Dumb OMC big bore carb question

[Snickers89]

Okay, been reading (head spinning) about Looper mods. throughout these threads, its mentioned that the late 80's "Big Bore" carbs had a mid range lean that isn't good for goin slow to big heavy boats. 96 and later carbs are recommended in th emid bore size partially because of the adjustable idle needle.

So......instead of finding a set of big bore carbs and risking the mid lean......

Could a guy "bore out" a late 90's mid bore carb to big bore specs? Anybody tried it? dumb idea? doable? I talked to a machinist friend and he thought it was doable.....but would it be worth it?

Just a dumb thought but wanted to run it by the gurus.

Thanks in advance and take it easy on me.

[roadkill636]

Be kinda like boring out a 16" tire to fit on a 17" rim

[Instigator]

Good question but no.

Those carbs, small, medium and big bore, have a reduced section of the throat that causes the Venturi effect. This speeds the flow through the carb, making it work.
If you bored that section out of it, assuming the meat is in it to do it, that would drastically slow the air flow and the efficiency of the carb.
Their bodies are also plastic, which makes them tuff to modify.

The big bores can be tuned to work on anything, I’ve done it.
But what you get may not be that good.

People way smarter than me swear by properly tuned mid bores.
Their argument is, they do everything better other than WFO.
And then, only on a light rig.

After many attempts to prove them wrong, I tend to agree.

The latest versions of the mid bores are great carbs and properly tuned, do everything very, very well.

Unless you have a bunch of power, on a 500 lb hull, the late era mid bores are best.

[Snickers89]

Thanks guys....

[rude tim]

The big carbs can be fixed so that they do not have the lean spot. Racer knows the key.

[powerabout]

The big carbs can be fixed so that they do not have the lean spot. Racer knows the key.

the secret drilled hole....

[phillnjack]

Well now you have open a can worms.
"the secret drilled hole "

where to drill what size drill and picture if possible .. wont be able to sleep until I know this trick .
and what carbs for what motor are we talking about. ? 3cyl ,v4 , v6 ?
come on spill the beans.

[Instigator]

I know Al has tricks for them he has divulged to me.

The trick I use to tune them is the infamous pullover tubes.
People confuse and way over complicate them.

Al explained to me 20 yrs ago that it’s basically a vent to the float bowl.
Smaller the opening the stronger the vacuum to pull fuel and starts pulling from the mains about 300Rs sooner than w/o.

That made it click for me and have proven the theory billions of times.

MikeR, I think this is what you were asking about😉

20 yrs of notes, specs and measurements.
I plan to be buried w/it and my jet kit.

[mrichartz]

I know Al has tricks for them he has divulged to me.

The trick I use to tune them is the infamous pullover tubes.
People confuse and way over complicate them.

Al explained to me 20 yrs ago that it’s basically a vent to the float bowl.
Smaller the opening the stronger the vacuum to pull fuel and starts pulling from the mains about 300Rs sooner than w/o.

That made it click for me and have proven the theory billions of times.

MikeR, I think this is what you were asking about��

20 yrs of notes, specs and measurements.
I plan to be buried w/it and my jet kit.

EXACTLY. ..Gary'..if you see A trespasser with a printer/copier don't shoot !!
I'm just there for copies.lol

[Instigator]

When we lived in Fla we were a 1/2 from Monty’s shop.

I used to go see him all the time and used to joke about not getting my damn camera past his metal detector!
He always laughed.

He always gave me cart Blanche and the run of the place.
He let me do this because I ALWAYS asked him what pixs I was allowed to post and always stuck to my word.

EXACTLY. ..Gary'..if you see A trespasser with a printer/copier don't shoot !!
I'm just there for copies.lol

[mrichartz]

When we lived in Fla we were a 1/2 from Monty’s shop.

I used to go see him all the time and used to joke about not getting my damn camera past his metal detector!
He always laughed.

He always gave me cart Blanche and the run of the place.
He let me do this because I ALWAYS asked him what pixs I was allowed to post and always stuck to my word.

Gary
That's something missing a bit these days.. respect and privacy....they all have to post every damn thing...
And the stuff in his shop is definitely... life's work and his bread and butter etc..
And letting people in with a camera has to be some respectfull people...


Michael

[mrichartz]

Gary
Jets are sore subject...had someone who had tons of them... But for some reason got rid of all of them thinking I won't want them.. lol.. told him are you crazy would have paid more than dumping them out..oh well

Oh and you have to pass a copy on to the younger ones..
Got to be a kid looking to do this..

Michael

[Instigator]

I left Monty’s one time after shooting a bunch of shots of his gorgeous record attempt 8 w/permission to post them.
Got home and forgot.
They called and reminded me ��

One jets, I posted pics before.
I may have the biggest private collection in the world.
If u figure current discount prices of $10 per, I have tens of thousands of $ of.

And, no kids to pass to.
Only nephews who could care less.

[mrichartz]

I left Monty’s one time after shooting a bunch of shots of his gorgeous record attempt 8 w/permission to post them.
Got home and forgot.
They called and reminded me ��

One jets, I posted pics before.
I may have the biggest private collection in the world.
If u figure current discount prices of $10 per, I have tens of thousands of $ of.

And, no kids to pass to.
Only nephews who could care less.

Hope I'm not hijacking his thread to bad..

Gary,
Are you the reason we can find any jets your hoarding.. lol
And there's kids out there might have to become a big brother to some poor little 2 stroke kid somewhere..
With a little old stock motor dying to get some HP.

Michael

[Snickers89]

Thanks for the chats guys! LOL