Need More help.....

[LuckyWinner]

So it sounds like cylinders 3 and 4 are not firing. I pull the spark plug wires on both and there is no change in that horrible sound from the exhaust. The sound that I thought was a exhaust leak was the sound of these two cylinders not firing. It looks like I have spark to the plugs. Next I will pull the plugs and see if they have spark. My question is....if there is spark to each of these cylinders....what could the problem be? Running carb, no vacuum.

[Bren]

Is it possible that you had the spark plug wires crossed (i.e., 3 on 4 and 4 on 3)?

[Bob Cowan]

You only need three things for a cylinder to fire: Spark, fuel, and compression. Start by making sure you have all three.

If you do, then make sure they're all happening at the proper time.

As said above, check your cam card, and then make sure you have the proper firing order.

[CraigS]

Pull those two plugs and show us how they look.

[LuckyWinner]

So I pulled the plugs. Dark black soot covering the whole tip, so pretty sure they are fouled. I was running Autolite 3924s and after looking around the forum and also the edelbrock site I should be using 3926s (hotter plug). So after work I will put the new ones in and see what happens. Hopefully this will fix it.

[68GT500MAN]

I believe that it is a timing issue and not the plugs causing the problem. Double check all of the wires to make sure they are in the correct firing order for your cam.
Doug

[LuckyWinner]

I believe that it is a timing issue and not the plugs causing the problem. Double check all of the wires to make sure they are in the correct firing order for your cam.
Doug

Doug, I thought the firing order was 1,3,7,2,6,5,4,8 for all 351w's. When I bought my engine, I didnt get any info on my cam. Are you saying that my cam could change the firing order???

[68GT500MAN]

That is the correct firing order for your 351w. Many builders get the 302 and 302HO confused, they would put an HO cam in the engine and not change the wiring. In your case, I would just double check the spark plug wires and then that part should be good to go. Another thing to check is to make sure the distributor is NOT 180 degrees out of time (on the exhaust stroke instead of the compression stroke).
Doug

[LuckyWinner]

Ok, changed spark plugs and 4 is now firing. I dont think 3 is though. I pulled the wire and plug and I have spark. I pulled dizzy cap and i am on 1 at top dead center. I think the next thing to do is to pull the valve cover off and make sure that I dont have a valve that is not closing.