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1098 valve diameter-Head transplants
Posted: Fri Aug 04, 2023 6:32 am
by Tomas
I have a 1098 motor with I believe a 803cc head. I understand all 1098s had a temp gauge fitment near the front drivers side, Although mine goes well I wonder if the valve size is very different on the 1098. Can anyone tell me the diam of the valves on the 1098 and 803cc also 948cc eng if possible?
Re: 1098 valve diameter-Head transplants
Posted: Fri Aug 04, 2023 7:55 am
by svenedin
If you remove the rocker cover then you can see the head casting number and that will tell you what head you have. A standard 1098 head is 12G202
If you are sitting in the car, the tapping for a temperature sender is on the front right of a 12G202 head. If no gauge in car it has a blanking plug fitted.
This page gives information about various cylinder heads and valve sizes:
http://www.minispares.com/article/Techn ... -head-2022
An 803 head has a smaller inlet valve and a smaller combustion chamber compared to a 12G202 1098 head.
- IMG_8997.jpeg (2.58 MiB) Viewed 312 times
Re: 1098 valve diameter-Head transplants
Posted: Fri Aug 04, 2023 8:04 am
by philthehill
- cyl head details (1).jpg (762.93 KiB) Viewed 307 times
If as you believe your engine is a 1098cc 'A' Series unit it should be fitted with a 12G202 head.
The casting number can be found on top of the head under the rocker shaft.
The performance of the 1098cc engine will be reduced if the 803cc head (casting numbers 2A628, 12A1456 or 2A629) is fitted.