250 or 200?

Hey everyone;
Here is my question or questions. I have a 79 200ci, stock with a C-4 (high mount starter) in a Fox Mustang. I would like to get a little more performance out of it and an extra gear (overdrive) I picked up and AOD for 100 bucks and I know, I know, it won't bolt up without a lot of re-configuring things. bolt pattern, starter location, etc).
But...I have the opportunity to buy, cheaply, a 250ci out of a 70 Mustang. Low mileage and well taken care of out of Arizona. I looked up the HP. and Torque ratings on this motor and was surprised that it had 155 HP. and 240 Tq. Why is that if it has the smaller log 1240cc and 1.65 valves? Is it a better motor all together or just the fudging they were doing with the horse power and torque ratings back in the late sixties? I see all the other years of 200's and 250's seem to make sense but the 69-71 250's?
Anyhow I was thinking of buying the 250. Swapping out the heads and running the 250 head on my 200 while I drive the car (daily driver)
Then, work over the 250 block. make sure it is worthy and upgrade to ARP stuff, new oil pump, etc. And, do some work on the 200 head to make it perform better. It is the later larger log 1345cc with the 1.75 intake. Some porting milling to increase CR and maybe even a Triple carb set up (Offy?). Not set on that as of yet.
This all gives me time to get the motor to where I would want it and then I can bolt the AOD to the 250 block, run a Lokar TV cable, and I should be half way there! Is there any issue with putting the 250 head on the 200? and vice versa?
Does anyone see any issues with this plan or suggestions...good or bad.

Thanks, Randy

Howdy Randy:

Oh the disappointment! For the 1972 year and after all engines were required to be rated at rear wheel HP not flywheel HP. For 1972 a 250 was rated at 99 hp with 184 tq.

Your '79 head is preferable on several count.

Your '79 200 engine is down on HP and Tq for several reasons; 8:1 compression ratio and a cam with advanced valve timing. Both making for a very lazy, slow revving engine. The solutions are to mill the head, next time you need a valve job, to get CR back to the 9:1 range, and replace the cam with a more balanced profile. The Holley 1946 carb is not user friendly and prone to problems due to the many EPA required crutches to clean it up.

I'm wondering what rear end gear ratio is in your car. Most '79 Mustangs with 200 C4 combos had a 3:1. Some came with a 2.89:1 ratio.

The 250 block can accommodate V8 transmissions with some modification. Check with Modern Driveline in Caldwell, ID for details. The last number I have for them is 208-453-9800.

While the 250 block increases cubes, it has some pitfalls that you should be aware of. It is taller by almost 2" (hood clearance), has a pan configuration that is not compatible with a Fox unibody, and a huge deck height that ruins quench effect and is prone to pre-ignition.

Have you tried increasing the initial advance Yet!

I hope this info is helpful to you. Keep us informed on your decisions and progress.

Adios, David

I have a 2.73, 7.5 rear in it now and a friend is going to swap me a 8.8 locker (same ratio) for now, but a better rear to handle any upgrades. (upgrading the rear control arms...free deal). He also has several different gear sets that I could put in it. 4.11's being the the highest ratio. so I have options in that regard...

Randy

CZLN6":1s78yfnx said:

Howdy Randy:

Oh the disappointment! For the 1972 year and after all engines were required to be rated at rear wheel HP not flywheel HP. For 1972 a 250 was rated at 99 hp with 184 tq.

Click to expand...

With the utmost respect, this is not true. Its been debunked many times, and I've got the chassis dynoed figures to prove it.


Ford Fudged the results the world over, Ak Miller discussed it, and even the Ford literature proved it.

1. Gross Hp is engine out of car, flywhwheel Hp "without" ancillairies (no air cleaner, no heat factor increases) and with tubing exhaust and optimised ignition, spark plug heats and retuned to give a number with a nice low heat test.

2. Net Hp is as if the engine was in the car, but flywhwheel Hp "with" engine ancillairies (fan shroad, hood covering, air cleaner and full factory exhausts with its bends and its silencers, catalyst if requires, engine acessories, air pump, A/C, alterenator/generator, water pump....the exhaust without any tubing exhaust and no igntion advance optimisation, no retuning to give a number with a nice low heat test. The test engine then has the engines areodynamic and chassis load combination applied as presented for the Federal FTP 75 Test, Los Angles Basin 7 mile emissions and later CAFE fuel economy test.

Re: Adding some modern zip to a 200 Post #21 by xctasy » Tue Feb 16 said:

CZLN6":1s78yfnx said:

....federally mandated requirement to state rear wheel HP rather than higher flywheel HP ratings and it ends up comparing apples to elephant.

Click to expand...

David, live for ever, but know this...the SAE Net J1349 rating was, and is, still an engine flywheel rating, not rear wheel roller hp at all. SAE Gross in specification J245 and J1995 was engine flywheel too. There' s no excuse for a 50% loss in Gross to Net horspower, unless Ford was cheating and cooking the books. It did so because J245 ALLOWED them to do so. The 1968 Tunnel Port G code engine was a case in point, the 69-70 G code Boss 302 another. Just taking the horspower reading at just 4600 rpm instead of its peak power rpm got the issurance indusrty so incensed that Ford was stuck in making its permnace cars more than 10 pounds per horspower under the old scheme. The free market rapidly grew sick of anual increases in size, to the point that the only fresh MPG option was buying a Celica or Mercury Capri or Datsun 260Z. Those Gross hp ratings have a heck of a lot to answer for.

J245 allowed Ford to cook the books on the 250 by playing with settings, and getting away with it. That cannot happen with Certified J1349. There is honesty in it, right down the line. Its the best horsepower fist thumper ever. Its picked up some pretty amazing aberations on transmission loss, and continues to show that its possiable to lose 50% or more from the engine dyno to the chassis dyno.

Click to expand...

Fords one time 1969 to 1970 rating of 155 Hp Gross for the 250 was (in the Australian 250), 102 hp net.


The tall deck 200 (a destroked 250 block) gave a 19% increase, but the USA 69 and 70 250's were rated in the gross test as 35% more power full than the 115 hp Gross 200. That was what the Gross, stripped tests points of detail allowed. The rear wheel horspower figures from Ak Millers numerous and plentifull Maverick and Mustang Six rear wheel as installed dyno tests showed a stick shift 115 hp Gross 200 made 65 rear wheeel horsepower.


The 1971 Maverick 250 made 65 rear wheel hp as an automatic, and if you could get a 3 speed manual or stick shift manual, something like 78 hp, or 20% more than the same years 200.

In every instance, the installed figures of the 250 engine weren't proportional to the capaity increase, and the weight of the US 250 9.469" talll compared to the 7.83" tall 200 was 450 pounds installed weight ready to run (from Popular Mechanics Big Four Ford Chev Mopar AMC family car test in 1971) verses 385 pounds. 17% heavier. In the Australian engine, the tall deck 250 and 200's both weighed just 410 pounds read to run.

When Power steering and A/C options are added, that becomes 510 pounds as installed, 125 pounds heavier, 33% more.

Most 250's ran the 8" corporate Sao Paulo axle, which was also much heavier than the 7.25", so the axle added and extra 30 pounds. A 8.7 or 9", like the 1980 Granada had, added 60 pounds to the weight of a 250, a 49% car combinations weight gain over a no option 200 base engine of 385.


You couldn't order a 250 without the stronger axle, so a 250 engine was a 185 pound weight penalty anytime you ticked the option box in the 1975 to 1980 Fords.



The 250 in any Ford car never, ever gave a 25% horspower increase over the 200. You'd expect that, given the 25% capacity increase.

But thats not what happened, ever. In the last year the "4.1 liter" engine was offered in the USA and Canada, 1980, the 250 gave 99 hp net , and the 200 gave 85 hp. A meger 16% increase.

Proof/Evidence? The 410 pound Aussie tall deck 200 and 250 engines. Internally, the Aussie 250 engine was similar to the the US 250.

xctasy":1s78yfnx said:

BCOWANWHEELS":1s78yfnx said:

my 70 250 engine is 155 hp stock. no substitute for cubic inches

Click to expand...

No its just 102 hp net. The 200 is 93 hp net. 10% different as installed. And horsepower governs top speed, 60 foot times, eighth and quarter mile times and 0-60 times, not torque.

http://fordsix.com//viewtopic.php?f=1&t ... 36#p554236

Click to expand...

You'll also notice that when listed as net hp, the 25% bigger short 5.88" rod, 3.91 stroke 250 yields only 10% more power than the long 6.275", 3.126 stroke 200. Both Aussie engines, unlike the USA 200 and 250, ran the same camshaft timings. As gross power, the bigger 250 is only 19% more powerful for a 25% increase in capacity.

But torque wise, its 25%.


The point being that at either 93 net or 130 gross, the long rod 200 is over 17% up in power over the same US 200 engines. The Big Aussie 250 is the same as the pre emissions US 250.

Click to expand...

If Ford were able to do there job with the 250 engineering correctly

CNC-Dude":1b4ykhur said:

At the bare minimum if done correctly you should always be able to gain 1HP for every cubic inch you add, so yes it's always worth doing.

Click to expand...

Click to expand...

That's exactly what DOESN'T happen with a 250 Ford engine. It never happened anywhere, the world over, in any 250 combination, anywhere. For a 25% capacity increase, you'd expect a 25% power increase if it were engineered right for the purpose, irrespective of how the engine was rated.

The only time a 250 or perhaps 221 in line six became proportionally better than a 200 was in the over seas 1971-1975 170 hp Gross 2-bbl 2V headed M code 250

or 1973-1978 164 Gross HpSP 221 Argentine engines,

or the EFI 1983-1985 149 and 1985 164 hp and 1986-1988 164 Hp 4.1 liter X f-low engines.

The 4.9 EFI F150 spec cam profile of the Aussie 1985 to 1988 4.1 liter EFI engine gave the engine 13 to 15 more horespower, and 10 lb-ft more torque.

Each of these had the better breathing head, and each gave a further 10% power increase gross. In fact, the 2V heads of both types, Australian or Arentine, made 149 hp net.

A 1979 or 1983 2.8 V6 with a 1.08 5.0 Ford V8 2-bbl 2150 Motorcraft carb makes 109 to 114 hp net, while the 1980 1-bbl YFA Carter equiped 4.1 made 99 hp.

Yes, in a 250, torque always goes up proportionally, but weight goes up disportionally, and the only way to make a 250 haul some serious butt is to add the best flowing head. Which is also 68 pounds lighter.

The reason why a 200 or 250 US engine is so emasculated compared to any other 3.3 to 4.1 liter engine the world over was described by Wheels jounralist and Editor Peter Robinson in 1985 in the 1985 Commodore verses Falcon comparison, where he clearly described the EFI engine as being very conservatively timed.

Specfic to the US 200 and 250, the power loss compared to other Ford empire engines in the 2.8 to 4.9 liter engine range was a result of having

1. the very conservative cam lift,

2. cam duration and

3. low compression ratios.


The real proof is what happened the same carb in engine combinations with more than 260 degrees cam duration and more than 380 thou lift

Example 1. The 1967 240 Big Six Autolite 1101 1-bbl carb was a 1.29, which is a little bit smaller than the Holley 1946 or Carter YFA (both 1.31).

The 1.31 YFA 1 bbl Carb on the 1972 to 1986 300/4.9 gave about 120 hp net and 245 lb-ft net.

On the best Ak Miller 1-bbl combination, a 1967 200, the 1-bbl 1.29 gave 100 rear wheel hp net, up from 65 rwhp, or about 126 hp flywheel net as installed. 65 rwhp hp is 82 hp net installed, down from 120 hp gross.

In the later years, the 1968 to 1971 netgross hp figures were de rated to 115 hp for 200 engines, clearly a paper decrease. The net hp figures from 1972 to 1983 of 83 to 94.5 flywheel hp were 100% correct.



In 1969, the 250 engine was rated 155 hp Gross, the 240 Truck and Taxi engines, 145 hp Gross.

Clearly, Ford only ever reported what it was required to.

Ak Miller:-

http://www.allfordmustangs.com/forums/a ... page-4.pdf

You have been given great info by the best. I would modify the 200 with a Schneider camshaft, Call Jerry & he will advise you.
Get your compression over 9-1 by milling the head, zero decking the block if you pull the engine for an overbore & new rings & as David said call several of the driveline specialists to adapt the AOD. If you need distributor help i can advise you there.
With an AOD you could go up to a 3.55 rear gear & that would help the drive ability of the Stang a lot.