Hi 

I am planing on rebuilding my 272 eventually, (Not right now, just collecting parts) It pretty much goes like this

272 0.040 over (278ci)
-B intake
-G heads
+10 cc dome pistons
Mummert ram horns
Mummert 270 cam (max 5800)

If I make some number crunching it says that the carb should be at 378 cfm at 83% volumetric efficency and 466 cfm at 100% but I guess this setup would never come near 100%

This is going to be stock(ish) looking/handling truck with some grunt under the hood. So I prefere some streethandling caracteristic like low end torque instead of dragstrip ET performance

So I have been hesitating between the Holley vac 2:nd 4160 model 390 cfm or 465 cfm......

Put out a question in a facebook group and got replies everywhere from "390 is perfect" to " 390 is WAY to small" " 465 is the absolutley minimum" "you could use a 650 at least"

I am at the moment leaning towards the 390 (as the numbers tells me), as I have a hard time understanding that the vac secondary would really be much use on a 650 carb when the numbers says the engine setup only needs abput 390 at the top end??

I know the are some gurus on here that might lead me in the correct way.

Thanks in advance



Best regards Jimmy Carlsson, Fagersta (Sweden) Ford F100 1956, 272 , 3 manual with OD
Follow my restoration on http://dinnerhillspeedshop.blogspot.se/

First, is the vehicle actually going to be used normally as a truck?


Paul

Sure, I will be towing stuff up to 3300 lbs once and a while and the bed will see the city dump more than once.

Not a streetrod of any kind more of a truck. And maybe a redlight race when I feel for it (not very often)

Best regards Jimmy Carlsson, Fagersta (Sweden) Ford F100 1956, 272 , 3 manual with OD
Follow my restoration on http://dinnerhillspeedshop.blogspot.se/

I don't think you're going to be towing 3300lbs with the 270 cam.  That cam is getting closer to the street rod / hot rod end of things and your low end will not be as strong.  The rpm range for it is 2000-5800.  You need a cam that works from idle for towing.

I stand by my recommendation that a 465 is the minimum and a 570 will probably work well for you.  Err on being a little bigger than necessary with a vacuum secondary carb. 





Lawrenceville, GA

I am open to suggestions would the 265 cam be more appropriate.

Or is it the stock cam that is need?



Best regards Jimmy Carlsson, Fagersta (Sweden) Ford F100 1956, 272 , 3 manual with OD
Follow my restoration on http://dinnerhillspeedshop.blogspot.se/

Or are there any other cam manufacturer and grind you could recomend?

Best regards Jimmy Carlsson, Fagersta (Sweden) Ford F100 1956, 272 , 3 manual with OD
Follow my restoration on http://dinnerhillspeedshop.blogspot.se/

The rear axle has a ratio of 4,89. That should effect the towing as well to the positive....

Its also a manual trans, alot more formgivning than an auto when towing

Best regards Jimmy Carlsson, Fagersta (Sweden) Ford F100 1956, 272 , 3 manual with OD
Follow my restoration on http://dinnerhillspeedshop.blogspot.se/

Are you sure the rear ratio is 4.89 and not 3.89?
I have a 3.89 rear with a 3 speed OD, 292 with a Isky E4 cam and use a 390 Holley and have no complaints, runs great in town and on the hiway. I did go to a larger squirter and upped the main jets a little..

I think with the rear end ratio the 270 should be fine and I'm with Charlie on the 465 cfms Holley, even the 570 would work. I'm running around a 265 duration in my stock built 292 in my 56 convertible and feel like it needs to be a 270 duration cam at least. We tend to forget with our solid lifter engines we lose a little duration and lift with our lash adjustment which lowers the cam profile some from what I've read.


-Gary Burnette-

Hi,my truck has an Isky E4 cam G heads and the 3.89 rear axle and i use a 390 vacuum secondary and 1 inch spacer and it is a pleasure to drive even in traffic with really good low end torque,with manual trasmission you should have no problems with this set up.
Smaller carburetors have a better signal at the Venturi by lower rpm than larger,on the othe other end you loose power on higher rpm range.