'62 Ranchero - 250 - Aluminum Head update

62Ranchero200

62Ranchero200

Famous Member
Greetings Ford Six Fans,

My COVID-19 project is a cam upgrade (from a Clay Smith 274H to a Clay Smith 280H, their largest hydraulic cam), milling the aluminum cylinder head for more compression, mild porting, and possibly carburetion upgrades.

Had the chance to visit the head today at the machine shop and discovered the following:

I CC'd the cylinder head at 55 cc; the machine shop found the same. My goal was to mill the head down to a 47 cc chamber for one additional point of compression; the machine shop milled .056 off of the head to get to the 47 cc chamber.

The intake valves were lapped; lapping was not sufficient for the exhaust valves because the values are apparently not perfectly concentric with the seats, so the valves/seats were reground.

Some mild porting was done, mostly removing small "steps" that existed around the valve seats.

My new Clay Smith 280H cam will have .512 lift with my 1.6:1 rockers; according to the machine shop, the springs will take up to .600 lift before coil bind, but I found out today that maximum lift before the retainer hits the valve seal is about .525. So, the machine shop is removing about .100 from the valve guides. This should open up the future possibility of .550-.575 lift, although the single springs may not handle that much lift correctly (I don't currently have any plans to go beyond the 280H cam).

The valve guides should be cut and I should be able to pick up the head early next week.

Thanks
Bob
 
Bob, what is your decision on more carburation??
 
Sounds pretty impressive. You must have a good machine shop.
 
47cc is a pretty small combustion chamber. Whats the compressed thickness of your head gasket?

Any idea what the hp/tq numbers will be?
 
Bob da Builder?...
Sorry so late to the game.
Where's RichCrearions & rbohm on this cam?
I'd say U can do better w/Schinder on same $ custom ground...good
on da lift tho, bra.
 
bmbm40":rak39yvo said:
Sounds pretty impressive. You must have a good machine shop.
Click to expand...

I’d recommend my machine shop. The owner seems to understand what I’m trying to do and he doesn’t charge too much (about $500 for all the work on the head). The same shop prepped the 250 short block.

Thanks
Bob
 
chad":tchyqekw said:
Bob da Builder?...
Sorry so late to the game.
Where's RichCrearions & rbohm on this cam?
I'd say U can do better w/Schinder on same $ custom ground...good
on da lift tho, bra.
Click to expand...

I bought this cam several years ago, for a good price, new in the box, from Does Tens. I suspect serious improvements beyond this would require a solid lifter cam.

Thanks,
Bob
 
Georgia200":waek0m2w said:
47cc is a pretty small combustion chamber. Whats the compressed thickness of your head gasket?

Any idea what the hp/tq numbers will be?
Click to expand...

I measured a minimum thickness of .040 with the old head gasket, compressed as much as I could.

I don’t want to be overconfident. I was 157 hp/220 tq at rear wheels with the previous combo. I’m hoping for 180-200 rw hp with new combo.

Thanks
Bob
 
xctasy":2gu8xy8a said:
wsa111":2gu8xy8a said:
Bob, what is your decision on more carburation??
Click to expand...
Times Two. :)
Click to expand...

In order to assess the performance impact of the cam/compression upgrade, first I’ll break it in, drive, and dyno it with the “500 cfm” carb I’ve been running.

Then, either the same type carb modified for more cfm, a Quick Fuel 600 cfm 2-v, or a 4-v. I want some street drivability and decent gas mileage, so 4-v would have to be vacuum secondaries. My thoughts so far are: if I can buy the Quick Fuel 600 cfm, why do extensive mods on the 500 cfm for more air flow? Second, how difficult to tune vacuum secondaries? Theoretical advantages of very large 2-v vs. small 4-v?

Any of these, I will ask Bill (wsa111) to help me tune the carb. I do have wideband and vacuum gauge permanently mounted.

Not ready to delve into throttle body or MPFI at this time.

Thanks
Bob
 
Greetings Ford Six Fans,

On the initial build, the 250 had a Fel-Pro 7916 PT-1 (composite) head gasket, and I have a new one of those for the rebuild.

I keep seeing a figure of .050" for compressed thickness on this gasket. How consistent is this measurement for new Fel-Pro 7916 PT-1s?

Just as a reality check, exactly how do you measure compressed thickness on a new or used (for reference only, not to reuse) gasket? In how many places on the gasket, and where on the gasket do you measure? Do you go for a snug fit on the calipers, or do you compress it as much as you can with your hand while measuring?

I follow the FoMoCo recommendation of 75 ft-lb head bolt torque for my '74 250, but with ARP main studs, anti-seize, an aluminum head, and ARP nuts and washers, I may not get exactly the same results as I would with an original iron head and head bolts.

I measured the Fel-Pro 7916 PT-1 head gasket from the original build and I can compress the calipers enough to read between .040" and .045". It seems to have been compressed thinner on the valve side, less so on the lifter side. If I don't compress the calipers, it's still thinner on the valve side but close to ,050".

Thanks
Bob
 
Bob, if you go the 4bbl route, get one with annular discharge nozzles.
The only thing you can do to your 500 is have the throttle shaft thinned. Thats 20 CFM.
Replace the nozzles with proflow annular nozzles & enlarge the venturi to 1 7/16".
Thats better fuel atomization & another 20 CFM air flow.
In 4bbl #'s thats close to 395 CFM.
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I have one with all of the above mods & even comes with a chrome float bowl & removable plugs so you can change jets without removing the bowl. This carb is one i custom built for my spare engine. It has a Braswell road race float & a special needle & seat which supplies fuel below the fuel level to prevent bubbles. Also a QFT metering block with the idle jet relocated below fuel level. This prevents pulsations to the idle mixture with a large cam & narrow L/C.
I really don't want to sell this gem, but I might consider $750.00.
 
Econoline":2gdai6in said:
What's your compression going to be with this combo Bob?
Click to expand...

Funny you should mention that, I just performed this calculation, resulting in a calculated 10.614 SCR.



Thanks
Bob
 
Hi Bob, I believe FelPro states a .050 crush on their web site this would be with using the stock head bolts. I have also seen .047 stated, if your using head studs you should torque them down to their recommend specs this would probably put you closer to that .047 crush. Good luck on the upgrades (y) :nod:
 
Georgia200":1307y28e said:
MAHLE advertises its 3910VC head gasket to have a compressed thickness of 040.
Click to expand...
Thats also a Victor part #. It has a .044" compressed thickness.
I have one on my engine & it seems to seal better than the Felpro.
 
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