Early 72 340, is this one of the de-tuned ones?

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Project_Fish

I'm on a Low Budget!
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santa fe nm
February 11, 1972.
Hot or Not?

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detuned ? I think they just rated hp in a different way . IT is still a 340 with a little lower compression , nothing that can't be fixed easily
 
The only things they really changed were the compression ratio, went to a cast crank w/external balance, and 1.88 intake valves/hardened valve seats. Nothing that couldn't be addressed during a rebuild.
 
So I would say by vin number on side of block on boss and the fact it was poured after Nov 1971 it was originally a lower HP block with the lighter compression.
My Sept 1971 build date - 1972 Demon 340 has a steel crank and the left over 71' higher compression pistons. Last 6 are 162797
I was told some time around Nov 1971 is when they made that change BUT I was also told some engines as late as Jan 1972 had the same components as the earlier 1971 engines. Chrysler trying to use up engines before the mandatory emissions swap over. Can anyone else confirm or deny that one?
 
That's not an early 72. An early 72 would be something like 09/71 FOR the 72 model year.
 
It was a cast crank motor but a pretty decent block being a 340-5. Every car I ever stripped the motor was poured the year prior to the model year of the car. And I stripped pretty many cars in my time. . There may be times when they match but very very rare, Mostly if the car was ordered very late it will have the same cast year.
 
That ridge is quite a bit of wear for a 340. The "de-tuned" 340 used the same block but with low comp pistons, cast crank and 1.88 intake valves. Take it to a machine shop and have them measure the bore to see where its at now. Judging by that ridge it will need to go at least +.010-.020. Have them check for taper as well.
 
That ridge is quite a bit of wear for a 340. The "de-tuned" 340 used the same block but with low comp pistons, cast crank and 1.88 intake valves. Take it to a machine shop and have them measure the bore to see where its at now. Judging by that ridge it will need to go at least +.010-.020. Have them check for taper as well.
First is pressure test, Then magnaflux, then sonic check the bores. Without doing those things you never know what you have
 
I'd be more worried about that cylinder ridge...
The only things they really changed were the compression ratio, went to a cast crank w/external balance, and 1.88 intake valves/hardened valve seats. Nothing that couldn't be addressed during a rebuild.
Well I dug through the bin of parts for this motor and found the external balance, so I am learning!
thanks.

cast.jpg
 
First is pressure test, Then magnaflux, then sonic check the bores. Without doing those things you never know what you have

Exactly. Also sometimes the ridge "look" can be deceiving. Best to measure first. I've seen a few that were still in spec even after honing back round. It's rare but it happens.
 
detuned slug ~ yes, yes it is.. if you don't want it my number is 555-5150.... :D

My best friend Rick, (RIP) ordered a new 1972 340 Duster, 3.23 SG, 4 speed. We took it to Dragway 42 early spring 1972 when it had about 5000 miles on it..
He only made one pass and it ran 14.51. That was pretty good for a totally stock 1972 car except for G70-14 Pokyglas tires on the rear. His mom had a Goodyear credit card, LOL.
 
My best friend Rick, (RIP) ordered a new 1972 340 Duster, 3.23 SG, 4 speed. We took it to Dragway 42 early spring 1972 when it had about 5000 miles on it..
He only made one pass and it ran 14.51. That was pretty good for a totally stock 1972 car except for G70-14 Pokyglas tires on the rear. His mom had a Goodyear credit card, LOL.
I have heard people comment that they are still really good motors!
I will probably just have it rebuilt with any additional work it needs and just run it. This is a low budget build.
 
My best friend Rick, (RIP) ordered a new 1972 340 Duster, 3.23 SG, 4 speed. We took it to Dragway 42 early spring 1972 when it had about 5000 miles on it..
He only made one pass and it ran 14.51. That was pretty good for a totally stock 1972 car except for G70-14 Pokyglas tires on the rear. His mom had a Goodyear credit card, LOL.
My 1970 Swinger 340/3.55/4-gear, went 14.4 at a tic under 98, with 12,000 miles on the clock, on the E70-14 Polyglass tires it came with. It weighed 3330 with me in it. Daymn that car was light. Also 1-pass only.
Yur right about tires; from fall of 1970 when I bought it to fall of 1974 when i parked it; it had gone thru 7 sets of rear tires. That beast laid rubber in three gears, for hundreds of feet.
Not to mention she was on the second engine, second trans,second rear gear,second driveshaft, multiple clutches, second set of shocks,and the usual assortment of alternators, starters,water pumps , and such; and she was banged up pretty bad.
I remember the kid who came to buy it in the spring of 75. He offered 1300 and I accepted. Just about 4 years earlier I had paid 2800 for that ill-handling,over-powered , trouble-making, pos car. We had to tow start it, before he arrived, as the starter died just prior to his arrival. "Whatever you do" I told the kid, "don't stall it",lol.
Good riddance to the "pink dink", hyup Panther-Pink.
I never saw it again.
I was just going on 21 an a half years old.
 
Most 72 340 4spds I had and I had more than one LOL came with 355's. 70 on back 323 and 391's. I had one 69 4spd with a 294. Tghat car was like and airplane. It never wound 4th gear tight it couldn't it didn't have enough power with a stock 340
 
Exactly. Also sometimes the ridge "look" can be deceiving. Best to measure first. I've seen a few that were still in spec even after honing back round. It's rare but it happens.
With all this talk about Ridge I decided to add some pics of the pistons to see what you all think?

piston1.jpg


piston2.jpg


piston3.jpg
 
Here is the manifold that came with the rest of the parts, made in 81.
Is it any good or do I buy a different one?

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The factory manifolds are actually pretty good- but they're heavvvy. That said, clean it up good, plug the EGR port in the bottom of the plenum, an EGR blockoff plate, and you may as well block the heat crossovers too (you won't need it in NM), port match if you feel so inclined; and you'll have a solid, decent performing manifold.
 
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