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STock Hitachi CFM rating


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I believe the 32/36 is around 270. the Hitachi is much less.

 

BTW: an L20B revving at 6,000 RPMs needs 211 CFM. A larger carb can't give an engine more air, it's more likely that a larger carb is slightly less restrictive than a smaller one. The motor doesn't have to work as hard to breathe so there is a slight power gain. To use the full 270 CFM the poor L would have to rev to 7,700 RPMs.

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Dont get technical just do the weber.If not,a nice hitachi is fine.If its a decent hitachi I can rebuild one and make it run better than the weber but I like the many bonuses of a weber.(dude look at my weber)Mostly it requires less maintenance and easier to work on.DO IT.

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Dont get technical just do the weber.If not,a nice hitachi is fine.If its a decent hitachi I can rebuild one and make it run better than the weber but I like the many bonuses of a weber.(dude look at my weber)Mostly it requires less maintenance and easier to work on.DO IT.

 

 

by less maintenance if you mean over 30k and have not had one problem with my stock Hitachi?..Yep Boys and Girls, my son Ray and I have been running the stock carb for these past few years and have NO issues with them at all...granted the weber is a bit simpler to work on, but, given the time to learn it, The Hitachi is not hard either....just my opinion.(and we all know what that is worth!!)

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Sure the Weber 32/36 will feed a 2300cc engine. There were literally millions produced and fitted to the Ford 2300 and the Chevrolet 2300.

 

Remember that 2-bbl and 4-bbl CFM is measured differently and cannot be directly compared.

 

 

By the way, which Hitachi is fitted to the 620? The smaller Datsuns used a DCH306, which is only a 30mm primary and was only good for about 85hp MAX.

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Lol, I started a fierce debate on carbs :eek: I know i can get a weber and all said and done, but why be like everybody else?!? And its really that big of a hassle to get a BG carb instead of a weber? cause i would need a diff adaptor plate? I like BG Demon carbs personally i have had a few, and i like them way better that Holley or Edelbrock, i dont have JY around here that i can go to to get a weber, everything here is crushed for scrap if its older than mid to late 80's. And im just stating my opinion,(so nobody needs to get offended) even though opinions are like assholes, everybodys got one :lol:

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Lol, I started a fierce debate on carbs :eek: I know i can get a weber and all said and done, but why be like everybody else?!?

 

So that you dont have to start a "HOW TO TUNE A BG ON A L-SERIES" thread a few weeks after you install it.:lol:

 

Just my opinion, sometimes you dont need to fight the trend. The trend is a trend for a reason.

 

But we are here to help when you need it:)

 

Jason

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So that you dont have to start a "HOW TO TUNE A BG ON A L-SERIES" thread a few weeks after you install it.:lol:

 

True, but if i do a BG carb,then i could put up a how to page ;) but i know what you mean about it being a trend for a reason, its a proven Carb that works good, but if people dont try different stuff, then stuff never happens, and that would be boring :lol:

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If anyone is cheap (like me) and needs to keep running a Hitachi, here is a link to an good article:

http://dimequarterly.tierranet.com/articles/tech_carb_tuning_guide.html

This is Part 1 of a two part series that ran in Dime Quarterly. I think the second part is available from DQ for $4 or thereabouts. Well worth the money. There is also Weber 32/36 jetting/tuning info included. The author makes a good case that you need to re-jet either make carb if you do engine mods - cam, bigger exhaust, whatever.

 

Len Robertson

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  • 14 years later...

I believe the CFM for the 32/36 was around 270.

 

Hitachi's are not rated by CFM. L20B and L16 (at least on the 620s) carburetors are 30/34 so in theory might flow less than a 32/36. Take into account the size of the venturi that is necessary for producing a vacuum to suck in fuel and how much it blocks flow. Weber 32/36 and Hitachi venturi are not going to be the same.

 

L16 and L20B car carbs run the same primary and secondary jets which sort of bares out what I have always believed that a carburetor simply mixes gas with air relative to the amount of air that passes through it. A carburetor doesn't know what engine is under it only the amount of air going through it. An L16 at 6,000 needs about 169 CFM. An L20B at 4,800 RPMs needs 169 CFM. Why would an L16 need smaller or an L20B need larger jets??????? Naturally the L20B at 6,000 will need more air, like 211 CFM.

 

So if an Hitachi carburetor, is jetted for a good mixture it should work equally well on any displacement engine provided it can flow enough CFM demanded of it. 

 

Now all this said about jetting changes.... doesn't a Weber primary jet also have something to do with the idle mixture? Now there, an L16 will use 20% less air than an L20B idling.

 

 

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