The elusive 224/3.7 MerCruiser banger

Any modern aluminum head would likely make a world of difference.

 

I'd dearly love one. Even considering their cost, they are not greatly more expensive than a new cast iron head. Iron heads are usually sourced from a swap meet or junk yard so they are quite cheap. I went the cheap way with its head planning to upgrade to an aluminum head if I liked the engine, and I do like the engine...at times it is phenomenal, mine just is not consistent. So with my mistakes cured, it will be new head time.

 

Lifters vary so if one is slightly tight in the bore, I read that it can be polished down. That seems much better than honing its bore slightly because lifters are inexpensively replaceable while the block is not. Better yet, find another lifter at a autoparts store. They wanted to know the application so I said, "just get any Ford lifter from about 1980".
I was not sure about it so I checked with the parts guy at the Ford dealer and on checking, he said that "Ford lifters were all the same in those days".
This may help some of you with your rebuilds.

Although lifters all being the same is logical, some were not the same. I bought one which was roughly 100 thousandths longer and had no hole to admit oil to the pushrod

 

Dennis,
I apologize for rolling so far back in this thread, but I just found it!. I have one of these motors I plan to use in an Austin Healey "T bucket" build - but more immediately I have 2 of them in my boat ! I am very interested in the very slick water pump conversion - for the boat and the Healey.
Is there any chance you can tell me exactly what pump and pulley you used? I think you've missed your calling, I think there are several of us that would gladly purchase that conversion in a kit - I already need 3 of them...
Any reason you can think of why it would not work in the boat ?? I am coming up on the third time dealing with those problematic cam seals...
Thanks in advance.

 

It takes such a long time to compose a good post that I can't post it as something times out on this site.

I spent 45 minutes but could not post it, so this will be quick:

pump was from a late 70's Corolla. Pulleys were Japanese from wrecking yard.

You'd have to redrill the pulleys anyway so just get the offset to match and go over the pump.
I carried my pump into the yard and bought several which had the possibility of working

Any of the pulley holes can be redrilled and the offset can be shimmed forward a little.
My dampener pulley was from a swapmeet, 50's something. I cut it down...actually i cut both pulleys down. eliminating extra grooves. Just don't bolt it on so tightly that its rim drags on the outer part of the dampener and stops the action of the dampener.

 

I used a 5/16" plate large enough to fit both sets of waterpump bolts. Match the oulets of the old mercruiser pump and the new toyota pump and move th toyota pump around until it fits. I had to resort to socket head cap screws in two places as the fit left no room for a socket wrench around the bolt head. Also used two 5/16" countersunk bolts under the center of the back of the Toyota pump to avoid turbulence from a conventional bolts interfering with adjacent fluid flow.

 

For anyone breaking in an engine ( or its replaced parts) you can make up a shaft to drive the oil pump from part of an allen wrench and a 18" inch length of pipe or tube, I brazed the hexagonal part in and brazed a round tube inside the other end as it was too large for a 3/8" chuck to go over it. chucked it up in my 3 jaw lathe chuck and a tailstock chuck. Then i\I got it spinning and heated the tube to redness up a little from the section of allen wrench. When it cooled, it ran true.

In the oil pump, it turned easily until it built up oil pressure. Then I noticed smoke---coming from my 3/8" harbor freight drill. Stopped , "put the smoke back in" and continued now with a 3/4" drill until the lifters were full.

 

Dennis,
Thanks a million for the water pump insights, off to the wrecking yard I go tomorrow with my sidekick... My wife says it's like kids heading into an amusement park...

 

Take your intended waterpump with you. Show it to them as you go in. Use it to determine if the hub of the pulley is large enough to go over the pump.

If you don't have your new pump, stop off at an autoparts store on the way there. I have been a customer at one store long enough that they let me wander through their stockroom and test parts. I opened their entire stock of about 50 waterpump boxes to pick out what I liked best.

If you have your dampener you might look for a crank end pulley. If you are using the Mercruiser alternator, does it have an integral pulley groove?
The spacing of that groove determines your choice of pump pulley offset.

 

A note on distributor advance. I recently added a centrifugal distribitor wilth vacuum advance.

Since then it has made a loud knock from 1800 rpm and up to 3000rpm. It was a fair mimic of a rod knock but no rod bearing is loose ( I checked them). I was deeply worried and had a very experienced prof. mechanic over today. Happily, It was just spark knock from to much advance (44 degrees total) when you add in 15 degrees from the vacuum can.
So you may be able to run half that much vacuum advance but not the full 15 degrees.
I made an ajustable vacuum advance pot from two others. ( One adjusted but did not fit, the other fitted but did not adjust so I combined the fitting end with the adjusting end).

 

Time for an update. In an earlier post, I put in a distributor which also has vacuum advance. It was not a plug and play sort of thing. With centrifugal advance delivering 32 degrees, vacuum advance added so much more that there was spark knock ( It sounds a lot like a rod knocking). The problem is that the vacuum advance used on alternate forms of a Mercruiser distributor are non-adjustable. It comes in too early and too strongly on an engine which will pull 20 inches of vacuum.
I had a useful (for parts) old adjustable vacuum unit with a ruptured diaphragm. The adjustable units have a hexagonal end. The non-adjustable ones just look like a funnel. They are the same diameter, so I made a series of slits in the edge where the front and back halves are crimped together one can pry the lip open and change the non-adjustable end for an adjustable one.
The adjustment screw changes spring pressure against the diaphragm so the beginning point of vacuum advance can be adjusted. There is also a short tube within the spring, it looks like an advance limit. Allen wrench access to the screw is through the little inlet tube.

 

After a cam change,I found a rocker arm lightly hitting the rocker arm cover.

I duplicated the rocker arm cover gasket in 1/8" aluminum and cemented a gasket to it. The point of the aluminum is to stabilize the gaskets so they can't squirm out of position. I now use two cork gaskets, one below the "stabilizer" and one above it. It gives an extra quarter inch clearance that I needed. It works.

 

Dennis may I suggesy you type out your replies in WORD then cut and paste when you are ready to post. Another advantage of this is if you save each WORD doc when you are finished you can keep or your tech responses handy if the same question gets asked again. Just a thought and thanks for your insightful posts to date.

 

I just gathered one of these engines and i see i have a lot of interesting reading in front of me.
What tranny can i use and do i drill/machine the original flywheel for the clutch? I want a 5spd of some sort.
Thanks, oj

 

I don't have one of these, but here are answers from earlier in this thread, from memory so check. Lots of stuff to read.

Flywheel in stock motor is Ford, and can be used (may need to remove paint on it). Don't remember if Chevy or ford clutch is used. If you cut 5/8 in off the back of the block it has normal Chevy transmission bolt pattern and depth. There may be other ways too, different transmission input shafts etc. may work without cutting block.

 

use a small block chevy bellhousing. bolts right on except for 1 bolt . The crankshaft has to be drilled for a pilot bushing flywheel of the merc is good , I used a pressure plate from a 84 mustang v8, it just bolted on all I did was take the paint off the merc flywheel. Chev clutch disk.
the block has to be milled 5/8" if you use a saginaw transmission. Different transmissions do not have the same input shaft lengths and thus require different spacing/bellhosing lengths. You are on your own with the 5 speed transmissions. It is then up to you to get everyhing right for its input shaft length. Unless you want the overdrive of a 5 speed, I think a 4 speed would be a better choice. ps some of the 5 speeds had a reputation of breaking easily.

 

That Sammi is impressive as all get out!
I have an '87, all more or less original but with added optional rust, cracked windshield and a few dings. I use it like a golf cart on the property. One of these days the engine will die. It's a fun thought to imagine the Mercruiser 470 in it's place!

Jim

 

Now that the Mercruiser guru Sarge Nichols has passed, who's the go-to guy for tech on these beasts ?

I have questions about deck hieght, offset grinding the rod journals for longer stroke, connecting rod lengths, compression distance.....ect.

I'd like to build one with a big fat torque curve for crawling and low RPM cruising in a flat fender Jeep.

Thanks,

MHF

 

I've never regretted having extra gears, even with "torque abundant" engines. Skip shifting (1st to 3rd to 5th) or just starting in 2nd or 3rd takes care of any issues of rowing through the gears on light acceleration.

Light vehicles with big engines are why we're here !

MHF

 

I consider Randy of this group to be the Mercruiser expert.

Considering that what you are doing does not require this specific engine, I'd suggest that any common engine would do equally well climbing slowly over rocks (if you had the right gearing). And it would be a fraction of the cost of a mercruiser engine.

The meruiser is very light and, properly cammed, has very good torque.
For extended high output use, its compression ratio should be lowererd to around 8:1. Its ratio is ok for what you will be doing. Some have complained about the engine knocking, but zero decking it reduces that. You should change its waterpump to a belt drive pump as there is a persistant waterpump seal problem resulting in coolant entering the crankcase. Mercruiser factory headgaskets seal well enough, but some of the others do not.

 

a 5 speed transmission would disqualify my car

 

Been reading this thread the last few nights and have a couple thoughts:

1. has anybody considered a copper head gasket? I'm a FNG on things like this, but a solid copper gasket works wonders in any number of other engines

2. what about fuel injection (TBI)?

 

I have a friend who used .030 annealed copper as the gaskets could be used over and over. He did not run mercruiser engines, so it does not say anything about copper gaskets use in them.

I got a tbi setup from an early 90's chevy Lumina for possible use in my Mercruiser. It is a little small (125 hp vs 170 hp) but I think it is possible.

 

Isn't technology wonderful!

I am involved in vintage open wheel race cars, and a while back decided to put one together myself. With so many using the SBC, as usual my endeavor is to be different almost to the point of being out of whack!

The 470 at 224ci and 4 cyl. is conveniently close to the Offy 220. So I'm thinking with the hood closed maybe no one will notice (!?) if I do this right? After all I am saving 20-30k lol.

Week or so ago I was fortunate enough to pick up a running 470 from a boat (heard it run before we pulled it out). Initial plan is to get rid of the Merc water pump and alternator, keep the 2bbl intake and fab a vintage style exhaust, as it is going in a 60's era Edmunds (looks like one anyway) sprint chassis. Later on, Aluminum head, Mechanical fuel injection, on methanol.

And I found this awesome collection of posts on this very subject! Thank you all for all this great information, and will try to keep this thread updated.

 

depends on the rules. I had a friend who could not run his aluminum block motor (he made it from two outboard motors) they did not want to get into aluminum blocks as those motors are so much lighter ( and often much more expensive). Your car will be a lot like mine..same engine and body but I used a jeep chassis (it was cheap) so your chassis will be considerably better.

 

You are ahead with a running motor. Its main weakness is the seal on the camshaft that keeps antifreeze out of the oil(for a while). Mercruiser used two seals both with the lip toward the water side and packed the chamber between them with grease.Even has a special water drain for the chamber..tells one something doesn't it?
You can run it as it is but when you change out the alternator you can add a toyota water pump and mount it on a plate over the back half of the merc pump.

Happy to have you with us.

 

The only rules that we watch out for in our club ( as far as I know!) is safety.

We just yellow flag lap, don't race, and just present our cars and the noise they make at selected open wheel shows here in the Midwest.

And yeah, Dennis, I've read all the pages on the thread here, so got a pretty good plan going I think. Their be some differences in how I couple the drive to it & mount it from what I've seen you guys do..

Thanks for the reply, looking forward to getting started on it. Brother's Shores chassis sprint car from late 70's is in process right now, then mine.

 

an in-and-out box and no starter will make things easier.

 

OK you stole my idea for my next project, a 4cyl vintage sprint. Wright now I'm building a copy of a '60s A J Watson Indy 500 roadster. I wanted to stay with a big 4CYL, but like you I don't have 60K to look for an offy. So I'm going with the MC 3.7, alum head, Hilborns on Alky. It will be different & cool! FYI I have a vintage sprint now, It's fun to go play with. Good luck with your sprint.
Later Dave

 

Thanks Dave, and I'll be interested in seeing how you work out your injection setup.