Rod Pin Width

[6-bolt]

I am custom ordering GRP aluminum rods in the near future. I am going to have a 6-bolt bottom end, which has a bigger width then the 7-bolt. Then I am going to have a 7-bolt top end, so the pin diameter will be 22mm, instead of the 21mm on the 6 bolt. This will allow me to use 7-bolt pistons in a 6-bolt engine.

I have all the measurements for the rods except for the rod pin width. I looked around on other rods, and they vary in sizes. Are there any rules on the rod pin width?

I plan on using custom Wiseco 1400D 7-bolt stroker pistons with a CR around 12:1 (E-85 & High Altitude). I am thinking about getting the specs on the piston to get the rod pin width. Find out how much space there is in-between the two pin holes on the piston, then minus some mm off of that and use that as the rod pin width. Is this the best option?

Thanks for the help.

Darren
6Bolt

 

[overkill]

I believe this was answered by Outlaw on CODSM.org! Here's the post Darren, but let us know if this doesn't answer your question.

"Just order 7bolt pistons and they come with the right 22mm pin. Tell GRP you are building a 6 bolt with 22mm wrist pins. That's all you have to do. I run GRP's in my 6 bolt with wiseco 1400HD's with a 22mm wrist pin."

 

[6-bolt]

I believe this was answered by Outlaw on CODSM.org! Here's the post Darren, but let us know if this doesn't answer your question.

"Just order 7bolt pistons and they come with the right 22mm pin. Tell GRP you are building a 6 bolt with 22mm wrist pins. That's all you have to do. I run GRP's in my 6 bolt with wiseco 1400HD's with a 22mm wrist pin."

It does answer my main question, but I was looking for more info then “just do what GRP says.”

I was looking for more design details. Like, the pin width cannot be bigger than the bottom width. But since I am mixing the 6-bolt and 7-bolt rod, should the bottom width be ~28.32mm, while the pin width be ~26.365mm, which is the 7-bolt rod bottom width. But I am just assuming with the details above.

Looking at different 6-bolt and 7-bolt rods, the pin width varies. If I am going to have custom rods made, I would like to know the design and it rules. Then I can make the best decision on the pin width.

Is there a standard on pistons with the pin widths for the 6-bolt and 7-bolt? Or does it vary from manufactory? Or is there a rule with the bottom end widths of the rods?

I guess the best option is to call GRP and to see what they have to say.