When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
85-90 is an average @400 rpms. If you can get the engine to turn over faster than that,then yes you can show higher compression readings than the manual calls for.It's all because of the decompression device on the exhaust cam.