HOWIN Inline Six Engine L6-210 Full Reviews by Customer | Stirlingkit

HOWIN Inline Six Engine L6-210 Full Reviews by Customer | Stirlingkit

HOWIN Inline Six Engine L6-210 Full Reviews by Customer | Stirlingkit
I would like to give a huge shout-out to the Sterlingkit team for their amazing customer support. My Howin l6-210 21cc engine arrived today, but it was missing the CDI unit and spark plugs. However, the team quickly confirmed that they have shipped out the missing parts, and they are on their way to me. I must say, the engine looks even more beautiful in person than it did in the pictures. The pictures do not do justice to the size of this engine, and there is a lot of work to be done before the assembly. I need to go over every machined surface, deburr any areas that I may have missed, and polish all the little high-wear pieces. For instance, the valve spring covers have a nub in the center that can cause significant wear in a short period. However, after polishing, I found virtually no wear at all. I plan to make a video of the building process. However, I'm unsure whether to do a time-lapse or standard video where I can explain each step. I'm happy to build and can't wait to see what others will create. Cheers!
Howin engine l6-210 21cc pre build notes

 It's a very nice engine. I'm very pleased with the overall quality of the workmanship of this engine. There are just a few things that we should know when we're building this engine. Always try to build from the center out. It is a long block, so I mean it's very easy for things to bind up while you're building.
Tips for Building an L6 HOWIN Engine
- Build from the center out to avoid binding
- Check for burrs and clean them up before forcing parts together
- Remove the nub in the center of valve spring covers to prevent wear on rocker arms
- Check and clean all machined surfaces and edges
- Install pistons in the order of 3, 4, 2, 5, 1, 6 to avoid binding
- Tighten and rotate each piston in order
- Drill oil return holes if necessary
- Check for any mistakes or oversights in the manufacturing process
- Appreciate the complexity and precision involved in making the engine

I'm pretty much going to build this exactly as you would build a Ford 300 engine. It's basically the same engine, so why wouldn't you want to build it like that? Very cool.
There are a couple of things that I've done on this. I'm also going to be doing that too just before I get into what I've done here. I'm also going to be doing that on the bottom side, working through the center and working your way out, and tightening everything from the inside out. Do that with everything. If you do it that way you will have less chance of warping parts and you know it's just the proper way of doing it.
If you have something that doesn't fit on nicely before taking that tool and banging or heating or something, take a close look. If you get a magnifying glass out if you need to, but maybe it's just a little burr as in the case with this tiny little gear here.
There's just a tiny little burr right on the ID there, and it's a little bit hard to see, but by taking an 82-degree bevel tool in there, I was able to just easily, 10-second boom, cleaned it right out.
I've also done and polished all of my valve spring covers, and this is what your rocker's arms actually push down on to open up the valve springs. Now, in the machining process, there's actually a little nub in the center of these from when the machine or mill it down. What you want to do is you want to get rid of that nub. That little nub will actually go onto you when this guy is pushing down.
It'll actually cut right into there and on the toy and well. When I didn't take that down in the first place, I noticed after like a couple of hours of running, I already had a nice little notch cut into my rocker's arm.
Also, just to make sure, there's a note that when you're going through this engine, you check and deeper everything. Go over every single machined surface edge, and feel it with your fingers.
What I've done on this is I've gone through and I've already cleaned up all the spark plug threads. I've gone and cleaned up everything, deburred every single hole, and as you can see there's a nice little bevel on everything.
When you're installing the pistons, you want to start from number three, then do number four, go to number two, then number five, number one, and number six.
If you follow that order, you will have less chance of binding, and hopefully, everything goes together smoothly for you. This block here does have the oil return holes in there, which is good.
Debur the ID edge of the timing gears for the Howin l6-210 and the timing gears will slide right on the crankshaft

I have decided to follow my gut and take a different approach to assemble the lower end. As of now, I have yet to install the pistons, but that can wait until tomorrow. One aspect that I particularly like is the appearance of the 45° spark plug boots in comparison to the generic ones. Additionally, I have swapped out the distributor timing adjustment screws for button head screws - specifically, one 2.5 x 8 screw and one 2.5 x 6 screw. In terms of the oil return cover, I have replaced the previous screws with six 3 x 10 button head screws. For anyone who is interested, I have documented the build process and would be happy to share it. Thank you for reading!
Howin engine l6-210 21cc Build All The Details part 4
the oil pan capacity is 100ml, and the oil is 0w-15, 0w-16. Full synthetic is ok too.
The engine was missing part #15, a pin to hold crankshaft pully so you will actually see me make a part in this video.
Howin engine l6-210 21cc Build Bottom End part 1
Can't believe how fast this engine is coming together it really is beautiful, my favorite engine
I did find my first missing part that I had to make.
Howin  engine l6-210 21cc Build Bottom End part 2
Howin l6-210 21cc Build Finishing Bottom End part 3
Got the bottom end finished I installed pistons in this order
everything does rotate smoothly piston cylinder 4 and 6 gave me difficulty.
I  use a light to clearly see that all marks are facing the front of the engine.

When the pistons are being installed follow these steps.
Step 1:  Make sure that you tighten the connecting rod capscrews tight.
Step 2:  Back capscrews off 1/4 turn.
Step 3:  Rotate crankshaft atleast 1 full rotation.
Step 4:  Finish tighten connecting rod capscrews tight.
Step 5:  Check that connecting rod assembly moves side to side easy and smooth, if not, return to Step 1.
Howin l6-210 21cc Build Upper End part 5
I installed the cylinder head and had a little to debur on the pushrod bushings.
set screw for water outlet was about .025   too long.. Basically not flush with the block so the hose nipple gasket will never have a water tight seal so by trimming the reducing set screw with a nut on the setscrew trim the excess with a dremal then back the nut off setscrew so threads are  not damaged and set screw will easily screw in to block.
Please enjoy and have a great day!


  • Vince: January 28, 2024

    Sad to hear that people are having problems with no answer for 5 months? Maybe I’ll look somewhere else for my engine

  • Vince: January 28, 2024

    After looking around at the various types of engines I believe it’ll be the Ford 6 cylinder that I will be building very shortly as I grew up around this engine in the trucks that we drove on the road. I was wondering if everything comes included From Radiator technician to everything needed to get it up and running minus the platform thank you for reading my post

  • Sergio: September 17, 2023

    This engine comes with terrible instructions. Stirling kit is not answering my emails. They mentioned updated instructions will be ready “soon”, but that was over 6 months ago.
    Very disappointed with their customer serivce.
    Every model they sell has tons of issues, at least at first.

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