The elusive 224/3.7 MerCruiser banger

Our 3.6L 4 cylinder with a single LS head concept engine has been a major hit at the Performance Racing Industry show. This small package will put out an astonishing 340 HP / 500 ft lbs torque with a turbo! We brought it in search of a market, and the ideas from attendees has been endless! Pontoon boats, midgets, S10's, early Jeeps, and more!
*12-12-22 UPDATE: Thanks everyone for the overwhelming response to our concept engine! This was brought to the PRI show in hopes of finding a market. And boy did you guys deliver some excellent markets! We don't currently have a price range or production ETA as this is still in the concept phase. If you would like added to the contact list for updates, please send your name, phone and email address to social@blueprintengines.com!
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I used the C168 chain as suggested earlier in the thread but the links are too narrow and it doesn't fit the sprocket properly. The cam sprocket is questionable but the crank is just obviously a no-go.

Any ideas? I know people have had luck with the Cloyes one and I know it's only like $30 but I really don't wanna drop the coin unless I KNOW it will work.

 

This Engine is right along the lines of a Gaerte Roxex which was based on a half SBC built with NASCAR components. That engine was aimed at the midget market. I think (but not totally sure) that the price tag for one of those was about $35,000 and that is back a few years. Nice concept updating to the LS architecture to get more HP but I think unless the price tag is a lot less than the Gaerte was it will encourage us normal guys to keep working on our 470's.... just sayin

 

It is my understanding that this 3.6 engine is a industrial engine made by Origin Engines.
3.6 Liter Industrial Engine (originengines.com)
From what I can tell is it comes with a 302 ford style head. Being LS and Windsor Ford are so close to interchange with just moving one row of head bolts out or in I don't remember. It looks to me Blue Print just stuck a LS head on and took it to a PRI show.

 

With no other easy option, you can:
1. cut the teeth off of your Mercruiser sprockets
2. find commonly available sprockets about the diameter of Mecruiser sprockets.
3. bore the commonly available sprockets to the fit o.d. of your turned down sprockets.
4. weld together and you are done.

I do something like this with motorcycle rear sprockets. On them I keep the lower part of the inner sprockets teeth and use them to connect with bolts instead of welding as they may be of dissimilar metals. Of course I file the outer sprocket for its half of each bolt hole you only need 4 and as the outer sprocket is aluminum it is easy.

The chain Mercruiser tensioner is not wonderful and it will limit what chain you use.

 

The genuine Cloyes C168 fits better but still appears to have the same problem. The chain links appear to be too short to properly fit the crank sprocket. What's really confusing is that it fits the cam sprocket fine despite there being more teeth in contact. This kind of calls into question the crank sprocket but that doesn't make sense since if the sprocket were worn it would be more accommodating of chain variation.

I'll guess I'll buy a used timing set.

 

Well, after using levels of force I'm not proud of the genuine Cloyes C168 chain did fit and does have just enough slack I can deflect it with my thumb if I try real hard so it's probably fine.

 

How do you guys think I did on the timing marks? They don't look perfect to me but I think they look less imperfect than a full tooth of adjustment would make them.

 

I agree, you can't get a better alignment by moving it one tooth. Are you planning to degree in the cam?
There are offset keys and other methods to dial it in.

 

Pictures are not straight on, but they look like you have them right. You can't get it any better than what you have without some way to adjust it.

 

Looks right to me. If it is off at all, it is off only a very small amount. Any closer than that and an offset key will be needed. You can make one.

The man who grinds my cams told me that after running the engine he could change the cam timing as needed. I think 4 degrees was mentioned. The grind he made for me worked so well straight-up that I left it as it was.

 

Thanks guys.

I'm going to skip degreeing it because it presumably ran fine with these components previously and I'm not going to advance it for fear of detonation on 87 and I'm not going to incur the power loss from retarding it unless it has problems and in light of that why bother.

 

read post #25 it puts much light on this topic.

I'd not degree it until putting some time on your engine and then deciding what you want or need.

I found that, depending on the cam profile, it may overheat and detonate on 87 or it may be ok.
The engine was not designed to run on low octane fuel. The fuels have changed since then and not for the better. E85 or race gas might be needed.

Advanced Ignition timing with lowered compression worked well for me. I had experienced overheating issues until I was able to advance the ignition timing. I tried a camshaft that was sold as a Mercruiser cam. With it, The most its ignition could be advanced at idle was 28 degrees. Its exhaust ran over 1700 degrees just idling along and it detonated. That new camshaft became a blank for regrinding.

Power at the top end of its rpm range does not matter on the street but it matters in racing and boating.
Giving up a few top end HP to gain in the midrange , to burn less fuel and to run cooler was a choice I am very happy with.

Just running a stock engine at first is a good way to proceed because changes can be made one by one and you can find out what works

 

I would check the cam timing even if I didn't intend to change it. That way you have a known baseline.

One of the things that seems to be lacking in this thread is cam timing specs. It doesn't take much effort to establish intake and closing points @ .050" and total duration (normally measured @ around .006" lifter rise). With total lifter rise, a lot of information can be derived and maybe we can get a handle on what works in various applications.

I'll post that info up for a stock cam as soon as I get a sheared key out of my mock-up engine crank shaft.

 

Lifts are on 1st page. When I had mine reground Reed said it was a 114* centerline so we kept it at that.

 

As far as timing sets, either chain sets or "dog-bone" sets, might a solution be to determine the center-to-center distance of the cam & crankshaft, find another motor with the same dimension, & bore & machine the cam & crank gears to the proper size for our needs? If something is not available, go "outside the box" like the early hotrodders did!! Just a thought/suggestion...

 

From the cam card of the grind that I like:
intake valve lift-------- 0.496"
exhaust valve lift------ 0.492"
overlap-----------------27 degrees
lobes------------------115 degrees apart
duration exhaust---210 degrees
duration intake-----203 degrees
cam advance---------- 4 degrees ground into cam
rocker ratio-------------1 to 1.73
cam purpose----------- supercharger use and non blown street cruising
comments:
- it is not a top end cam
- it is in an 1800 lb car
- cranking pressure is 170 psi
- the engine does not knock with stock pistons
-with 21cc pistons, and vacuum advance the ignition max advance can be 42 degrees the coolant runs cool under 200 degrees
- with 0 cc pistons I set the stock distributor advance to 32 deg before tdc and the coolant runs warm , 210 to 230 degrees.

 

IIRC we've already established that we have a center to center distance that's a few thou less than a 460. It was covered in the early middle of this thread.

But it still didn't knock under load, correct? Or did it never see much load because it was such a light car?

 

[QUOTE="arse_sidewards, post: 14714265,
But it still didn't knock under load, correct? Or did it never see much load because it was such a light car?[/QUOTE]

I used more than one cam profile. With the cam I described in post 3138 it never knocked loaded or unloaded. It would not knock under any condition. I liked it so much that I had several camshafts ground that way. It was a special profile made for me.

With the Ingram cam sold as a replacement Mercruiser cam It knocked at idle unless the ignition timing was pulled back to 28 degrees, it ran really hot (1740 F in the exhaust) and was undriveable for more than a couple miles.

This engine is zero decked and therefore resists knocking even if the compression is slightly higher.

Ingram will do special grinds . Mine was done by Redline cams in Albany Oregon. It did not cost much at all ( $65 a few years ago).

 

If your bore is stock or 30 or 40 over you can easily find low compression pistons*. Wait a month and 20 over pistons can be made for you. I'd consider 20 over as the 3.7 has so little room for overboring if anything goes wrong. For an iron block 30 over is fine and it works for the 3.7 but the cylinder walls are thin and if something goes wrong 40 is the last step. I'm pulling out my 40 over engine .
* speedpro a set of 8 for about $200 at Summit. I bought 4 individual pistons $25 each but as it was not a set, a lot of balancing was needed.

 

It would get very heavily loaded at times as load increases with speed. Aerodynamic drag increases at the square of airspeed .

 

I already have my short block more or less assembled. If detonation is an issue I'll try reducing compression by going from a .040 to a .060 head gasket and then when that doesn't work I'll throw a cam at it.

There's really no point obsessing over the hypothetical when there's so much other stuff the vehicle this is going into needs that isn't yet done.

 

what is your deck clearance?

 

.020" give or take a couple

Head is 95CC and piston is the OEM flat top with valve reliefs (IDK what their volume is) since I know that's the next question.

 

My first engine's deck was over 70 th I remember that as I asked the shop to take it down to zero and they did it again for free to get it there. my 2nd 3.7 came zero decked and the next I don't remember.
My head volume on the first engine is 103cc , the second head had to be planned to take out warp so it's less . the valve reliefs don't amount to much 3 or 4 cc compared to 19 or 21cc for the big trough in the low compression pistons. the height of the piston crown above the wristpins can vary with the brand of piston so that has its effect on deck ht.. I think that is "compression height" but I'm unsure. It is something that needs to be checked when ordering pistons.

 

Just came up from "Competition Products" catalog : Ford 429-460 "dog-bone" style gear drive SAG78430 listed as "noisy", so if the cam/crank separation is slightly smaller, this set MIGHT be useable?? Listed @ $205.79 "Speedway Motors" also has them listed as part # 453460C @ $176.79 Has anyone had any experience with these??

 

Brown truck Santa dropped off a mock up head for me this morning...

 

COOL!!!!!!

 

Who's head? I see it's not a Kaase head. Get the rockers?

 

Damaged OEM Ford head. I bought it solely for mock up. I am still looking for a damaged valve cover.

TM Enterprises (2009-2011 Engine Masters, I believe) is about an hour from me, and I have already talked to him about making a head for me. I believe we will be going the raised port route, but with smaller ports. Todd worked with T&D to get rockers to match up with his stuff. If that design has an extended exhaust rocker to move the pushrod to the intake side more, I will go with them. As of March, a head was $1900 and rockers were $1200.

Years ago Skip Kent in Florida built a swamp buggy motor with a TM head. That engine was sold to Chris Diggles in Australia to use in an altered. He later received a track record with a 10.025 @ 134.71mph pass. On the chassis dyno, he put down 346.6hp (to the wheels) with a carb on gas. I will be doing stack injection on methanol. My goal is the 9.50-9.90 range. 400 wheel horse might do that. We shall see...

My car was built in 1997, and raced in the 1998 season with a blown nitro Chrysler hemi and a clutch. It was a local car to me at that time. I bought it in March with the purpose of converting it to a bracket car and using a Boss Four. I will be using a Ford C4 three speed automatic. It has a shorty kit from Flat-O Products, and I just received his SBC to C4 bellhousing yesterday. Brown truck Santa did a job good.