Porting Question!

[Farley9n]

Hey Buck..... Just happened to be on the site when I saw you had replied to this old thread. You have made a good point on the piston but the cylinder I used is from a 372K and it matched up port wise with another stock 372 I have as did the pistons. I do have a bunch of 266 & 268 parts and have noted the piston differences. Maybe if I had just pulled it a few more times......???........Bob







PS.....Every time I see him I ask about the saw. Dammmmmmmm thing is still going good and he uses it often!

 

[Farley9n]

New Question!

Draging up my old thread again but what the hell! I now have my own 372xp and am about to port it. The stock cylinder and piston is in fine shape so I have set that aside and have a Bailey's BB set for it. I also have a Meteor 064 piston set that I hope to use. This should give me nice little pop-up with a stock gasket and provide a better flow into the lower transfers. However, it looks as if the ring end pins will be right at the intake port edge of the transfers.
I guess I need to ask a few questions before I screw this up!
Is this a combination that has been done before & is it worth it?
Do I really need to relocate the pins and if so, do you remove the old ones or just file them out of the way?
If the answer to the above is YES than some tips on redrilling would be very helpful.
Lastly ( for now ) I am planning on grinding away that part of the cylinder wall that sticks below the transfer openings until it's even with the gasket surface. My thinking is that this would improve the flow up into the transfers with the windowed 064 piston.
Well the typing finger is starting to die on me and I have some real measurements to take so that's it for now. Thanks in advance for any and all advice......Bob

 

[weenieroaster]

helpful.
Lastly ( for now ) I am planning on grinding away that part of the cylinder wall that sticks below the transfer openings until it's even with the gasket surface. My thinking is that this would improve the flow up into the transfers with the windowed 064 piston.

Good approach.

 

[troutfisher]

A 372 already has 4 transfer ports, I wouldn't worry about widening them.

 

[Farley9n]

Not making any change in the transfer port outlets. Just opening the lower portion at the crankcase gasket area.

 

[Farley9n]

http://www.arboristsite.com/attachment.php?attachmentid=110642&stc=1&d=1254531906 Hopefully .....Here is a picture of the area

 

[Jacob J.]

Bob- I've built a few of the 372 big bores and I've had good experience with opening up the lower transfers and doing a lot of fine shaping there, and only drawing the upper rear transfer outlet back towards the intake just a hair. I go fairly conservative on the exhaust and intake, since the BB cylinder is already moving more air and you want to keep the velocity up.

Be careful though, some of those new BB cylinders flake the plating off pretty easily.

 

[troutfisher]

OK, I understand now, you're port matching the cylinder to the gasket and base. Good plan.

 

[Farley9n]

Thanks Jacob! Not planning on timing changes. Just the usual, slightly wider exhaust - square up the bottom of the intake port and smooth up passage back to the boot, more compression with the 064 piston & opening up the lower transfers. Add a muffler mod and it should have real strong low and mid power with no decrease in top end. Well anyway that's the plan!.....Bob

 

[logging22]

How bout some pics of one that looks and runs right?