Hi guys going to rebuild my Johnson rds-23 super seahorse 40 and am looking a complete gasket kit
Oversize pistons and rings, does anyone know of parts available. eBay is coming up short with trying the match model numbers and I am not sure what cross references with 35hp or the likes. Any help is much appreciated

Talk to Mike Vincent at South Coast Marine. He ended up with most of the 'obsolete' factory stock. Failing that it's possible Hank at American Marine might have stock of older bits.

Hi

I am sure you've now found all the parts you want.

Years ago Derek Gowlett at Dunstable Sportsboat used to patiently help me out. with parts for my '62 Johnson 40. More recently Mike Vincent at South Coast has been very helpful for Evinrude and Johnson parts.

Just lately, Stu Allen at Dangar Marine in Australia has steered me towards the catalogues and website at Marineengine.com. Their catalogues are all neatly laid out by year, engine size and model number, so it's easy to find your engine. Amazingly they still have stock of most of the original part numbers, or replacement parts numbers, where these have been superseded. The only snag is that they refuse to ship outside USA, although I've overcome this sort of problem in the past, by organizing my own courier pick-ups with UPS.

With the correct part numbers, I've managed to find small suppliers for all the pistons, rings, etc. I've just had some rings from a chap in Padstowe.

Anyway, I'm sure your engine is long since rebuilt and running well!

Hi

My .025" oversize pistons arrived this week - from USA, at great expense, to say nothing of the £26 Customs fee I had to pay the Post Office. Part number 0383069, casting #311747.

Did you manage to find some for your RDS-23?

I'm 99% certain that these will be okay on my '62 Johnson 40, RDS-24 - but not 100%. I'm also hopeful that my powerhead can be re-bored to +.025" - but not certain.

I've found the marineengine.com catalogues to be a useful resource for tracking down part numbers, because you can look at your own model, and also the subsequent years, to get an idea of what later parts might work. For instance, the over-size pistons are not listed until '65 RDS-27. However as the standard piston for that engine is apparently okay for the older models, it's a reasonable assumption that the over-sized piston will be okay too. There is a slightly worrying note, on these engines about pistons needing to be replaced as matched pairs - but perhaps they just mean, don't mix new and worn pistons?

Cheers

Andrew

Is this a 24:1 oil to fuel ratio motor? The early 60's 40hp motors needed more oil to compensate 50's engineering, and there was a later redesign with stronger rods and other tweaks - think all changed from '64, but will look at my history - if you need to ask the question before I get to it, do so here..

https://aomci.org/resources/ask-a-member/

Hi

My 1962 RDS-24 is 24:1 mixture.

The RDS-24 catalogue (at Marine Engine) lists 0378695 as the standard piston, but lists no over-size piston.

The 1965 RDS-27 catalogue also lists 0378695 as the standard piston, but now lists 387697 as the .025 over-size piston, replaced by 0383069 - which I've bought.

However these are going to sit on the shelf for the time-being. The engine runs well enough and I haven't got the experience or confidence yet, for re-building the powerhead on this 40hp engine. From memory, the liner is gouged, so a re-bore may not even be possible. It may need to be re-lined, or perhaps another powerhead sourced and some standard pistons?

For now I'm making my mistakes and learning, by rebuilding the powerheads on a couple of very compromised 1970s 6hp Evinrudes.

I've two powerheads, separated from their mid-sections if you're interested.

Gosh - your powerheads sound good. I'd certainly feel more comfortable dismantling a powerhead and asking an engineering workshop to do some machining - if it's not the only one I've got.
What sort of price did you have in mind? Are your powerheads compatible with my RDS-24 model? If you are looking to move them on, I ought to have one - but I'm not going to be ready to get started on this project for quite a while.
I need to get a few others finished first!
Thanks

Will look at what I have and come back to you...think they're newer, but that's a good thing..50:1 mix and better rods, etc.

You're in luck. This is either a 1960 RD-22, or 1961 RD-23. It has the rebuildable fuel pump, high and low speed jets and the decompression style cylinder head - these had disappeared by 1962. It turns over, but I've no other history on it. £30 if you're interested, contact me via email...my PM not working at the moment.