Question about 340 "J" heads

[dpmalibu]

Can anybody tell me what size valves came in these 1973 340 J heads?

casting #'s are 3418915-F and 3418915-C

Also what cc combustion chambers?

 

[1970Duster]

Should be 1.88 in and 1.60 out

 

[Wheels]

casting # 3418915 used on 1970 - 340 6Bbl T/A
also on 1971 - 360
also on 1972 - 340/360

1973 used different casting numbers , you may have lucked out and got pre 72 heads - the good ones with 2.02 intakes , I suggest that you measure them , either way they are good heads with good sized ports and good flow,
if these heads are the 1.88 - 1.60 the seats can be ground to accomadate
the bigger valves . Cheers.

 

[perfacar]

hi, if they're original 73 heads, then 1.88 & 1.60 valves. chambers usually are 68 to 70 CC. just food for thought. 73 used the 587 head. mopar used up parts till ran out then used newer parts.

 

[ironracer1]

To c.c. the heads you have to have them measured by a good shop, or get some plexiglass and a graduated injection device (not a hypo needle), a 1/8'' drill bit, some white grease, and some alcohol. You can cut the plexi w/ a skill saw w/ a paneling blade installed backwards. There are good instructions available online. You just have to have the valves in (w/ some grease around the valves and a plug in) Check each combustion chamber.

 

[winstoninwisc]

i have a set of 3148195 that have 2.02/1.6 js if you would like to buy them there ready to build $400.00 and the ride there yours pm me

 

[dpmalibu]

I am not looking to buy heads right now. Just wanted more info on the heads I currently have. Thanks everybody for your input. I measured the vavlves and they are right around 2" across on the intake and the just over 1.5" on the exhaust.

So I am assuming by the casting # these are pre 72 heads I have and not 73's.

 

[Bad Sport]

http://www.mymopar.com/index.php?pid=68

 

[dpmalibu]

Thanks Bad Sport that's what I needed. Thanks to all who responded.

 

[swinger340]

There is a date casting on the head that will tell you what year they are. Js come in 1:88 and 2:02. You can tell by looking @ them if they are the 2:02s. 2:02s are real close to the exhaust valve. Most Js are 68-70 cc. You wont see a difference between the 2 heads if you dont plan on winding your engine above 6000 rpm. I had a 340 w 1:88 587s on it and it ran an 8:40 in the 1/8th I put a set of 2:02 Js on it and it was able to get a 8:30 out of it. Was not worth the expense and effort.