302 timing problem

I recently installed a new distributor in my '84 Ford Ranger 302. I set the # 1 to 10 deg BDTC and lined up the cap with the rotor. By the way, it uses MSD 6 AL for heat. Has Roush E303 cam. Starts fine, idles fine. Put a load on the engine and it misfires terribly and you hear unburned fuel igniting in the exhaust pipes. It has new timing chain, gears, and coil. The firing order is correct. I can't seem to adjust this out. I'm lost. I need help.


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check and see that you are not 1 tooth off retarded or advanced, fords like a straight up cam timming

When you mentioned firing order being correct and you stated that you are using the E303 cam remember Ford changed the firing order in 1985 when they went to roller cams,if you used the earlier 302 firing order it will do what you are describing.Also check the float level on your Holley.

The firing order is correct, and the issue began when I replaced the distributor, So that should eliminate carb problems. How would I tell being a tooth off? Theoretically, I could make any terminal #1 on a new install, right? And there is adjustment room on the housing, so would think I might be able to adjust out a minor bit.

I'm just thinking out loud here. Feel free to correct my logic. Thank you gentlemen for the quick response........

only high output ford 302s used the clevland and marine fireing order on roller cams. ijust went threw that senario being told all ford rollercams ave the 1 3 fireing order. Not the case. but you ar corect in sugesting the fireing order as the likly isue

Well, I've rechecked everything and replaced everything but the carb, MSD box and right door handle. Checked for vacuum leaks. Electrical gremlins. Nothing. And yet it will be simple when I find out what it is.

Any help will be appreciated.

This problem is mysterious. Just brainstorming; Are you certain you were at TDC before determining that you were 10 degrees BTDC. Just asking, but it seems if it was close enough to run at all you could dial it in. You didn't by chance change the timing set and misaligned the cam to the crank did you? If not it makes the distributor itself suspect maybe?

Did you check plugs for fouling? Maybe all your tuning you fouled a couple of plugs. If not, swap out the left door handle, see if that helps!

I've checked the timing tons of time in the last week. It was @ TDC. I pulled the timing cover again and checked it. Not out of timing. Think I'll check the compression. Wondering if its an exhaust valve, because at idle you might not know it with the cam lope. I'm thinking maybe the Lord is keeping me humble...

Ford 'E 303' roller cams have the 351W/HO firing order. There is no doubt about that. There could be doubt about push rod length though if the engine was originally a flat tappet. There is also doubt if the timing is 180+/- or some other number of teeth out as it WILL backfire in the exhaust and through the carb, barely run, if at all.

It that harmonic balancer is a replacement, many have 2,3 or more sets of timing marks, depending on the timing housing and pointer.

That distributor cap may be cracked, allowing cross fire, even a new one, the rotor may have a loose outer electrode, missing or with the current QC in many of the Chinese suppliers building parts, totally indexed wrong. The spark plug wires may be cross firing as well. With an MSD box, you DO NEED spiral type wires or they will have an inductive cross fire. An MSD box and coil will 'throw' a 2" spark with ease, so all that plug wiring needs to better then good. It will set you on your butt if you happen to grab the distributor top to set the timing.



The 5.0 engine above, full MSD, E303 cam, 1.7 roller rockers runs like a dream and for quite a few miles

But the baffling thing is, if the mixture is igniting in the exhaust, then the cylinder(s) are NOT firing at rpm. Note: even though this is a 5.0 and uses that firing order, I am using a vacuum advance distributor, intake and carb off an '82 302, Its been working for over a year now. Did away with all the EFI stuff. Gonna pull the valve covers and distributor cap and walk through the firing order today. Perhaps I'll find something there.... I do know all the cylinders are firing though, at least with the remote starter...

When you are doing that - just remember, all 302/5.0L engines do NOT have the same firing order

I knew it would be simple once I hit on it. The new distributor had different color wires. Guessing, i had it right, but had changed the firing order to 302. I changed the wiring AND the firing order at the same time. Lesson learned. Change ONE variable at a time.

So for all you 5.0 guys using an MSD 6AL, the black/red wire goes to the purple and the black/purple wire goes to the green on the MSD harness.

Thank you all for your time and help.