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slant six low compression how low is low?
#1344371
11/30/12 11:50 PM
11/30/12 11:50 PM
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Joined: Jan 2005
Posts: 597
Lost in the 70's
440gtx6
OP
mopar
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OP
mopar
Joined: Jan 2005
Posts: 597
Lost in the 70's
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Picked up an old Hobart G300 welder with a Chrysler engine. It's a 170 cu. in. slant six and I'm only getting 40 psi on each cylinder when I check the compression. I know it's only supposed to be an 8.5 to 1 comp ratio but doesn't 40 seem way low for even a 8.5/1 motor? I don't have any experience with these sixes so guess I could use some advice. Thanks 
69 EF8 GTX 440 auto
72 EB5 RR/GTX 440 auto
70 EW1 GTX 440-6 4 spd
70 EF8 Satellite 318 auto (452 coming soon)
70 FK5 Satellite 318 auto
71 FC7 Cuda 340 4 spd
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Re: slant six low compression how low is low?
[Re: 440gtx6]
#1344372
12/01/12 12:24 AM
12/01/12 12:24 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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it's almost deceased. Only a /6 could still run with it that low. You might adj the valves, .010" intake/.020" ex and I like to loosen the plugs several turns then tighten them up & reinstall the plug wires & start it & rev it to blow the loosened carbon chips out which can lodge under a valve & give a false low reading (but not low like you have) & only takes an extra minute or 2 when doing a compression test.
live every 24 hour block of time like it's your last day on earth
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Re: slant six low compression how low is low?
[Re: RapidRobert]
#1344373
12/01/12 12:38 AM
12/01/12 12:38 AM
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Joined: Jan 2005
Posts: 597
Lost in the 70's
440gtx6
OP
mopar
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OP
mopar
Joined: Jan 2005
Posts: 597
Lost in the 70's
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Lol, yea that's what I figured. I have no idea how long it's been since the thing ran, bought it at auction a few years back and just now getting around to messing with it. Hopefully they just parked her because the engine was weak rather than a problem with the welder head. I would probably spend a few bucks and overhaul the six but probably tough finding parts for the generator side and $$$ too.
69 EF8 GTX 440 auto
72 EB5 RR/GTX 440 auto
70 EW1 GTX 440-6 4 spd
70 EF8 Satellite 318 auto (452 coming soon)
70 FK5 Satellite 318 auto
71 FC7 Cuda 340 4 spd
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Re: slant six low compression how low is low?
[Re: 440gtx6]
#1344374
12/01/12 12:42 AM
12/01/12 12:42 AM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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You might pick up a /6 for cheap and or see if the welder head is OK first
live every 24 hour block of time like it's your last day on earth
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Re: slant six low compression how low is low?
[Re: 71yelladustr]
#1344378
12/01/12 05:30 PM
12/01/12 05:30 PM
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Joined: Jan 2003
Posts: 20,173
Park Forest, IL
slantzilla
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,173
Park Forest, IL
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Pour some turpentine down the plug holes and let it sit overnight. As said before, check the valve adjustment too.
One thing you will have to watch swapping a 225 in will be clearance for the top of the motor, and exhaust routing. The 225 is taller than a 170 by a couple inches. Also, the crank flywheel register diameter changed in 1968 so your coupler may not fit.
"Everybody funny, now you funny too."
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Re: slant six low compression how low is low?
[Re: slantzilla]
#1344379
12/01/12 05:33 PM
12/01/12 05:33 PM
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Joined: Jan 2003
Posts: 20,173
Park Forest, IL
slantzilla
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,173
Park Forest, IL
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FYI, 8.5 is probably optomistic. True cr is usually closer to 7.5:1.
"Everybody funny, now you funny too."
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You are going to need at least 100 psi cranking compression to get it to run.
