Author Topic: FM 246P piston  (Read 10272 times)

0 Members and 1 Guest are viewing this topic.

427John

  • Sr. Member
  • ****
  • Posts: 343
    • View Profile
Re: FM 246P piston
« Reply #30 on: January 14, 2021, 05:24:30 PM »
I realize the sunken seats were screwing up airflow and that was the cause of the limited rpm and not chamber volume but was just using that experience as an example of how much it can affect chamber volume.

SSdynosaur

  • Full Member
  • ***
  • Posts: 135
    • View Profile
Re: FM 246P piston
« Reply #31 on: January 14, 2021, 05:32:17 PM »
Ford always had a set of Society of Automotive Engineers specs they called the "Pikes Peak Engine" and beginning with certain 427 applications they submitted those those specs to NHRA as a "range" that a 427 could fall into that permitted 14.5:1 compression ratio at minimum deck and chamber volume utilizing maximum piston dome cc's of 12.1. The production 427 piston dome barely displaced 7 cc's before cutting valve reliefs and wound up yielding mid 11's to about 12:1 compression ratio.

WerbyFord

  • Sr. Member
  • ****
  • Posts: 335
    • View Profile
Re: FM 246P piston
« Reply #32 on: January 14, 2021, 09:40:10 PM »
I always assumed the 352/360hp would have:
a] decent quench & therefore a deck clearance of maybe .020
b] therefore, valve cuts due to the 228-228-114 .500 .500 net lift cam

Does anybody have pictures of an original HiPo piston? I know it complicates it since it was a mid-year engine so (as usual) not in the shop manuals.
I looked in 60-64 MPC and found:
c0az-a 60-63 2v and 64(up) 4v
c0ae-h 60 4v
c0ae-aj 60 HiPo
no detail on height or volumes.

x2 on the NHRA specs BTW, they are what Ford sent in (eg like how the C8AX-C cam was "optional" in your 428CJ), and cc's that gave 14.0 compression in the 427s. Ford was not the only manufacturer that sent in stuff like that.

NHRA lists a little 450 Holley for the 352/360hp engine, either a cut & paste from the 352/300hp (most came with a 4100 autolite) or an outright goof in the wrong direction. Ford should have sent to NHRA that dual quads were an option on the 352HP, like Mopar did on their 383. It worked!

I imagine the racers of the day were like tax accountants, combing thru those specs looking for "loopholes".

The Mopar 383/343hp-8v was a "loophole" engine, as was IIRC the 265/195hp Mouse. And (surprise) they won a lot, like those 14-to-1 427 Fords.
« Last Edit: January 14, 2021, 10:08:52 PM by WerbyFord »

frnkeore

  • Hero Member
  • *****
  • Posts: 1128
    • View Profile
Re: FM 246P piston
« Reply #33 on: January 15, 2021, 01:57:34 AM »
I think I would have to see a picture of a that piston, with FoMoCo markings, to believe it had valve reliefs. If so, I think it would have been the first FE with them. Even my 361 Edsel, with .008 deck clearance and a .030 gasket (.038 PTH), doesn't have them. The '60 300 hp 352 only had .014 deck clearance w/o reliefs.

It's possible that the reason the piston is so far down and they used a small chamber, is for valve clearance (.066 PTH), since before that, they ran the piston much closer. Of course it is possible that small chamber head and large quench, produced more hp, on a dyno, than a closer fit?
« Last Edit: January 15, 2021, 01:22:04 PM by frnkeore »
Frank

427John

  • Sr. Member
  • ****
  • Posts: 343
    • View Profile
Re: FM 246P piston
« Reply #34 on: January 15, 2021, 02:49:56 AM »
The pistons we pulled out of my friends documented 60 HP sunliners original engine were flat top with no valve relief,and the original cam that we checked for lift was not .500 lift,it was roughly .480 with no indication of excessive wear. We had seen conflicting references of listed cam lift figures some saying .500 and others listing .479,based on our observations I tend to believe the .479 figure. It appeared to be an early engine as it had a B9AE block,still had the stamped timing cover with timing pointer that matched the HP balancer and had the earlier C0AE dual point distributor they had 2 C0AE DP dist. with different suffixes,the K suffix dist.was the later one and his had the earlier one but I can't remember what the suffix was on it.It also had the earlier narrow beam rods,the later ones supposedly switched to a wide beam rod.

427John

  • Sr. Member
  • ****
  • Posts: 343
    • View Profile
Re: FM 246P piston
« Reply #35 on: January 15, 2021, 03:18:30 AM »
As far as the different C0AE part numbers for the 352 pistons the 2V engine was rated at a lower CR than the early 4Vengine,I had a 64 with the original lower CR 352 4V and had to pull the heads and it clearly had no VR pistons.I believe the early 352's all used used non VR pistons of differing CH,which would explain why the 2V and late 4V engines had the same lower CR with the same heads as the earlier higher CR 4V engines.I've never seen a 64 and earlier 352 that had VR pistons,if 352's did ever have VR pistons from the factory I believe they may have been 65 and later after they started being used in pickup trucks.I remember years ago the hop up trick when rebuilding a 360 pickup engine was to use .080 over 352 pistons   

WerbyFord

  • Sr. Member
  • ****
  • Posts: 335
    • View Profile
Re: FM 246P piston
« Reply #36 on: January 15, 2021, 08:12:14 AM »
The pistons we pulled out of my friends documented 60 HP sunliners original engine were flat top with no valve relief,and the original cam that we checked for lift was not .500 lift,it was roughly .480 with no indication of excessive wear. We had seen conflicting references of listed cam lift figures some saying .500 and others listing .479,based on our observations I tend to believe the .479 figure. It appeared to be an early engine as it had a B9AE block,still had the stamped timing cover with timing pointer that matched the HP balancer and had the earlier C0AE dual point distributor they had 2 C0AE DP dist. with different suffixes,the K suffix dist.was the later one and his had the earlier one but I can't remember what the suffix was on it.It also had the earlier narrow beam rods,the later ones supposedly switched to a wide beam rod.

Did you check the piston compression height on those original pistons or how far down the hole were they?
I'm guessing maybe .038 - .040 in the hole then?
Now, how thick was the original gasket, a .020 shim?
OK then with no valve reliefs, would they HIT? Probably not - but how much piston-to-valve clearance would that leave?

It doesnt depend so much on the max lift, since the piston is way down the hole by then.
Piston-Valve clearance depends more on Overlap, ie valve events at .020 or .050 lobe lift.
Do you still have that cam by chance?
The .480 net lift vs .500 net lift mystery seems to linger, but doesnt make much difference - about 3 hp or so.
Mainly though, if there is a .480 net lift cam (new, unworn), are its DURATIONS the same as the 228-228-114.5 cam used on the 390HP, 406, 427-4v?
The only way to know that would be to degree it.
Either way - I dont know what the piston-valve clearance would be. Maybe they cut it kind of close!

Royce

  • Hero Member
  • *****
  • Posts: 777
    • View Profile
Re: FM 246P piston
« Reply #37 on: January 15, 2021, 10:20:45 AM »
Well between the original flat top piston vs 4 reliefs and the greater compression height of the stock piston, That would explain my struggles to get the spec compression.. I did not even bother looking for the original flat top piston.. Does anyone even offer them?  I ended up with the .500 lift cam from Holman Moody

Does anyone know if DSC is open and doing business these days?
1955 Thunderbird Competition Coupe Altered Chassis "War Bird" 383 Lincoln Y block 520 hp
1955 Thunderbird 292 275 hp Y Block
1956 Ford Victoria 292 Y block

1957 Mercury 2dr Wagon "Battle Wagon" drag car 
1957 Thunderbird Glass body Tube Chassis drag car 333 cu in 500 hp Ford Y block
1961 Starliner 390/375 clone
1965 GT40 tribute w/FE
1966 Falcon Pro Touring project
Kaase Boss 547. 840 HP 698 Torque  pump gas
1992 BMW V-12 5.0
2001 Lincoln 5.4 4 cam.
1968 Cougar XR7

427John

  • Sr. Member
  • ****
  • Posts: 343
    • View Profile
Re: FM 246P piston
« Reply #38 on: January 15, 2021, 02:32:20 PM »
Royce,unfortunately we did not measure the deck clearance of the stock pistons on disassembly there was no consideration of reusing them,but they didn't seem to be down an unusual amount.As far as the the cam he may very well still have it I will check and see if maybe we can get it mapped.Based on what we gleaned from MPC we concluded that this grind was used on 60,61 and early 62 engines including the early 406's.We speculated that the late 406 C2AE cam was essentially a AA cam ground on an early thrust button core and that is when they went to the .500 lift.If he still has the cam,I'll see if we can get details such as mapping and ID marks and post them up.

FERoadster

  • Sr. Member
  • ****
  • Posts: 492
    • View Profile
Re: FM 246P piston
« Reply #39 on: January 15, 2021, 02:43:16 PM »
I've got a rebuilt assembled 1959 352 with flat tops w/ no relief. I'll measure the distance to the top of deck with a feeler gauge (that's all I have)
Not sure if the block was decked though. Is there a way to tell?
Richard >>> FERoadster

427John

  • Sr. Member
  • ****
  • Posts: 343
    • View Profile
Re: FM 246P piston
« Reply #40 on: January 15, 2021, 02:47:27 PM »
Another thing to keep in mind,is that early 390 dished pistons,and 406 pistons lacked valve reliefs also.I've got a set of 406 pistons here and they lack any sign of reliefs.

68fecyclone

  • Jr. Member
  • **
  • Posts: 44
    • View Profile
Re: FM 246P piston
« Reply #41 on: January 15, 2021, 02:50:05 PM »
   Yes Royce, DSC is still open, I just bought an item from him on ebay. Received it a couple days ago. Rob

frnkeore

  • Hero Member
  • *****
  • Posts: 1128
    • View Profile
Re: FM 246P piston
« Reply #42 on: January 15, 2021, 03:28:45 PM »
I've got a rebuilt assembled 1959 352 with flat tops w/ no relief. I'll measure the distance to the top of deck with a feeler gauge (that's all I have)
Not sure if the block was decked though. Is there a way to tell?
Richard >>> FERoadster
Richard, is that the .030 over one, with 2116 marking on the top?

If so, it's a TRW piston, with a 1.866 CH. It should be about .014 down.
Frank

FERoadster

  • Sr. Member
  • ****
  • Posts: 492
    • View Profile
Re: FM 246P piston
« Reply #43 on: January 16, 2021, 03:22:34 AM »
Best I could measure tonight was .015 down but not sure if the piston was at TDC so it could be less. I'll put a Flex plate on it tomorrow so I can turn it and get to true TDC

Royce

  • Hero Member
  • *****
  • Posts: 777
    • View Profile
Re: FM 246P piston
« Reply #44 on: January 16, 2021, 09:15:59 AM »
I ended up putting the AA cam in mine..  I would be interested in mapping the original if it is still available..
1955 Thunderbird Competition Coupe Altered Chassis "War Bird" 383 Lincoln Y block 520 hp
1955 Thunderbird 292 275 hp Y Block
1956 Ford Victoria 292 Y block

1957 Mercury 2dr Wagon "Battle Wagon" drag car 
1957 Thunderbird Glass body Tube Chassis drag car 333 cu in 500 hp Ford Y block
1961 Starliner 390/375 clone
1965 GT40 tribute w/FE
1966 Falcon Pro Touring project
Kaase Boss 547. 840 HP 698 Torque  pump gas
1992 BMW V-12 5.0
2001 Lincoln 5.4 4 cam.
1968 Cougar XR7