Johnson/Evinrude 9.9/15hp 2 stroke

[Dan0509]

Hi all. I am new to this forum but,have been reading it for a long time.
I am working on the 92 johnson 9.9 and need to run cylinder head bolt threads,but i dont know size and pitch of the thread. I know that smaller threads,for example bypas cover bolts are 1/4" unc 20 tpi,but need help with the other.
Could you guys help me out?
Many thanks.
Dan.

 

[kimcrwbr1]

Standard SAE course thread with flange head. What is the reason your replacing the bolts or are you doing helicoils? You want the bolts as deep as possible.

 

[Dan0509]

Standard SAE course thread with flange head. What is the reason your replacing the bolts or are you doing helicoils? You want the bolts as deep as possible.

Hi. I should have mentioned that i need to buy a tap to run threads before assembly because there is some salt in the holes. So need to know what tap to buy.

 

[kimcrwbr1]

Take a bolt with you and use their thread checker usuall by the bins of bolts.

 

[Dan0509]

Take a bolt with you and use their thread checker usuall by the bins of bolts.

I am in UK,so they are not very good with American standart of thread and pitch,theirs is either metric or British imperial.

 

[kimcrwbr1]

Spray some WD in the hole and just chase it with a bolt. Run the bolt in until it bottoms out.

 

[Dan0509]

Yep,thats the way i allways done it,just it can be a bit of pain to do it that way,much faster and easier using a tap.

 

[racerone]

5/16-NC is what they are.

 

[Dan0509]

Hi. Do you know how many threads per in inch they are?
Thank you.

 

[racerone]

18 tpi

 

[Dan0509]

Thank you.