GreasyNRusty
Active member
..."D"-shaped depressions in crown as used in EFI "4.9L".
Anything out there like that?
Eddie
Anything out there like that?
Eddie
240ci Suggestions: 240 Pistons, Thin Metric Rings, and...
- Thread starter GreasyNRusty
- Start date
This only applies to 240ci engines
Not for the 240.
The 1965 to 1968 240s use the Ford 289/303 V8 pistons.
The 1969 and later 240s used either a round dish or flat top pistons.
You could take the flat top pistons and mill a "D" dish into the piston top, but you would still have the 5/64" pistons ring grooves.
Total seal makes ring groove spacers so you can run 1.2mm rings in the 5/64 grooves.
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GreasyNRusty
Active member
Thanks!
The daydream, er, "idea" (pipe dream?) is to rebuild and update a 240 with a 4.9L EFI head and equipment (and other incorporating 21st-century technology): i.e., a "3.9L".
I'd seen the "D"-shaped recess in 4.9L EFI usage, and figuring Ford's engineers placed that "D"-shape there for a reason, I'd see if anything cheep was out there rather than do any further re-engineering. 302 EFI V-8 pistons are available in flat-top and dish design, but the 302 is a crossflow engine whereas the 4.9L is a reverse-flow, so that "D"-shape makes sense. Your suggestion of milling the "D" is a good one, thanks; I hadn't a-thunk that one up. And hey, if the OE 240 pistons are reusable...
Ideally, I rather use pistons with grooves sized for thin rings (low-tension); I'd thought 'bout using ring spacers but if possible I'd just as soon avoid weight and complexity but...Hey, if the OE 240 pistons are reusable...
Eddie
The daydream, er, "idea" (pipe dream?) is to rebuild and update a 240 with a 4.9L EFI head and equipment (and other incorporating 21st-century technology): i.e., a "3.9L".
I'd seen the "D"-shaped recess in 4.9L EFI usage, and figuring Ford's engineers placed that "D"-shape there for a reason, I'd see if anything cheep was out there rather than do any further re-engineering. 302 EFI V-8 pistons are available in flat-top and dish design, but the 302 is a crossflow engine whereas the 4.9L is a reverse-flow, so that "D"-shape makes sense. Your suggestion of milling the "D" is a good one, thanks; I hadn't a-thunk that one up. And hey, if the OE 240 pistons are reusable...
Ideally, I rather use pistons with grooves sized for thin rings (low-tension); I'd thought 'bout using ring spacers but if possible I'd just as soon avoid weight and complexity but...Hey, if the OE 240 pistons are reusable...
Eddie
GreasyNRusty
Active member
Engine's not yet sourced; I don't even know if I'm going to need it or not. I haven't even decided if I'm going to buy the truck the engine is proposed for (a 1994/5 reg cab short box 2WD F-150 5-spd.) The days of my hauling anything more than a couple of sheets of plywood are over (I think).
Should I buy that pickup I am going for MPG: lighten it as much as practicable, do what I can 'bout it's barn-door aerodynamics, and build the smaller high torque-rise engine for it.
Meanwhile, I am going to plan the engine out; I build nothing without a complete plan in place, and obviously I have a long way to go and a lot of learing (sic) to do to complete that plan. Texas state inspection and BS smog laws add yet another layer of complexity (Texas recently abolished SAFETY inspections but KEPT emissions inspections) (?).
Long way of saying that I can source either a '65-'67 or a '68-''72 series depending on the pistons used.
Eddie
Should I buy that pickup I am going for MPG: lighten it as much as practicable, do what I can 'bout it's barn-door aerodynamics, and build the smaller high torque-rise engine for it.
Meanwhile, I am going to plan the engine out; I build nothing without a complete plan in place, and obviously I have a long way to go and a lot of learing (sic) to do to complete that plan. Texas state inspection and BS smog laws add yet another layer of complexity (Texas recently abolished SAFETY inspections but KEPT emissions inspections) (?).
Long way of saying that I can source either a '65-'67 or a '68-''72 series depending on the pistons used.
Eddie
Eddie
The 4.9 EFI engine requires a 25 to 26cc deep "D" dish to get an 8.8 compression ratio.
The 240 only needs a few cc in the piston dish for the same compression ratio.
Depending on the piston height in the cylinder at TDC, the piston can be a flat top to having a very shallow 6cc dish at the most.
Say you get a 1969 and later 240 that has the .975" piston pins.
These DSS pistons are made for the 1.2/1.2/3mm metric rings
They have 5cc valve reliefs that would be directly under the EFI head combustion chamber.
You would simply ask them to change the CH from 1.79" to 1.60" to make them work in a 240 six
dssracing.com
The 4.9 EFI engine requires a 25 to 26cc deep "D" dish to get an 8.8 compression ratio.
The 240 only needs a few cc in the piston dish for the same compression ratio.
Depending on the piston height in the cylinder at TDC, the piston can be a flat top to having a very shallow 6cc dish at the most.
Say you get a 1969 and later 240 that has the .975" piston pins.
These DSS pistons are made for the 1.2/1.2/3mm metric rings
They have 5cc valve reliefs that would be directly under the EFI head combustion chamber.
You would simply ask them to change the CH from 1.79" to 1.60" to make them work in a 240 six
5900-4030 300 L6 Ford 6 Cylinder FX Series -5cc Flat Top 6 Cyl Ford 30
305 L6 Ford 6 Cylinder, FX, Comp Height: 1.79, -5cc Flat Top , PIN: .975", Full-Floating or Press Fit, Ring Groove: 1.2/1.2/3MM, Stroke: 3.980", ROD: 6.21, Approx Comp Ratio: 65cc-11.63, 72cc-10.76, 76cc-10.33 *
dssracing.com
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If you find a 1965 to 1968 240.
These pistons use a 1.5/1.5/4mm ring set and have a 5cc dish volume.
www.summitracing.com
These pistons use a 1.5/1.5/4mm ring set and have a 5cc dish volume.
FORD Silvolite 3133H.020 Silv-O-Lite Hypereutectic Pistons | Summit Racing
Free Shipping - Silv-O-Lite Hypereutectic Pistons with qualifying orders of $109. Shop Pistons at Summit Racing.
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GreasyNRusty
Active member
WOW! THANX, P! 
Way more piston than I had in mind, but: I've always wanted 'nuther set of piston-slappin' forged pistons...and since this will be abucket list, er, "retirement" project--Why Not? And since I already have the forged pistons I may as well plan on a "rotary exhaust valve... ("Project Creep", anyone?)
In yer Magnum Opus: https://fordsix.com/threads/ford-240-300-engine-information-read-here-first.81788/ I did not find "block deck thickness" (bifocals, probably, if not outright A.D.D.). Any idea what that number might be? I'd like to get this monster as close to Zero as I can without weakening the block in any way.
Following your earlier post, if additional dish is required I could have the "D"-shape milled in. (Yeah, that still bugs me.)
Eddie
Way more piston than I had in mind, but: I've always wanted 'nuther set of piston-slappin' forged pistons...and since this will be a
In yer Magnum Opus: https://fordsix.com/threads/ford-240-300-engine-information-read-here-first.81788/ I did not find "block deck thickness" (bifocals, probably, if not outright A.D.D.). Any idea what that number might be? I'd like to get this monster as close to Zero as I can without weakening the block in any way.
Following your earlier post, if additional dish is required I could have the "D"-shape milled in. (Yeah, that still bugs me.)
Eddie
GreasyNRusty
Active member
Again, THANX!
Options!
In my defense, I forgot all about that handy-dandy lookup on Summit; I'd waded through https://uempistons.com/themes/UEM/images/Silv-O-Lite 12.20.20.pdf and didn't find what I was looking for.
These suggestions have certainly cleared up a "logjam"; I now know the "3.9L" project is possible, and (snicker) even doable as a straight rebuild.
(Yeah, Eddie, g'head, jinx yerself...)
Eddie
Options!
In my defense, I forgot all about that handy-dandy lookup on Summit; I'd waded through https://uempistons.com/themes/UEM/images/Silv-O-Lite 12.20.20.pdf and didn't find what I was looking for.
These suggestions have certainly cleared up a "logjam"; I now know the "3.9L" project is possible, and (snicker) even doable as a straight rebuild.
(Yeah, Eddie, g'head, jinx yerself...)
Eddie
GreasyNRusty
Active member
P
I hadn't gotten that far as I really didn't know if the project was even feasible until today...pistons are kinda a necessity and without 'em no need to pursue further as full custom pistons were out of budget. The DSS pieces seem as though they may be within budget, tho.
Head: My initial thoughts on a head were Promaxx: Valves/seats are always the bottleneck, I'm guessin' they're 30/45/60; unshrouding those valves is almost equally important; followed by port enhancement, hence I'm thinkin' the Promaxx CNC head. Cheep at the price as the hand work is already done and the valves are stock length which decomplicates things. A big plus (to me) is the enhanced casting thickness' durability.
Camshaft: Mild. Hydraulic roller. Specs unknown at this point: High torque-rise. Probably one of Straubtech's as they are easily available and with all those profiles availble it looks as though they have the low-end thing covered; again, I gotsta evaluate the combination now that I know it's feasible.
Pushrods: Unknown, but: Aluminum. Inertia is the enemy.
Rocker arms: Again, full roller, preferably steel rather that aluminum for durability.
Unasked but important: 1. Static CR needs to be a minimum 9:1, preferably higher. 2. Ceramic heat-coating on chambers and exhaust valves.
Eddie
If you are going for MPG you do not want to modify the stock EFI head combustion chamber.
You will want to keep the high swirl, fast burn characteristics of the closed chamber design.
You also do not need a ported head.
If you are going to use the CNC ported head then you are looking at a high performance, high revving 240 engine.
You will want to keep the high swirl, fast burn characteristics of the closed chamber design.
You also do not need a ported head.
If you are going to use the CNC ported head then you are looking at a high performance, high revving 240 engine.
GreasyNRusty
Active member
Good enuff!
Then I guess that, yes, I would indeed be lookin' at Promaxx's stock replacement head (as long as it is the enhanced-durability Promaxx casting), with SS valve material and a multiangle valve/seat and valve deshrouding to .25D. Agreed?
Good guidance, my friend; Thanks.
Eddie
Then I guess that, yes, I would indeed be lookin' at Promaxx's stock replacement head (as long as it is the enhanced-durability Promaxx casting), with SS valve material and a multiangle valve/seat and valve deshrouding to .25D. Agreed?
Good guidance, my friend; Thanks.
Eddie
GreasyNRusty
Active member
Hmmm. Interesting. "Shrouded valve curtain" for fast-burn efficiency? Makes a certain sort of sense, and will drive piston selection as well.
I shall be picking up a used complete head assembly to measure and evaluate. There is certainly historical precedent for shrouded valves used in heart-shaped combustion chambers.
'Preciate the insight!
Eddie
I shall be picking up a used complete head assembly to measure and evaluate. There is certainly historical precedent for shrouded valves used in heart-shaped combustion chambers.
'Preciate the insight!
Eddie
GreasyNRusty
Active member
MPG/EMISSIONS LEGALITY THE GOAL
Harris County (Houston) Texas is an EPA Nonattainment Area and has a very strict emissions inspection procedure, arrived at by plugging
in at the OBD II access port, communicating directly with state capital. Whatever I do HAS to pass because the sticker issued contains the
cars' license number for that year.
RPM Range I drive for MPG; Mostly city driving, i.e., off-idle, gentle acceleration to the highest vacuum number to 40 MPH, shift at torque peak in slow lane, play all the stop lights, piss off every body behind me. Very occasional blast down the freeway.
I would like to build it for, say, 6000 RPM capability.
And, just for grins'n'giggles (or outright LOL guffaws of disbelief
)...the TEXAS MILE top speed event ain't but an hour down the road from here. Maybe I'll take home Event Speed winner . Maybe I'll hit the Lottery for a Billon dollars. Maybe I'll grow up.
Fuel Injection OEM Ford EFI, i.e., 1994 or '95, whatever was OEM on this F-150. Have fingers crossed whether the OE FI can accommodate
60 CID less displacement, higher CR, and different camming without throwing codes.
Eddie
Harris County (Houston) Texas is an EPA Nonattainment Area and has a very strict emissions inspection procedure, arrived at by plugging
in at the OBD II access port, communicating directly with state capital. Whatever I do HAS to pass because the sticker issued contains the
cars' license number for that year.
RPM Range I drive for MPG; Mostly city driving, i.e., off-idle, gentle acceleration to the highest vacuum number to 40 MPH, shift at torque peak in slow lane, play all the stop lights, piss off every body behind me. Very occasional blast down the freeway.
I would like to build it for, say, 6000 RPM capability.
And, just for grins'n'giggles (or outright LOL guffaws of disbelief
)...the TEXAS MILE top speed event ain't but an hour down the road from here. Maybe I'll take home Event Speed winner . Maybe I'll hit the Lottery for a Billon dollars. Maybe I'll grow up.Fuel Injection OEM Ford EFI, i.e., 1994 or '95, whatever was OEM on this F-150. Have fingers crossed whether the OE FI can accommodate
60 CID less displacement, higher CR, and different camming without throwing codes.
Eddie
1994 F-150? I remember on one of your earlier posts you having a 1991 F250.
In any case the 1987 to 1995 4.9 came with OBD I
Only the 1996 4.9 came with OBD II
This would be so much easier with a carburetor.
I don't know what a 4.9 EFI system would do on a 240 with a 6000 rpm upper limit.
Would they be able to emissions test an OBD-1 system or would they do a tail pipe sniff or no emission testing?
In any case the 1987 to 1995 4.9 came with OBD I
Only the 1996 4.9 came with OBD II
This would be so much easier with a carburetor.
I don't know what a 4.9 EFI system would do on a 240 with a 6000 rpm upper limit.
Would they be able to emissions test an OBD-1 system or would they do a tail pipe sniff or no emission testing?
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GreasyNRusty
Active member
1994 F-150? I remember on one of your earlier posts you having a 1991 F250.
In any case the 1987 to 1995 4.9 came with OBD I
Yeah, the '91 F-150 (F-250 was probably a typo on my part; my figners often do stoopid things)(thank God for "edit") is in my driveway being slowly parted out/cut up for scrap; the fella that collects and sells scrap drives a '92-up F-150; he also has the '94 (?) F-150 I've been questioning and "learing" (sic) about. I'm going to pull the OEM-optional rear overload springs and HD tires/wheels off and give 'em him...boy, does his rig need 'em, too (poor thing). He and I will talk about the reg cab/short box after he accepts the springs/tires gift...
A glance through the State of Texas DMV site about six months ago showed that Austin had gone to California-style engine swap and vehicle engine modifications regs vs. the looser, earlier SEMA-SAN style regs they had circa 2010-ish, effectively nixing my '23-T project (luckily before I got too far done the road on that).OBD I is a tailpipe sniff--or do I mean "was"? Another thing for me to check on! If so, BOY IS THAT GOOD NEWS!
If I recall rightly, Ford went to an MAF system over Speed Density in '92, which I assUmed was the opportunity for the mfg. to upgrade to OBD II.
Also, AFAR, MAF is supposed to better compensate for modifications--a good question for me to ask Ted & The Boys in the appropriate Forum.
The 6000K upper limit is wishful thinkin' on my part; in fact, I'm beginning to think this whole thread has been a good exercise in "goal refinement". The '91 ran out of breath around 4,500 but I think that was more a function of camshaft, small valves, and head design.
My reasons for the 240 over the 300, other than MPG are: 1. Ridiculously big rod/stroke, and 2., Lessened displacement.
Smokey Yunick was a huge proponent of big rod ratios: "Big rod ratios park the piston at TDC forever, allowing a forever spark dwell" (Or something like that, probably with lots of bleeped-out profanity; read his autobiography
). That additional dwell at TDC, plus modern aftermarket spark intensifier, is what leads be to believe I can get away with swapping in an appropriately-updated 240.
Hard to get my head out of "go-fast" , into "go-slow" though....
Eddie
In any case the 1987 to 1995 4.9 came with OBD I
Yeah, the '91 F-150 (F-250 was probably a typo on my part; my figners often do stoopid things)(thank God for "edit") is in my driveway being slowly parted out/cut up for scrap; the fella that collects and sells scrap drives a '92-up F-150; he also has the '94 (?) F-150 I've been questioning and "learing" (sic) about. I'm going to pull the OEM-optional rear overload springs and HD tires/wheels off and give 'em him...boy, does his rig need 'em, too (poor thing). He and I will talk about the reg cab/short box after he accepts the springs/tires gift...
A glance through the State of Texas DMV site about six months ago showed that Austin had gone to California-style engine swap and vehicle engine modifications regs vs. the looser, earlier SEMA-SAN style regs they had circa 2010-ish, effectively nixing my '23-T project (luckily before I got too far done the road on that).OBD I is a tailpipe sniff--or do I mean "was"? Another thing for me to check on! If so, BOY IS THAT GOOD NEWS!
If I recall rightly, Ford went to an MAF system over Speed Density in '92, which I assUmed was the opportunity for the mfg. to upgrade to OBD II.
Also, AFAR, MAF is supposed to better compensate for modifications--a good question for me to ask Ted & The Boys in the appropriate Forum.
The 6000K upper limit is wishful thinkin' on my part; in fact, I'm beginning to think this whole thread has been a good exercise in "goal refinement". The '91 ran out of breath around 4,500 but I think that was more a function of camshaft, small valves, and head design.
My reasons for the 240 over the 300, other than MPG are: 1. Ridiculously big rod/stroke, and 2., Lessened displacement.
Smokey Yunick was a huge proponent of big rod ratios: "Big rod ratios park the piston at TDC forever, allowing a forever spark dwell" (Or something like that, probably with lots of bleeped-out profanity; read his autobiography
). That additional dwell at TDC, plus modern aftermarket spark intensifier, is what leads be to believe I can get away with swapping in an appropriately-updated 240.Hard to get my head out of "go-fast" , into "go-slow" though....
Eddie
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