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343 build

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myrambler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote myrambler Quote  Post ReplyReply Direct Link To This Post Topic: 343 build
    Posted: Oct/17/2017 at 12:11am
I am in the process of tearing down a 343 to install in my 67 Rogue. The engine was running last year briefly after years of sitting idle. It has been on an engine stand waiting for tear down for over a year. When my son and I tore it apart this weekend we discovered one cylinder had a fair amount of crud and rust in it and the motor is now locked up. we are soaking it in marvel mystery oil and Pb Blaster to try to free it up so we can complete the tear down. Bottom line at a minimum it will need new bearings as original ones are worn, (copper showing on mains, rod bearings not horrible but while we are at it!) new lifters, likely a new cam, and bored to clean up the cylinders, so that means new pistons as well. Heads checked and a complete reworking likely.  Looking for a cam recommendation as I am reading of the horror stories of cams being junk lately. Summit 8600 or 8601 was recommended previously as a good all around option. Any other suggestions appreciated at this point, besides the obvious 360 swap. I had a 343 Xcode Rogue back in high school so right or wrong I'm going with that engine for now. Leaning towards installing a 5 speed or a overdrive automatic in the car as the original transmission is a M/40 with 3.15 rear end.
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Oct/17/2017 at 5:57am
Love the 343, an underrated engine.

My 343s were factory built with the pistons
about .05 below deck. You may want to "correct"
this since new head gaskets are a lot
thicker than the factory gaskets.

Shoot for .035-.040 assembled quench and 10.5:1 compression
and that little motor will be a rocket ride on pump gas
with a stick shift.

Any cam with an advertised 270-280 degrees will make it smile.

Normally I would suggest a 360 as a starting point
but the 343 is a wonderful high revving motor.
I wish I had one on a stick shift. My 343s were on
those wonderful BW automatics.
Gremlin Dreams
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1982AMCConcord View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1982AMCConcord Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2017 at 7:44am
Originally posted by myrambler myrambler wrote:

I am in the process of tearing down a 343 to install in my 67 Rogue. The engine was running last year briefly after years of sitting idle. It has been on an engine stand waiting for tear down for over a year. When my son and I tore it apart this weekend we discovered one cylinder had a fair amount of crud and rust in it and the motor is now locked up. we are soaking it in marvel mystery oil and Pb Blaster to try to free it up so we can complete the tear down. Bottom line at a minimum it will need new bearings as original ones are worn, (copper showing on mains, rod bearings not horrible but while we are at it!) new lifters, likely a new cam, and bored to clean up the cylinders, so that means new pistons as well. Heads checked and a complete reworking likely.  Looking for a cam recommendation as I am reading of the horror stories of cams being junk lately. Summit 8600 or 8601 was recommended previously as a good all around option. Any other suggestions appreciated at this point, besides the obvious 360 swap. I had a 343 Xcode Rogue back in high school so right or wrong I'm going with that engine for now. Leaning towards installing a 5 speed or a overdrive automatic in the car as the original transmission is a M/40 with 3.15 rear end.

Well... the one thing that would trick out this 343 is add a 360 crank for a little extra oomph. The stock pistons would stick out of the block by about .20. So if you want the compression lower... you'll have to get different pistons that keep the compression lower. It was noted in this thread that some of the aftermarket cast pistons are actually .20 lower... so it might work out just fine.

http://amccars.net/cgi/yabb2/YaBB.pl?num=1220839676/5

Also.. as the thread mentions.... The later crank will only work with the later TF trans... so if you plan on using the BW trans.. you'll have to stick with the 343 crank.
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amc67rogue View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amc67rogue Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2017 at 8:26am
70- 71 crank will fit the Borg warner . 70-71 304 crank is the same as the 360.
Keith Coggins 67Rogue X code
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Midnight Rambler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Midnight Rambler Quote  Post ReplyReply Direct Link To This Post Posted: Oct/19/2017 at 8:58am
Originally posted by 1982AMCConcord 1982AMCConcord wrote:

Originally posted by myrambler myrambler wrote:

I am in the process of tearing down a 343 to install in my 67 Rogue. The engine was running last year briefly after years of sitting idle. It has been on an engine stand waiting for tear down for over a year. When my son and I tore it apart this weekend we discovered one cylinder had a fair amount of crud and rust in it and the motor is now locked up. we are soaking it in marvel mystery oil and Pb Blaster to try to free it up so we can complete the tear down. Bottom line at a minimum it will need new bearings as original ones are worn, (copper showing on mains, rod bearings not horrible but while we are at it!) new lifters, likely a new cam, and bored to clean up the cylinders, so that means new pistons as well. Heads checked and a complete reworking likely.  Looking for a cam recommendation as I am reading of the horror stories of cams being junk lately. Summit 8600 or 8601 was recommended previously as a good all around option. Any other suggestions appreciated at this point, besides the obvious 360 swap. I had a 343 Xcode Rogue back in high school so right or wrong I'm going with that engine for now. Leaning towards installing a 5 speed or a overdrive automatic in the car as the original transmission is a M/40 with 3.15 rear end.

Well... the one thing that would trick out this 343 is add a 360 crank for a little extra oomph. The stock pistons would stick out of the block by about .20. So if you want the compression lower... you'll have to get different pistons that keep the compression lower. It was noted in this thread that some of the aftermarket cast pistons are actually .20 lower... so it might work out just fine.

http://amccars.net/cgi/yabb2/YaBB.pl?num=1220839676/5

Also.. as the thread mentions.... The later crank will only work with the later TF trans... so if you plan on using the BW trans.. you'll have to stick with the 343 crank.


Isn't there a 360 crank that mates well with T5s? 

'66 American 440 Convertible 290/M-40/AMC 20 3.15/PS/PB
'04 Jeep Wrangler X Rocky Mountain Edition 4.0 5sp
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1982AMCConcord View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1982AMCConcord Quote  Post ReplyReply Direct Link To This Post Posted: Oct/21/2017 at 11:14am
http://amccars.net/cgi/yabb2/YaBB.pl?num=1227761661

Reply #1...  farther down he listed an estimated power rating based on 1/4th mile performance.... Lots of power from a 343 block/360 crank Combo...I've often read that this combo likes to rev a little more than a 360... 

"Glad to help. 
Based on 3250 lbs. weight and 1/4 mile 107 MPH in Oct '08, it made 305 HP net, 
and between 381 & 407 HP gross using 20% or 25% drivetrain power loss."
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Oct/21/2017 at 1:40pm
IMO if it's a 360 crank, buy a cheap boneyard 360, they are still lots of them.
It is a better motor in most respects.

If you want the faster turning lighter 343 it will be more costly.

As to an automatic, my converter builder would build a converter for a
727 or A904 for both new or old cranks. This is an issue only
if you want a stock converter. I will PM his name and addy if asked.
Gremlin Dreams
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