Hi there. Done this several times in the past. All I did with the 273 mounts was swap one side in front of the 340 ears. I think I left out one bolt as it didn't line up with the ears. This was a long time ago so my memory may be a little off. I (personally) didn't like the fenderwell headers. Had to use small tires and I didn't like the exhaust set ups. I haven't used the TTI headers yet but I am going to order a set soon, they look real nice but are not cheap. The manual valve bodies worked well no hassles and my wife drove them all. Probably the tallest carb/manifold set up was a stock 1971 340 set up Thermoquad with the stock air cleaner. It fit fine. If the engine and trans/convertor is stock 3.23/3.55 gears will be fine and I'm sure you will love it.
340 in early abody
- Thread starter nick455440
- Start date
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Are you using the 273 clutch set up or the 340?
nick455440
Well-Known Member
Going to do a mild 340, mildly ported jheads, looking at the voodoo cam or something compareble, I have a early 70’s. 904 no converter yet, I picked up a few 340 motors and 489 83/4 posi unit for a hellacious price so I want to run that rear end for atleast while but the gears in are like high 4,s don’t remember specifics but they were big, the Trans is supposedly good but would hate to show horn everything in the car to find out otherwise so I may have it build, with the manual valve body have heard u need a cooler, other than that anything outside of the norm,
If you are talking about a auxiliary cooler if you are running a automatic radiator you don't need one just because of the manual valve body. But it's always a good idea to run a aux. cooler. The biggest enemy to a automatic transmission is heat. Run it with the radiator cooler. You want to run it thru the radiator first and then thru the aux. cooler. It's a good idea (very good) to use A&A's low band apply manual shift valve body. It helps keeps your toe's where they belong and it's just about $100.00 more.
Rapid Robert
Well-Known Member
could you educate me on this with a bit more info, I am interested. thank you.
lo23 yes thats what i had in it behind the 273 than the 318 , now going 340 6pxk . it will not handle this motor . so i'm looking at a multi disc setup , these cars are tight through the frame rails . i need all the room i can get . and the 10'' double disc clutch should be able to get it done . after all they make a 10'' double disc for mustangs gt's .
That originally had the 9 1/4" and a 10" would fit. A dual disc would be great for it. Best would be the orig. type 340 10.5" but room and some fabrication is involved. Make sure the flywheel has no heat spots on it. If it does it has to be replaced because if you have it machined it will look good but just for a minute. They will come back and it will chatter. If you have to replace the flywheel you might as well look for a 340 bellhousing and use the 10.5" I used to use the 10" a lot as it was lighter but I replaced the clutch assy. a lot, I mean a LOT! But I always had a lift available to me and a clutch rebuilder 2 miles away. And they were reasonable back then. I've thought about using a hyd. set up on my next one but never have done one yet. It should solve a lot of issues with fitment. Maybe someone on this site has done it so they might give you some insight on it. I just love those 340's in the early A-bodies.
The original type of reverse manual valve bodies did not apply the band that holds the low/reverse drum. By holding the low/reverse drum along with the sprag increases safety from a sprag failure which would spin the high gear clutch drum over 10,000 rpm and it could come apart (explode) and could come thru the floor and oil the tires. Bad deal. The sprag on the old valve bodies are the only thing holding you in first gear. If you don't follow the correct procedures they can come apart. If you are able a good drum is a good idea but personally if you are making 400hp or so and use the good valve body I've had no problems.
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Rapid Robert
Well-Known Member
thank you, much appreciated!
i'm going to go talk with a clutch guy here in town , the only one left i think .
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