EXACTLY..........I had a crappy engine builder that talks a good game and "rebuilt?????" 2 engines for me 2 1/2 years ago. He had done a few drag cars, or so he says, and knew him somewhat. Well after installing/pulling engines 3 times and over a year not getting to boat for various engine problems, I said screw him. Took engines elswhere in 30 days had them back and in and no problems since. In fact last time the engines where out with "other" guy he had them dynoed, made 3 pulls, seemed ok. Then put the engines in run 3 hrs had water in oil from loose head bolts and no sealant on head bolts. So dyno is not fool proof but I would NEVER do another without it. A $5,000 job wound up costing me over $18,000. Now the guy has gall to sue me for $2,500 for micallaneous parts he says I owe him. Be carefull having an engine built in Hattisburg Miss. Sorry for sounding off.......I have court next month.
DO THE DYNO.....and have someone reputable do it and one that has experience with marine engines. I have learned some hard lessons.

Thanks guys allot of good advise/ experience, Ill get it dynoed in the next week or so .

what a dog !!!

We dynoed one of my engines last week ... 4.280 bore x 4.25 stroke . 9 to1 compression , 731 crane hyd roller, oval port Edelbrock rpm performer marine (Ported). 489 cid made 614 hp @ 5600 torque peaked @ 4300.
your 496 should be real close to 625 depending on cam selection.

Bob

I also agree. I drove 400 miles one way to do a complete marine dyno. Wet headers, my fuel system, etc.
Just an example we found that the pin connection for the knock sensor to the computer was not connected and may never have been, causing it to code and retard timing and messing with A/F ratios. This would have never been found without the computers.

I know, anyone have a good lawyer? Is there such a thing?

I spent $700 on the dyno last season to set my engines up. Seemed like a lot at the time but glad that we did. Were able to play around with a lot of different options prior to placing in boat.

Dyno with the engine builder present so he can make the necessary corrections based on A/F and EGT data. You sig says that you're in Indiana. You may contact Pantera28-650HP about th shop where his engine is. I wouldn't think it would be too far away, and well worth running it in a shop with a guy who's business is tuning marine engines. That way, when it goes in the boat, you get to play rather than work.

I live in IL. and drove 400 miles. Can't speak for others but that was my choice after homework. Ask around and do your homework.

what should egt's be on the dyno,and is there a way to figure out vol ef% using bsfc and hp/torque numbers