Cyinder head, bolts, valves

The original heads were cracked and some valve seat wear.

 There was some existing repairs. The threads and fins were good.

 New reproduction cylinder heads manufactured by STD developments were purchased. New Black Diamond valves and guides were fitted. The seats were cut and valve lapped in.

There was a tiny pin hole in the casting leading to the oil drilling that fed the rockers. Oil leaked profusely (at mains pressure). Arrow indicates hole.. (Click on pic to blow up).

The repair was made using 3/16" brass tube from a model/hobby shop. I bought a 12" length chosen from a large selection of tube, rod etc. The drilling from the head gasket face was first cleaned up with a 3/16" reamer then carefully cleaned with acetone. Loctite 620 was used because of its' high heat rating. The chart said resistant to 230°C (446°F). Overnight cure before testing to 30 psi. Despite the close proximity to the combustion chamber, 230°C Loctite sounded reasonable especially when considering the oil flow would help draw heat away.

Panheads have 5 head bolts per head/barrel. Some of my bolts had yielded so I elected to upgrade to Shovelhead type which supercedes them by part# 16814-77.  Pictured is Shovel type to left. OEM Pan type to right..

I zinc plated these bolts as part of my refurbishment.

I bought 2 NOS bolts. The packet was crumbling but the bolts were perfect. Pan washers were used to achieve correct length.

New STD Development heads were fitted and these bolts were checked for length. Instructions warn than the bolt under the intake can break through into the port. Mine were clear by 3mm/1/8".

I used locally available valve guide seals with Teflon wiper. They were too long so I trimmed the bottom, losing the circlip and groove. I used hi-temp RTV to glue them in place after thorough degreasing with acetone.

The pan cover screws were not cut deep enough by the maker (STD). They are 10-24 UNC, same TPI as BSW. I hunted and hunted for a 10-24. I did not have one amongst the hundred or so taps I own.  A friend had one in a large set. I borrowed it but while it was brand new/never used, it would not cut the thread! I was as though the tap was blunt and simply slipping over the surface. The further I screwed it in, the tighter it got. The tap was marked "carbon steel", not the preferred HSS (high speed steel). The head material is very hard and difficult to work. I gave up and returned the tap. I had a BSW 3/16" HSS tap and I pondered over whether it would do the job. Especially I didn't want the screws to be a loose, floppy fit in the thread. I drilled and tapped in scrap aluminum and was happy with the result so I proceeded to deepen all pan cover screws holes. The BSW HSS tap was up to the task and the screws fitted nicely.

I made an adaptor to fit a 3/8" drive socket set to tighten and torque the bolts.

Thanks for viewing.