Jetting a cross-drilled 2.5 intake

[nitro_rat]

Good to have options! I prefer Marine Tex in most cases because the heat from welding can warp stuff. Anything non-structural I try to epoxy.

[Baker343]

James Perry lil 2L 5 petal crossed drilled
https://youtu.be/Z1swTfzN-uE

[rjdubiel]

Update, I swapped to a stock 2.5 200 intake (not crossdrilled ) and went out with my buddies and with two in the boat we ran 93 with 1.87 and 26 yamaha. Running 80 mains with wh46 carbs. Starting to test my new to me 20p for drags and I ran 78 mains in 2 and 5 and 80 on the rest. Still 1279 and 1330 on egt's and wet piston tops. Dark brown plugs. Jetted down and will go.again this week and hopefully big improvements.

[Merc 2.5]

Update, I swapped to a stock 2.5 200 intake (not crossdrilled ) and went out with my buddies and with two in the boat we ran 93 with 1.87 and 26 yamaha. Running 80 mains with wh46 carbs. Starting to test my new to me 20p for drags and I ran 78 mains in 2 and 5 and 80 on the rest. Still 1279 and 1330 on egt's and wet piston tops. Dark brown plugs. Jetted down and will go.again this week and hopefully big improvements.

Sounds like its kicking ass , doin alot better with that intake?

[rjdubiel]

Yep. Much better throttle response on the bottom.

[Merc 2.5]

Yep. Much better throttle response on the bottom.

Did it turn more rpm as u jetted down?

[rjdubiel]

I ran the same jets and it bogged on takeoff but still went well on top end (80's mains in all) as that was where I was jetted at with the crossdrilled intake. so then went to 78's with 80's in 2 and 5 like I jet a 2.4 and it picked up some rpm as I am getting closer to the correct jetting. You can still feel it bogging till about 300 feet when you WOT from an idle. I went down again to 76's with 78's in 2 and 5 but have not taken it out yet. I do not think I would run this lean of jets to run the river. I would jet 80 in all if I am going to do long river pulls, maybe 78 with 80's in 2 and 5. But with the leaner jets I am just tuning for 800 food drags, I think I am going to need to go to 74's with 76's in 2 and 5 with my 2:1 lower and a 20p yamaha drag to get me enough RPM to run max speed of 75 mph for my class (Lake Racer 1). I am going to run the next faster class with an 85 mph max speed (Lake Racer 2) also at the next race. Hopefully I can turn my 22p 8700 rpm or so to get there in 800 feet!