I'm doing a mild performance upgrade on my 76 mav 250 and I can't find a good answer about the 76 head. I'm taking the head off to do a valve job, 2v conversion, and shaved deck (which I understand is necessary due to the new gasket being thicker). Anyway, I'm reading that the 77+ heads are better due to hardened valve seats, larger intakes (1.75 vs 1.64), and log cc (1345 vs 1240). The problem is that I can't find info anywhere about the 76 head. Maybe it has some or all of these features and swapping to a 77 would be a waste of time. My goal is not major horses, just making the thing a bit more fun to drive. The plan is headers, 2v conversion, and a better cam if necessary. Can someone point me in the right direction? I've already checked these resources and come up dry: Falcon Performance Handbook http://classicinlines.com/SmallSixSpecs.asp http://1bad6t.com/Maverick/maverick_45.html Thanks! Cody
According to 1981 Hollander interchange there are two different heads, if yours is a D5xxx casting it's likely is same as 1975... The D7xxx casting is the 1977 head... Nothing is mentioned about a D6(1976) casting, usually it means the previous year part was continued... BTW the D7 head was apparently used till '80 when a revised E0xxx head was used...
Maybe by subscription I dunno, mine is a counter copy I found at a yard sale, apparently unused... Got it and a somewhat beat up 1968 issue for $15 the pair, too good to pass up...
If you do the header, there use to be a cast iron exhaust port divider on the market that you can weld in. I think it went in 3 and 4. It is supposed to help the flow. I got one from Clifford Research 20 years ago. Not sure if they are still being sold. Micah
The 77 Head was supposed to have slightly larger intake valves (1.75" from 77-80' and 1.649" from 72-76' ) and shared the 200's larger log of 1345cc's vs 1240cc of the 72-76. hope this is still ... http://www.classicinlines.com/HeadSwap.asp In practice most simple intake, exh. and ignition mods to the torquey 250 can make quite a difference and if you need that last squeeze of power the slight differences in heads might count. Typical age and 'not great' factory tuning losses can be dramatically improved with fresh valve job and targeted CR increase. Adding the 2Bbl and targeted CR for a little more power will definitely make the thing a bit more fun to drive . 3/4 Port Divider available from Summit , Clifford - Epay.. ( valves can always be machined much larger , hardened seats , decked block , multi carb , balancing, if you plan on max power or miles a year. My machinist says: ... "it's just horsepower per cubic dollar"... ) have fun Comet with Ford D6DE 250 Six; Bored .070 over with TRW AMC 258 Pistons, Clifford Shot Peened Rods, Clifford 272H Cam, 1.88" int/1.5 exh SS valves, Cloyes timing set, Melling blueprinted HP oil pump, Fisher Dampener, Offenhauser Tri-Power 3X1 aluminum intake manifold adapter w/log Hi-Rise Plenum - Holley 4412 500CFM performance carb, GM HEI ignition trigger, Champion racing spark plugs., SFI 157 neutral balance-lightened racing flywheel spinning Centerforce Stage II Clutch, T5-Z Cobra 5speed tranny, Pinned engine mounts, Short throw Hurst Indy shifter, 8” 3.80:1 TracLoc Posi rear, Cal-type Traction Control devices and Shelby sway bar, Mustang front strut bars, Scarebird Disc front brake mod, Fabricated subframe connectors, tranny crossmember and rear spring mounts, 8 Point Roll bar, 5 point Safety Belts, Mustang 5.0 alum. racing radiator, Perma-Cool electric pusher fan, Holley fuel pump/pressure regulator, Hooker 6602 dual out longtube headers, Matte black/alum. 6=8 Clifford valve cover.Smithy silencers, Original tube radio, vacuum wipers and front fender Gunsights…
Might as well go with pre '72 timing gear setup, actually it's a '69 part number. It's marked differently to give better valve timing. http://www.fastfairlane.com/Tech Tips/Timing/index-retardedcamtiming.html Re-curve the Duraspark distributor for faster advance by using Mr Gasket #925D spring and bending the anchor tab toward center 3/32". Use a TFI coil for hotter spark.
one of the hard things about my 250 build was finding someonre to do the machine work. we have a lot of machine shops in town but they were reluctant to do what I asked "to a 6 cyl". I ask one shop to replace all the valves and seats and was told they only replace what was needed...one said they only deck the block if needed"...another said they don't mill the head, they run it on a sanding table to make sure it's flat... I had the Clifford header and divider, wish I would have had Jeff's info. back then. most people mistook the sound for a 5.o......
Looks like the head is a D5DE, so '75 and the valve sizes match those for the 74. Not sure about the intake log CC, but I bet it matches the '74 too. Now is the time to do the cam upgrade, but I'm on the fence if it's needed. Jeff, I like your suggestion to just swap out the timing gear setup for the pre-72. Maybe I'll do that instead of monkeying with the cam. Got a spare?
The C9-D6 head has a 1240cc log with 1.649" intake valves. The D7-E0 flat log is 1345cc and the hex log is 1420cc both having 1.75" intake valves. All 250's have 1.38" exhaust valves and 62 cc combustion chamber. I bought my 69-71 timing gear set from Napa. Don't forget the timing cover gaskets and seal. You have to drop the oil pan on a 250 to swap timing chain because of the chain snubber inside the cover. My E0 head was shaved 0.070 and I have 0.60" flat head bolt washers to prevent the bolts from bottoming out. I also have early Falcon adjustable rockers and custom length push rods. As far as cam...ain't crossed that bridge yet.
Man I never thought about bottoming bolts and custom pushrods. Jeff, how much compression does that thing have?
I'm thinking about 9.3 to 1 or close to it. The head bolt washers help spread the load to seal the head gasket. The 250 pushrods are 1" longer than the 170-200 hydraulic lifter pushrod and they come will a ball on each end. The adjustable rockers use a ball and cup pushrod. If your serious about building a 6 cyl I recommend buying the Ford Falcon Performance Handbook written by David and Dennis Schjeldahl. It's full of helpful information and cheap tricks...and expensive tricks.
