what size carb?

[1967JMG]

i have an OZ 250 head, stock size valves, isky 262 cam, headers, t5 tranny, and 3:73 rear end.
Im shooting between 9:1 and 9.5:1 CR.
What I and trying to find out is what the best 2 barrel carb for my application would be. I like the autolite 2100's but I'm not sure what size would be best to go with... would a holley 350 be just as good?
Thanks for any help and opinions.
JMG

 

[FalconSedanDelivery]

If you can find a 350 Holley Use it, much easyer to tune ( parts availabilty )

 

[CZLN6]

Howdy JMG:

An Autolite 1.21 or 1.23 well be very comperable to a Holley 350 in CFM. The advantage of the holley is tuneability and ease of getting parts and jets. The pluses for the 2100 is annular discharge venturi boosters, very close to right as is, from a 351 application and super easy to rebuild and work with.

Adios, David

 

[1967JMG]

my only concern is getting an oversized carb. I doubt I will ever run the car past 5k rpm. and I was looking at some of the dyno results on the CI site and the 2100 with the 1.02 ventury performed better then the larger 1.08 and that was on a build much involved than mine. Im looking for a good balance of getting the best torque down low, but i'd like to have it pull pretty nicely up to about 4500 rpm...
I've tried sending PM to a few people that have pretty similar builds to mine to see what experience they have had to get any recommendations but so far have not heard anything back...

 

[CobraSix]

To give you an idea of flow:

I'm running a Holly 4V 390CFM (I know they calculate the CFM different for 4Vs I think), and the Oz 250 with an upgraded cam uses EVERY BIT of that carb.

If I weren't working on an EFI system, I'd upgrade to a 500 CFM.

You'd be safe with a 1.08+ for Autolite. The 1.02s are RARE. I have one somewhere in my garage. I even rebuilt it intending to use it. I think I may have a 1.08 as well, somewhere...

However, I ended up modifying the intake for a 4V base and went to a Holley. I still prefer Autolites. Best everyday performance IMHO.

 

[1967JMG]

so would a 1.08 or a 1.14 be a good choice? Would a 1.23 be too big? I dont think I would need a 500 cfm carb. Im not going to be doing much highway driving and and my top rpm is only going to be about 5k. My other main reason with going for an autolite is gas mileage because of the annular discharge...

 

[rocklord]

Doesn't anybody ever read the stuff that Mike does:

http://classicinlines.com/PCdyno.asp

Granted, the head used was his aluminum, but since it is based on the 250 2V, the results should be comparable.

 

[1967JMG]

Doesn't anybody ever read the stuff that Mike does:

http://classicinlines.com/PCdyno.asp

Granted, the head used was his aluminum, but since it is based on the 250 2V, the results should be comparable.

Yes, I've read that, but in the tech article on choosing the right carb it also says that a stock OZ head needs between 250 and 275 cfm. I would consider my build somewhat on the mild side which the website says it would need between 290 and 315.

So im just trying to compare Mikes dyno results with what everybody else in the world is doing according to there experiences.

 

[rbohm]

8) when it comes to carb sizing, if some is good, and mire is better then too much is still not enough. put an 1150 holley dominator on your motor. :rolflmao: :rolflmao:

j/k

when i picked an autolite 2bbl for my old 66 falcon, i grabbed one from an early 70's 302, and it was a bit large but not enough to worry about.

 

[ozconv]

I am building an engine similar to yours (with the exception of slightly larger OZ valves and 1.6 roller tipped rockers with the 264/274 112 cam from CI). After reading the same article from Mike's site, I plan to use a 1.08 2100 from a 69 302 (287 CFM) that I rebuilt with a kit. I only have about $75 in the carb at this point and figure it is a good place to start.

 

[1967JMG]

thanks! I haven't quite decided but i think I'm either going to go with the 1.08 or the 1.14...