RGA / RGS head Vs Jota Series 2
- Thread starter GT
- Start date
Marmite
Hero member
GT said:
As far as I understand, the RGS head is the most developed. It certainly seems to be the most wanted. The earlier series 1 heads have various issues at different times. Not heard of any particular issues with series 2 heads (and the head on my series 2 Jota gave me no problems, unlike the rest of the engine :
).All triple heads are interchangeable (although a very early 3C head wouldn't work with the normal carb stubs).
Pete
breganzane
Hero member
- Location
- NSW Australia
Aside from detail improvements, cam block grooves are deeper on RGS heads (7 vs 4mm IIRC). RGS camblock locating bosses need to be relieved to fit on earlier heads, otherwise they are interchangeable. Have done so myself, no problems.
Cheers
SteveB
Cheers
SteveB
Glenn,
The actual casting of the final 120? series heads is the strongest in all aspects, as all the cracking issues have been dealt with. In respect of porting/valve sizes, the 1000SFC type (CR) is the best choice.
Never understood the "Jota" exhaust valve sizes, seems the factory didn't either.
They quickly reverted to the early 35mm exhaust valve for the RGS and went even smaller with the 1000SFC. Around 1982, Cico confided to me the Jota sizes were crap and that the factory actually used 34mm ex. valves in the works triples as far back as '74!
Although all triple heads are interchangeable, there are subtle differences along the line. Apart from the inlet stubs and cam bearings Pete and Steve mentioned, a few '80-ish heads were fitted with thin-walled dowels over the head studs at the "corners" where the o-rings are. These prevent the o-rings collapsing and blocking oil flow. The cylinder block needs modifying to fit these heads.
piet
The actual casting of the final 120? series heads is the strongest in all aspects, as all the cracking issues have been dealt with. In respect of porting/valve sizes, the 1000SFC type (CR) is the best choice.
Never understood the "Jota" exhaust valve sizes, seems the factory didn't either.
They quickly reverted to the early 35mm exhaust valve for the RGS and went even smaller with the 1000SFC. Around 1982, Cico confided to me the Jota sizes were crap and that the factory actually used 34mm ex. valves in the works triples as far back as '74!Although all triple heads are interchangeable, there are subtle differences along the line. Apart from the inlet stubs and cam bearings Pete and Steve mentioned, a few '80-ish heads were fitted with thin-walled dowels over the head studs at the "corners" where the o-rings are. These prevent the o-rings collapsing and blocking oil flow. The cylinder block needs modifying to fit these heads.
piet
Rufustbear
Hero member
- Location
- Manchester
series one ( 1980 big valve head) are fine just get a few thou taken off the valve edges stops them touching and throw away the short cam buckets