1956 javelin 30hp

Outboard Related Only
Clemg
Posts: 80
Joined: Wed Sep 09, 2015 8:56 pm
Location: St. Louis

1956 javelin 30hp

Postby Clemg » Sat Sep 15, 2018 9:37 pm

I will try to explain this as best I can.
Started to tear down the power head. I took the head off and intake. I hand cranked the motor over and noticed a little play whe top piston is at top dead center. It sounds like a poping sound. I put my fingers on the top piston and hand turned again and I can feel some play on the top piston. Is this normal or do I have issues!
Any advise would be great!!!
Clemg

Adam1961
Posts: 421
Joined: Sat Mar 14, 2015 7:46 pm
Location: Montreal, QC Canada

Re: 1956 javelin 30hp

Postby Adam1961 » Sat Sep 15, 2018 9:55 pm

These motors are often a little loose as you described. 1956 was the first year for a needle bearing at the wrist pin end of the rod. They were and improvement over the bushing from 1955 and earlier, but still too small. Turn the motor so that the rod is pulling the piston down the cylinder. Then stick a screwdriver through the plug hole and gently push down on the piston. If you hear and feel a "click" then you likely have slop in the wrist pin bearing.
The big end of the rods can be checked by measuring the crankpin diameter and the inside diameter of the rod bore. I find that as long as the needles on the big end look good with no galling or bad discoloration from heat, they will usualy work just fine.

Clemg
Posts: 80
Joined: Wed Sep 09, 2015 8:56 pm
Location: St. Louis

Re: 1956 javelin 30hp

Postby Clemg » Sat Sep 15, 2018 10:02 pm

Thanks for the help I’ll try that and let ya know.

Clemg
Posts: 80
Joined: Wed Sep 09, 2015 8:56 pm
Location: St. Louis

Re: 1956 javelin 30hp

Postby Clemg » Sat Sep 15, 2018 10:06 pm

I tried and found a little play or pop in both pistons.
Would replacing the needle bearings help the cause or is this normal. I haven’t torn down enough to see rod bearings yet.

FrankR
Posts: 3768
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: 1956 javelin 30hp

Postby FrankR » Sun Sep 16, 2018 2:56 am

Those wrist pin needle bearings in 1956 had a nasty habit of the needles getting out and scoring deep grooves in the cylinder walls. Apparently that has not happened to yours or you would see the damage.

User avatar
VinTin
Posts: 542
Joined: Tue Mar 10, 2015 11:13 pm
Location: N/E Georgia

Re: 1956 javelin 30hp

Postby VinTin » Sun Sep 16, 2018 3:33 am

Were improvements made in this area in the 1957 35hp RD19?

Seems I remember it being mentioned in an Outboarder article some years ago.

Adam1961
Posts: 421
Joined: Sat Mar 14, 2015 7:46 pm
Location: Montreal, QC Canada

Re: 1956 javelin 30hp

Postby Adam1961 » Sun Sep 16, 2018 7:45 am

Yes, the 1957 bearings were better and by the time OMC was producing the 28,33 and 40HP motors in the mid 60's they had them figured out.
The 1956 bearing is a full complement needle bearing. There are many small needles that make up the full diameter of the bearing. The only thing that holds them in place is the outer race of the bering that is drawn over and crimped around the ends. A full complement bearing is great for high load applications (because there is more bearing surface) but has shortcomings in a high speed application. The needles are more likely to try and run out of square to the inner and outer surfaces.

For 1957 and up they went to a caged needle bearings. This has gaps between the needles and they are held in place by a cage that can spin withing the end of the rod. This bearing is better suited to high speed. The later bearings are also wider (the small end of the rod is wider) so the later rods wont fit the earlier engines unless you machine the back side of the pistons to expose more of the wrist pin.

User avatar
Garry in Tampa
Posts: 2866
Joined: Mon Mar 09, 2015 2:32 pm
Location: Florida

Re: 1956 javelin 30hp

Postby Garry in Tampa » Sun Sep 16, 2018 12:20 pm

One of the ways OMC got the extra five horses in '56 was by adding needle bearings to the wrist pins. Early testing did not show any problems and so those needle bearing connecting rods were used in the first production run of the '57 35. One thousand hour wide open testing of the prototypes ( A standard instituted by Ole Evinrude in the 1920s ) had not shown any problems. The first production run of 5000 outboards was made in November for Christmas sales and December boat shows. Sales to Florida and Texas were particularly important because early use in those warmer regions constituted "real world" testing outside of the engineers laboratory. Spring sales were well under way when reports of wrist pin failure hit the company. It was found at high speed the needles circulated and stayed centered, but that in as little as 200 hours of trolling the back and forth rocking wore through the retainer and dropped the needles into the powerhead with disastrous results. The bearing specs were changed and needle bearings with a heavier retainer were used for the rest of the year. Ralph Evinrude had 5000 of the newer 35 horse powerheads sent out to dealers for warrantee replacements of the defective outboards. The dealers were supposed to arrange for this replacement with there customers and letters were sent out to registered owners. It was found many did not read or chose to ignore these letters. Some were pleasantly surprised when the outboard failed five years later to find that they got a new powerhead under there one year factory warrantee . . . 8-)
Image
Living my dream because Reality is too expensive . . .

FrankR
Posts: 3768
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: 1956 javelin 30hp

Postby FrankR » Sun Sep 16, 2018 12:48 pm

Thanks for that lesson in history, Garry. I sort of knew it but not with the detail that you provided.

Good job, and hats off to you, Garry.

Chris_P
Posts: 2624
Joined: Tue Mar 10, 2015 4:59 pm
Location: Hamilton ON
Contact:

Re: 1956 javelin 30hp

Postby Chris_P » Sun Sep 16, 2018 1:44 pm

Garry,

Great info!


Return to “Ask A Member”

Who is online

Users browsing this forum: No registered users and 5 guests

cron