The elusive 224/3.7 MerCruiser banger

That tractor is fricken awesome, a real hotrod tractor! The motor is pretty much what I hope to build , except I will use a pair of 50 or 55 DCO Webers, or vintage Hilborn mechanical injection. I have both to experiment with.

Do you have a build thread somewhere?

 

There is a 170 on Detroit Metro Craigslist. Looks to be complete. I have no connection to it.

 

I don't have a dedicated build thread. Most of the info is scattered here in the last many years. If going through my posts beware, I have a couple engines that have been posted about. The major one is filling the deck. That has NOT been done on this motor.

I believe the Webers would be amuch easier build, although I hear they are difficult to tune.

 

I have been building , reconditioning and tuning carburettors since 1974 , and owned the business since 1977, I have pretty much "retired" now. In the business I was a Weber agent. At the same time I built tuned and flowed etc Hilborns for local speedway and drag racers, so neither of them bother me in that respect. I still have a Dyno , lots of hard to find carbs and parts, and all my equipment, and NOW I have more time to do stuff for myself .

 

Beck, some of my small blocks had that kind of cranking compression and worked fine. My key was to crank it then turn on the ignition. I see you are EFI with probably fixed timing. How does it crank without the ignition on?
I didn't get a cam card with my cam, but did get 13 pages of info that was over my head. But with talking to him, the most lift available without reheat treating was .575. I had my cam changed to a solid cam, so my lift is .564 with lash. He set my duration at int 206 and exh 219 at .050. I thought it was a wimp. but he says try it first. Mine is to be driven on the street. I have a 11 to 1 pistons but as you can see on this page my dynamic compression is anywhere from 7.922 to 7.103. Its all because you can't make compression till you close the intake valve. By varying my lash and where I put the cam well I can sorta tune the compression.

 

As for my fake MSD dist, what would you like to know about it? I am currently gathering parts to build another one with real MSD parts.
That's a great looking engine you have, but with your intake I don't think my dist will fit. I had to kick my injector up to get things to fit.

 

I have 2 more motors. 1 I have posted photos of closing the open deck. My plan is to put that motor together much more mildly. I plan to use the Mercruiser intake. The dist would go on that one. You are correct, it would not clear the intake on the red motor.

Your motor is looking really good. Those Boss heads are amazing. Your injection is too!

 

ran across this about sparkplugs today, it is worth reading
http://www.strappe.com/plugs.html

 

The cam arrived at the grinder. It is NOT like the one in the photo. The one he shipped has a hex nose and the stud is stuck in it. I need a round nose. Does any one have a spare cam with the round nose?

I'm mounting a cam position sensor trigger on the nose. Being round it allows me to move it to adjust the trigger to get it in the ballpark before final computer dial in. Click to enlarge.

 

Has that cam (in picture) been modified already? I changed my cam to be just like a 460 cam with a pin and bolt on gear. Then I looked everywhere for a 3/8 hex drive bolt to bolt it down. All the cam spuds they sell now are sbc 3 bolts adapted to the Ford. Don't work for me. I don't have any extra cams, so I can't help. Just wonder what you have, cause it looks like what I need.

 

Flatrod17, The end of the pictured cam is stock.
The cam shop sent a photo of my cam and it's problem.
It is the correct round cam. The hex they were referring to was the hex inside the stud.
IF they can get the stud out. It is useable.
I suggested welding a nut onto it to get a better grip. At this point the stud is sacrificial.

 

My cam did not look like your picture. I will look back at my pictures to see what I had. But from what I can tell that stud is screwed in and is left handed. Are they turning it in the right direction to remove? Just a thought.

 

This is what I had on my cam that I cut off. (first pic) From what I can tell there are 3 different ends on these cams. I did not know that. Anyway I think you should be able to get that stud out turning it the right way. Maybe a little heat on it if it is lock tight in.

 

Success. They got the stud out. No damage to the cam.
Mine is like your last photo. It looks a bit different in my photos. Because so much of the snout is in the seal, it looks short in my photos.

 

Good to hear! Now gettr ground and close that intake a little later to get some cranking compression out of it!

 

I need to get cranking cylinder pressure with the throttle open for the cam grinder. My previous pressure was with the throttle closed. I didn't know that it mattered??
It seems I am having hydraulic lifter issues now. When I take the slack out of the pushrod and give my adjustable rocker nuts 1/2 turn the valves are opening. It appears the lifters are collapsed. I have primed the oil pump, have 65 psi oil pressure, and have oil to all but 1 rocker arm. I guess I need another new set of lifters. These have never been ran, but have considerable starter cranking on them. I'm guessing I had them to tight and hammered them to death?

Anyone have any thoughts?

 

Beck,
It will make a little difference throttle open or closed, but not enough to fix your problem. My cam grinder did not ask for that, but everything else!
Your lifters are probably ok. You have pumped them up so, yes they will open the valve when adjusting. You can let it sit at full lift and the spring will bleed it down in a hour or so. Have to do each one! I always adjust with out pumping the lifters up. Also I do not twist the push rod to find no slack, I lift them up and down to feel when the slack is gone. 1/2 turn is a little deep, I would try a 1/4 turn from zero lash. You want about .050 in the lifter. I wouldn't worry about that one that didn't get oil, it will when you fire it up. Running the pump with a drill isn't even close to idle speed. Fire it up, then check to see that it is oiling.
Hopefully you had some cam lube on those lifters with all that cranking, they should be ok, but I guess you will have them out so you will be able to inspect them before you put them back in.

 

I have taken another set of cranking compression readings. This is a different gauge/hose setup. I got 270# with the throttle body closed and 265# with the throttle body open. I have sent that information off to the cam grinder.

I got a discouraging comment from them yesterday. “You got 280# of cranking pressure “With That Cam?”. In other words it is bigger than we had previously thought.

When I talk to the cam guy I am going to ask if the reground cams are compatible with solid lifter cams. I’m tired of trying to adjust these hydraulic ones. They should be so simple. Not this week. I will try as Flatrod17 suggested and roll the motor to put each valve fully open, wait 2 hr, then roll the motor back so that valve is fully closed and try to adjust the rocker arm again.

 

Tom,
I had my cam converted to a solid cam spec. The only thing I will caution about it is swell from the block and head. A cold lash and a hot lash will be very different. I expect to be as much as .010. to .012 between the two. If you go this way set about .007 tighter cold, then warm it up to temp, then check hot lash, make a note. Let it cool over night, then check to see what the difference is. That difference will tell you what to set cold, to have the right lash hot. You can never get accurate doing it hot, because by the time to get to the last cylinder to set, the block and head have cooled down.
Now on you cam, your card says your intake closes at 44 degrees, my cam closes at 76 degrees. If you get that to close later, you can't make that kind of cranking compression.

 

I was in contact with the cam grinder again this morning. He can cut a cam to drop my cranking cylinder pressure BUT it would be a really radical, high rpm, cam. That is not what I want at all.

I had worked to get my compression ratio up to utilize E85 fuel (13.6:1). Now it appears I am going to have to try to knock that back down. The easiest way to do that is to install a thicker head gasket. If you recall this motor already has its 2nd head gasket in it, but has never ran. I had sealing issues before, so changed it.

My decision now is to use a Cometic MLS or MLX gasket or an SCE Titan solid copper gasket. I also need to decide how thick I want it. .060 - .062 gives me 12.8:1 compression .080 gives me 12.0:1 compression.

 

Would you be better off adding some volume in the "bowl" around the valves instead of just adding thicker gaskets? If you loose the recommended "quench" height of about .045 aren't you going to increase your detonation issues?

 

Beck,
I can give you my cam grinders name and number if you want to talk to another about cams and profiles.
And I would not let it get over .060 for quench, after that it does start to affect timing and other problems.

 

The other option is to cut some off the tops of the pistons, or just buy new pistons with less pop-up. This set was $600. I don't want to do that to many times.

I have a mill and lathe, but not the knowledge of how to chuck them or fixture them without damage.

 

Beck,
here's a few ideas for holding pistons. The lathe jaws are for cutting tops off. These were bought but could be made. The piston vise I made, its mostly for cutting valve reliefs. Disregard that pin sticking out on the lathe picture. I just chucked the piston for a picture. That pin will fly out if spinning.

 

And you need some way to measure how thick the piston top is, so this is my way. Its just a pushrod in a vise with a indicator zeroed on it. Slide the indicator up and slip the piston in-between to see how thick it is. Slide the piston around to find the thinnest spot. I wouldn't cut the piston any thinner then .125.

 

I believe the tops of my pistons are solid, so there would be no issues with the thickness.
If I would cut them I would need to figure out how much to cut off. The tops are irregular shaped so calculation would be hard. Here are the piston tops. The small dimples were required for spark plug clearance. I considered using rubber / wood / nylon blocks between the jaws and piston for a pad. I like the idea of the pin sticking out to avoid rotational slippage. I could take baby cuts allow minimal clamping pressure.
Click to enlarge

 

Flatrod17 - That piston vice is a real nice piece of work!

 

I just put that piston in for a picture, should of took the pin out. I would NOT let the pin in there to FLY out and hit you in the head!!
You won't be able to hang on to the piston without some kinda fixture like shown. Maybe if you used a 4 jaw chuck. Pistons are egg shaped, so maybe a 4 jaw could work with light cuts.

I would be surprised if that dome is solid, if it is that is one top heavy piston! Does your paper work with the pistons say how many cc's the dome is? Do you have a way to measure cc? Find a online compression program and play with cc input to find what you need, then when you know you need, say 10cc less, that will probably be about .100 off the top, but yes needs to check with some way to cc it.
I don't care for your pockets for the spark plugs. I think you will find it would be better to put in a fire slot as we called them, to get the spark to spread up over the dome. If the piston is solid adding a slot will knock off about 3 to 4 cc from what I have in my mind.

 

Flatrod, you have beautiful piston holding fixtures.

I'm posting to say that I fired up my engine with a Sierra gasket with locktite #518 on the edge where the good head gaskets have sealant beads. I did widen the narrow edge out about 3/8 inch near the lifters with aluminum and JB weld. Squish is about 40 thousandths. The headgasket as a half hour on it and has not leaked anywhere. One collapsed lifter is why I limited it to 2000 rpm during this its second assembly.

Beck: Don't use double or even thick headgaskets as thicker gaskets give the cylinder pressure more area to apply force to blow out the gasket.
Buy less expensive pistons to get your engine running so you can develop it as your pistons are much too expensive to cut down and you may be able to use them later. Solid lifters are sometimes used on a hydraulic lifter camshaft and are said to give 500 rpm over the hydraulic ones on the identical cam. With shorter connecting rods, you would have lower compression and could use your high domed pistons without cutting on them.

now back to Beck and Flatrod:

 

I have the same problem except that I ran my engine and one lifter would not pump up, one was very quiet and six were slightly noisy.