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Author Topic: H75, H74, and H73 engine cylinder upgrade  (Read 642 times)

rodnoc

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H75, H74, and H73 engine cylinder upgrade
« on: December 03, 2022, 03:04:05 am »
If your engine is leaking water into the crankcase, Microcosm is making upgrade cylinders with two additional o-rings.

The pair for my H74 arrived assembled.

I couldnít find them at Jinís site, so here is the eBay link https://tinyurl.com/4dn3dzmj





MadeForThat

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #1 on: December 03, 2022, 12:49:06 pm »
I'd be interested if you could disassemble your original cylinder liners when you have completed installation of these, I would like to  know if I can just add an additional oring groove to it or if there is more changed in the upgrade. Also might be interested in purchasing your old cylinder liners and jackets so I can experiment with modifying them, it would offset your cost of upgrade!

70Rcode

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #2 on: December 06, 2022, 01:03:23 am »
Considering the H70 series engines serious design  (reverse cam timing, non-lubricated crank, rod & piston, etc,) issues & Not exactly built like a Swiss watch loose,.....Why would one expect the original Oem Cylinder groove & O-ring Dimensions + O-ring Shore A durometer to be anywhere Near functional sealing optimal ?? ....Fine tuning the original 2 groove cylinder O-ring ID/OD/Cross Section & Durometer selection will most likely correct the leaking issue.....2 x Bad = More Bad !!

rodnoc

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #3 on: December 06, 2022, 03:27:19 pm »
These engines are Ďmodelsí for hands-on gearheads.  They are big-boy toys.  Do you guys who are critical have any machinist experience at all?  Hire one to build an H75 from scratch and see $6K disappear from your bank account. If you have the knowledge and build one yourself, the cost of the machines and the required tooling will be close to the price of a car.  If CNC equipment, think second mortgage.  Jinís products, courtesy of the price of Chinese labor and restricted value of the Yuan, are an incredible bargain.  If you buy his engines and they donít make you happy, or you donít have the ability to tinker with them, it is probably a good idea not to buy them.  Only in imagination can you expect to get a Swiss watch for the price of a Timex.

rodnoc

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #4 on: December 06, 2022, 03:28:42 pm »
.... might be interested in purchasing your old cylinder liners and jackets....

EngineDIY has cylinders for $7.99


https://www.enginediy.com/collections/hit-miss-engine?page=3&grid_list=grid-view

MadeForThat

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #5 on: December 06, 2022, 10:36:16 pm »
I'm with you Rod, I think perhaps there are a lot of people who think they are owed replacement engines due to minor manufacturing deviations. Jin has always been willing to do anything to make the engines work. As someone who worked in fast food, people always demand an entire replacement meal for getting a small fry instead of a regular. A behavior reinforced by "customer is always right,"  free returns, and companies just shipping replacement product rather than require returns. Despite these engines being manufactured they are still hand made, and that means you are buying functional, not flawless. Fortunately Jin is willing to replace your small fry in order to correct your meal. I bet Tom Jensen didn't give away free engines due to minor leaks and cosmetics, but I'd bet he certainly sent free replacement parts.

Fullraceflathead

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #6 on: February 10, 2023, 01:15:53 pm »
JohnnyQ90 has a Video on YouTube where his new H75 leaked water. He removed the Cylinders and replaced the original (Undersized?)  O rings with 19 X 1.9 mm O rings and this fixed the water leakage problem.
 https://m.youtube.com/watch?v=-tuZeMifCoc

RedRyder

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #7 on: March 02, 2023, 06:41:08 pm »
Considering the H70 series engines serious design  (reverse cam timing, non-lubricated crank, rod & piston, etc,) issues & Not exactly built like a Swiss watch loose,.....Why would one expect the original Oem Cylinder groove & O-ring Dimensions + O-ring Shore A durometer to be anywhere Near functional sealing optimal ?? ....Fine tuning the original 2 groove cylinder O-ring ID/OD/Cross Section & Durometer selection will most likely correct the leaking issue.....2 x Bad = More Bad !!
..
The new ones don't leak at all. Out of 5 H-75s and an H74.... Only one had a leaky cylinder. I sent it's new owner a set of for new cylinders.

As for the oiling, I open the crank case on the cam side and with a needle oiler hit all the friction bearing surfaces. Given that at shows I usually start and run it for 30-40 seconds at a time, multiple times all day, without the need to add more oil. I use a high quality synthetic clock oil along with an oil rich fuel mixture. When oiling I tilt the engine so I can lubricate each cam lobe and bearing along with a drop or two on the piston skirts. You can also place a few drops of oil on the lifters from the outside and it will wick inside to the cam lobes. My own thoughts on rotating the wrong direction..... I am glad it goes the wrong way. It is much easier to hand start clockwise and these are clearly not designed for severe duty service. If you want that, you can spend 7,000 or so to get one built or if you have the skills and equipment and hundreds of hours to spare... well...you know. I rather suspect that 5-10 years from now my H74 and H75 will both still run well. There is no slop in the bearings like we found in some of the hit and miss engines. While it may appear to have all these faults, it is still a lot of motor for the money and nowhere else is anyone duplicating anything close to them (for the money).

MadeForThat

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #8 on: March 03, 2023, 09:18:06 am »
Expecting Ferrari while spending Ford money

engine-man

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #9 on: March 03, 2023, 04:51:24 pm »
Expecting Ferrari while spending Ford money

Not a valid point at all, when someone like you makes a comment like that, it justifies companies like Microcosm charges people for a defective product then expecting them to pay to get a corrected part. No one is expecting Ferrari ( despite them having issues too) but if I pay for Ford I want Ford quality not some cheap Chinese knock off.

rodnoc

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #10 on: March 03, 2023, 08:22:41 pm »
Not a valid point at all, when someone like you makes a comment like that, it justifies companies like Microcosm charges people for a defective product then expecting them to pay to get a corrected part. No one is expecting Ferrari ( despite them having issues too) but if I pay for Ford I want Ford quality not some cheap Chinese knock off.

I have a simple solution for your ongoing engine dilemmas.  Don't buy them.

engine-man

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #11 on: March 03, 2023, 11:33:53 pm »


I have a simple solution for your ongoing engine dilemmas.  Don't buy them.
[/quote]

That's not the point. If a manufacturer knows the product they designed and sold has defects, they shouldn't charge for replacement part to rectify their shortcoming.
I will buy them and if they have issues I insits on refund. There is potential in what they sell and if customers keep their expectations high they will improve.

MadeForThat

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #12 on: March 04, 2023, 12:50:17 am »
See that is where I disagree. I buy a low cost engine expecting to need to fix the details that bother me, but also expect it to run (not expecting a swiss watch, but functional) When a manufacturer has to deal with people demanding returns on a running model, they are forced to charge more per unit. So for those of us that want to take the time to make it perfect, it hurts to see the prices being driven up. For the people expecting a well tuned machine, they are let down because they are certainly not that right out of the box. For example, the chatter I found on the crankshaft of my H75 was totally functional, and the engine would run for a long time. It wasn't good enough for me, so I fixed it. For people that would never care that it was there, the engine is perfect. Why should all of the people buying these engines have to pay the extra cost of the manufacturer polishing these parts, when most people will realistically never run them long enough for it to matter? The manufacturer's obligation is to deliver a running engine, and there is no possible way for them to guarantee how long or how well it will run, because the operator must oil and manage it. I'm picky about my engines, but don't have the money for a meticulously made engine, and that is why I love the low cost engines. I can make them perfect in my own eyes, with my own effort. If you are picky about your engines, either get saving, or get polishing haha. 

SteamerJ

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Re: H75, H74, and H73 engine cylinder upgrade
« Reply #13 on: March 04, 2023, 02:01:40 am »
Not a valid point at all, when someone like you makes a comment like that, it justifies companies like Microcosm charges people for a defective product then expecting them to pay to get a corrected part. No one is expecting Ferrari ( despite them having issues too) but if I pay for Ford I want Ford quality not some cheap Chinese knock off.

I have a simple solution for your ongoing engine dilemmas.  Don't buy them.

I have to totally agree. I have rolled my eyes over several posts and thought customer from hell.
Best Regards
John