Using Automotive Parts on Marine Engines
I had recently become a Vessel Examiner for the Coast Guard Auxiliary when a boat owner came to me with a question. He had work done on his inboard engine, and the marina had installed an automotive carburetor. Other boaters told him that that would likely cause his boat to explode, and he was, in a word, “concerned.” He talked with the marina and was assured that all was well, but he was not convinced. Many marine engines are merely slightly modified car engines, so shouldn’t automotive parts be OK?
When we do a vessel courtesy exam, we do look that the backfire arrestor is Coast Guard approved, but we do not check the carburetor at all. I checked with asked other vessel examiners, but nobody had ever had that question before. I also inquired with the active duty side of the Coast Guard, and got no more help there.
The boat owner was really hellbent on finding out, and had found that the Coast Guard does indeed have strict specifications for what carburetors can be used on marine engines. (If you really are interested in the requirements, look in CGD 74-209 42 FR 5950 Jan. 31, 1977 (https://www.govinfo/app/details/CFR-2021-title46-vol7/CFR-2021-title46-vol7-sec182-415) as amended by CGD 7798 42 FR 36253 July 14, 1988 Sec. 183.526) The simple answer, it turns out, is to check with the manufacturers. While some marinas might not know which carburetors are CG approved, the manufacturers do indeed know and will quickly point you to a list of their approved parts. The requirements are very specific and detailed, and looking at the box that a carburetor comes in might not even have the detail you need. One possible source of valid marine carburetor information for your boat may be on the National Carburetors website, https://nationalcarburetors.com/.
The bottom line: Some automotive parts for marine engines could cause a fire onboard, but there are automotive parts that do qualify. Check with your boat engine manufacturer to ensure that you are using the right parts for your marine engine.