1975 head flow better??

[yellowstang]

Hey guys,

merry christmas!!

anyway, I was reading thru the ford falcon perfomance book and I read that the 1975 head had 1.65 intake valves and 1.38 exhaust valves. more importantly the manifold plenum volume was 1365 cc.(the 1978 or later head was 1265cc)

i think i would want the better flow for my turbo application. the 75 head is about 10% better than the 78 head but 25% better than the 68 head(1100cc). hey you gotta take it when you can get it - right??

ok so what are the head markings for a 1975 head? anybody got one for sale? are there any nuiances to the 75 head that are different than the 78 or later head?? which cars in 1975 did the 250 come in so i can go look for them in the bone yard??

i would probably then take the valves to 1.88I and 1.5E. what do you think???
Pete

 

[CoupeBoy]

I have a '74 250 head if anybody knows if the dimensions/volumes are the same.

ron

 

[CZLN6]

Howdy Pete:

Merry Christmas back at'cha.

Glad to hear you've found the FPH useful. A couple of points though- don't equate volume with flow. Volume is good, and may contibute to increased flow in some cases. Increased volume may actually decrease flow in other cases. In theory, more volume is better for higher rpm, larger displacement, and because of the log/plenum design, may compensate for an engine with a carb that is too small.

In your case, for turbo application, You may see less turbo lag with the later 1265cc head. In either case, I doubt that the difference will be noticeable, when using a turbo. The real advantage of the flat log head is the convenience of a flat surface in cutting off the carb flange and opening the hole for directly mounting a two barrel carb.

The flat-topped log head first appeared on the '69 Maverick 250 engines. It's casting # is C9DE-M. We have also found later 200 & 250 engines with flat-topped log heads with casting #s C5DE-BA & D7BE-AB. If you could locate the latter casting, you'd likely find larger intakes, a 1.75" carb hole, hard seat inserts- the best of both worlds.

Enjoy the journey.

Adios, David

 

[yellowstang]

ok that brings up an interesting point. i realize volume is not flow. however given a larger volume, flow goes up. anyone washing a car with an 3/4 dia hose knows the difference with a 5/8 or even a 3/8 hose.

ok lets say i am running 10 lbs of boost. then out of the turbo via 3 inch pipe to an intercooler in front of the radiator thru the intercooler and then back down the drivers side of the engine up and over to the carb and then into the fuel log(plenum). if i use 3inch pipe for the plumbing and there 10 psi in the 3inch pipe wouldnt there be 10 psi the plenum?

i think i am getting confused between pressure and flow. its the same as volts and amps!!!! i always do that

 

[CZLN6]

Howdy Back Pete:

Theoritically, pressure may go up as volume decreases, but total volume will likely stay the same.

EI- Thinkd of it as pushing water through a hose into a buck. It may take 10 lbs of hose pressure to push X gallons of water (volume) through a 2" hose, but it may take 15 lbs to push same X volume through a 1" hose, or 5 lbs to push Same X volume through a 3" hose. In a given amount of time all may move the same amount of gallons (volume). Flow rate and pressure go up as diameter decreases, and inversely.

Ron- Most '74 250 heads have one of the following casting #s -D3DE, D4DE. They will likely have a hex shaped log and the same deminsions that Pete posted above. It will have a 1.75" carb hole and (I believe) induction hardened valve seats. If the casting # is different than these please let me know. With FoMoCo- never say always!

Adios, David

 

[CoupeBoy]

yup sure is a D3DE

but how does one tell if the seats are induction hardened or not? Most of my previous motoring experiences have been with old 283's which I never bothered to change the seats in. And aluminum which you can see the seat has been machined into the head. And again yes on the carb opening hole, the EGR spacer that came on it is actually a reverse funnel from 1.5 to 1.75" (strange if you ask me).

ron

 

[yellowstang]

ok the 1974 head is not listed in the Falcon performance handbook on page 5......,

so how much is the volume is the D3 head ron has?

what are the castings for the 1975 head?would it be D5DE-BA as listed in the fordsix/tech/inlinecasting numbers???

i really love putting all the parts together!!!

 

[CZLN6]

Howdy Back:

Ron- there is no way I know of to detect induction hardened seats. This type of seat was hardened throught a heating process to make the seat harder. Later heads, somtime after 1975 FoMoCo started using hardened seat inserts. If you are in dougt it would be wise to have inserts added to an early head or find a D7XX or later head to start with.

The larger volume goes with the flat-topped log, Late model hex shaped logs have a volume in the 1250 cc range. We are finding more heads all the time, and cataloging the differences. The chart on Page 5 will soon be updated and refined to reflect the latest information.

It appears that Ron's head has a flat-topped log, but it's hard to tell. Ron, could you take another photo, from a little farther back. The whole casting number appears to be D3DE-6090-AA. Is that correct?

It would also be helpful to know the volume of the Combustion Chamber on this head.

Thanks in advance.

Adios, David

 

[yellowstang]

hey fordman,

so how large are the intake valves? what are the casting numbers? can you tell physically if it has a larger intake plenum? what size is the carb opening??

what does it come with? head alone? do you have any other goodies you are willing to part with??

lemme know
Pete

 

[CoupeBoy]

Well I will be gone from Friday Dec 20-29th but when I get back if y'all are interested I will take the 60CC syringe and fill the compression chambers and the intake log (things I have been meaning to do anyhow)

Merry Christmas everybody
ron

anybody gonna be in Bismark, Jamestown, or Fargo over the holidays?