630 to 670 Jonsered build

[huskihl]

I've always been interested in this family of saws. Decent power to weight ratio, respectable a/v, and downright sexy to look at.
Dad gave me a 625 (open port, 34mm x 48mm bore)) that I converted to 272xp last year. It runs strong, but I've always felt a 670 (closed port 50mm bore) might be a bit better. I have a 630 and thought I'd give it new life. Picked up a 670 cylinder courtesy of @cgraham1, and it's in great shape. And here's the saw. A 1984 630 model that was retired for years before getting cleaned up in my shop.
The saw had seen water, so I assumed the worst. Case bearings were siezed, but some pb blaster loosened them up enough to remove the cylinder and piston. I separated the case halves and cleaned everything in the parts washer. New bearings and case gasket, and I realized I should start taking pics cuz there haven't been many build threads on here lately. Soooo, 2 layers of motoseal and a case gasket later, I'm installing new seals.
I believe the previous owners may have been cutting frozen round bales with this saw before it met it's demise. The oil pump had about 20' of baler twine wrapped up around it, rendering the oiler useless.
New seals in place

 

[huskihl]

And finally, flywheel and sem ignition modules in place This is a work in progress while the wife and her mom are visiting Opryland, so I'll be updating day by day from the deer blind lol.
I'd also like to thank @bplust for keeping spare parts lying around for stihls, huskies, and their little red headed cousins. More to come...

 

[Zero_sum]

I'm liking this build...... Looking forward to the rest of it.

 

[huskihl]

Just installed a meteor slab side piston and the jug. Squish without base gasket is .022". Degree wheel is on. Ex opens at 103.5°, duration 153°.Transfers open at 119 and 121. Intake is 69.5° btdc, for a duration of 139°. Dropping the jug will get the intake duration up a bit more. Seems low to me. Any thoughts?

 

[Gypo Logger]

I noticed some of the 630's have a coarse thread output shaft and some have the fine threads.
Also, have you considered taking some off the intake side of the piston skirt?

 

[huskihl]

I noticed some of the 630's have a coarse thread output shaft and some have the fine threads.
Also, have you considered taking some off the intake side of the piston skirt?

My 1988 625 (now 672) has a fine thread. This 1984 630 has a coarse thread.
While porting the jug, I lowered the intake down to 146° duration. I may still cut the squish and base if compression isn't where I'd like when I'm done.

 

[taplinhill]

Nice thread!

 

[BigDee]

I believe the previous owners may have been cutting frozen round bales with this saw before it met it's demise. The oil pump had about 20' of baler twine wrapped up around it, rendering the oiler useless.

Many years ago I bought a cheap well-used Poulan, a 3400 I think, that had heavy nylon twine wrapped around the drive side of the crankshaft. When I removed it, the seal leaked. I later learned that I was not the only one who bought a saw from that mechanic with his special economy seal repair.

 

[Agrarian]

Just installed a meteor slab side piston and the jug. Squish without base gasket is .022". Degree wheel is on. Ex opens at 103.5°, duration 153°.View attachment 464940Transfers open at 119 and 121. Intake is 69.5° btdc, for a duration of 139°. Dropping the jug will get the intake duration up a bit more. Seems low to me. Any thoughts?

Why the slab sided piston? I just replaced a piston in a 670 and used a Meteor 266 open window piston (got from Northwood) which was equivalent to the OEM.

 

[huskihl]

Why the slab sided piston? I just replaced a piston in a 670 and used a Meteor 266 open window piston (got from Northwood) which was equivalent to the OEM.

I thought the same thing. While there may be room for the charge to reach the lower transfers, popular opinion is that it will run better with windows. I had planned on using a windowed one

 

[Agrarian]

I thought the same thing. While there may be room for the charge to reach the lower transfers, popular opinion is that it will run better with windows. I had planned on using a windowed one

I used Meteor #PC1314, looks just like the original.

 

[huskihl]

Running into a few problems along the way. The 625 and 670 intake styles are more similar, ie rubber block with wire clamp, vs the 630 style intake, which is a cross between a 625 and 272xp block. The 630 carb linkage hits the intake boot and there are no holes in the 630 case to bolt down the 670/625 intake. So,...the 625, converted to 272xp, is now going to be the platform for this 670 build. From what i can see, this is a bolt on mod. The cylinder and intakes are the same, and my 625 carb is the same size as far as i can tell. The 272xp intake, piston, and cylinder will be removed from the 625 and bolted onto this 630 case. The hs218 carb on the 630 is quite a bit smaller than a hs260 on a 272xp, so I removed the shafts from the 218 and installed them in the 260 to retain the original hi idle function which is set by a linkage on those shafts. Pics tomorrow

 

[BigDee]

removed the shafts from the 218 and installed them in the 260

Was this as simple as it looks?

 

[huskihl]

Was this as simple as it looks?

Yep

 

[huskihl]

Still waiting on a piston and other small parts. Here are some pics showing the differences between these 2 case styles. 625/670 style on left. 630 on the right. Note the 2 holes behind the cylinder mount on the 625. These are where the rubber boot/block style intake bolt down. The 630 has none.

 

[huskihl]

Since the 272xp style intake doesn't require these mounting holes, it's easy to see why I opted to go this route

 

[huskihl]

Here's the 630/272xp nearly complete. I fired it up today and noticed a vacuum leak after passing pressure and vacuum tests a half hour earlier. A quick shot of carb cleaner around the intake block revealed the leak. New intake and carb gaskets on the way

 

[BigDee]

Where did you block off the intake for your vac test? And how did you know it was a vac leak after it had tested ok?

 

[huskihl]

Where did you block off the intake for your vac test? And how did you know it was a vac leak after it had tested ok?

I blocked off between the cylinder and intake adapter. It leaks either there or between the adapter and carb. They've been problematic on this saw since I did it.

On detecting the leaks, I started the saw, warmed it up, eventually to full throttle. Usually with small vacuum leaks, you won't be able to tell til you've pinned the throttle for a few seconds. Rich and burbling for a second or 2, then just like you turned the high speed jet in 1/2 turn it gains about 2000 rpm

 

[Onan18]

OK I am a little confused, the 630 and 272 both have the impulse circut to the carb in the intake block. Only the 625 and 670 use an external pulse line and have a port on the cylinder for pulse. Your first picture shows an external pulse line on the carb, where are you getting vacuum from?

Joe