A guy has a 1991 boat for sale ......says it has HP500s in it (carb) sounds fishy to me......but how can you tell?.......the numbers on the block?......oh yeah, and what year did they come out??

Back in 1991 they were either HP465 Gen IV or Gen V..they both the 465's and the 500's in 1994..but for sure the 500 is no older than 1994..their first full year was 1995....to tell wether it is a 500 or not is very simple..they were all painted mercury racing blue..and the valve covers say mercury hi-performance racing on them..the old 465 version was black in color but the flame arrestor said HP465 on them

I did forget to mention though, the 500 bulldog was built around 1990...basically the same engine as the HP500 only it was 540CI...

The regular HP500/502ci came out in 1994. The 500/540ci were made from 1990 until about 1998.
All the blocks and heads are painted BLACK. The intakes, carbs, valve covers, pulleys, and other misc stuff is painted blue. True HP500/502ci are Gen V or VI blocks.

Is he saying that these are original engines????

the motors are not the traditional HP500 colour scheme.....thats the problem

thanks for the reply......do you know if the 465 has a hyd roller or a flat tappet cam set up?

The HP 465 came with a hydraulic flat tappet ....to convert it to A HP 500, all you have to do is install a roller cam and switch to single plane intake...been there done that !

They had flat tappet..actually all the HP engines did up through 1998..then the Gen + series HP500 that came out in 1999 went to roller lifters, and the 500EFI was the same roller lifter setup from then on. Get a serial number off the engine, that may be the only way to know for sure what you have..other than some disassembly of the engine..some pictures might help!

Actually, all of the HP450 and HP500 had roller lifters from their start in 1994. The Bulldog 500 started in 1990 and there was a Bulldog 575 starting in 1986. If you can get a serial number, go to www.go-fast.com and use their parts look up feature to find your engine.

Well, don't take this to the bank, but...Gen IV & V had flat tap & Gen VI had roller lifters...for the most part..but not always.