360 heads have more water passages than a 340????

[scamp72]

I have a 360 its a 1988 , I was considering putting j heads on for the larger valves and so i could run headers with out having to block off the air holes. I noticed the 360 heads and the block has more water passages than the 340 j heads. Any one ever ran it to this? Is there a fix? Just leave the 360 heads on and block the air holes? Help need some insight.

 

[moper]

Go ahead and run them..no big deal.

 

[mikedevore]

be sure to block those air holes, you can just tap them to 1/4 inch & use an allen head plug

 

[rumblefish360]

There right. If you want to run the newer head, drill and tap the air holes for a 1/4 X 20 flush setting screw. Then add valves or whatever else you deem. The added cooling holes are a bennifit, but there not all cooling holes. Some are there for sane removal. No big deal.

 

[340mopar]

Won't those heads on that '88 360 be the 308s

 

[rumblefish360]

I think so, not certain. 90% sure your right.

 

[340mopar]

The reason I ask is because I have an '88 B350 van with a 360 4 barrel and I was told they should/could have 308's which I hear flow as good or better that J's given the same size valve. Any truth to that?

 

[perfacar]

answer is ,no. 308 is an okay head, but 596, 587, 894 will out flow it. the exhaust on 308 is somewhat better. i've tested them and was suprised to see this.

 

[D-mailman]

also you can add the 915's to that list. Those are the 915's. Terry.

 

[D-mailman]

correction...I meant to say the 'J' 's are the 915's. Sorry.. Terry. (FF) Fat Fingered ...again...