302 heads

[towtruckerfour]

My wifes 70 F100 has a cracked driver's head. I picked up another head from a wrecking yard out of a 72 I think but not positive. I didn't look while I was there but I got home and noticed the spark plug size in the new head is smaller than what I have now. The head says 302 on it. Did they change the spark plug sizes each year or something? I'm going to look at the heads I have in the truck now and see what they have stamped on them. Worst case, I have to go get the other side so they match I guess. I don't really want to run two different plugs. Thanks for any help.

[Dragon]

You have a 351 Windsor head if I remember right and the head bolt holes are bigger by 1/16th of an inch. 302 guys ought to pop in here and give you more insight or tell me I am wrong.

[basketcase0302]

noticed the spark plug size in the new head is smaller than what I have now.

I'm a "shadetree" for sure / no expert here. But I'd say yes, sometime around there (I thought it was 73 or 74) the head changed. Thank our government for that and a lot of other things done to our trucks. I've never heard of anyone running different heads, I imagine having different compression on each side of an engine would be pretty destructive?
I'd go get the other head for sure.

[towtruckerfour]

I was thinking since it was off another year, maybe that was the difference. I let you guys know what I find on the motor in the truck. To my knowledge it is a remanufactured 302 longblock when I bought it years ago. All else fails, I go get the passenger head to match. I'm always up for going to the junkyard to see what I can find.

[convincor]

77 was the year they changed to the small plug which would be like a D7## casting
You want something older like D3, D4, or ever back to C8, C9 as the fisrt 2 digits in the casting #

[FreakysFords]

Too bad yur too far, I'd give you a 70 302

[towtruckerfour]

The new head has a D5OE and 302 stamped on the cylinder side. As long as it will work on the 302 I have I guess it should be ok. I don't think they will let me return it. I haven't looked at the one on the motor yet. Thanks Freakyfords for the offer. If this head doesn't work maybe we can work something out.

[Hawkrod]

The new head is a 1975 design (although the year of design does not mean that is the year of the engine, it could have been a later than 75 engine). It is not true that your old head is a 351 head, the other guys were right, you just got a later head. In 70 a 302 and a 351W used the same size spark plugs. It was a year dependant issue not an engine size issue. Hawkrod

[towtruckerfour]

Thanks guys for the answers. I am just wondering if I use the new heads once I get the other one, will I have any problems or will they work ok? I don't want to redo them again.

[fordman]

sounds liek if you get a matching pair of heads they will work and use the same spark plug. the only thing i can think of is it may be a pair of emission heads. so they wont be quite as good for hotrodding and so forth.

[Doug F]

You got dupped by the motor in the donor car having been replaced sometime.

Just go get the other one and you are fine.

[towtruckerfour]

Thanks for the help guys. I went back and got the other head. The truck was a 72 with a 75 motor in it I guess. After pulling the bad head off and comparing them, I couldn't see any differences except spark plug size. Now I have to pull the other head and put the motor all back together again.