77Datsun620 Posted February 2, 2008 Report Share Posted February 2, 2008 just as the title says, whats the CFM for the stock hitachi and the weber 32/36? Quote Link to comment
datzenmike Posted February 2, 2008 Report Share Posted February 2, 2008 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. Quote Link to comment
77Datsun620 Posted February 2, 2008 Author Report Share Posted February 2, 2008 thanks for the answer, Im gonna look into getting a carb down the road, and Barry Grant has a 250 CFM 2 barrel, so I might look into that instead of a weber to replace the Hitachi Quote Link to comment
datsunfish Posted February 2, 2008 Report Share Posted February 2, 2008 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. Quote Link to comment
OL YELLER Posted February 2, 2008 Report Share Posted February 2, 2008 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!!) Quote Link to comment
Z-train Posted February 2, 2008 Report Share Posted February 2, 2008 I'm building a 2300CC stroker based on the L-20.We'll find out soon about the(1) Webber feeding the motor.I would stay away from Barry Grant-not worth the hassle. Quote Link to comment
datzenmike Posted February 2, 2008 Report Share Posted February 2, 2008 A 2.3 liter motor needs 243 cfm at 6,000 RPMs. To use the full Weber carb the 2.3 is good to just under 7,000 RPMs. But again a slightly larger carb than you need is probably less restrictive. Quote Link to comment
ggzilla Posted February 2, 2008 Report Share Posted February 2, 2008 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. Quote Link to comment
datzenmike Posted February 2, 2008 Report Share Posted February 2, 2008 From the early L-16 to the later '80 L20B they used the DCH-340-(and models from 8 to 98 depending on geographical location and year) Quote Link to comment
77Datsun620 Posted February 2, 2008 Author Report Share Posted February 2, 2008 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: Quote Link to comment
yello620 Posted February 2, 2008 Report Share Posted February 2, 2008 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 Quote Link to comment
77Datsun620 Posted February 3, 2008 Author Report Share Posted February 3, 2008 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: Quote Link to comment
LenRobertson Posted February 3, 2008 Report Share Posted February 3, 2008 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 Quote Link to comment
Gene Climer Posted February 27, 2022 Report Share Posted February 27, 2022 Does anyone know the DCH306 CFM. I want to use this on an engine build if the CFM is right. Quote Link to comment
Gene Climer Posted February 27, 2022 Report Share Posted February 27, 2022 On 2/1/2008 at 7:46 PM, 77Datsun620 said: just as the title says, whats the CFM for the stock hitachi and the weber 32/36? Can someone please answer this question? I am wanting to use this Carb in an engine build. Thanks, Gene Quote Link to comment
datzenmike Posted February 27, 2022 Report Share Posted February 27, 2022 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. Quote Link to comment
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