any help.

All the best,

Mike