manifold crossover filled for 38's

[sjetrider]

I was thinking that only one piston draws at a time and that with a crossover that piston can draw some from both carbs when needed at higher rmps??? But what do I know. I would think blocking the crossover would in a sense cause your boat to run as if it were running a single 38mm carb?

 

[#ZERO]

I was thinking that only one piston draws at a time and that with a crossover that piston can draw some from both carbs when needed at higher rmps??? But what do I know. I would think blocking the crossover would in a sense cause your boat to run as if it were running a single 38mm carb?

Filling the crossover passage on the intake manifold greatly improves the pulse signal clarity to the fuel pumps and makes the carbs more tunable.

It's a great idea to fill the crossover on the 38's because they only run a single fuel pump and it helps provide more fuel flow on the top end.

The passage is originally intended to offer smoother low-speed response for the stock engines.

Devcon Aluminum Putty is what I used to fill in my 760 intake manifold.

Then I used 120 grit sand paper on a glass table to sand it down smooth and finished it with 600 grit wet sanding.

 

[sjetrider]

Filling the crossover passage on the intake manifold greatly improves the pulse signal clarity to the fuel pumps and makes the carbs more tunable.

It's a great idea to fill the crossover on the 38's because they only run a single fuel pump and it helps provide more fuel flow on the top end.

The passage is originally intended to offer smoother low-speed response for the stock engines.

Devcon Aluminum Putty is what I used to fill in my 760 intake manifold.

Then I used 120 grit sand paper on a glass table to sand it down smooth and finished it with 600 grit wet sanding.

I agree with all the above as I stated in an earlier post. But, would you not need to go richer when eliminating the crossover??????

 

[Matt_E]

I agree with all the above as I stated in an earlier post. But, would you not need to go richer when eliminating the crossover??????

No. The mod brings in greater, clearer signal to the carb in question. That means more airspeed, and more vacuum through the carb. That means it will pulll harder on those jets.
So, if you want the same amount of fuel as before, you'll need to decrease jet size.

 

[SUPERTUNE]

Decrease jet sizes and fuel pressure (higher pop off) for stronger signal. Crossover between manifold runners means weak carb signal means you need richer jetting formats.

 

[Matt_E]

:biggthumpup:

 

[douglee25]

I stand corrected. +1-MattE 0-Doug :smile:

Doug

 

[SkiDaddy]

WOW, that is interesting.
I would be curious to see what you end up with. Please update this post once you get the non crossover mnfld. tuned.

It's a little too late, I'm running OEM 44's now - with a filled crossover.:biggthumpup: Finally got the jetting perfect, running 105 mains, 120 lows, 25 PSI pop-off. Pulls clean & hard from off idle to a very strong top end.:woot: :woot: :woot: :woot: :woot: :woot: :woot:

 

[cukie alicea]

i im goint to do tha intake c how work !!!!!!