Is it possible to inspect the primaries with just the valve covers off? If so do you need a borescope? Or does the timing cover have to come off?
Thanks in advance.

 

It's difficult to see down there without the timing cover off, although not impossible. To really get an accurate assessment, a scope would help a lot...I bought a Milwaukee model last year and it's helped me out several times already.




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If you seach on ebay for borescope, there are some ultra cheap under $20 Chinese borescope cameras that plug in a PC USB port. I have not tried them, but they may be adequate for this job.