Oliver Super 77 Gas Head

RCP

Well-known Member
Location
Grove City Pa
I am trying to understand the evolution of cylinder heads for the 77 series of gas engines. I have researched the AGCO online parts books, and it appears to me that although the parts numbers change, the Super 77 head has the same valve sizes as the 770, 1550, 1555 and 2-70 head. Do the later vintage heads have a performance advantage over the Super 77 head?

Thanks
Rich
 
Rich: What do you mean by performance advantage? One of the changes resulting in part number changes was the installation of exhaust valve seats and those seats were changed several times again changing the part numbers. Looking for larger valves, have a machine shop install valves for a 3-5/8 inch bore 550 engine.
 
I meant engine performance improvements, such as higher compression ratio, better intake and exhaust ports etc.

Thanks
Rich
 
The compression is slightly higher on later engines. Me, when I worked in the shop I had a set of bowl cutters and I could open up the ports as well as install the 550 valves. Do your homework, check your CC's and do some port work. MY 2 cents worth.
 
if it has the same valve spacing as a 770 then 880 valves go in nicely with a thirty second space between .
 
just checking the Nebraska tests shows the 770 head has slightly smaller pocket 7.3 to 7.0 compression .
 
The 1550 has a compression ratio of 8, however the bore is 3-5/8 as compared to 3-1/2 for the Super 77 and the 770.
 
taking the bore to 3.75 will take the compression ratio to 8.16 to 1 and with a 30 cc dome 11.4 to 1 , it will go keep it to .5 high .
 

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