fireing order again

[marvink]

I am asking again to make sure to the fireing order on this motor,The rescue squad bought this motor and it had a burned valve in it so we went to get it fixed.Now this motor is in a big boat,they told us that the head was cracked beyond fix but they had a 302 head that would work.The broke head was a 351 winzor head,so we bought it and put it on.The motor runs great at a idle but when you shove the coal to it ,it backfires through the carb.I know that the fireing order is correct for the 302 but someone told me that that motor was a older one it was a 302HO MOTOR IN WHICH IT HAD A WINZOR CAM shaft,well the fireing order for a 302 will not work as I am told The Question I am asking is the fireing order for the 351 winzor going to work 13726548 any help on this we would thank you very much for we need this boat for water Rescue
Marvink

[surfsup]

I’m an up and coming gear head so I’m still learning , but from reading your post if you have the firing order wrong the car won’t run right at idle either so I would think your back fire lies else where, did you check the timing ?

[StrokedStang]

That is the correct firing order for a 302HO and 351W but the older 302's use a different firing order.

[surfsup]

ok here ya go my hanes manual says this 1979-1993 5.0 HO 1-3-7-2-6-5-4-8
All others 1-5-4-2-6-3-7-8
hope this helps

[~The Jester~]

Bottom line: ALL 351w and 302HO motors use 1-3-7-2-6-5-4-8 period.

If you take an older 302 which uses the 1-5 firing order, and swap in a 351 cam, it'll use the 1-3 firing order. That's exactly what I did, used a 1980 truck 302, 351 cam (and firing order), and some other goodies and had it going 11.71 at 118MPH. Your backfire is caused by something else, not the firing order. You got that part correct.

As far as the heads go, a 302 won't "bolt on" to a 351 block. ALL 302's use 7/16" head bolts, 351's use 1/2". Have a machine shop drill out the holes and you'll be fine. However, I personally would NEVER EVER run one 302 head, and one 351. Heads HAVE to match. If you're gonna change them, change them both.

I have a set of 1969 351w heads that need gone over, but aren't cracked or otherwise trashed. I'm a union firefighter, so if you're using them on an FD boat, I'll be happy to help out. Let me know on here, or PM me.

[andy669]

1-2-6-and 8 will fire correctly, but 3-4-5-and 7 wont.

Andy

[~The Jester~]

Years ago when I wrenched on heavy equipment, we had a Grimmerschmidt air compressor, you know the big mobile jobsite trailer ones. Anywho, all it was was a basically stock 351w and an air tank. Had a special head over 5-6-7-8 to pump the air, and it ran on 1-2-3-4!! Factory distributor and everything. Just grounded the plug wires for 5-8. Quite impressive, it actually ran really well on 4 cylinders.

[marvink]

Originally Posted by ~The Jester~

Bottom line: ALL 351w and 302HO motors use 1-3-7-2-6-5-4-8 period.

If you take an older 302 which uses the 1-5 firing order, and swap in a 351 cam, it'll use the 1-3 firing order. That's exactly what I did, used a 1980 truck 302, 351 cam (and firing order), and some other goodies and had it going 11.71 at 118MPH. Your backfire is caused by something else, not the firing order. You got that part correct.

As far as the heads go, a 302 won't "bolt on" to a 351 block. ALL 302's use 7/16" head bolts, 351's use 1/2". Have a machine shop drill out the holes and you'll be fine. However, I personally would NEVER EVER run one 302 head, and one 351. Heads HAVE to match. If you're gonna change them, change them both.

I have a set of 1969 351w heads that need gone over, but aren't cracked or otherwise trashed. I'm a union firefighter, so if you're using them on an FD boat, I'll be happy to help out. Let me know on here, or PM me.

Thank you so much, You have been a lot of help,The heads are going on a Rescue boat.If we decide to change the heads again or do something else I will give you a yell we would be proud to purchase them from you
Thanks Again
Marvin