• J3-Cub.com is the largest community of J3-Cub pilots, owners and enthusiasts. With over 1000 active members, we have fostered a vibrant community and extensive knowledge base. J3-Cub.com hosts a library of over 13 years of technical discussions, J3 data, tutorials, plane builds, guides, technical manuals and more. J3-Cub.com also hosts an extensive library of J3-Cub photos.

    Access to the J3-Cub.com community is by subscription only. Membership is only $49.99/year or $6.99/month to gain access to this community and extensive unmatched library of knowledge.

    Click Here to Become a Subscribing Member

    You will also get two J3-Cub decals as well!

C85 conversion to C90

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

JimC

Well-Known Member
Supporting Member
Joined
Feb 25, 2007
Messages
14,383
Reaction score
2,255
Most of you probably already have a copy of Continental Service Bulletin M47-16, Supplement No. 1, dated Feb 26, 1960, but in case you don't, it's the one that allows a C85-8 or C85-12 to be converted to the corresponding model C90, including either the 530788 cam with 530872 lifter assembly, or alternatively the 531076 cam with 533822 lifter assembly. This resolves the low lift - low revving restrictions of the presently existing C85/O200 stroker STC's, by providing for the cam and lifter change that increases the lift and revises the duration.

One of the more interesting statements in the referenced Service Bulletin Supplement No. 1, was the following:

"In the original bulletin M47-16 and subsequent revisions, it was stated that conversions from a C85 to a C90 was prohibited. This has now been changed and conversion will be approved when complied with in accordance with the above instructions". Those instructions detail the parts changes required.

Your thoughts? Your preference for the 530788 cam vs. the 531076 cam?

I have a copy of this Service Bulletin Supplement in Word format, if anyone wants one.

It now seems to me like the simplest way to substantially more power might be one of the two presently existing C85/O200 stroker STC's, combined with the cam, lifter, and second valve spring change provided for by M47-16, Supplement No. 1, Feb 26, 1960. That supplement resolves the only reservations that I've had about the C85 stroker STC's.

All the best,
JimC
 

Latest posts

Back
Top