71 demon 340 tips?

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mar-tay1

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Unearthed a demon 340 from a neighbors yard that had been sitting ten years in the same spot. Working on dis-assembly and managed to get 6 pistons out so far (the others are soaking in ATF / penetrating oil). It has the forged crank, factory looking windage tray, etc. The question is what to look for and keep and what to update and throw away? Thanks!:twisted:
 
What are you wanting to do with the motor? stock rebuild, or stroker with new everything?

Id keep most of it if you are going the stock ish route, pistons need to be replaced as well as the bores cleaned up. Also keep the windage tray, I had a really hard time finding a stock windage tray for my 360.

Timing chain goes in the trash, lifters and cam would be good to replace, heads will need to be completely gone through. The crank should be looked at as well and polished/turned if need be. Probably not a bad Idea to throw a new intake on there either, saves weight and just better. Stock rods can be used, but they will need some work (re-sized with arp rod bolts).

I just put together my 360, and the only things I re-used was the block, crank and rods, everything else was new.
 
if it is all original keep all of it untill you know what you need. also some stuff may be date coded and worth cash to another guy doing a resto.
 
mar-tay1 said:
The question is what to look for and keep and what to update and throw away? Thanks!:twisted:
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That may be the question but there won't be a good answer until you tell us what you want to do with the car. With what info you've said so far I'll say keep the crank, rods, heads, block, windage tray, and anything else that can be reused or sold. Update the cam, carb, intake, valve springs, timing chain, don't go nuts with compression, and put some headers on it. Then just have all the machine work done to the heads, block, crank, rods, and have it balanced. Put some quality parts and work into it and you'll have a quality engine when you're done. It's hard to say update _____ with _____ without knowing what you plan to do with the car. Do you want a cool mild mannered cruiser or a street/strip monster? It makes all the difference with parts selection.
 
Check to see if the block and the transmission are the original ones.
If you have a matching numbers car, i would be hard pressed to modify it.
Take LOTS of pictures and post some on here for us all to enjoy!
Sounds like a great score!
 
I got the engine torn down for inspection and found the whole engine appears to have been re-built at some point in time, not really what I was told but figure it is par for the course. The original heads appear to have been replaced by some 273/318 heads, a little disappointed at that, the block seems to be correct date code etc, correct crank too. The crank is .010 on the mains but oddly enough standard on the rods, which I think will work out as the rod journals should be turned to .010 to clean them up as needed. The whole thing (minus heads) seems to be painted orange from the factory (heads were blue). Only problem now is that one piston is still stuck in one of the cylinders, been soaking it hoping to dislodge it without completely destroying it. Now standard practice would be to just overbore it .030, and my cheap *** is thinking re-ring it. I want to keep the 10.5 to 1 ratio (approximately) the same and (I guess) was hoping to find some nice maybe .010 over slugs to keep as much life in this thing as possible (any recommendations here?). I already have a set of 1975 360 heads that are rebuilt and, shy of paint ready, to bolt on. So that said, it's a matter of selecting the cam and lifters. I have a set of headers already, and mufflers and pipe to run 2-1/2 out the back with a crossover of course. Now I have a tendency to over cam motors, but I usually lighten them up and gear them for it, not this time though. It'll be the stock 3.23's and full interior with the 4 speed, so I'm looking for recommendations for a cam. Hydraulic (non-roller) recommendations here please. I'll take some pics and post them later today. Thanks!
 
What kind of condition are the cylinders in? I did a re-ring on my 318 and it was fine. No blow by and I kept my stock '68 pistons. If there's a good sized ridge then you're better off just boring it out and getting new pistons. Id say XE262 or a voodoo 256/262 cam.
 
mar-tay1 said:
I got the engine torn down for inspection and found the whole engine appears to have been re-built at some point in time, not really what I was told but figure it is par for the course. The original heads appear to have been replaced by some 273/318 heads, a little disappointed at that, the block seems to be correct date code etc, correct crank too. The crank is .010 on the mains but oddly enough standard on the rods, which I think will work out as the rod journals should be turned to .010 to clean them up as needed. The whole thing (minus heads) seems to be painted orange from the factory (heads were blue). Only problem now is that one piston is still stuck in one of the cylinders, been soaking it hoping to dislodge it without completely destroying it. Now standard practice would be to just overbore it .030, and my cheap *** is thinking re-ring it. I want to keep the 10.5 to 1 ratio (approximately) the same and (I guess) was hoping to find some nice maybe .010 over slugs to keep as much life in this thing as possible (any recommendations here?). I already have a set of 1975 360 heads that are rebuilt and, shy of paint ready, to bolt on. So that said, it's a matter of selecting the cam and lifters. I have a set of headers already, and mufflers and pipe to run 2-1/2 out the back with a crossover of course. Now I have a tendency to over cam motors, but I usually lighten them up and gear them for it, not this time though. It'll be the stock 3.23's and full interior with the 4 speed, so I'm looking for recommendations for a cam. Hydraulic (non-roller) recommendations here please. I'll take some pics and post them later today. Thanks!
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Without the original 2.02 J heads you can forget about 10:5 compression(really 10.1 if you are lucky) and all that other stuff. If that piston is really stuck then you will have to pound it out(down not up) which will require a sleeve in that cylinder anyway. And most likely you will have to go 0.40 over.
With that being said you will need full machining/rebuild on the short block.
Best do things once. Don't be cheap. Its a 340 Demon. If you can find a pair of 915 2.02 J heads with a casting date close to but not after the casting date of the block then that would be the cheapest as most of the folks on this forum have a bunch of them.
71 was a great year for the 340. You'll need a Thermoquad. Sweet carbs if they are kept tuned.
 
I've got a set of core 915 J heads in SoCal if you are interested.

Nobody know whether the head has a 2.02 or 1.88 valve in it when it's on the engine. A 1.88 set up can easily be swapped to 2.02 if desired. Find a set of 915's and go with it.
 
I would get it running first before installing 340 exhaust tips....
 
AJ/FormS said:
I put a set of 318 heads on a 340 once. That thing flew. To 4000 at least.Maybe a bit more. That was 1975. I think.
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I always thought it'd end up like this. [ame="https://www.youtube.com/watch?v=X-rkFaIPyL4"]https://www.youtube.com/watch?v=X-rkFaIPyL4[/ame]
 
Soooo..... yes snowballing. I've played this game before. I'd take some pics but at this point everything is covered with nasty sludge and nothing notable as of yet. However, the block is at the machine shop to get bored, the 318 heads will go on a 318 I have for another Duster, and I have a set of 360 heads that were ready to go for a 360 in another car that I think will work here, unless I do buy those 915's from crackedback. So much for keeping it on a budget. The block is original to the car as I hope the trans is. The seller , a neighbor, said his brother bought the car new with a 4 speed and a bench seat. That's what I'm putting back in, will check all the numbers and such when I move that way. Putting a 1973 318 Duster together to fund the thing now, the 318 heads will do more good on that one I think.
 
Have you asked the neighbor if he happened to know where the original heads are?
 
71 340 pistons come up to .045 above deck if you put 318 heads on a stock 340 it could be a big problem have seen this before when people try to save $$ on a cheap rebuild when the stock 340 heads are cracked just my $.02 worth
 
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