The elusive 224/3.7 MerCruiser banger

We have the Chev patterns but a modern 4 or 6 speed auto needs a tcm which are very expensive here.. $1300+ the Old Turbo 350 / 400s go for silly money... easy to make an adaptor then use a stock flywheel with a crank hub adapter and spacers for the convertor to the flex plate. Im looking at EFI / Turbo setup on my engine, would rather throw money for that than a TCM controller.. also with the adaptor it gives me the option of using a ZF 6 speed auto. Has anyone talked about an AEM V3 water / methonal system on this thread? One way to sort out any knocking issues..

 

Finally putting mine together, Dennis G did you ever find a source?

 

Ask the man how owns one...
https://www.marineengine.com/boat-forum/threads/mercruiser-3-7l-470-inboard-help.479215/

 

I'm still here. I was just reading through all the pages since I had checked in.

I pulled my setup out of hibernation today to take another look at it. NOT good. I went through the pre-startup checklist, added new fuel and hit the switch. Thats when the racket and sparks appeared. The starter gear is no longer attached. The front of the starters teeth are eaten up. The flexplate doesn't look good. It did manage to rumble for a few seconds. I have assembled something wrong. It is just too hard to crank.

 

Sorry to hear it still wants to fight you. Hope you can get it fixed up and running good! After about 1000 miles mine is starting to fight me! Fuel issues, but I knew that they were going to be there. Might be time for a carburetor.

 

I have one of the HiTorque starters from IMI on the motor. I was surprised how reasonable the replacement pinion gear kit was from them. $20 for the kit and $11 for shipping.
I have a new flex plate on the way also. $98 from Summit. I added another small item to get free shipping from them.

 

Ughhh, finally getting back around to this project after it collecting dust in my shop for 6mo

Do you guys think i "really" need a damper. I don't like how much the zero-balance SBF stuff and the OEM stuff increases stickout (I want that space for a mech fan). The OEM alternator pulley doesn't have any sort of damping. It's just dead weight and these engines aren't known for any sort of crank problems. I could whip up an equivalent that satisfied my belt drive needs.

I'm not really gonna exceed the OEM 4800 redline much if at all and probably will only rarely sustain operation above 4k (but when I do I'm gonna be going wide open for minutes on end pulling a particular grade near my house) but I figure that's pretty comparable to what Mercury designed these engines to do.

 

I think a damper would help stop some of the vibration that big 4's are known for.
I probably crossed into "shakey ground" when I removed the flywheel from mine. I installed a flexplate mounted dirt track mini clutch. I have taken a lot more weight out of the rotating assembly than you are considering.
Mine is still not cooperating. I am having someone else double check my cam degree abilities. After me doing it about 10 times it makes no sense for me to check it again.

 

Mine's been on the road for over 1000 miles. Ford 302 balancer works fine. Its in an old Land Rover 2A, so I rarely break 4200 rpm and the vibrations are minimal - normal for the truck.

I did not fill the deck of the block, but rather used the Blockmaster in my shop to machine the deck flat, which was WAY off. I used block filler to stabilize the bores - about 2/3 full in the back, ramped to the water pump output in the front. Aluminum head from Ebay - 429/460 design using Chevy roller rockers and custom pushrods. Stock manifold with a few modifications and a Holley Sniper for the large 2GC bolt pattern. If I recall the #1 intake cam centerline was around 108? That works better on a 4 cylinder than 112. If you veer much, also check the valve to piston clearance as the exhaust valve chases the piston down the hole and can get within .100" or closer. Stock cam in mine since the 485 cam is really an ideal hotrod cam.

 

My motor update;

After having the starter/flex-plate issues I disassembled the motor to a long block. I put the motor at TDC and installed a degree wheel. I then took the motor to a motor builder/machine shop with the instructions to check the cam installation. I also instructed them to look over the valve train for problems.

It turns out I got the cam right on spec, however I had the hydraulic lifters way to tight. When I installed the rockers I had been told to rotate the push rods between my fingers as I tightened the rocker arms, and when they snugged up I was at 0 lash. That didn’t work for me. It turns out when they quit rotating easily I had the lifter springs completely compressed… When the motor was at higher RPM it was making enough pressure that the lifters were not allowing the valves to close completely. WE THINK!

I have a dyno/tuning session Wednesday the 10th of July. I will let you know what happens.

 

What fuel to use??
When I initially built the engine, the compression was supposed to be 14:1 with the intent to use methanol for fuel. I had issues with the pistons smashing the spark plug electrodes. At that point I removed the head and installed dimples in the piston domes for the plugs to clear.
Then I had very high cylinder pressures when cranking, which the starter/battery didn't like, so I again disassembled the motor and machined the top of the piston domes off, reducing compression.
At this point I am unsure what my compression ratio is, but it is still high. My guestimate would be 13:1.
When I was at the dyno tuning last time I wanted to use VP MS109 because I was running 2 other motors on that and didn't want to carry multiple fuels. Those other motors are now gone so I am open to any fuel. I am running an O2 sensor for my EFI so was looking for lead free. The tuner says he runs a lot of motors on VP C12 (leaded) that have O2 sensors with no issues, so that is an option. I can buy good quality E85 at a local station cheaply, 5 gal for under $15. I'm cheap so that sounds like a good option.

What do you guys think??

 

Beck,
Glad to see you're back at it.
I looked back in the thread to see if you had listed the cam specs, but did not find that. What I did see is that you had cranking compression around 250 lbs. With that in mind, I think you would be okay with the E85, at least for starters.

You have so many unique pieces that it seems that it would be hard to dial it in. Ever think about maybe just using a carburetor until you can get the basic tune close?

I'm rooting for you!

 

I would have to have a custom manifold to mount the carb. I have an A460 head which has much different ports than the stock BBF intake.
My cam specs;
Duration at .050" Intake 230 Exhaust 236
Lobe lift Intake .3000 Exhaust .3000
Gross valve lift Intake .519 Exhaust .519
Separation 113
Degree intake lobe to 109

Just paid attention to the 109 figure. I have it at 113 which I believe I was given when I had the hard cranking issue due to high cylinder pressures.

 

I just tested my some E85 for actual ethanol content.
My local station which had junk E85 before is consistent with before. It is actually E43 - junk.
The station which had good stuff before now has dropped purity and is at E74 - not so great.
That E74 is the best I can get at the gas station. I may need to buck up and buy some canned VP fuel. E74 would be fine if it was always that percentage, but I doubt that would be the case. Another option would be to put a meter in the fuel line that reads the percentage. The pricing of the meter kind of defeats the purpose of running cheap fuel. If I run unleaded racing fuel I wouldn't have to worry about the E85 corrosion and fowling injectors. OH, what to do, what to do?

 

Beck, I was going to ask what was the cranking pressure, but Bruce answered that. I have 11 to 1 pistons in mine and cranking is 175. In the small block race engine, we had 265 cranking. It has 13 to 1 pistons in it, so you seemed to be about right with yours. But that has a lot to do with where the cam is degreed at.
Now your cam specs.... That doesn't sound like much of a cam for what you have. Mine is .595 lift with my .020 lash and I think it is 268/278 duration at .050. Mine is very street able on pump gas we have here, but I did put some supreme in and really could tell much difference.
As for race gas and your O2 sensor, it will work just fine but in time the lead may get it and you may have to replace it. We ran VP C16 as I remember.
Also I would be very interested in what you find at the dyno!

 

I agree with Flatrod,
I think most of your problems come from a mismatched Compression/Camshaft combination.
Too much static CR not enough Camshaft timing. My bet would be something along the lines of his cam with 108 degrees of lobe separation.

Let us know how the dyno session goes.

 

The dyno doesn't lie. It says my motor is NOT happy.

Everything seams goes well up to 5000 rpm and it just hits a wall. It won't go higher. Even at 5000 rpm it isn't making the power it should, 150 hp.

We had an issue of how fast it went from 2000 to 5000 rpm. I had such low gearing that it was nearly instantaneous. That makes accurate measurements difficult.

After leaving the dyno session I took my quick-change transmission gears out and discovered I had installed them upside down. I wanted a .625 overdrive, instead I had a 1.6 reduction.

We tried the motor on several fuel types, gas, E85, and methanol, with no changes.

Conversations with some knowledgeable guys led to the conclusion that the intake has got to be replaced. Some of the Comp 4 cylinder drag guys have spent a couple days on the dyno working with runner lengths to get them to perform.

I will also look into having another cam reground to 'bigger' specs.

No one has a spare factory big cam laying around, do they? I'm having a senior moment... Was that called a 285 motor? Or 185?

 

485 motor

 

Did you get a vacuum reading while on the dyno? That will tell you if its choked up from the intake or throttle body or headers.
Why do you need a 488 cam? I have never come across a 488, all I have is the 470's. To go in the .600 lift range they would need to rehardend the 470's, according to the guy that did my cam. I do have a Demos cam in the low .625ish range I plan to put into my next engine. I do have extra used 470 cams.

 

I don't think it is a choked-up issue. I think it is a turbulence issue at some motor rpm. My exhaust is big. 2 1/2" primaries and 4" collector. My intake has large straight runners about 4" long. The air does need to make a corner going into the runners. Those runners have bells built into them where they meet the plenum.

A competitor that I used to run with was using some factory cam in his motor. I have to think it was the 488. I'm just guessing that it is the biggest factory cam.

 

So no vacuum reading... Your's is the red tractor puller right? I still don't think its the intake so much, but looking at it again and when I was starting to make a manifold, I was looking at plenum volume. I don't remember how I came up with it, but I had a plenum volume of 75 sq in in my head. What I made turned out to be 95 sq in volume. I never did finish it. Looking at your intake, that is a lot of volume! Can you reduce it some without having to remake it? Baffle of some sort inside of it? I think your runners are ok, long enough to work. I have seen shorter that work, but no plenum on them. Exhaust primaries is bigger then needed, but that's not what's killing you on the dyno. 4" collector is fine.

 

Cam lift is .481/.503 for 470, .497/.517 for 488 and .497/.536 for 485 with 1.73 rockers. 470 was 269/274 (216/220 @.050") on 114*

 

Oh, the vacuum reading is there, I am just too stupid to figure out how to open the data logger to find it. The tuner guy did look at it but didn't comment on the reading. I ask him if it still had the big spikes that it did the last time. They were reduced but still visible.

Yes, this is the red tractor puller.

I started making my rounds of local buddies that have helped me in the past. I visited the fiberglass shop that did the hard work on my existing manifold looking for ideas to form the new runners. I also visited an all new vocational machine shop training center that opened today. Wow, talk about a LOT of top-quality equipment. They have it! It would take me years to progress through that program to use it all to be able to fully machine a new intake manifold. However, they do have some pretty sharp students that may be persuaded to do a project. I need to call another contact that thought he could 3D print the entire manifold. This new technology is way beyond my senior mind.

 

Thanks. Those won't help me. Mine is bigger than them (.519).

 

Looking at motors for sale. Does anyone know what the specs are for the 190 motor camshaft? I found one of those with a hole in the block. It is priced too high I think at @ $250. The #2 rod can be seen through the hole. The cap is loose from the rod with a super loose bolt. It comes complete, it has it's 4bbl intake and carb, but no exhaust. It is about 5 hr. from me.

I also found a pair of complete 488s. Supposedly ran when pulled and stored in a barn for years. Price is $500. These are about 4 hr. from me.

I really don't need any more. I was just surfing, thinking about a bigger cam and came across these.

 

Starting on a new intake for ITBs. This is the CAD generated image. It is going to be 3D printed. The tubes on the manifold ends are where I discharge cooling water for my setup. I should have a small end piece of it test printed to check fit in a week or two. I'm excited about this. I don't know squat about designing on CAD type software, so I had some MAJOR help yesterday. This guy was good! They used the latest in laser scanning to get a high-definition image of the side of the head/block with studs installed and built off of that. 8 hours later this is what we had. It's designed to use silicone o-ring material around the ports, but there wasn't enough room to insert them around the water passages. I decided to just use RTV in those areas and around the bottom. Not real crazy about that due to the difficulty of cleaning it off at a later removal. I imagine RTV will really stick to the printed surface.

 

Beck,
That looks a lot like the start of my new manifold. But mine was done in lost foam casting. Here is my flange that he sent to me for test fitting. It still doesn't have the lower part to seal under the head. But machined up and it fits.

 

You guys are too cool for me!

 

Not that I remember, possibly by the foot and you make up your own. There is an o ring company in Portland (Ore.) I went there and was told that I had to phone in my orders in so I went across the hall
and phoned in my order to the sales counter from the office. They didn't like that and refused the order so I went to the next building and phoned my order in from 50 feet away. It worked. Now I just buy my O rings from Motion and Flow here in Salem. But they have not seen any square cross section If you have to have a square ones. , would one from a spin on oil filter be the right thickness? Do not stack them, I have seen them leak if stacked.

 

I have made a modification to my head. I plugged the threaded holes next to the water outlets. I then redrilled and tapped them at 90 deg to the surface. I was concerned that all of the downward pull from the bolts across the intake would pull the head down, misaligning the ports. I discovered doing the laser scan that I didn't get those holes exactly square. This modification makes my CAD program useless to others without some changes either to the program or their head.