nova rossi 7 port

[steve wood]

i'm really confused by this one! i opened up a new nova 7 port 21, and found that the piston has a 5 degree angle on the outer edge, similar to the 3 degree on the 35 plus, but the head button is has a 3 degree angle, same as the 35 plus and the 5 port. the head and piston will mate up at about the head/piston bowl diameter, with about .010 or so clearance at the o.d. of the piston. with no shims i have .0095 clearance at the bowl diameter,and maybe .020 at the o.d. now to me either someone really screwed up or is the some kind of "new " technology i don't know about. i can mate the head angle to the piston angle ok. but am wondering if anyone can shed any light on this. intake and exhaust timing numbers are good, even with the angle on the piston. i just can't help thinking this can't be right

 

[aaron alberico]

Steve

which 7 port motor do you have,

regards Aaron

 

[Richard Dahlheimer]

Stevewhich 7 port motor do you have,

regards Aaron

Steve, does the 7 port you are working on, have a dished piston? Richard D

 

[Chris Wood]

richard,

i beleive it is a dome with a dish like the plus motors

chris

 

[Glenn Quarles]

Yeah I am checking to see what they did...

Aaron, it is the TX21SSM2A4....I have just sold all I had in stock so I don't have any others to check...dp you have any?

Steve, I'll let you know as soon as I can find out if it was an "accident" or "some new tecn"

Glenn

 

[steve wood]

Yeah I am checking to see what they did...
Aaron, it is the TX21SSM2A4....I have just sold all I had in stock so I don't have any others to check...dp you have any?

Steve, I'll let you know as soon as I can find out if it was an "accident" or "some new tecn"

Glenn

thanks Glenn

 

[Glenn Quarles]

Steve, I have found some info for you.

It looks like they put a 8013 P/S in the engine instead of the normal flat top 8048 P/S. The 8013 in that engine is a VERY good P/S...it is just not the traditional flat top like most of us are familiar with. This is the P/S that comes in the TX21R1WC/MS engines.

The difference you are seeing in the angle between the top of the piston and squish band is a little deceiving. The dome on the top of the piston is actually a 66mm radius (not a flat angle) and so depending on where/how you measure it you will come up with a different number. It is OK that the head clearance will be slightly different across the width of the squish band.

I would suggest running it like it is...I think Bob will be happy.

Please let me know if you have any other questions.

Glenn