The next 066 top end
- Thread starter mtngun
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mtngun
Addicted to ArboristSite
Woodland Pro synthetic, 40:1.BTW what type of oil and at what ratio are you going to run?
mtngun
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Decomp fit well enough, but some plastic had to be trimmed around the spark plug, since the plug sits at a higher angle compared to a stock head.
mtngun
Addicted to ArboristSite
Ceramic coating on Meteor piston.
Exhaust flange was opened up about 1mm and polished, but the port at the cylinder wall was left alone since it was already max width.
Intake port was lowered and intake flange was opened up about 1mm.
Lower transfer was bell mouthed, but not much else.
Not a lot of porting going on here because this particular jug was pretty much ported when it left the factory.
Final specs, as actually measured on the saw:
0.025" squish (it measured 0.022" dry, but gasket sealer added a few thou)
6.6 cc chamber with zero squish, 8.05 cc with 0.025" squish.
7.9 : 1 swept compression ratio
12.2 : 1 uncorrected compression ratio
1.66 base compression
intake opens 277 ATDC, 167 duration (but port map says 172)
exhaust opens 94 ATDC, 171 duration (but port map says 170)
transfer opens 118 ATDC, 24 blowdown (port map also 118 ATDC)
I still got do a carb kit and some other stuff, so it may be a few days before it's running and can be speed tested.
Blue line is as-built.
Red line is stock jug with muffler mod.
Violet line is stock jug & stock muffler.
Exhaust flange was opened up about 1mm and polished, but the port at the cylinder wall was left alone since it was already max width.
Intake port was lowered and intake flange was opened up about 1mm.
Lower transfer was bell mouthed, but not much else.
Not a lot of porting going on here because this particular jug was pretty much ported when it left the factory.
Final specs, as actually measured on the saw:
0.025" squish (it measured 0.022" dry, but gasket sealer added a few thou)
6.6 cc chamber with zero squish, 8.05 cc with 0.025" squish.
7.9 : 1 swept compression ratio
12.2 : 1 uncorrected compression ratio
1.66 base compression
intake opens 277 ATDC, 167 duration (but port map says 172)
exhaust opens 94 ATDC, 171 duration (but port map says 170)
transfer opens 118 ATDC, 24 blowdown (port map also 118 ATDC)
I still got do a carb kit and some other stuff, so it may be a few days before it's running and can be speed tested.
Blue line is as-built.
Red line is stock jug with muffler mod.
Violet line is stock jug & stock muffler.
Last edited:
mtngun
Addicted to ArboristSite
Back to the 066, with Mr. Murphy following me every step of the way.
This is how you are supposed to tighten the flywheel nut -- with a torque wrench. Did I do that ? Nooooo...... but it felt tight !
So naturally I sheared the flywheel key. If Lakeside were here, he'd read the riot act to me. :blush:
Anyway, it runs so much better with the flywheel nut torqued down to factory spec. :cool2:
Break in consisted of running about 15 minutes without bar or chain, just long enough to check basic functionality and adjust the carb. "H" screw was set to 12,500 rpm WOT rather than tuning by ear.
165 psi cold at 4500 feet elevation, after only 15 minutes run time. That's equivalent to 194 psi at sea level. I had guessed it would blow 160. :msp_thumbup:
My usual speed test milling a 12 1/4" ponderosa pine cant. 36" bar and 3/8" WP milling chain. Sorry, no video capabilities here.
0.82 inch/sec today, an average of 3 speed tests.
Previous times in the same 12 1/4" cant with 3/8" chain:
0.62 inch/sec with current NWP 066 BB
0.57 inch/sec with a popped & ported 066 OEM that wasn't sealing the rings very well.
0.64 inch/sec with a popped & ported old-style 066 BB that wasn't sealing the rings very well.
0.59 inch/sec with a ported Makita 84cc BB, 24" bar & cross-cut chain
0.45 inch/sec with a stock Makita 84cc BB, 24" bar & cross-cut chain
Tomorrow I'll repeat the speed tests with lo-pro chain. Think it'll hit 1.0 inch/sec ?
30+% faster than the other 066 top ends I've tested, so it definitely makes good power.
Next question is, will a milling saw hold up with a 7.9 : 1 compression ratio ? This is new territory for me, so I don't claim to know. Time will tell.
This is how you are supposed to tighten the flywheel nut -- with a torque wrench. Did I do that ? Nooooo...... but it felt tight !
So naturally I sheared the flywheel key. If Lakeside were here, he'd read the riot act to me. :blush:
Anyway, it runs so much better with the flywheel nut torqued down to factory spec. :cool2:
Break in consisted of running about 15 minutes without bar or chain, just long enough to check basic functionality and adjust the carb. "H" screw was set to 12,500 rpm WOT rather than tuning by ear.
165 psi cold at 4500 feet elevation, after only 15 minutes run time. That's equivalent to 194 psi at sea level. I had guessed it would blow 160. :msp_thumbup:
My usual speed test milling a 12 1/4" ponderosa pine cant. 36" bar and 3/8" WP milling chain. Sorry, no video capabilities here.
0.82 inch/sec today, an average of 3 speed tests.
Previous times in the same 12 1/4" cant with 3/8" chain:
0.62 inch/sec with current NWP 066 BB
0.57 inch/sec with a popped & ported 066 OEM that wasn't sealing the rings very well.
0.64 inch/sec with a popped & ported old-style 066 BB that wasn't sealing the rings very well.
0.59 inch/sec with a ported Makita 84cc BB, 24" bar & cross-cut chain
0.45 inch/sec with a stock Makita 84cc BB, 24" bar & cross-cut chain
Tomorrow I'll repeat the speed tests with lo-pro chain. Think it'll hit 1.0 inch/sec ?
30+% faster than the other 066 top ends I've tested, so it definitely makes good power.
Next question is, will a milling saw hold up with a 7.9 : 1 compression ratio ? This is new territory for me, so I don't claim to know. Time will tell.
woodgrenade
ArboristSite Guru
Cool thread, looking forward to the vids.
mtngun I can't think you enough for posting all the information that you have, very informative, and it sure helps guys like myself get a better understanding of things.:msp_thumbup:
MCW
Somebody's talking crap here & it ain't the tree!
Good stuff MTN but just thought I'd let you know that some toothy critter looks to have been chewing on your saw's handle 
mtngun
Addicted to ArboristSite
Yes, it saw a rough life before it came into my possession, and I don't exactly baby it, either. :msp_wink:Good stuff MTN but just thought I'd let you know that some toothy critter looks to have been chewing on your saw's handle
If forgot to mention that I ran into a problem with the length of the spark plug lead. It just barely reaches the plug now, with no slack in the line. If the plug had been centrally located like most 2 piece heads, a new spark plug lead would definitely have been required.
MCW
Somebody's talking crap here & it ain't the tree!
It's refreshing to see people who aren't concerned about their saw's looks but how they run
mtngun
Addicted to ArboristSite
Speed testing the 2-piece head with WP lo-pro milling chain and a 7 pin rim.
It had picked up a few RPMs since yesterday -- it's still breaking in -- so I turned the "H" out about 1/16 turn more to bring the WOT down to 12,500. It's rich, and that's the way I like it, especially with this high compression head.
Will it hit the magic 1.0 inch/sec mark ?
1st test -- 1.0 inch/sec
2nd test -- 0.96 inch/sec
3rd test -- 0.92 inch/sec
average -- 0.95 inch/sec
That's 16% faster than 3/8 chain. I bet it would cut slightly faster with an 8 pin, but it would have to work harder and would run hotter, so I'll stick with the 7.
It had picked up a few RPMs since yesterday -- it's still breaking in -- so I turned the "H" out about 1/16 turn more to bring the WOT down to 12,500. It's rich, and that's the way I like it, especially with this high compression head.
Will it hit the magic 1.0 inch/sec mark ?
1st test -- 1.0 inch/sec
2nd test -- 0.96 inch/sec
3rd test -- 0.92 inch/sec
average -- 0.95 inch/sec
That's 16% faster than 3/8 chain. I bet it would cut slightly faster with an 8 pin, but it would have to work harder and would run hotter, so I'll stick with the 7.
Stihlman441
Addicted to ArboristSite
Good stuff there mate,very interesting thanks for sharing.
mtngun
Addicted to ArboristSite
Easier to get power out of the current NWP BB's. I went with the high compression head mainly as a learning experience, just to see what it's all about.
mtngun
Addicted to ArboristSite
As discussed in more detail over on the milling forum, the 2-piece 066 was eventually able to smash the magic 1.0 inch/sec barrier in the 12 1/4" pine cant. In fact, it averaged 1.24 inch/sec.
The trick was applying a 40/10/10 grind to lo-pro chain, similar to what Will Malloff recommended in his book "Chainsaw Lumbermaking." Rakers had a 6 degree angle.
The trick was applying a 40/10/10 grind to lo-pro chain, similar to what Will Malloff recommended in his book "Chainsaw Lumbermaking." Rakers had a 6 degree angle.
cowboyvet
ArboristSite Operative
:msp_thumbup:Thanks again for all the great data and pics.:msp_thumbup:
There is so much on here about porting yet at the same time very little about numbers which have worked for the guys who know how to port. I understand every saw can be a little different but it is good to see some numbers which can be referenced for starting points. My 66BB is a dog (compared to other 66's) but runs great. I'll be checking my numbers and comparing them when I get a chance to see if I can find a reason. I'll also start playing with the hook angle on my milling chains more but I'm interested in how long they will stay sharp. Trade offs for everything and meet in the middle.
There is so much on here about porting yet at the same time very little about numbers which have worked for the guys who know how to port. I understand every saw can be a little different but it is good to see some numbers which can be referenced for starting points. My 66BB is a dog (compared to other 66's) but runs great. I'll be checking my numbers and comparing them when I get a chance to see if I can find a reason. I'll also start playing with the hook angle on my milling chains more but I'm interested in how long they will stay sharp. Trade offs for everything and meet in the middle.
thomas72
Addicted to ArboristSite
Great information you presented. These are the threads I enjoy reading and learning from. You show facts and exceptional machining skills. Have you ever thought about machining the skirts of the piston a few thousandths and having them ceramic coated to help prevent skirt wear? Just a little food for thought I have been having lately. I am also really thinking about making my own full circle crank, but still in the brain storming stage though.
mtngun
Addicted to ArboristSite
The ceramic on the top is intended to be an insulator, to reduce the piston temperature. It would be abrasive if put on the skirts. I did consider applying ceramic to the chamber top and to the exhaust port, but chickened out.
A full circle crank would increase the base compression, which might help a race saw a tiny bit, but the base compression on Stihls is a bit high for a work saw as it is.
Glad you enjoyed the thread. It was a good learning experience for me.
A full circle crank would increase the base compression, which might help a race saw a tiny bit, but the base compression on Stihls is a bit high for a work saw as it is.
Glad you enjoyed the thread. It was a good learning experience for me.
mtngun
Addicted to ArboristSite
Another speed test on the hi-comp 066, in the usual 12 1/4 ponderosa cant.
Today it was running a 3/8 x 36" WP milling chain, reground to 40/0/2.
Average speed was 1.22 inch/sec. That's 48% faster than the 3/8 WP with the conventional 60/10/10 grind. :msp_ohmy: And it's right on the heels of the 40/10/10 lo-pro.
I'm impressed with this saw. It cuts faster than my 084 ! ! ! Though, it still remains to be seen if the high compression engine will hold up on a hot summer day. :msp_unsure:
Today it was running a 3/8 x 36" WP milling chain, reground to 40/0/2.
Average speed was 1.22 inch/sec.
That's 48% faster than the 3/8 WP with the conventional 60/10/10 grind. :msp_ohmy: And it's right on the heels of the 40/10/10 lo-pro.I'm impressed with this saw. It cuts faster than my 084 ! ! ! Though, it still remains to be seen if the high compression engine will hold up on a hot summer day. :msp_unsure:
