Efco 8200 transfer ports

[mtngun]

I'm suggesting that there are no simple rules for porting transfers, other than correcting any obvious casting imperfections and dialing in the timing.

Quite unlike the intake and exhaust where bigger and straighter is usually better.

 

[Mastermind]

When porting transfers, consider that transfer flow is pumped into the cylinder, not sucked into the cylinder. Because it is pumped, the friction losses in the transfer port are not important. What is important is length and velocity and direction. Length and velocity give the charge momentum that keeps charge moving into the cylinder even after the pumping action has shut off.

When Joe Porter makes the transfers wider and shorter, he loses velocity and length and momentum. Bigger is not necessarily better. Shorter is not necessarily better.

I'm suggesting that there are no simple rules for porting transfers, other than correcting any obvious casting imperfections and dialing in the timing.

Quite unlike the intake and exhaust where bigger and straighter is usually better.

I'm in complete agreement.

Compression and flow velocity is key to a stout work saw IMHO. When I match lower transfers to the case I only go into the transfer port as much as necessary to get a good match. Hogging out the lowers kills flow velocity, and hinders the performance on a work saw. I've also seen too much intake timing kill the torque band. Tuning the exhaust and transfer timing, while maintaining a reasonable intake timing will net a very strong, fast revving engine.

 

[parrishturf]

I'm in complete agreement.

Compression and flow velocity is key to a stout work saw IMHO. When I match lower transfers to the case I only go into the transfer port as much as necessary to get a good match. Hogging out the lowers kills flow velocity, and hinders the performance on a work saw. I've also seen too much intake timing kill the torque band. Tuning the exhaust and transfer timing, while maintaining a reasonable intake timing will net a very strong, fast revving engine.

Focusing on the inflow port path, again for stock timing, and as a control keep the port area stock. enlarging, radiusing smoothing beyond casting marks, are of little or no difference. Is that what you are saying?

So for say this jug, knife edging the divider and lowering it into the tunnel, increasing the radius at the tight ends, straightening the path in general, working the turn, and reshaping the ports to send more flow toward the intake side, all was a waste of my time? What about jugs that have no inner wall, are you saying do nothing there?

You may be right on your assesment, but I respectfully have a totally different experience.


Thank you for your input!

 

[Mastermind]

Focusing on the inflow port path, again for stock timing, and as a control keep the port area stock. enlarging, radiusing smoothing beyond casting marks, are of little or no difference. Is that what you are saying?

So for say this jug, knife edging the divider and lowering it into the tunnel, increasing the radius at the tight ends, straightening the path in general, working the turn, and reshaping the ports to send more flow toward the intake side, all was a waste of my time? What about jugs that have no inner wall, are you saying do nothing there?

You may be right on your assesment, but I respectfully have a totally different experience.


Thank you for your input!

I'm not saying that what you have done is of no value. I'm saying that without any knowledge of the engine's port opening timing, just grinding the ports larger.......especially the transfer ports is a shot in the dark. But hell, a blind hog will find an acorn sometimes.

 

[parrishturf]

You got that right!!!:hmm3grin2orange:

 

[Mastermind]

You got that right!!!:hmm3grin2orange:

You got some rep coming as soon as I get reloaded Brother.

 

[mdavlee]

The best running 372 I've built I didn't match the lowers to the case or hardly touch the lowers at all. Flow velocity is much more important than volume in those it seems. The only thing I did to it was raise the transfers a little to get back close to stock blowdown and widen them a little.

 

[Mastermind]

The best running 372 I've built I didn't match the lowers to the case or hardly touch the lowers at all. Flow velocity is much more important than volume in those it seems. The only thing I did to it was raise the transfers a little to get back close to stock blowdown and widen them a little.

That's what I'm talking about. :msp_wink:

 

[parrishturf]

Lets refocus on the OP.

Here is what I found while porting an Efco 8200.

The transfer ports are a split pair. I knife edged the inflow tract, blended the walls, and decided to do more than just pointowardds the intake. Surprise!!! The exhaust side port was cast over by about 1/3 the size of the tunnel. I opened up all four ports. Raised .020" and lowered .040" but the width is now hugcompareded to stock. Squish without base gasket was .018

After some readon lineline I think the 2010 8200 got a cheap retool for emissions standards and they simply cast over the existing tunnel forms in the sand casting.

Any way this saw came alive and required about 1 turn of h/l screws out to tune.

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I do enjoy the conversation and a chance to look at things from anothers perspective.

Lets focus on the original point. I thought I found a design inclusion that could be exploited. I still think that "the blind dog did find an acorn". I have never seen a motor with this large of stroke and this small transfer ports. The exhaust is massive, the intake wide and tall. Even the muffler in factory form has twice the opening of a 660. The internal baffel of the muffler has two 3/4" holes lateraly. All things to me that point toward a saw that was once bigger and badder before emissions restraints.

I accept that I need more experience with a degree wheel, if for no other reason than to fight with you guy's about the numbers!:tongue2:

 

[Mastermind]

Did you say you wanted to argue???

Cool, I'll go get Audible Fart.....BRB.



How the saw runs is the big deal. Is it stronger? Does it hold the RPM in the cut well?

Can we see a video????

 

[parrishturf]

Argue!

Yes.

I have cut with the saw 28" bar the chain is a stihl skiptooth factory sharp. The skip is only because I had two 25" skips for the 441 and I never used them. The saw cut ok stock and consistantly beats my ms250 now. I can post a video sometime.

 

[Metals406]

Bump. . . To see the saw video.

 

[ncfarmboy]

Don't want this to get lost. I have 2-8200's and a 181 with a spare cyl.
Shep

 

[parrishturf]

Don't want this to get lost. I have 2-8200's and a 181 with a spare cyl.
Shep

Do you plan work the 8200?

Take a close look at how the factory screen mounts on the side of the muffler. My first attempt at opening up the saw used the screen cover with tubing brazed to the cover. That way you could have a screen, and never cut the muffler up. If you are not considering the upper transfer work, and choose to only remove the base gasket, and neetly braze a pipe onto the screen cover it makes a great improvement over stock, I ran this for a couple of days and liked it.

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[parrishturf]

Efco 8200 Video

Here is a video of the 8200 with a 28" bar full skip chain. I have used this saw for a couple of weeks. After comparing it to the video of the 441 or the 660bb it is slow. It cuts best when loaded, but I thought when working with the saw it was faster than looks here.


<iframe width="420" height="315" src="http://www.youtube.com/embed/_k-nTo-GqQY" frameborder="0" allowfullscreen></iframe>

 

[Metals406]

That saw doesn't seem "slow", nor lacking in torque. Looks like a runner to me.

 

[parrishturf]

That saw doesn't seem "slow", nor lacking in torque. Looks like a runner to me.

Thanks man, I think the big efco saws are a bargain.

 

[slipknot]

I've been playing with the smaller efcos and really like them. They really wake up with just simple modding like widening of the intake and exhaust and muffler mod and going gasket less with the jug. Your right they are a bargain.