Thread: Riva Valve Train EXTRA Washer
02-22-2011, 05:16 AM #1
- Join Date
- May 2007
- Auckland, New Zealand, New Zealand
Riva Valve Train EXTRA Washer
So I am stripping down this spare head I have acquired. It has the Riva Retainers and spring kit in it. And when I get to the Riva spacer/base washer I find a second washer underneath that, sitting on the valve seal. Its roughly .78mm thick, silver, obviously a valve spring spacer/washer but not what Riva puts in their kit. As anybody got a theory as to why it would be there. Somebody must have thought it was a good idea. Riva didn't. The engine had been running only a S3 Riva wheel upto about 8600-8800rpm. I already run the Riva kit that high in other engines and don't have the extra spacer, just the standard Riva set. I know it is going to increase spring pressures, but is it neccessary when you are already running Rivas springs and spacer. However I do plan on running this new engine to at least 9000rpm, maybe more.
02-22-2011, 05:57 AM #2
You should be good with the Riva kit alone up to 9k rpm.
How many hours are on those springs? I would check the tension that the springs have because if it has alot of hours it might have lost some tension.
The Riva springs should have around 90 psi of spring tension.
02-22-2011, 09:16 AM #3
Thats a 30thou shim . Who ever has worked on it before has put them in to get the correct install height for the spring. Probably had seats cut etc so required a shim to get install height back. Take that shim out and you will lose seat pressure!!!!!
02-22-2011, 10:02 AM #4
Sounds to me like someone put a set of rotax spacers in as a precautionary measure but not needed. I have a set here I will measure.
Correction: measured a rotax shim and only measures 18 thou so it's not them. Plus I just caught that you said the spacer was on top of the seal instead of under it.
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