2300 350 cfm jet reduction?

[stu simpson]

As of yet I have failed to find a 275 cfm 2300 holley for my 68 800 w/266. Nobody has any used/core for rebuild, and 'new' holley carb sellers insist they don't exist (including the idiots at holley). I do not have a Holley master cross book nor do I know anyone who does, so I am having a hard time deciphering the three I have. I have two I think are 350's and one I think is a 500. The best cantidate has a list of 2977. What I was wondering is can I rejet the 350 down to the 275 specs, like putting in a #52 or #53 jet instead of the #61 they now come with new? What other components would I need to change, like the power valve etc?

Is all of this just stupid, unnecessary work to get the carb to be closer to the 275 settings? My mileage has been terrible with the rebuilt 350, and I don't know what is in it anyway. All other engine settings are nominal and I am down to the damn carb again.

Or has someone found one of those elusive 275's that they want to lay on me?

[M. Mayben]

Stu,

Backchannel email comin' to ya.

MM

[Tom Walker]

The only difference between a 270cfm and 350cfm is the size of the ventuies (the 275cfm having smaller ventuies). A 350cfm carb. should be ok on a 266. Have you tried one out, yet?

Stu,

The old Holley Reman web site had part numbers for rebuilt Holley carbs used on IH vehicles. I down loaded that info some time ago and have it on my PC.

I just check on two of the part numbers listed in that info (64-3141, 64-3257 ) and PartsAmerica.com shows both are available for under $200.

If this is an option you would like to persue then give me a call or send an email and I can share the info with you.

Doug

[stu simpson]

Doug, I will check on those numbers, but when I last checked Holley was only offering 2210, 2245 and 2300 350 and 500 cfms, nothing else for 2bbl. Anyone who offers 2300 new or rebuilt will say the same. New 2300s come w/#61 jets, too much for my 266. Someone just emailed me about maybe sending a 275 over, I will probably pursue it....otherwise, back to a 350.

Originally Posted by stu simpson

Doug, I will check on those numbers, but when I last checked Holley was only offering 2210, 2245 and 2300 350 and 500 cfms, nothing else for 2bbl. Anyone who offers 2300 new or rebuilt will say the same. New 2300s come w/#61 jets, too much for my 266. Someone just emailed me about maybe sending a 275 over, I will probably pursue it....otherwise, back to a 350.

Stu,

The new 350 and 500 cfm carbs available today are after market carbs designed for racing. That is why the jets are so big.

I suspect there are other 2300 Holley Remaned PN's in that list I have but if you or anyone else are not interested than I'm not going to do the searching.

I cannot imagine Holley using anything but an original IH core (at least the same sized carb) to come up with these remaned carbs that they list for IH applications.

[stu simpson]

True they used IHC cores but the cores are 350's and 500's. When someone brought in a bad carb, they didn't rebuild it they gave them an exchange off the shelf. It's all about volume and inventory. Most of the time, a 275 got exchanged for a 350. You cannot find a 275 by going to Holley, something I have found out the hard way. In fact, they claim they never made them, nor the 270cfm 2300, nor the 230 cfm etc etc. I am sure everyone has had the same experience at NAPA or Autozone or whatever when the counter monkey tells you something is impossible because the computer wouldn't lie and you know different.

Ps most parts counters will not have listings for the 266, some don't go back very far at all, most only want to sell you 2210's and 2245's, doesn't the 2300 go on a Loadstar? etc etc

That is why I have been holding out for a 275cfm, but I might have to go back to one of the 350's.

[stu simpson]

doug, are those p/n's showing for the 275 cfm? I had some 275 p/n's but the holley folks don't list them (at least not anymore...)

Originally Posted by stu simpson

doug, are those p/n's showing for the 275 cfm? I had some 275 p/n's but the holley folks don't list them (at least not anymore...)

They don't actually show a list number or crfm. Below is a segment of the data:
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1968 1000D 266" 2BBL 64-3137 Manual choke; Holley 2300
1968 1000D 304" 2BBL 64-3257 Holley 2300
1968 1000D 304" 2BBL 64-3137 Manual choke; Holley 2300
1968 1000D 345" 2BBL 64-3257 Holley 2300
1968 800 196" 1BBL 64-3134 Holley 1920 79
1968 M1100 196" 1BBL 64-3134 Holley 1920 79
1968 M1200 266" 2BBL 64-3137 Manual choke; Holley 2300
1968 M1200 304" 2BBL 64-3257 Holley 2300
1968 M1200 304" 2BBL 64-3137 Manual choke; Holley 2300
1968 M1200 345" 2BBL 64-3257 Holley 2300
1968 M1500 266" 2BBL 64-3137 Manual choke; Holley 2300
1968 M1500 304" 2BBL 64-3257 Holley 2300
1968 M1500 304" 2BBL 64-3137 Manual choke; Holley 2300
1968 M1500 345" 2BBL 64-3257 Holley 2300
1967 1000B 266" 2BBL 64-3137 Manual choke; Holley 2300
1967 1000B 304" 2BBL 64-3137 Manual choke; Holley 2300
1967 1100B 266" 2BBL 64-3137 Manual choke; Holley 2300
1967 1100B 304" 2BBL 64-3137 Manual choke; Holley 2300
1967 800 196" 1BBL 64-3133 Holley 1904 79
1967 900A 152" 1BBL 64-3132 Holley 1904 79
1967 908B 266" 2BBL 64-3137 Manual choke; Holley 2300
1967 908B 304" 2BBL 64-3137 Manual choke; Holley 2300
1967 M1100 152" 1BBL 64-3132 Holley 1904 79
1967 M1200 266" 2BBL 64-3137 Manual choke; Holley 2300
1967 M1200 304" 2BBL 64-3137 Manual choke; Holley 2300
1967 M1600 266" 2BBL 64-3137 Manual choke; Holley 2300
1967 M1600 304" 2BBL 64-3137 Manual choke; Holley 2300
1967 M700 196" 1BBL 64-3133 Holley 1904 79
1967 M800 196" 1BBL 64-3133 Holley 1904 79
1967 M800 266" 2BBL 64-3137 Manual choke; Holley 2300
1967 M800 304" 2BBL 64-3137 Manual choke; Holley 2300
1966 1000A 266" 2BBL 64-3137 Manual choke; Holley 2300
1966 1000A 304" 2BBL 64-3137 Manual choke; Holley 2300

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The 64-xxxx number is the Holley poart number for the remaned carb.

[G Wade]

So what is typically the best jet size for ideal fuel economy without sacrificing to much power? I'd be interested in Mr. Mayben's back channel email because regarding this topic. Thanks in advance.

Garrett