1971, 70hp, chrysler

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juice71

Petty Officer 2nd Class
Joined
Jun 10, 2003
Messages
139
Hello:<br />I am have been a johnson user and am not familiar with these motors. I have the opportunity to by one of these motors very cheap. The compression is kinda low 90 to 95 across the board. My question is are these decent motors and what problem areas are there with them and are parts hard to find?
 
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novicetech

Petty Officer 1st Class
Joined
Jan 19, 2004
Messages
267
Re: 1971, 70hp, chrysler

Some parts are still avialable, some are pricey.<br />I have a 70 ,70 hp Chrysler. Last winter i tore down to drill and install helicoils, where bolts broke. I looked into replacing my rings but, i would have had to bore and replace with larger, aftermarket pistons and rings. I just reassembled with new gaskets. My compression did not get any better, stayed at about 120 across the board. The compression new should be 130 to 140 psi.<br />Good luck.
 
WillyBWright

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: 1971, 70hp, chrysler

Depends on the gauge you're using. It could be off. But with a good one, I'd expect about what novicetech said.<br /><br />Most of what you'd need (within reason) is still available except for the black box for the ignition system. If that goes, then you have a parts motor. I guess there's a conversion kit, but you wouldn't want to spend that kind of money on that motor.<br /><br />If you buy it, these are automatic...rebuild the water pump, change the gearlube, put in a fresh set of sparkplugs, and rebuilding the fuel pump would be a real good idea. They're good strong motors and quite reliable if well maintained. If the paint on the powerhead is discolored, don't buy it. It turns kinda pinkish to tanish if it overheats.
 
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thedude7803

Petty Officer 3rd Class
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Aug 15, 2004
Messages
95
Re: 1971, 70hp, chrysler

I recently bought a 71' chrysler 70 h.p. and had to replace the CD Ignition box. Is that what you are refering to Willy? It is still available, but I did pay $195 for it. The motor now runs fantastic. I have never checked compression on my motor, and I don't want to. I am going to run it till it dies and throw it in the dumpster!
 
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juice71

Petty Officer 2nd Class
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Jun 10, 2003
Messages
139
Re: 1971, 70hp, chrysler

thanks guys, I think i will buy it. The head looks clean and he has a brand new ignition system in it ( black box). Are seals and things readily available for this motor? I mean for $250 canadian its a good deal no?
 
J

juice71

Petty Officer 2nd Class
Joined
Jun 10, 2003
Messages
139
Re: 1971, 70hp, chrysler

Oh Ya. I am running a 55hp johnson (1969) right now, will I notice much of a difference in terms of speed going to this motor?
 
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thedude7803

Petty Officer 3rd Class
Joined
Aug 15, 2004
Messages
95
Re: 1971, 70hp, chrysler

I don't know about the seals. That sounds like a pretty decent deal to me. I don't know what kind of boat you have, but my 70 hp is on an old 14'deep V fiberglass Larson that weighs a lot. I can go between 30-35 according to my GPS. Good luck.
 
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juice71

Petty Officer 2nd Class
Joined
Jun 10, 2003
Messages
139
Re: 1971, 70hp, chrysler

My boat is a 16' runabout, I am getting between 20 adn 25 mph with my current 55hp, will I get an extra 5 mph? Has anybody any input as to problems or good things with these motors that go across the line with all made?
 
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Terry H

Lieutenant Commander
Joined
Sep 25, 2001
Messages
1,862
Re: 1971, 70hp, chrysler

If the boat and motor are tuned well you could see over 30mph. If your compression guage is reading accurately you might still be good with a good decarb...should do that anyhows allowing the age of the motor. I had a '71 75hp motor that was always run hard, when I sold it in 2000 it still had 148psi compression and is still running well today. I might say that I have to go to the new owners house and check it out every year. I change the gear oil and plugs, and make him run some "Sea Foam" in his fuel....you should be just fine :)
 
J

juice71

Petty Officer 2nd Class
Joined
Jun 10, 2003
Messages
139
Re: 1971, 70hp, chrysler

Sea Foam,,,I've heard of this stuf,,,but don't believe we have it in Canada,,,,,is there any product we have in canada?
 
F

fatpratt1996

Petty Officer 1st Class
Joined
Sep 19, 2004
Messages
221
Re: 1971, 70hp, chrysler

Always be sure the cooling system are in good working order. My '71 70 horse overheated on me and I had no way of knowing at the time it was getting hot. It has 15 psi now on all 3. If everything is good order it is a good motor. once they fall, they're expensive and it is harder to find parts.
 
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loi

Recruit
Joined
Jan 15, 2002
Messages
5
Re: 1971, 70hp, chrysler

Yes, you can get Sea Foam at Napa auto part store.<br />I live in Windsor, Ont and I got it at local Napa store
 
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