Engine Modification Help: Automotive Technician Q&A

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The discussion focuses on the impact of oversized studs on oil flow in a 1982 KZ1000 "J" engine following performance modifications. The larger studs reduce the cross-sectional area for oil flow to the camshaft bearings, raising concerns about potential oil starvation in the bottom end. Participants emphasize the importance of maintaining OEM oil flow characteristics to prevent engine damage and suggest that enlarging the cylinder head stud holes could help restore flow without compromising structural integrity. Calculations indicate that while enlarging the head hole can return flow to original levels, it may eliminate beneficial turbulence created by the original design. Ultimately, a cautious approach is recommended, with one participant deciding to slightly enlarge the head holes to balance flow without risking overcompensation.
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Pressure might actually increase in that hole. Pressure doesn't matter as much as flow rate in cases like this.

Heads get hot. Heads with insufficient oil get even hotter, due to possible insufficient lubrication as well as decreased cooling rate (heat getting transferred into the oil).

The increase in head temperature can increase risk of warping heads. The higher peak temps can also weaken fastener joints such as valve cover gasketed joint, exhaust, and head gasket. Higher peak temps will also expose the small amount of oil in the heads to higher temperatures. That means the oil will degrade faster. The light ends of the oil molecules burn off more quickly, which will leave you with a lot of sludge. That sludge will further worsen the root cause of the problem.

Keep an eye on the engine's oil level. Also be sure to do a leakdown test. Compression tests are good, but leakdown will tell you a lot more. Compression tests won't change much until the engine is very worn out.
 

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