Different firing orders?

[nibs]

Alright, Im doing this for my dad because he has really slow internet, but its kinda hard for me to explain because Im overseas and he is in Colorado. HAHA Anyways, my dad bought a 350 for his truck from a guy that claimed that the engine was from a race-based car. Well, today he went to start it up and it wont go. He has spark, he has fuel, and he has compression. Everything is good to go. After he talked to a buddy of his, he learned that you can change up the timing and be able to change the firing order for high performance. Now, my question to you is, how many possible firing orders can there be? I can only imagine there are only one or two that could actually work, and keep a smooth running engine. Any firing orders that I can give him to try? I really appreciate your help!

[ont_guy_38]

You can put a cam in that swaps 4 and 7 . Changing the firing order alone will not accomplish anything but a bad runnig engine if it does run at all

[djracer]

I agree it would still run on 6 cylinders.

[bigsnookmaster]

I run the 4/7 swap and will never have a performance engine without it! It runs smoother, idles better, and is very responsive. I've been told they only grind them in a billet blank also.

[nomrlz]

the 4/7 swap is very controversial. i've had as many engine builders tell me it works as i've had to tell me it aint worth it.

[Marv D]

Jay Allen did a 4/7 - 2/3 cam for a big inch SBC (421 as I remember) and they took it to the dyno with a standard cam and the swap cam. Like bigsnorkle said, lower rpm showed the most improvement in torque but wasn't anything to write home about,, and max HP improvement was somewhere less than 6 or 8HP on a 920HP n/a small block. Unless I'm mistaken it was on Butch Kemps (Uratchko built) Nova motor. Like everything you add a few foot pounds here, toss in a couple of HP there, tweak one or two here and it all adds up.

That said,,,,,,
nibs, not questioning your dad, but have him pull #1 plug, have someone put their thumb over #1 plug hole and roll the motor over (bump it with the starter of PREFERABLY by hand with a breaker bar on the balancer bolt) till it starts to build compression. Keep rolling it gently till the timing tab says 12° before,,, NOT zero, not anything else... set static timing as you want it to be. Then pop the top on the distributor, Pull the distributor and point it at #1 plug terminal and replace the cap,,, with aligning the oil pump shaft obviously) Then energize the ignition. Turn the distributor 20+ degrees clockwise, and SLOWLY turn it back counterclockwise till you hear the snap of the coil firing. Turn the ignition off, tighten the hold down, give it a small squirt of fuel (about three squirts of an old mechanical oil squirt can is just perfect to build a nice puddle in the butterflies,,, and I bet your dad has one around) and crank it up.

If it doesn't fire, I'll bet there is mechanical issues somewhere else.

To check the firing order of the cam,, just in case there is a 7/4 swap cam in it (I SERIOUSLY doubt it but here's how to check) He will have to remove both rocker covers.
Bump the motor over to #1 tdc. Slowly and carefully roll the motor over til #1 EXHAUST rocker JUST begins to lift the valve. At about 90 degrees after TDC the #1 EXHAUST rocker will just begin to open the #1 exhaust valve. At that point he needs to mark the damper somehow at 90° intervals. Accuracy counts, but it doesn't have to be rocket science,,, just get it as close as he can with the pulleys and belts in the way.
NOW, every 90 degrees of the crank it will begin to open the next exhaust valve in the firing order. If it doesn't follow the normal sbc order,,, then you can consider a alternate firing order as a cause,, but otherwise........................

[Ont67shortbox]

check the spark plug wires from dist to plug, firing order should be 18543672 find number 1 go counter clockwise around the cap

[nibs]

just to give more back ground on the engine, it ran minutes prior to pulling it out, so I doubt there could be much mechanical issues.

[nxtruck]

Originally Posted by Ont67shortbox

check the spark plug wires from dist to plug, firing order should be 18543672 find number 1 go counter clockwise around the cap

Actually, the standard sbc (or bbc) Chevy firing order is 1-8-4-3-6-5-7-2, and if you're checking the plug wire order on the cap, you would start with #1 and work clockwise around the cap in the proper firing order.

[cableguy0]

We had similar results on the dyno with the 4-7 swap. 5hp or less gains on big inch small blocks. The engines did run smoother at idle with the swap cam but it wasnt really worth the effort of doing the swap.

[raveer2000]

Originally Posted by nxtruck

Actually, the standard sbc (or bbc) Chevy firing order is 1-8-4-3-6-5-7-2, and if you're checking the plug wire order on the cap, you would start with #1 and work clockwise around the cap in the proper firing order.

I was thinking the same thing.

[Ont67shortbox]

sorry Nx I stand corrected