Valve guide replacement on cb350f
- Thread starter Corsair
- Start date
Tune-A-Fish
BOTM LOSER Proudly Deplorable
For what it's worth,
I drill the guide with two progressively larger drills leaving enough material to run a tap through the guide and then using a grade 8 allen bolt turned in with the head left just above the guide, I drive the guide out with a drift inside the allen head. Driving force being applied to the threads in a way sucks the guide out leaving little or no chance of mushrooming or dragging material from the head because the guide is stretching not swelling in the bore.
Longer process but I rarely have any aluminum on the guide or a distorted bore.
I drill the guide with two progressively larger drills leaving enough material to run a tap through the guide and then using a grade 8 allen bolt turned in with the head left just above the guide, I drive the guide out with a drift inside the allen head. Driving force being applied to the threads in a way sucks the guide out leaving little or no chance of mushrooming or dragging material from the head because the guide is stretching not swelling in the bore.
Longer process but I rarely have any aluminum on the guide or a distorted bore.
Corsair said:
Yes, always heat the head when removing or installing guides, the expansion rate for most types of aluminum is much greater than that of the guide material. ...wait 'till the wife isn't home and stick it in the oven at about 400 F for about 20min. (the BBQ works well too). Knock out the guides immediately. Have the new ones in the freezer and tap them in before the head has a chance to cool.
crazypj
Split personality, I fake being smart
Tune-A-Fish said:
That's probably the best way to do it.
I would probably drill for 8mm (5/16") thread
Heat the head to around 350f~400f to remove or re-fit guides. use wood blocks to hold head off bench
Re-cutting valve seats will require special seat cutters or grinders. They are pretty damn expensive so it may be cheaper long term to get a 350 specialist to do it (cutters are around $100.00 each, you may need 4~6)
Tune-A-Fish
BOTM LOSER Proudly Deplorable
thats the thing... now you have a new guide and the valve no longer seats. next step hone the seat and match cut the seat to valve... or just bite the bullet and ship the head off for a valve job, really the best option unless you have a machinist buddy.
