Differences between '63 and '64 Johnson Seahorse 10?

[dougandmel]

Hi, I have a '63 Johnson Seahorse 10 model QD-24B, and have a few questions. The "offical" fuel mix is 24:1, but my local dealer who does a lot of work on old Johnsons says to use 50:1. I thought I'd read that the reason for 24:1 was the use of babbit bearings in the connecting rod assembley? The parts manual I have (for model qd-qdl-24m) shows this unit to have needle bearings in the crank and connecting rod. I know the qd-qdl is for short/long shaft, but what's the difference between a qd-24b (mine), and a qd-24m as listed on the parts manual? Also, are there any other differences between the 1963 and 1964 models that requires the use of 24:1 fuel versus 50:1? I want to trust the local dealer, but I also want this motor to last for a long time yet. Any advise is appreciated. Thanks, Doug

 

[tashasdaddy]

Re: Differences between '63 and '64 Johnson Seahorse 10?

63 is 24:1 the change to 50:1 was 1964. several changes to make it 50:1.

 

[F_R]

Re: Differences between '63 and '64 Johnson Seahorse 10?

'63 was the last 10hp. '64 was a 9.5hp, a totally different animal.

There is much controversy and many opinions concerning running the earlier models on 50:1. You can hear whatever you want to hear. But you can't go wrong using the original mix, 24:1. Anything else is up to your decision. I will say that the 61-63 10's had pretty good bearings. Pre-61 had problems with beating the wrist pins out of the pistons, even with 24:1.

 

[samo_ott]

Re: Differences between '63 and '64 Johnson Seahorse 10?

Yep, FR is right, unfortunately '63 was the last year of that great 'lil engine.

 

[dougandmel]

Re: Differences between '63 and '64 Johnson Seahorse 10?

OK, I guess I'll just stick with 24:1 then. Does anyone know the significance of the letter "B" atrer the 24 in the model number QD-24B? Like I said my parts manual shows QD-24M, but I don't know the significance of this, and Johnson customer service won't provide and help other than to identify the year of the unit.

 

[F_R]

Re: Differences between '63 and '64 Johnson Seahorse 10?

They always started the model year with a letter suffix that they seemingly pulled out of the air. Then, if during the year they changed any part or parts in the motor, they changed the letter suffix. Only important if you need to order that particular part, and it will be indicated in the parts book...assuming you have the latest revision of the book.