300 Six Compression Ratio, Intakes, Heads, etc

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300 Six Compression Ratio, Intakes, Heads, etc

Gary Lewis
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Jonathan has just suggested, and rightly so, that I move some of the discussion regarding the 300 six to a new thread from the gear ratio calc thread so we can pursue both topics more thoroughly.  So this will be the initial post to open up the thread and I'll start moving the other posts over......  
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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1986F150Six
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Gary Lewis wrote
Jonathan:
I agree, that is one tall OD ratio, and it explains why David can cruise at such low RPM and yet have good MPH.

 
If I could pursue my dream [had enough money and talent?], I would raise compression, lightly port and polish [clean valve pockets, etc.] the head, install either F.I. exhaust manifolds or H.D. [preferable] exhaust manifold with a free flowing exhaust and find an Edelbrock 1 barrel intake manifold to use with my present carburetor.

Hmmm? I might even try an adapter and install a 32/36 Weber carburetor.

This would be to further the quest for best gas mileage.


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Gary Lewis
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I think a compression ratio boost would give you the biggest MPG improvement, followed by a better intake manifold.  Compression helps efficiency, and an even distribution of the air/fuel mix allows you to tune the ratio to get the best economy.  And I doubt that the spider of an intake from the factory can have even distribution.

It would be interesting to put a wide-band AFR meter on the individual exhausts for a 300 and see how poor the distribution is.  Then you'd know if you are fighting a losing battle tuning the carb - whatever carb it is.  My guess is that the end cylinders are way off from the center cylinders, so aren't contributing to the efficiency of the engine as they should be.  And, if I'm right, it won't make a whole lot of difference what carb you have.

Having said that, I believe that having a split manifold with two small carbs would significantly improve the distribution and let you tune the carb much more precisely.

But, that's just my guess with no empirical data.  Perhaps the Frenchtown Flyer knows?
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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1986F150Six
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Gary Lewis wrote
But, that's just my guess with no empirical data.  Perhaps the Frenchtown Flyer knows?
I hope I am not misquoting him, but a number of years ago, he attributed the broad [desirable] torque curve to the poor intake and exhaust manifolds! I believe what he meant was that at any given RPM range [probably ~1200-2000 RPMs], a couple of the cylinders were at their peak, so as some "came on" and others "dropped off" in efficiency, the torque band was widened.


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Gary Lewis
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Probably true, but an engine is most efficient at its torque peak.  So, I would guess that the more pronounced that torque peak the better the efficiency when operating at it.  Conversely, a broad torque peak would reduce the efficiency at that torque peak.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Ford F834
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In reply to this post by 1986F150Six
David, is this the intake? Looks like it would even out the carb to cylinder distance quite a bit, yet is still for 1 bbl.



I agree that raising compression would help with efficiency, but what about cam/valve timing? Is there a profile and timing set that could help build cylinder pressure and hold gear at lower rpm? I know most performance parts are geared towards maximum power but the rock crawler crowd must create demand for low end torque parts...
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2
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1986F150Six
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Yes, Jonathan, that is the manifold. The runner diameters are reportedly smaller with smoother bends [radii?] when compared to the factory log intake manifold. This was to enhance lower speed power [gas mileage] rather than higher speed power like a 4 barrel intake [i.e. Clifford or Offenhauser].

Regarding the camshaft: looking at the 1982 Ford Specification Sheet as provided by Gary, it is noted that a "reduced overlap camshaft" was used in all 300 engines with all manual transmissions & 2.47 or 2.75 rear axles - 49 states only.
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1986F150Six
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In reply to this post by Gary Lewis
Gary Lewis wrote
Having said that, I believe that having a split manifold with two small carbs would significantly improve the distribution and let you tune the carb much more precisely.
How about a split manifold with three small [stock] carburetors? This was made using three middle sections from a stock intake manifold.

https://www.jalopyjournal.com/forum/attachments/int3x108-jpg.3824400/
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85lebaront2
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The trick on that would be if you can make them progressive, i.e. center, then ends. I helped a friend years ago with a 240 engine build a setup using dual Holley/Weber progressive two barrels. It ran great, but then so did the kid's who worked for me Chevy 250 with dual Stromberg 4A1 carbs.

The front/rear firing order on an in-line six lends itself to a front-rear carb setup where the intake sequence is 1,3,2 front and 6,4,5 rear or if you think about it, center to ends alternating. Many European and Japanese in-lines used dual carbs with excellent performance and economy.

If you split the carbs front and rear, you have two 150 ci engines, the Holley/Webers are commonly a 32/36 size with 32/36 being the throttle sizes in millimeters. Pinto engines were 140 ci. The Pinto carbs used (a) removable jets for both main and idle circuits (b) mechanical secondaries and (c) hot water chokes. We used a Clifford manifold and a pair of adapters to take the Pinto carbs to the small square bolt pattern on the intake. We made two plates for the "hot spots" under the carbs and ran the heater circuit through there, teed both chokes in parallel and then to the heater and back to the water pump. A bypass valve was put in so the heater flow could be shut off in warm weather.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: New Page - Calculators Input Requested

Gary Lewis
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In reply to this post by Gary Lewis
Ok, I apparently have the calculator perfected and no one can find anything whatsoever to suggest.  

That being the case, now let's go back to the 300 six intake discussion.  I've been thinking about the multi-carb setup with a progressive linkage.  It seems to me that if you are trying to fine tune the AFR, and if the loooong intake is causing cylinder-to-cylinder differences, then the best way to fix that would be with two or three smaller carbs - but not with progressive linkage.

I say that because progressive linkage runs off the center carb until more power is needed.  But that puts you right back where you started from with one carb and a long manifold.  So, it would seem to me that several little carbs with a linear linkage would be better.  In other words, run two 3-cylinder engines or three 2-cylinder engines, each with their own carb.

But, having said all of that, why not go with the later EFI setup?  However, I don't know if the 300 ever came with EEC-V, mass air flow, and SEFI.  If it didn't it wouldn't be that difficult to convert it.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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85lebaront2
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Of, first, my internet was out from 1800 yesterday until 1030 today so I couldn't see let alone comment.

On the multiple carb 6, dual progressive 2 barrels (Pinto Holley/Webers) work quite well, have water heated automatic chokes and are designed to mount sideways on the engine. This essentially works as 2 3 cyl engines sharing a common distributor. Many European cars (Mercedes-Benz, BMW) some domestic Japanese cars (Nissan Maxima, Toyota Crown) used similar setups, and I suspect some of the early Australian Barra engines may have had something on the same order.

A single 4 barrel in the center worked well on the Chrysler Slant 6 due to the long runners, other examples, Pontiac Sprint OHC 215/230 used a sideways facing Quadrajet, Mercedes-Benz 280C and S before switching to injection, used a Solex 4A1 (Quadrajet copy) but it used a very peculiar intake, carb was mounted like it was on a V8, the manifold was split so each pair of barrels (primary and secondary) fed 3 cyls. It was not a real efficient design, and coupled with the total lack of power enrichment made for a real POS as far as running. Low throttle acceleration was abysmal, WOT decent at the expense of poor fuel economy.

If you go to 3 carbs, the manifold should allow for each to primarily feed a pair of cyls, good examples of that are, early Corvette, 3 Carter YH side drafts, Jaguar E-type 3.8/4.2L, 3 SU HD8s. Both of these were synchronized, meaning all 3 carbs opened together. There was a kit for the old Falcon/Comet/Mustang in-lines that put 3 stock carbs on the integral log manifold, these did run as a progressive system, 1 then 3 as that gave the best distribution. Best 3 carb system, 3 40 or 45DCOE Webers, wicked sound, lots of power.

EFI, 1996 300 had MAF/SEFI and some 1995 CA spec engines, but that would have been EEC-IV which is in the EFI pinouts, I have just added the 1996 4.9L pinouts and before I send you the updates will add the 5.0L and 5.8L 1996 information.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Ford F834
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In reply to this post by Gary Lewis
Gary, what I was told was that SEFI for the 300 six was a one-year wonder in 1996 (last year of production) and 1995 in California. It had 150 hp @3,400rpm, and 260 tq @ 2,000rpm. (Compare with batch fire EFI which was 145/265). The main problem with SEFI is that the computer requires crank position sensor input, so you need the block with the sensor port. The heads are also different with a higher compression ratio (all EFI) and the computer has to match your transmission (auto or manual). So if you talk about a SEFI “swap” you are really talking about a 1996 engine transplant in an older truck, not SEFI components on an older engine. A regular EFI conversion does not need the crank sensor, but you still pretty well need the EFI head to have the compression ratio where the system was designed to run. Again, although you can put that stuff on an older short block, you are probably money ahead to just do a full engine swap. Even though 300’s are “cheap” engines on the used market, that is where I stopped researching it since all I really wanted was to get rid of my carb headaches. FiTech on a 4 barrel custom intake is another popular route, and it works well, but it simply replaces carburetion in the center of the log.

Gary, I just took a quick peek at the dealer facts book pages you posted and noticed something odd. I have been under the assumption that all carb’s 300’s had a CR of 8.0 but according to the book all Bronco, F100,150 and light duty F250 under 8500gvwr were 8.9 and only HD F250 above 8500gvwr and F350 were 8.0 🤷‍♂️ It is also notable that the gvwr and axle gearing seem to determine whether the torque rating was given at 1,200rpm 1,400rpm or 1,600rpm. Interesting that the heavy trucks got less compression?
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2
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Gary Lewis
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In reply to this post by 85lebaront2
Bill - Dual progressive 2bbls would be ideal as you'd have tiny primaries for 3 cylinders and then quite a bit more when desired.  I think this would be a good arrangement - a bit more complexity than 1 carb, but not nearly that of 3 carbs.

But, I still think EFI is the way to go.  Stand by to comment on my response to Jonathan - or beat me to it.  
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Gary Lewis
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In reply to this post by Ford F834
Jonathan - Bill may beat me to it, but EEC-V doesn't require a crank position sensor.  It does have an input for it, but it will work just fine taking its cue from the distributor.  Bill's running Darth w/o a crap position sensor, and Big Blue will be as well.

So, it would just take the EFI head to make it truly up to snuff, and it would probably be fine with the lower compression due to the MAF sensor.  And yes, you have to tell the ECU if it has an auto tranny to control and which one, but that is programmable.

As for the HP and torque spec's, I found that interesting as well.  So, to say the SEFI 300 had 150 hp @ 3,400rpm and 260 tq @ 2,000rpm is one thing, but to compare it to a batch fire EFI with 145/265 begs the question of which truck it was in?  We know that the ratings varied significantly by truck, so it is a bit like comparing a Granny Smith to a Golden Delicious.

Anyway, I think Ford's EFI on a 300 would be the bee's knees for MPG.  
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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85lebaront2
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The 1995 SEFI was still EEC-IV, so the only crank position sensor was the PIP in the distributor. Ford designed the distributor portion of the EFI to give both a crank (leading edge of the shutters) and cam (width of the shutters). The EEC takes the leading edge pulse as 1-6 TDC, 2-5 TDC and 3-4 TDC on a 6cyl engine. The width of the pulse is then used to identify 1 vs 6 to start the 153624 sequence.

This is why even on a bank fired engine it is not recommended to "clock" the plug wires if the distributor is installed wrong. The DIS engines use a crank sensor and a cam sensor. The cam sensor has to be aligned at TDC with a setting tool so the injector sequence is correct. On the 3.0, 3.8 and 4.2L engines, a failed cam sensor causes the system to revert to a bank fired mode. Since the 3 coils each fire 2 plugs, know as "wasted spark" the engine will run, set a code and not run as well, but will get you there. FWIW, Chrysler V6 engines with DIS, if they lose the cam sensor will shut off or never start.

On the compression difference, heavy trucks are much more likely to see higher loads on the engine and possibly detonation, particularly with a manual transmission.

Raise the compression to around 9:1, mild cam, and if you are going EFI, use the MAF, it is more forgiving than the SD system. On tuning, to do anything with an EEC-IV, you need a piggyback tuner that attaches either inside or outside the case to the J2 port (rubber plug), EEC-V can be reflashed using the correct cable and software. I have the misfire detector, 3rd O2 sensor, catalyst temperature sensor and air system all turned off, and have my EGR set for "sonic" rather than the DPFE sensor.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Ford F834
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In reply to this post by Gary Lewis
Gary, do you have any thoughts on the compression? I hate to be skeptical of the literature, but I do question what the difference was between the half ton truck engines and the 1 ton & 3/4HD engines... how was the .9 difference in compression achieved? Why then all the fuss about tracking down a 240 cylinder head to bump up the compression?

Bill, just so I understand you correctly, SEFI for the 4.9L was 1996 only, but the system will work without a crank position sensor? And do you need to find the transmission-specific computer or can it be programmed for the transmission you have?
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2
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Gary Lewis
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Jonathan - Bill will correct me and/or add detail, but he's at the salvage today so I'll chime in.  Yes, the EEC-V system will work w/o a crank position sensor.  Somewhere I read that it uses the CPS for mis-fire detection, but that it can be turned off in the setup.

As for the transmission, IIRC there are basically two different ECU's - ones with the right hardware to control an auto tranny and those w/o the hardware.  You can tell the ECU to not control the tranny, like when you have a manual tranny, but even if you say you have an auto tranny and yet don't have the hardware it won't work.

And then there's the silly question of if I have thoughts?    Go take a look at my ramblings here: Engines/300 Six on the Compression Thoughts tab.  It isn't done, but I kinda hit a wall so I need HELP!

Oh yes, click the Part # tab while there.  
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Ford F834
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Gary, the plot does seem to be thickening with the head and piston differences. Those are the obvious factors in CR, but as you point out it does not quite tell the whole story. So I looked at the head gaskets in case some had a greater compressed thickness. Nope. Only one head gasket part number. Next I looked at the valves, since valve height in the combustion space can have at least a small impact on the volume. I have no idea if that is true in this case, but there is indeed a difference in the light duty vs. heavy duty valve part numbers.



SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2
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Re: 300 Six Compression Ratio, Intakes, Heads, etc

Rembrant
In reply to this post by Gary Lewis
Since you guys are discussing the 300/6 here, have any of you seen this video recently?

https://www.facebook.com/157130251058147/videos/556472388114263/

Pretty interesting stuff as far as modifications go.

1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

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Re: New Page - Calculators Input Requested

Gary Lewis
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In reply to this post by Ford F834
Jonathan - You have a point, but only amounts to a little bit of compression.

The '84 and '86 documents on the Specifications tab show that the exhaust valves have different heads for the under-8500 GVW engines as opposed to those over 8500.  Under has "flat head" exhaust valves, and those over have "flexible head" valves.  That suggests to me that the valve heads are dished on the HD engines and actually, because of the dish, give a bit when they seat.  But, I think the difference in cc's and, therefore, compression ratio would be pretty small.

Anyway, I do hope you can get some of the others with 300 experience to join the conversation.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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