Massey 165 Gas..rebuild issues :O

[Farmwithjunk]

No, both valves will be slightly off the seat @ tdc. That is basic theory for virtually any four stroke motor. Even the mildest cams will have some degree of overlap.

He was right in mocking up the assembly to check for clearance. It is not the correct part.

Difference here is, you're talking "theory", and I'm talking specifics with the Continental 212 gasser that is specific to the Massey 165, the subject of this thread.

Yes, he was right for checking fit. It's HOW fit up was checked I'm questioning.

I wonder if there was a head gasket in the mix during loose fit? Don't recall reading about that. It would effect clearance also.

From what I gather, there was no valve train used in the fit up. Just ahead set on the block and a valve shoved open while piston is @ tdc. So, odds would be stacked against the fit having ANY signs of correct valve timing. (Valve position relative to piston's position) That's kinda important.

I wonder how "scientific" the measurement was for the "shove the valves open and see if it hits a piston" as that relates to the very low lift of the stock camshaft? ...........


As I mentioned in a previous post, the OEM "high altitude" pistons for that motor have a BUNCH of piston dome above the deck of the block. I haven't heard the first thing that would lead me to believe they're the wrong pistons. I guess we'll see shortly!

 

[tcartwri]

I wonder how "scientific" the "shove the valves open and see if it hits a piston" as that relates to the very low lift of the stock camshaft?

I missed that part until I re-read it. :confused2: It is not a valid way to test for clearance.

 

[Mike476]

MBMassey's question remains a valid one, and personally I think I would want more than an "I think it's alright" from my supplier before bolting everything back up. I did quit working as an auto mechanic 30 years ago to begin working on aircraft, but I can remember that if you were going to install higher performance pistons / cams and the like, you did so with the knowledge of the risks associated with it. From what I can gather he received this kit without any indication that while the pistons removed may be flat, or in this case possibly recessed, that the new domed pistons can be installed without having to consider replacing older components with newly engineered components to handle what, if any, additional loads may be placed on main bearings etc.

All that to say that inserting a document explaining the difference between OEM parts and components found in the kit, along with a guarantee of conformance, would have prevented MBMassey from having to ask the question in the first place. The absence of any indication of conformance is enough to raise the question in anyone's mind, IMHO.

 

[MBMassey]

MBMassey's question remains a valid one, and personally I think I would want more than an "I think it's alright" from my supplier before bolting everything back up. I did quit working as an auto mechanic 30 years ago to begin working on aircraft, but I can remember that if you were going to install higher performance pistons / cams and the like, you did so with the knowledge of the risks associated with it. From what I can gather he received this kit without any indication that while the pistons removed may be flat, or in this case possibly recessed, that the new domed pistons can be installed without having to consider replacing older components with newly engineered components to handle what, if any, additional loads may be placed on main bearings etc.

All that to say that inserting a document explaining the difference between OEM parts and components found in the kit, along with a guarantee of conformance, would have prevented MBMassey from having to ask the question in the first place. The absence of any indication of conformance is enough to raise the question in anyone's mind, IMHO.

Bang On.....If they would have put a notification page in the box that explains that these pistons add to the exsisting engine and do not require further changes then i would have been good to go...but you get nothing in the box but the typical notes on sealing the liner and ring placement. I'm going to go ahead and install everything, but first turn over will be by hand to make sure nothing is up.

As for the placing of the head on as a test, I wasn't about to wreck a piston,liner or any other parts of a new set to do the "test", I was more curious to see how bad things were out, and the addition of the headgasket is only a few mm of difference especially after it's torqued down it will be of no real difference in clearances. I have a strong belief in only doing something once and doing it right, that of course doesn't always happen, but mocking up to the degree of a proper test in this case is way more work then I should have to put in on a kit that cost me what this one did.

My only fear later down the line is the extra stress this will put on other components..this kit must create a lot more compression I would imagine, filling the chamber this much, so how long before it affets rods and bearings and crank? I guess the new mains and everything will go in and I'll keep up on the oil changes...but I almost have a thought that I should rebuild and send it on down the line....I could always use a bigger tractor anyway

 

[Mike476]

MBMassey, as you say just slave the motor over by hand once you've got it bolted up, in all liklihood you'll be fine and probably delighted with what is essentially a new motor. Would be a shame to give up what you know is a solid tractor for what might be someone elses problems. You had the good sense to call the supplier, people on this forum have stated they've replaced stock pistons with pistons similar to what you have and haven't suffered any ill affects, I have to believe it will work fine.

The only real shame here is that you'll have this in the back of your mind during what should be a very enjoyable experience, nothing like tearing something apart and restoring it to new or better condition. :thumbsup:

 

[tcartwri]

MBM, check the clearances properly with the valvetrain installed, valve clearances set to cold specs and timed. You just have to clay the cyl with the new piston and verify your clearances. Minimum 0.100" on the exhaust, 0.080" on the intake. Better to make sure than guess. You don't have to torque the head on but you should account for the crush of the head gasket. It wont take very long to do.

 

[Mike476]

Using modeling clay across rhe top of one of the pistons is not a bad idea and is an old method that will give you an idea of clearances, but not entirely accurate - valves will float during higher rpms which aren't replicated when turning the motor by hand.

MBMassey, you can google the process, model the clay strips to a thickness that will ensure clearance for both valves should you decide to use this method, not a lot of work and may save damaging your motor.

 

[MBMassey]

Using modeling clay across rhe top of one of the pistons is not a bad idea and is an old method that will give you an idea of clearances, but not entirely accurate - valves will float during higher rpms which aren't replicated when turning the motor by hand.

MBMassey, you can google the process, model the clay strips to a thickness that will ensure clearance for both valves should you decide to use this method, not a lot of work and may save damaging your motor.

I'm more worried about damaging the head gasket between doing the clay and then re-installing the head...I really hate even tightening on a head gasket and then doing it again...can lead to leaks if the gasket gets crushed one way the first time and another way the second.

I'll go on the word of my supplier for now....if anything breaks it will most likely be their parts, so it would be just crammed back in the box and sent back with a great big middle finger drawn on the box.

I am a little concerned now though...tonight I was cleaning the deck of the block and now have some small cracks showing up between cyls...it shouldn't matter IMO in the grand scheme as those coolant areas are connected anyway, but if the head gasket wasn't just right it could lead to leaks into the combustion chamber...funny thing is the tractor never got hot when it broke...so they have been there a while and never used or burnt any coolant before....again..another reason to ponder sending it down the road...even with a new HO motor :thumbsup:

 

[Farmwithjunk]

Using modeling clay across rhe top of one of the pistons is not a bad idea and is an old method that will give you an idea of clearances, but not entirely accurate - valves will float during higher rpms which aren't replicated when turning the motor by hand.

MBMassey, you can google the process, model the clay strips to a thickness that will ensure clearance for both valves should you decide to use this method, not a lot of work and may save damaging your motor.

You aren't apt to get much (if any at all) valve float on an engine that peaks out around 2000 rpm.

 

[Farmwithjunk]

I'm more worried about damaging the head gasket between doing the clay and then re-installing the head...I really hate even tightening on a head gasket and then doing it again...can lead to leaks if the gasket gets crushed one way the first time and another way the second.

I'll go on the word of my supplier for now....if anything breaks it will most likely be their parts, so it would be just crammed back in the box and sent back with a great big middle finger drawn on the box.

I am a little concerned now though...tonight I was cleaning the deck of the block and now have some small cracks showing up between cyls...it shouldn't matter IMO in the grand scheme as those coolant areas are connected anyway, but if the head gasket wasn't just right it could lead to leaks into the combustion chamber...funny thing is the tractor never got hot when it broke...so they have been there a while and never used or burnt any coolant before....again..another reason to ponder sending it down the road...even with a new HO motor :thumbsup:

If you still have the ORIGINAL head gasket, you can use it while doing the fit-up. Save the new one for final assembly. And you would be astounded at how much difference it makes having that thin little head gasket in place. Also consider valve clearances.