compatibilty of Perkins 4108 with Lehman SP90

[tom jones]

Trying to find a working man's solution to replace my Lehman90 on our 43 ft Brewer cutter. most shops price a rebuild at around $8500-10000, a Beta 50 will run us about $12,000, but there seem to be lots of used working Perkins in our price range ($5k or under).
is the footprint on the Perkins basically the same as the Lehman, and will the external components off the lehman be compatible with the perkins. we have a Hurth ZF25M tranny, Leece-Neville HD 2800 LE, and a Hehr Aqualine Marine Regulator.
Also will the existing engine mounts work on the Perkins.
Thanks in advance for your advise.
Tom s/vBlue Trust currently in SW Florida
tj5035@gmail.com

[stormalong]

Can't comment on the Perkins vs Lehman but the 4-108 is very similar in size to the Beta 50 (BV2303). I replaced a 4-108 with a Beta 50. It is a little narrower and slightly longer than the 4-108. It is also lighter.

IMHO the Beta 50 is a far superior choice than the 4-108 which is why I chose to replace rather than rebuild. The Beta is more powerful. The 4-108 is not really a 50 hp engine, more like 35 unless you run is at 4000 RPM which no one does. The 4-108 is an upgraded 4-107 which is a 1940's design. The Beta is a cleaner running engine. Both are very reliable. Installing a used 4-108 that has not had a full rebuild is just too risky and a fully rebuilt one is would be no bargain compared to a new engine.

When I was deciding what to do I wrote down everything that would like to change on the Perkins and visited the Beta factory. Things like re-positioned oil and fuel filters, second alternator. They were able to do everything on my list.

That was sixteen years ago, I still have the same boat and I am still happy with the choice.

[Wainui]

Originally Posted by stormalong

Can't comment on the Perkins vs Lehman but the 4-108 is very similar in size to the Beta 50 (BV2303). I replaced a 4-108 with a Beta 50. It is a little narrower and slightly longer than the 4-108. It is also lighter.

IMHO the Beta 50 is a far superior choice than the 4-108 which is why I chose to replace rather than rebuild. The Beta is more powerful. The 4-108 is not really a 50 hp engine, more like 35 unless you run is at 4000 RPM which no one does. The 4-108 is an upgraded 4-107 which is a 1940's design. The Beta is a cleaner running engine. Both are very reliable. Installing a used 4-108 that has not had a full rebuild is just too risky and a fully rebuilt one is would be no bargain compared to a new engine.

When I was deciding what to do I wrote down everything that would like to change on the Perkins and visited the Beta factory. Things like re-positioned oil and fuel filters, second alternator. They were able to do everything on my list.

That was sixteen years ago, I still have the same boat and I am still happy with the choice.

Second the choice of going with the Betamarine 50
You won’t regret it!

[kristjan]

I’ve tossed around a lot of options for my own boat, have and MD17C, I’ll probably get a Beta 43.

[Lepke]

I've rebuilt a number of 4108s and have one on a generator, but it runs at 1800 rpm. The 4108 is a good reliable engine, but probably not enough hp for a direct replacement. Either you'd have to run slower or wear out the engine too quickly at 4000 rpm. The ones that go for 30 years are usually run at under 3000 rpm.

A new engine would add to the value of your boat, a used 4108 would probably detract. An alternator can be made to fit any engine.

If you were a mechanic, the Lehman can be rebuilt for about $2-3000 if it's not damaged, just worn bores.

[skipperpete]

Originally Posted by tom jones

Trying to find a working man's solution to replace my Lehman90 on our 43 ft Brewer cutter. most shops price a rebuild at around $8500-10000, a Beta 50 will run us about $12,000, but there seem to be lots of used working Perkins in our price range ($5k or under).
is the footprint on the Perkins basically the same as the Lehman, and will the external components off the lehman be compatible with the perkins. we have a Hurth ZF25M tranny, Leece-Neville HD 2800 LE, and a Hehr Aqualine Marine Regulator.
Also will the existing engine mounts work on the Perkins.
Thanks in advance for your advise.
Tom s/vBlue Trust currently in SW Florida
tj5035@gmail.com

The Perkins 4/108 is a good engine but it would be from the same era as the ford lehman with potentially more problems in the future, and still a bit light on for horsepower. A Perkins 4-236 is a pretty good option and would be a closer match for the Lehman. It really depends on how you use your boat and if you plan to do some serious coastal cruising rather than light weekend use you would be better off with an engine closer in power and rpm to what you already have.

[RABenko]

Have you tried Bomac Marine for your Lehman?
http://www.bomacmarine.com/ford-lehman-engines.html
They've been wonderful in service of our 80 HP Lehman in our Hudson Force 50. The father of the guy who runs is now was one of the builders of the original brand new Lehmans.

[StoneCrab]

Random info: The Perkins cylinders are replaceable sleeves that get pressed into the block.

I have a 4108 which I rebuilt 20 years ago. It was failing the compression test. It used to be an easy starting engine. Now it hates a cold start. I'm not a fan of the high rpm either. I wish I replaced it with something else.

[tom jones]

Thanks capns for your feedback looks like we’ve narrowed it down to either rebuilding a Lehman or try to buy/afford a Beta looks like a new Beta 50 can match the lehman 90 for power and thrust your views are helpful
Tom Jones S/V blue trust

[Sojourner]

I had this decision a year ago. Rebuild old perkins or buy a beta (after a lot of research). Should have gone with the beta. I've spent almost as much on the rebuild/swapping out parts as I would have on the brand new amazing never-read-a-bad-review NATURALLY ASPIRATED simple-as-a-brick strong-as-a-brick-chithouse beta but nooooo I did not. The perkins still smokes and eats/spits oil. The beta I will buy whenever I scratch some more money together in a few years. If you can find a bad review of beta, don't do it. But that's a big if.

[stormalong]

Originally Posted by Sojourner

I had this decision a year ago. Rebuild old perkins or buy a beta (after a lot of research). Should have gone with the beta. I've spent almost as much on the rebuild/swapping out parts as I would have on the brand new amazing never-read-a-bad-review NATURALLY ASPIRATED simple-as-a-brick strong-as-a-brick-chithouse beta but nooooo I did not. The perkins still smokes and eats/spits oil. The beta I will buy whenever I scratch some more money together in a few years. If you can find a bad review of beta, don't do it. But that's a big if.

Let me get this straight. You have an Amel Super Maramu, 53 foot and it has a Perkins 4-108? Is that for a generator?