2.7 heads, Stock Johnson V6

[Tightrig 12]

Would any Johnson / Evinrude users out there have any input on running 2.7 heads on an 89 johnson v6 ?
The motors are fresh rebuilds with all the best parts. I would like to run the 2.7 heads without gutting the airbox or jetting up 10 sizes....
The boat now is a 23 ft Eliminator Daytona, twin 225 johnson v6's. It currently runs 70mph at 6000-6200 rpm wot.
Any input would be helpful
Thank you

[racer]

Yes they will help and can be run without gutting air box. You will still need to rejet the carbs.

[Tightrig 12]

Thanks Racer for response
Stock jets now are 62 top 4 and 64's #5&6...do you recommend up 10 sizes ?

[racer]

When you gut the air box you go up 11 with no other changes over original stock jets on stock engine.. Just heads depends on chamber depth

[Tightrig 12]

Awesome....thank you so much for input

[Tightrig 12]

Racer...
You mentioned 11 sizes if I gut the airbox.
I would like to make some runs without, can I run the stock jets (62 top / 65 bottom) without being to lean. ?
Or would you recommend jetting 1/2 way to 67 & 70 ?

[racer]

To run without the air box you need to jet like it has been gutted.

[Tightrig 12]

Excellent...
Thank you

[powerabout]

how many sizes to go up if leaving stock airbox and either of the 2 different 2.7 heads?

[Tightrig 12]

Racer recomends 11 sizes up weather you gut
The air box or not. My guess is it will be a little on the fat side with stock air box...always better than lean

[powerabout]

have you measured the 2.7 heads to know which ones you have?

[Tightrig 12]

Chamber depths have been posted on the heads that I have. They came with the boat when I purchased it. Just trying to get the most information possible before i install. I don't want to risk a melt down....he spent $$$ on the rebuilds The boat runs good now, but always nice to have an extra 10mph. I'm thinking Racers advice to go 11 sizes up and not gut the air box, is a safe bet.
That, for me, would be 73D"s for 1-4 and 76D's for 5&6.
Bart

[powerabout]

post the cranking comp once you install them and what fuel you will use.

[Tightrig 12]

I will do that for sure...thanks

[racer]

No I said you go up 11 from stock jets on a stock motor when you gut the box or run without one.