Mercruiser 292's

[gregga]

Hey guys,

I have an older 28' Cigarette with merc. 292's. Both engines are overheating pretty badly and knocking last time we ran the boat which was roughly 4 years ago. Instead of pulling them apart and all that fun stuff, we are wanting to just swap in some merc. 250's. I have a pair on hand as long blocks pretty cheap and I know my exhaust will swap over. but just wondering what else will swap over from my 292's into the 250's? I can't find any 292's for sale nor find parts for them so i'm just wanting to swap to the 250's but would like to be able to just swap my existing parts over. Any help is greatly appreciated. Thank you.

 

[Don S]

Re: Mercruiser 292's

Merc doesn't have a model 292. What type engine do you have, year would help, serial number of the engine would help even more.

 

[HT32BSX115]

Re: Mercruiser 292's

That must be a pretty old boat....

I think the 292 he's talking about is the GM 292 inline 6cyl. Without knowing the actual serial number of the engine it's going to be hard to determine exactly what you have...... I think they rated it at 190 hp

The following online manual might help
http://boatinfo.no/lib/mercruiser/manuals/mercruiser1.html#/0

 

[Don S]

Re: Mercruiser 292's

I think the 292 he's talking about is the GM 292 inline 6cyl.

That's why I asked before spending time posting things that don't help.

 

[gregga]

Re: Mercruiser 292's

Yes GM 292 Inline 6

 

[HT32BSX115]

Re: Mercruiser 292's

Yes GM 292 Inline 6

I believe those are the Mercruiser "200" I-6 engines.

Many years ago I was "that close" to putting a 292 in my previous 150Mercruiser (GM 230-6) powered boat. I found that most or all the parts interchange. even the heads. The local truck wrecking yard had several (and still has I think) 292 and 250 cu-in engines. I found that there are many blocks (292 & 250) that do not have the correct (front) mounting points to work with Mercruiser engine mounts.

Most everything else *should* swap. Even the 250 (165) heads will bolt to the 292 blocks. The deck height is not the same though (by approx an inch higher) so your exhaust "down" pipe might be a little long from the riser.

The rest of the accy's should swap over. You need to look closely at the engine mounting though. I'm not sure Merc used the same type of bell housing/flywheel/coupler/rear-mount arraignment with the 292 and all the 230/250 engines.


It looks like that manual does cover that engine. Are those Mercruiser II drives? The 292 is a great engine. I would want to rebuild them if everything else was ok. If you have Mercruiser II drives, I feel for you! (And good luck, you'll need it)

 

[gregga]

Re: Mercruiser 292's

They are Alpha drives. And pulling them out to rebuild them would work as well but the only problem I have had is finding rebuild kits for them? In fact I can barely find any parts for the 292. Seems it would be almost easier to swap for the 250? Guess it just may be a personal decision and not a blow out difference between the two?

 

[HT32BSX115]

Re: Mercruiser 292's

They are Alpha drives. And pulling them out to rebuild them would work as well but the only problem I have had is finding rebuild kits for them? In fact I can barely find any parts for the 292. Seems it would be almost easier to swap for the 250? Guess it just may be a personal decision and not a blow out difference between the two?

I hope you don't mean you want to rebuild the drives too! Depending on the year models, I don't think you can rebuild REALLY old Mercruiser drives. Even if you can buy the parts, you're better off getting SEI drives and later model gimbal mounts. If you do, you'll have the problem of the inner transom plates possibly not matching up with 292's. either with the gimbal OR the engine(s) so I TOTALLY "GET" the reason to swap out the 292's for the 250's.

And it depends on what you mean by "parts".

Those 292's really just truck engines. I wouldn't hesitate to use truck pistons, valves, cam, gaskets etc. A decent machine shop can easily get 292 rebuild kits. Or you can just buy them online......

http://titanengines.com/chevrolet-292-4-8-1968-70-engine-rebuild-kit.html

http://www.northernautoparts.com/ProductDetail.cfm?ProductId=954

http://www.rpmmachine.com/shop/index.php?l=product_detail&p=4597

Even found one on ebay

http://www.ebay.com/itm/GM-Chevy-292-4-8-Master-Engine-Rebuild-Kit-1963-1967-/250762498764

There will be a small problem going to the 250's in that you'll be essentially pulling 200HP engines and replacing them with 165hp engines. That will reduce your performance a bit and maybe more than a bit if they're going in a big boat that's a little under powered already.

THEN, you might be better off going to V-8's. If you want to do that, you'll need to also get different drives since the drive ratios you have will be all wrong for a V-8.

You're probably finding out that trying to work on REALLY old boats with antique engines and drives is not easy when this stuff is no longer well supported.

Could be worse! You have an old OMC engine and drive!


Good luck,


Rick

 

[achris]

Re: Mercruiser 292's

and it's more than just the horsepower drop. Those old 292 had enormous torque. That will will really feel.

The issue with dropping a couple of bent 8s in will be the centre-line spacing for the engines. If the existing engines are less than about 36 inches apart (crankshaft centre-line to crankshaft centre-line), forget it....

Chris........

 

[Scott Danforth]

Re: Mercruiser 292's

The 292 is one heck of a truck motor, coveted by those on inliners.com

the 292 shared many SBC parts, including pistons and the bolt pattern on the flywheel housing. Like Achris said, you WILL feel the difference between the 292 and the 250.

The 292 shares many things with the 250, however the right side engine mount is not one of them. you will be making a new right side mount for the 250. if your going that far and you dont want to rebuild the 292, then I would suggest you put in a complete new set of drives and motors and go with a set of 5.0's

by the way. the last 292 rebuild price I had gotten from a local machine shop was $1300.

you still have a cooling system issue, which lead to the engines being overheated and knocking, which the first place to look is the impellers.

 

[gregga]

Re: Mercruiser 292's

Rick, Drives are not being touched. We replaced the water pumps in the drive and replaced water pumps in both engines and impellers. Also replaced the whole manifold and risers on both engines as well as thermostats, checked all the cooling lines and everything was ok. So I really don't know where else to look as far as the cooling system and as to why it wouldn't be staying cool? Could it have to do with the block and the water jacketed system maybe being blocked by rust or corrosion being so old? My thought was it maybe be easier and cheaper in the long run to swap to 250's by the time I pull the 292's out, tear them apart, have them rebuilt, put them back in the boat ad still have a cooling issue then Im still back to square one? Thanks for all the input guys it is greatly appreciated.

 

[Silvertip]

Re: Mercruiser 292's

On the other hand you could install a pair of 250's, lose a bunch of performance AND still have a cooling issue. Part of the rebuuilding process is to "hot tank" the block to remove corrosion and scale from the internal passages. The block is magnafluxed to check for cracks. Cranks are turned, block is line bored, cylinders bored and honed to next oversize, valve guides knurled or replaced, valve seats replaced if necessary (a complete valve job). The cam may or may not be replaced and new lifters installed. You essentially end up with a new engine from a seasoned block since it has gone through many heat/cool cycles and is now stable unlike a brand new engine.

 

[gregga]

Re: Mercruiser 292's

I'm thinking pulling the 292's out and just rebuilding them is going to be my best bet for sure. Another question I have is Im running these in a 28' Cigarette with twin Alpha drives one counter rotating obviously, If I buy two rebuild kits with the same cam setup being that they are truck parts with that hinder anything in my setup? Also right now the engines aren't using a two barrel carb I have Holley 4 barrels on them and i'm wondering if that is too much carburetor for these engines? Should I just have these rebuilt and put them back on? Or should I swap to a two barrel carburetor? Thank you again guys.

 

[matt167]

Re: Mercruiser 292's

you can very easily have the original camshafts welded and reground to factory specs. There are machine shops that can do it, but also some of the performance cam companies will do it. Holley 4bbl will be fine for a 292 as long as they are marine carbs. 600 CFM is probably good.

 

[kilowatts]

Re: Mercruiser 292's

Hi Guys:

Can I ask that you please post some photos of your installation including the outdrive? I'd love to see what you have and how it's been installed.

kilowatts

 

[HT32BSX115]

Re: Mercruiser 292's

I'm thinking pulling the 292's out and just rebuilding them is going to be my best bet for sure. Another question I have is Im running these in a 28' Cigarette with twin Alpha drives one counter rotating obviously, If I buy two rebuild kits with the same cam setup being that they are truck parts with that hinder anything in my setup? Also right now the engines aren't using a two barrel carb I have Holley 4 barrels on them and i'm wondering if that is too much carburetor for these engines? Should I just have these rebuilt and put them back on? Or should I swap to a two barrel carburetor? Thank you again guys.

It's a "Backwards" drive? or the engine is a backwards engine? Those are marine carbs?

I don't remember what carb those engines had originally but it seems a 2bbl carb is more than enough for an engine that is less than 300 cu-in and turns 4500 RPM or less....

Also, if the engines have been run in salt all their lives, you might want to peruse a truck wrecking yard to find a couple of 292's if the blocks are rusted severely.

I didn't mention anything about the overheating but if you have had impeller failures the pieces will frequently plug hoses, (oil/PS) heat exchangers t-stat housings etc.

Also, if your risers and exhaust manifolds are rusted/plugged, you will get over heats too. Salt water can destroy manifolds and risers in as little as 5-7 years.

Just saying......

 

[gregga]

Re: Mercruiser 292's

Yes it was a saltwater boat but has been flushed for at least 15 minutes after each time the boat has run. Manifolds and risers were replaced four years ago and only one sea-trial was accomplished after and they still overheated. We are pulling engines, ordering rebuild kits and pulling them apart to have the blocks checked out at a machine shop and while they are out and apart we can go through the WHOLE cooling system and every hose, line and fitting and get a thorough check of everything. As stated the manifolds and risers are fairly new and have barely any hours and the actual engines themselves have less than 100 total hours but did sit stagnint for four years so they will be pulled out and gone through and rebuilt. If they don't need a complete rebuild we are still going to do it for piece of mind and starting from scratch. Thank you guys for your all your help.

 

[Scott Danforth]

Re: Mercruiser 292's

the engines would be fine with 2 or 4 barrels. I have seen 292's with 6 individual throat carbs as well. however for your boat, if you have about 450 cfm carbs, it will be fine. you can get custom marine cams from Elgin.

 

[achris]

Re: Mercruiser 292's

Summit racing CFM calculator says 325CFM is all you would need. Most 2 bbl carb deliver that easily. If you run a 4 bbl you may find it will be down a little on low end torque. (I used 4500 rpm as max revs in the calculation. Spec is 3900-4300). Do you have the Merc service manual for your engine?

Chris......

 

[gregga]

Re: Mercruiser 292's

Chris I do not and I could not find one either if you know a link of where I could purchase one that would be fantastic!! Also one more question guys, I know these engines are based off of a truck engine so if I order one of the rebuild kits from one of the companies Rick suggested a few posts earlier will I be ok with using their gasket setup that is used in trucks? Or will I need a gasket kit specifically for marine use? So would I need A different head gasket or piston rings for a marine application as oppose to the normal gasket and rings they provide in the kit?