Connecting Rod Bolt Corrosion

I am building up a performance 2 liter street engine to go into my G. Super, which has nothing to do with a Veloce. However, the information presented is worth reading as it applies to Veloce engines.  This article  has to do with corrosion on the rod bolts themselves. I have a small box of used rod bolts and some of them have corrosion on them. I am thinking they are useless as the corrosive spots might be a place where cracks start. So I did some research on the subject.

Corrosion cracks are called “fretting”. This can be caused by moisture, caustic chemicals or other environmental issues. This corrosion etches the metal surface which allows micro cracks to start. When the bolt is put under a stress of being torqued or high rpm, the cracks have a tendency to grow. This will eventually lead to the bolt stretching enough to spin a rod bearing or bolt failure altogether.
On the BME website that builds rods, this is what they say about assembly of rod bolts:

[B][I]During assembly of a BME rod, proper rod bolt lubrication is absolutely critical. Use only high-quality racing engine oil for for this purpose. Do not use moly-based assembly lubricants. Do not use antiseize. Do not use any lubricant other than racing oil or rod damage may occur.

Bill Miller Engineering recommends Red Line SAE30 Race Oil or Red Line Liquid Assembly Lube for rod bolt lubrication. BME is not responsible for damage due to use of improper lubricants.


Disassemble each rod. Blow the parts clean of contaminants with shop air. Pay special attention to the serrated mating surfaces and rod bolt holes. If the connecting rod or bolts must be cleaned, use only a solvent bath. DO NOT use any aqueous cleaning process, aerosol “brake clean” products, MEK, acetone, lacquer thinner or any caustic cleaning process, such as “hot tanking”, as all of these will cause the connecting rod bolts to corrode which may lead to stress-corrosion cracking and bolt failure.[/I][/B]

Next is a text paper related to connecting bolt corrosion for compressors with varying duty cycles. The paper presents some interesting points in the first few paragraphs worth reading.

If your rod bolts show any surface corrosion you might want to seriously consider getting some new ones.


About alfadoc

I have been involved in Alfa Romeo cars since 1970 when I bought my 1600 Veloce spider. It was in 1972 that I started the Veloce Register for 1600 cars. It was in 1998 that I added the Sprint Veloce, 750 Spider Veloce and Sprint Speciale registers. Currently I own 2 Alfas: a 1994 164 Quadrifoglio.and a 1991 Spider "Automatic"
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