I'm installing a Edelbrock Performer intake,heads, and 1.6 roller rockers on a set of 260hp Merc 350's. I also plan on upgrading the exhaust to either GLM or EMI Thunder 4 inch exhaust.

Will I need to recalibrate/re-jet the Rochester Carbs???? Will be boating at LOTO or surounding Missouri lakes

If you are moving more air through the engine you will need to retune carbs, I would probably gowith the emi exhaust, I think glm is mostly aftermarket stock replacement pieces. Randy

With all the other mods why not cams as well Edelbrock has a complete top end kit that includes everything but exhaust

+1

Well the original reason is because my boat is the Cobalt Condurre 269 and Its heavy with a deep v and no steps. I didn't want to lose any low end as the boat is pretty sluggish out of the hole and at lake of the Ozarks I can't run but around 25 to 30 on the weekends without getting tossed around pretty good. The other reason was I checked out thse specs of the Performer cam compared to the 260 cam and there wasn't a great deal of difference. I just really didn't want to get into the motor that far.

I also would have rather went with roller cams if I was going to swap and that was more money than I wanted to spend on that part of this.

My biggest goal in this is to lighten up the back of the boat significantly, improve hole shot, and reduce planing speed if possible with more low end power and the lighter weight. I figured I might pick up a little on the top end but figure the old boat is probably never going to be very fast. I was also hoping this project would make the boat more efficient too.

You are spending allot of money to lighten the load on the back of the boat. You will not notice much if anything with the changes you are talking about.
Becarefull if you change cams, Edelbrocks are for automotive engines, just watch the LSA if you go that route.

IMO unless its broke keep what you have and enjoy it. Spend the money on beer and expensive gas. You will be ahead in the long run.

Well I hate to hear I won't notice much. I had one set of edelbrock heads just laying around so I only bought 1 set of heads and an intake.

I guess I probably should have left it alone but I blew a drive coupler and the engines had to come out. I figured why not since they were already out and 26 years old. I guess my biggest hope was the slower speed performance, hole shot, planing speed, etc. would be better, and I hoped that the difference in weight may cure the porpoising problem along with the change of props from clevers to 1st generation Mirage propellers.

I did not catch the part of being 26 year old engines and you had them out. You said you did not want to tear into them.

I would rebuild both engines, go to roller cams, put good exhaust valves in the Edelbrocks, then yes you will see a slight noticiable difference.

This thread started out asking about jetting the carb

Any ideas on what metering rods or , jets I should start with?