Decode head

[Dreaser]

Can anyone help with head numbers? It is pictured below but it is 3418915B. I can find info on the numbers (1970 340TA) but what is the B and is there any way to know what car it came out of originally? And does LA just mean small block? I find the number listed under LA.

 

[Chryco Psycho]

The A engine was the original small block , La started in 64 with the 273 so yes it is the small block .
The B may designate the later casting withe the 188 intake valves rather than the 70-71 version with 2.02 intake valves , either way the casting is the same

 

[NoCar340]

Depending on the storyteller, "LA" means either "late A" or "light A" and indicates any of the late, narrow wedge-head versions of Chrysler's A engine: 273, 318, 340, and 360. The original A engine had polyspheric combustion chambers had several different displacements, although the 318 is the most common. A engines used two centrally-located valve cover bolts but the LA used 5 around the perimeter of the valve cover flange. The LA was a redesign for 1964 to fit a small-block V8 into A-bodies (273 only until 1968).

The chart shown above is incorrect. There is no "casting number" for T/A heads; the difference is in the machining. All 1970 340s were supposed to have 915 heads. I've yet to encounter an untouched, original '70 engine with 894 (a.k.a. "X") heads but I'm sure they exist. The 915 heads are colloquially called "J" heads, as many have a large, >1" letter "J" cast near the spark plugs. Other letters that might be cast in that area are O,U, and Z. The letter will not tell you if they are T/A heads either. You must look at the location of the intake pushrod holes. All J heads use the same casting; the T/A heads require special intake rocker arms not used on any other cylinder head.

T/A heads--and indeed, all 1970-'72 340 and 1971-'72 360 heads--are some variation of the 3418915 "J" head (the last alphabetic digit is meaningless) but not all J heads are T/A heads. The vast majority of them are not. 360s and late 1972 340s used 1.88" intake valves; 1970-very early '72 340s used 2.02" intake valves. All J heads used 1.60" exhaust valves. Any 1.88" head can be a 2.02" head simply by grinding the intake seats for the larger valves; there is no inherent extra value in an original 2.02" head. Conversely, one cannot (easily) turn a standard J head into a T/A head since the intake pushrod holes are located differently. The original pushrod hole would need to be filled somehow before redrilling in the T/A location... and then you'd need to locate the rare, dreadfully-expensive T/A rocker arms.

There is no way at this point in time to even tell which engine, never mind which car, on which the heads were originally installed unless A) you pulled them yourself off a known original car or B) they're T/A heads, in which case they came from a Challenger T/A or AAR 'Cuda (340 with three two barrels). As mentioned, any small-valve version becomes a large-valve version with a simple, inexpensive valve job.

In terms of performance, they're a bit better than the '68-'69 894 X head by virtue of a slightly-better exhaust port. The T/A heads perform no better than other J heads; the pushrod was moved to allow greater porting but the port itself was not changed--it was a DIY deal. The only better factory head is the late-'80s/early-'90s truck "308" casting, to my knowledge. The J heads were replaced by the inferior "587" casting on 340s and 360s for 1973.

Take a picture of the whole head from the valve cover side, and one of us can tell you whether you have true T/A heads or just basic 340/360 heads.

 

[Dreaser]

Depending on the storyteller, "LA" means either "late A" or "light A" and indicates any of the late, narrow wedge-head versions of Chrysler's A engine: 273, 318, 340, and 360. The original A engine had polyspheric combustion chambers had several different displacements, although the 318 is the most common. A engines used two centrally-located valve cover bolts but the LA used 5 around the perimeter of the valve cover flange. The LA was a redesign for 1964 to fit a small-block V8 into A-bodies (273 only until 1968).

The chart shown above is incorrect. There is no "casting number" for T/A heads; the difference is in the machining. All 1970 340s were supposed to have 915 heads. I've yet to encounter an untouched, original '70 engine with 894 (a.k.a. "X") heads but I'm sure they exist. The 915 heads are colloquially called "J" heads, as many have a large, >1" letter "J" cast near the spark plugs. Other letters that might be cast in that area are O,U, and Z. The letter will not tell you if they are T/A heads either. You must look at the location of the intake pushrod holes. All J heads use the same casting; the T/A heads require special intake rocker arms not used on any other cylinder head.

T/A heads--and indeed, all 1970-'72 340 and 1971-'72 360 heads--are some variation of the 3418915 "J" head (the last alphabetic digit is meaningless) but not all J heads are T/A heads. The vast majority of them are not. 360s and late 1972 340s used 1.88" intake valves; 1970-very early '72 340s used 2.02" intake valves. All J heads used 1.60" exhaust valves. Any 1.88" head can be a 2.02" head simply by grinding the intake seats for the larger valves; there is no inherent extra value in an original 2.02" head. Conversely, one cannot (easily) turn a standard J head into a T/A head since the intake pushrod holes are located differently. The original pushrod hole would need to be filled somehow before redrilling in the T/A location... and then you'd need to locate the rare, dreadfully-expensive T/A rocker arms.

There is no way at this point in time to even tell which engine, never mind which car, on which the heads were originally installed unless A) you pulled them yourself off a known original car or B) they're T/A heads, in which case they came from a Challenger T/A or AAR 'Cuda (340 with three two barrels). As mentioned, any small-valve version becomes a large-valve version with a simple, inexpensive valve job.

In terms of performance, they're a bit better than the '68-'69 894 X head by virtue of a slightly-better exhaust port. The T/A heads perform no better than other J heads; the pushrod was moved to allow greater porting but the port itself was not changed--it was a DIY deal. The only better factory head is the late-'80s/early-'90s truck "308" casting, to my knowledge. The J heads were replaced by the inferior "587" casting on 340s and 360s for 1973.

Take a picture of the whole head from the valve cover side, and one of us can tell you whether you have true T/A heads or just basic 340/360 heads.

Wow, thanks for all the info. We have a little more digging to do!

 

[NoCar340]

These photos show the differences in the pushrod drilling on one pair of the intake ports (it's the same on both pair, obviously). They should help you identify which J heads you have:

Here's a shot of the three types of iron adjustable intake rocker arms. T/A and 273 are production units, while the W2 is a Direct Connection race part--notice the extra thickness. There are left and right T/A and W2 intake rockers; their exhaust arms are similar very to the 273 part, with the W2 parts being extra beefy just like the intakes. There is no offset to the T/A or W2 exhaust rockers. None of the 273 rockers have offset; the intake and exhaust arms are the same.

Side note: The 273 parts are about the best street rockers you can use, hydraulic or solid cam.

 

[moparleo]

Light "A". Lighter weight , improved casting. Very few interchangeable parts with the original "A" engine series. "Poly" head series.
No story, just fact.
64 through the "Magnum" 5.2, 5.9 . All had the same basic casting with many interchangeable parts through out the years. 273, 318, 340 All same stroke, different bore sizes. 360 Longer stroke, bigger main journal size. Different oil pan required because of the different crankshaft size.
Mopar History...

 

[volunteer]

I noticed a mistake already, from the text printout on post no.1 - claiming that 1971 340's had 1.88" intakes - while we all (most of us) know that the intakes were 2.02's.
Mopar lists the -894's as being available from 1968 thru 1971, however all the '70 - '71 340 engines I've ever worked on had the -915's. Listings show that this was also same (casting) no. as the T/A and (1971) 360. All 340's and 360's between '72 and '75 utilized the -587 castings. And, no, they were not inferior as far as flow potential, having identical port runner volumes as earlier heads, but did see slightly larger chamber volumes. I just looked at my original 1970 (Dart) 340 heads. The casting numbers are 3418915 E and the date codes are 12 10 9 and 12 11 9. The extra solitary symbol is O. Also cast into the top, adjacent to AAWJ is the number 360 which is also cast on to my original '73 Challenger's -587 heads. Interesting that my '360' heads cast a full 8 months prior to the August '70 introduction/production of first 360 engines. I would suggest checking those T/A heads for same (360) designation. Of course this is just a 'numbers game' and nothing to do with quality or performance. Finally, the 2.02" intakes, as used from '68 thru '71, did not show benefits until engine revved over 5500.

 

[MoparCarGuy]

Another graphic for standard head versus Trans Am head.
FYI - The original poster did not say he had T/A heads or thought he had T/A heads, he only referred to finding info showing T/A heads were also 3418915 castings.

 

[Darn Dart]

Depending on the storyteller, "LA" means either "late A" or "light A" and indicates any of the late, narrow wedge-head versions of Chrysler's A engine: 273, 318, 340, and 360. The original A engine had polyspheric combustion chambers had several different displacements, although the 318 is the most common. A engines used two centrally-located valve cover bolts but the LA used 5 around the perimeter of the valve cover flange. The LA was a redesign for 1964 to fit a small-block V8 into A-bodies (273 only until 1968).

The chart shown above is incorrect. There is no "casting number" for T/A heads; the difference is in the machining. All 1970 340s were supposed to have 915 heads. I've yet to encounter an untouched, original '70 engine with 894 (a.k.a. "X") heads but I'm sure they exist. The 915 heads are colloquially called "J" heads, as many have a large, >1" letter "J" cast near the spark plugs. Other letters that might be cast in that area are O,U, and Z. The letter will not tell you if they are T/A heads either. You must look at the location of the intake pushrod holes. All J heads use the same casting; the T/A heads require special intake rocker arms not used on any other cylinder head.

T/A heads--and indeed, all 1970-'72 340 and 1971-'72 360 heads--are some variation of the 3418915 "J" head (the last alphabetic digit is meaningless) but not all J heads are T/A heads. The vast majority of them are not. 360s and late 1972 340s used 1.88" intake valves; 1970-very early '72 340s used 2.02" intake valves. All J heads used 1.60" exhaust valves. Any 1.88" head can be a 2.02" head simply by grinding the intake seats for the larger valves; there is no inherent extra value in an original 2.02" head. Conversely, one cannot (easily) turn a standard J head into a T/A head since the intake pushrod holes are located differently. The original pushrod hole would need to be filled somehow before redrilling in the T/A location... and then you'd need to locate the rare, dreadfully-expensive T/A rocker arms.

There is no way at this point in time to even tell which engine, never mind which car, on which the heads were originally installed unless A) you pulled them yourself off a known original car or B) they're T/A heads, in which case they came from a Challenger T/A or AAR 'Cuda (340 with three two barrels). As mentioned, any small-valve version becomes a large-valve version with a simple, inexpensive valve job.

In terms of performance, they're a bit better than the '68-'69 894 X head by virtue of a slightly-better exhaust port. The T/A heads perform no better than other J heads; the pushrod was moved to allow greater porting but the port itself was not changed--it was a DIY deal. The only better factory head is the late-'80s/early-'90s truck "308" casting, to my knowledge. The J heads were replaced by the inferior "587" casting on 340s and 360s for 1973.

Take a picture of the whole head from the valve cover side, and one of us can tell you whether you have true T/A heads or just basic 340/360 heads.

I have a very early built 72 Demon 340(7-71) It was all original when I bought it in 1985. I recently disassembled the engine for a rebuild. It came with the 915 J head with 1.88 intake valves, it is also a forged crank engine.