Dhadley, Intake manifold mod.

[R.Johnson]

When you cut out the wall on the V/4 manifold, I'm not sure how you did this. Could you possibly show a sketch, or explain a little more about it. What engine had the 1 1/4 in. carbs? Thanks in advance. At 7400 RPM, that engine you built must of had quite a sound.

 

[walleyehed]

Re: Dhadley, Intake manifold mod.

^

 

[Dhadley]

Re: Dhadley, Intake manifold mod.

Basically you remove the wall between the 2 intake passages. Then each cylinder can draw from 2 carb venturis rather than 1. And it looks factory stock with the carbs on. Its almost (well, about 75%) as good as running 4 2 barrel carbs without the linkage nightmare. <br /><br />The 1 1/4" carbs I like the best were on V6's and mainly on V6 Sea Drives. We played with them all from 1" to 1 1/38". The smaller the venturi, the more acceleration and the bigger (to a point) venturi meant more top end.<br /><br />Take a carb mounting gasket (late model) and cut the center out so that the gasket is a constant width. Lay that on the manifold. Thats what you remove. Leave the center rib in the manifold about 1/4" thick.<br /><br />Dont forget to fill the hole in the carb base side with epoxy.<br /><br />Now were havin fun!

 

[walleyehed]

Re: Dhadley, Intake manifold mod.

Dhadley, I've got 1-1/4's on my 115......what would this do longevity-wise, if I cut that out??????

 

[Dhadley]

Re: Dhadley, Intake manifold mod.

It wont hurt anything as long as its done right. However, it doesnt help much on motors that wont turn over 6000. At least thats what we found here at sea level.

 

[walleyehed]

Re: Dhadley, Intake manifold mod.

I've got a stock intake manifold I've been looking at here, and am studying what you are describing to cut out. From front to back you have to cut all but 1/4" (remaining) on the crank side of the manifold....am I reading you right?? The divider between the 2 ports, looking from a side view, could the center web be removed in a "C" shape, like you took a bite out of the center....this would allow flow from both venturies, right???<br />Next, and final question...would it allow more power in the 6k range...as in more pitch capabilities, or would this simply increase the power curve at higher R's??<br />I think short of adding 2 more cylinders, I'm pushing it as it is now, and may just leave it as is.....it does run well, but always looking for a little more I guess.<br />Thanks!

 

[R.Johnson]

Re: Dhadley, Intake manifold mod.

Dhadley: I measured the manifold on the 135. From the face of the manifold, to the reed cage seats is .875. Would I plung down .625 to leave the .250 that the reed cages seal on? Am I looking at this correctly? That would leave a channel .625 deep, and the width of the manifold bores under the carbs.Could I use the carbs from an early V4 with the adjustable low speed needles to solve the low end of the jetting problem? As I recall, the 1969, 115 had 1 5/16 carb bores.