Stihl 046 port timing

[Thoroughbred]

Hi,

I am about to start my first chainsaw port on a 046 with low compression. I have a meteor p&c that is kind of a disaster (just doesn’t look like it was cast very well... ports misshapen, etc) that I will be attempting to make run better than OEM.

Not asking for trade secrets, just looking for a good port job timing numbers. Should I just try for 100 exhaust, 120 transfers, and 80 intake? I know the first time you should just focus on widening the ports, but I have no faith that the top end I have is anywhere near where it should be timing-wise.

If you don’t want to reply to this thread with timing numbers I completely get it. But, if you have some that you’d be willing to PM me I would appreciate that!

Thanks!
Jud

 

[JonCraig]

Here’s where my “good timing” D-jug is:

https://www.arboristsite.com/community/threads/which-046-did-i-just-buy.310907/

 

[blsnelling]

You'll do better with less blowdown on a 460.

 

[Thoroughbred]

Thanks everyone! I think I’m gonna start with the numbers that JonCraig found on his D jug and see where that gets me.

Thanks,
Jud

 

[JonCraig]

Thanks everyone! I think I’m gonna start with the numbers that JonCraig found on his D jug and see where that gets me.

Thanks,
Jud

For the record, those are stock numbers; I didn’t do any grinding. It’s certainly a strong runner, but if you get advice from an expert that tells you something different, you should probably go with their numbers. ;-)

 

[Thoroughbred]

Yep, thanks. Stock runner is good enough for now (until a pro sends me a PM with their secret sauce )

For the record the OEM jug I have now has the following numbers (base gasket deleted)
Exhaust: 102
Transfers: 122
Intake: 77

So the blowdown could use some work since snell recommended less than 20.

 

[Thoroughbred]

Here is how the meteor looked out of the box, only work has been done on the outside of the cylinder and isn’t cleaned up yet. That’s why you see sharpie on the exhaust (trying to figure out width as compared to the piston) and a couple of aluminum flakes here or there.

Intake:


Exhaust:


Transfers:



Squish band:

 

[Thoroughbred]

Intake:
https://www.arboristsite.com/community/attachments/09a16a2d-780c-4595-a13f-d67f4dab0485-jpeg.6

Seriously?!!!!!!!

Yeah, it’s awful. That’s why im using it as a cylinder to learn on. Not useable otherwise

 

[blsnelling]

Here is how the meteor looked out of the box,

Intake:
View attachment 677717

Seriously?!!!!!!! Is that open to the ring end?

 

[Thoroughbred]

That jagged point is slightly below the lowest point of the bottom ring. Definitely can’t take material off the top to clean it up

 

[Axotopia]

Here is how the meteor looked out of the box, only work has been done on the outside of the cylinder and isn’t cleaned up yet. That’s why you see sharpie on the exhaust (trying to figure out width as compared to the piston) and a couple of aluminum flakes here or there.

Looks like that cylinder should not even have left the factory, guess the workmanship and QC for Meteor can be as questionable as all the other AM brands. I was looking last night to replace the P&C on a 461 and has Meteor sitting in my shopping cart, think I may bite the bullet and go OEM. Thanks for posting the pictures!

 

[Thoroughbred]

You may have better luck than me! I’ve heard nothing but good things about meteor, that’s why I bought one.

 

[blsnelling]

Meteor cylinders are just another Asian cast cylinder.

 

[wcorey]

You may have better luck than me! I’ve heard nothing but good things about meteor, that’s why I bought one.

Pistons yes, cylinders not so much, hit or miss like most china stuff.

There were a batch of those cylinders, all with pretty much the same nasty looking intake and whatnot.
I believe they've since corrected the obvious issues but there's still some of these floating around.
I have a couple of them, it all appears to be fixable with some grinding.

Good if you planned on porting anyway and can find them cheap, not so much if you paid all the $'s and/or planned on just bolting it on...

 

[Axotopia]

Meteor cylinders are just another Asian cast cylinder.

Though they are Italian machined, finished and QC?

 

[drf255]

Those were factory recalls. If you actually purchased that, you can get it replaced.

I used one for a Build because the competition dictated use of an AM jug.

Some observations:

The plating on that jug exceeds oem quality. It’s truly tough as nails and should outlast an oem cylinders plating.

Trying to cut the squishband is nearly impossible. Go with a popup if you can, I certainly will next time.

The intake port and ex ports are both fixable, they just take a lot more time than an oem jug. The beak on the intake plating is near the edge of the skirt, but doesn’t cross it. You pretty much need to square it right there and leave that drop of plating on the edge.

The transfers are awful. They are smaller than OEM and lack direction. Since I wanted something that would last (the plating is that good), I spent hours on the tunnels and I’m sure that an oem jug would still out perform what I did. Because they have no direction, I used the extra real estate between the intake edge of the upper and intake centerline to carve fingers in. Also added bridge ports to (arguably) aid in direction from the upper.

Its simply a sows ear I’d never use again. Return it.

 

[drf255]

 

[drf255]

One more point,

Theses jugs, unlike OEM, have headbolt locating depressions on the upper side of the base. If you plan on using them for a hybrid 440/460, those areas need to be flattened or they will shift the jug around. Look at the area I’m talking about and you will see. See first pics above where threaded rod goes through base.

Good 046 numbers are 100-101/ 118/ 78-80. Brad pretty much posted this years ago, and it still holds true.

 

[drf255]

Look st the plating thickness at the band/chamber interface. It’s really that thick. I ruined 4 cutter tips on this one, and it’s still not that great at all.

Here’s a better pic of the intake port and transfers after modding. I didn’t widen the uppers at all. That’s factory placement.