Porting an Echo 355T

[MemphisMechanic]

Arrived new in the box this afternoon. Did some test cuts in a 13” piece of ash and then tore it utterly down to do some mild port work.

I see no discussion on the numbers generated when this style of saw is worked on, and man… Echo’s port timing is WAY different from the stihl 026/044/662 jugs I’m used to mapping out with a degree wheel.

A little help? I’m not looking to replicate a full blazing pro level build from the likes of @Mastermind … just something 10-20% hotter which has a bit of a chance at pulling a 16” chain decently when I’m up in a tree.

 

[Ketchup]

@Nutball

 

[ElevatorGuy]

@Red97

 

[Nutball]

@Ketchup

 

[Nutball]

Muffler mod is good for at least 10% if not 20% on most saws depending on how wide open and loud you want it, so forget the porting.

 

[Ketchup]

@Ketchup

Well, it’s not a saw I mess with because it’s a clammy. Muffler mod for sure.

You could try widening the exhaust to 65% of bore and raising the primary transfer 2 degrees. If you want more intake I wouldn’t lower it. I would raise the port up to the skirt at TDC. But make sure the ring doesn’t travel in to the intake port. Or just leave the intake alone. Get rid of all the port imperfections and smooth out sharp edges.

It’s a clamshell. Without complex machining you can’t really improve the compression or lower the timing. I wouldn’t do anything drastic.

 

[Miller Mod Saws]

Muffler mod is good for at least 10% if not 20% on most saws depending on how wide open and loud you want it, so forget the porting.

I’m with nutball. Muffler mod. They like a little timing advance. And modify the air intake under the air filter.

 

[MemphisMechanic]

I’m with nutball. Muffler mod. They like a little timing advance. And modify the air intake under the air filter.

okay - .020” off the key and shoot for around 8 degrees of advance? (The usual process for Stihl or something else?)

I have seen mention here and there that some Echos don’t like having their timing bumped. Glad to hear a definitive answer in this regard.

 

[MemphisMechanic]

If you want more intake I wouldn’t lower it. I would raise the port up to the skirt at TDC.

The fact that it’s a clam is why this thread exists. My previous experience is all on Pro stihl saws.

The intake times at 71 and I was planning to drop the floor to 78 if it would not free-port in the process. Would that be your reasoning for not lowering the floor? I haven’t scribed the locations on the piston and pulled the jug off yet. I’ve only torn it down to the bare powerplant and timed it.

(71 intake, 119ish exhaust.)

Since it doesn’t need to run at 100% of it maximum potential, I may well just play it safe and widen the ports if it’s possible, and raise the intake to any reasonable degree the saw permits.

 

[Nutball]

If Stihls usually like a lot of timing advance, and Echos just a little, I'd try .010" off the key unless Miller can give better advise.

I don't have any degree numbers on a 355t, but 119 looks about right. I'd be tempted to try raising the exhaust to 109 from my experience with other saws, and a more conservative 74 on the intake just to see how it runs that way first. But, I haven't messed around much with porting the 355t. I know there's not much room for widening the ports.

Here's an air filter I modded for one

 

[Ketchup]

The fact that it’s a clam is why this thread exists. My previous experience is all on Pro stihl saws.

The intake times at 71 and I was planning to drop the floor to 78 if it would not free-port in the process. Would that be your reasoning for not lowering the floor? I haven’t scribed the locations on the piston and pulled the jug off yet. I’ve only torn it down to the bare powerplant and timed it.

(71 intake, 119ish exhaust.)

Since it doesn’t need to run at 100% of it maximum potential, I may well just play it safe and widen the ports if it’s possible, and raise the intake to any reasonable degree the saw permits.

In general, little saws need case compression more than intake. Raising the intake port adds time area without sacrificing case compression.
74 might be fine. That’s still a pretty high intake.

Consider stock intake on 2511 is 66 degrees.

Edit: 119 seems unusually low for exhaust.

And like everyone said, the biggest and easiest gain is the muffler. Get a hole through all baffles and smooth out any rough edges where the cylinder meets the muffler inlet. I like the outlet to be about 100% of the inlet or slightly bigger.

 

[MemphisMechanic]

Muffler mod is handled. See below. I will, of course, also port match the muffler and cylinder. The muffler on these is a wide open can, not at all like many other Echo saws.

I agree on the 119-ish timing being odd. But I checked it 3 times.

 

[Ketchup]

Muffler mod is handled. See below. I will, of course, also port match the muffler and cylinder. The muffler on these is a wide open can, not at all like many other Echo saws.

I agree on the 119-ish timing being odd. But I checked it 3 times.

I agree 109 exhaust is in the ballpark for a lot of modded Echoes. But if you’re starting at 119, I wouldn’t go that far. Maybe 114-112. You can’t put it back, but you can take more later.

What is stock timing for the transfers? Curious what squish is as well.

 

[MemphisMechanic]

I agree 109 exhaust is in the ballpark for a lot of modded Echoes. But if you’re starting at 119, I wouldn’t go that far. Maybe 114-112. You can’t put it back, but you can take more later.

What is stock timing for the transfers? Curious what squish is as well.

Because the exhaust exits at a 90% angle I can’t reliably time the transfers by eye: I haven’t pulled the cylinder off yet.
I think you’re guys are definitely correct on making timing changes. 3-4 degrees is all I want to push for on such a small engine, which is a climbing saw and as such? It doesn’t need a 30% power gain in order to make me happy. I’m not going to move anything by 8-10 degrees like I did on my Stihl 044.

 

[huskihl]

Because the exhaust exits at a 90% angle I can’t reliably time the transfers by eye: I haven’t pulled the cylinder off yet.
I think you’re guys are definitely correct on making timing changes. 3-4 degrees is all I want to push for on such a small engine, which is a climbing saw and as such? It doesn’t need a 30% power gain in order to make me happy. I’m not going to move anything by 8-10 degrees like I did on my Stihl 044.

Another thing to consider on these motors where the exhaust makes a sharp 90° turn, there is a point I believe where you can try making them spin more RPMs, but as soon as that 90° turn becomes the biggest limiting factor, any more changes in the motor to offset that and you’ll go backwards due to an imbalance. The carburetor can also be a limiting factor. If it was already a small carb and designed to make power at 8000 RPM, you won’t get great gains if your motor wants to spin 11K but the carburetor can’t feed enough air

 

[Wood Doctor]

Muffler mod is handled. See below. I will, of course, also port match the muffler and cylinder. The muffler on these is a wide open can, not at all like many other Echo saws.

I agree on the 119-ish timing being odd. But I checked it 3 times.

Here's my version:

Engine seems to like it.

 

[Red97]

@Red97

Not been in one yet.

Lots of good ideas mentioned so far.

 

[MemphisMechanic]

Here's my version:
View attachment 327410
Engine seems to like it.

For anyone reading this in the future? Do it his way.

Mine seems to flow very well… but his exits through the factory opening in the cover over the muffler. Mine required significant trimming to avoid melting plastic near the muffler’s exit.

 

[MemphisMechanic]

@huskil yet more valid points. The carb is tiny. The exhaust exits around a graceful bend, but it’s still a bend.

I am certainly planning to make extremely minor porting adjustments to this saw. Focus will be more on smoothing out airflow than radically changing the timing.

On another note, my 16” Panther 1/4” pitch bar (and clutch drum) from August Hunicke’s shop showed up today. Man… that thing is SUPER light and I’m looking forward to trying out the latest fad among the YouTube tree guys.

 

[tek9tim]

Here's how I did mine, about 30 seconds with a cutoff wheel. Agreed, put the extra area low where you don't melt plastic. No idea if it added power, did this before even firing it up.