Drylakes, blacktie- thanks for that estimation. I’ll be sure to post the results. I just have to find a tuner with experience tuning carburetors on the dyno, not too many here in Australia unless you’re in the know.

Cliff- thanks mate, so happy with the heads now!


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

With the engine as is, what would you estimate the safe max rpm? After a bit of reading it seems like 5000-5500rpm max is the limit for safety. What are the limiting factors? Is it the just weight of the rotational mass and the lack of roller rockers, roller cam for the Y block?

What is likely to happen if revved up to 6000rpm frequently? (Don’t worry, I keep it below 5000rpm)


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

My two cents worth here.
 
The bottom end is more than capable of running up to 6500 rpm when all is correct in that area but head/intake flow and valve train will be your limiting factors.  Dead stock 2V engines were typically peaked out at 4500 rpm and would eventually go to 5000 rpm if just staying in the throttle before valve float set in.  In your case, I suspect that your engine will be peaking at 5400-5500 rpm with the camshaft you have selected along with the other parts.  As a general rule, the 2.02 inch intake valves are not as good at producing low end power in those small bores as the 1.92-1.95” valves but can understand using the larger valves when trying to salvage the existing valve seats.  Intake valve shrouding tends to be more of a power deterrent than whatever is gained by increasing the actual valve size and especially when dealing with the smaller 272 bore sizes.
 
While the Carter and Edelbrock carbs can be counted on in cranking up and idling just fine, they can be finicky in getting the tune just right for making those peak power numbers.  You will need a collection of jets and metering rods on hand to make adjustments during the dyno session.  Keep in mind that those carburetors are fuel pressure sensitive and may require some float adjustments to compensate for your particular fuel pressure.  Having a wide band oxygen sensor hooked up will speed up the tune up process versus just reading the spark plugs.
 
Consider removing some weight from the secondary counter balance weights to allow the secondaries to open a little earlier.  I do that using a scale to measure first the overall weight of the counter balance weights and then take the same amount off of each weight.  If you have one of the newer Edelbrock AVS carburetors, those do have externally adjustable secondaries and eliminates the need to pull the cover off of the carb to manually modify the secondary opening rate.
 
My estimate for rear wheel horsepower will be 200-210.

Lorena, Texas (South of Waco)

Thanks Ted, that’s some good info!

I’ll keep in mind valve float up around 5500.

The edlebrock carb is a new performer 14063. It seem pretty good but I wouldn’t mind some o2 sensors to get it right. I’ll make sure I’ve got a handful of bits and pieces for tuning. I’ll have a look at the secondary’s weights, thanks for that tip.

It might be a while until dyno day but I’ll post up the results.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

I built a 312 back in the '80s. A trusted old Ford mechanic told me not to rev it over 5500. He said the HP engines had a different valve keeper and that the standard version were prone to shake loose and drop a valve at higher RPM. I'm not sure if the 2x4 version had the HP keepers, or if it was the F engine. Hopefully, someone can add some info. 

The dual four engines also had the one piece retainers like the blown engines.

John - "The Hoosier Hurricane"

Just for clarifiction going back on these postings.. A regular stock 272 engine, prior to 1957, was about 167 h.p. not 182 as stated. That was only found in the special 4 Bbl dual exhaust versions..  
Further; As this particular engine was only bored  0.020" over, & assuming that a particular 272 block doesn't have a serious core shift in it, what is a safe overbore allowing for say one more 0.20" overbore if needed ?..    


Paul

Almost all Ford Y engines are good for being ‘safely’ bored to 0.060” over.  There are exceptions to this but sonic testing does separate out those blocks that have excessive core shift.  While some of those blocks cannot be successfully over bored without offset boring the cylinders, there are those on the other end of the scale that can be bored much more than 0.060” over.  I have taken a fair number of 292 blocks that had good sonic test numbers to 0.110” over and made them into high horsepower producers.
 
There are a large number of 272 engines out there that have been bored 0.125” over to make them into standard bore 292’s.  Fred Jones Engines in Oklahoma City (authorized Ford rebuilder) did this to a large number of 272 engines and made them into 292 engines.  These engines worked well with stock compression ratios but when measuring them for cylinder wall thickness, they are poor candidates for a performance build.
 
My ’55 Customline still has the original 272.  At 112K miles I was into the engine and bored it to 0.020” over simply because I was in there and wanted it fixed for the long haul.  Cylinder wall wear was minimal and could have gotten by with just a re-ring job.  I did sonic test that block at the time and it was a candidate for a +060 over 312 bore or more but being as I’m a believer in only boring out the engines only just enough to clean up the cylinders, 0.020” over it was.  It was upgraded with the ECZ-B 4V intake and Isky E4 camshaft along with a balance job at the time and still runs good today with over 300K miles on the car now.  The crankshaft in that engine is still STD/STD and the oil pressure is still very good at all rpm.  While I did not dyno test this engine, I always felt it was in the 200-205 HP range with its original 272 small valved heads

Lorena, Texas (South of Waco)

Ted, in regard to what these engines can stand, would a 1955 3-speed Fordomatic be adequate for a mildly upgraded 312(4bbl, mild cam upgrade, G heads, 1.54 rockers)? If not, what would you recommend? Thanks.

... would a 1955 3-speed Fordomatic be adequate for a mildly upgraded 312(4bbl,

IMO -

That would all depend on how hard you want to run it. At the least, a 56 coolant cooled trans or if it is going to get serious street use, either an FMX or possibly C4 upgrade. Is the car remaining stock other that the engine upgrade?

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