340 or 360 heads?

[titanium]

Trying to figure out what heads these are.I was told they came off a 340 but not sure.They are J(3418915-2.02 heads).The date codes are 03180 and 03160.I think that is March 16 & 18 1970?They also have a code that reads AAWJ 360 on them.The bottom of each head has a large U on them with 3418915 P on one and on the other head has 3418915 O.Are these 340 heads or 360 heads?
Thanks in advance.

 

[racerbob]

I have 2 1971 340 engines that came with 2.02 valve J heads with those (3418915) casting numbers. If you read the MP A engine book it will tell you those heads came on a 1971 360 engine and 1971 340 came with "X" heads (2531894 casting number), but I have seen engines that I believe to be original that came with big valve "J" heads on a 1971 (or 1972 ) 340 engine.

Could be they were modified by someone earlier, maybe ?

Don't sweat it too much, those heads with big valves will flow as well if not better than the "X" heads. The difference in compression is minor (only a few cc's).


Bob

PS: My "J" head 340engine makes 50-60 more HP than my "X" head engine , both with big MP hyd. cams and .030 flat top 10.5:1 pistons. I think the "J" head engine has a few other tricks done to it before I got it, but it is still more powerful than the "X" head engine!

 

[rumblefish360]

The letter heads are the same minus the valve size installed in them.

 

[titanium]

I have 2 1971 340 engines that came with 2.02 valve J heads with those (3418915) casting numbers. If you read the MP A engine book it will tell you those heads came on a 1971 360 engine and 1971 340 came with "X" heads (2531894 casting number), but I have seen engines that I believe to be original that came with big valve "J" heads on a 1971 (or 1972 ) 340 engine.

Could be they were modified by someone earlier, maybe ?

Don't sweat it too much, those heads with big valves will flow as well if not better than the "X" heads. The difference in compression is minor (only a few cc's).


Bob Not sure if they have been modified but the date on the heads (03160) made me think they are '70 340 heads??.Is 03160 March 16 1970? If that is the date would that have been on a '70 340 or '71?Not sure what the cut off date is for parts between model year.

 

[christineman]

can anyone out there give me some advice on a 360, I got a stock 360 and I want to build it up on a budget..something that has some guts and of cours very streetable so the wife can drive it too,,, Id like to get close to 350 HP if possible.. I will bore it and put in 9.5 flat tops, use the factory crank and rods,, I need to know what exact cam will be good for me, same with intake and carbs, I plan on useing some type of headers, also elec ign, roller chain and gears, so,, with that info,, give me some good advice guys,,, I just love this club,,, Im into the 50s mopars so this is all greek to me,,,, thanks in advance,,

 

[1wild&crazyguy]

J heads.

 

[rumblefish360]

Christineman, your question is called thread hi-jacking, please start one of your own and no e-mailing answers to you.

 

[christineman]

Christineman, your question is called thread hi-jacking, please start one of your own and no e-mailing answers to you.

really sorry bout that guys,, Im kinda new to this and sure wont do that anymore,,,thanks for letting me know that....


christineman :thebirdm: