76' 250 vs. 81' 200 intake, cam, and valve specs???

[hellcat81]

Ok here is my problem:

I am on an extremely tight budget right now, my goal is only to get this car running again as it is my only car and daily driver, performance will come later. I am doing a 200/C3 to 250/C4 swap in an 81' Mercury Cougar. I have a 76' 250 that I am tearing down to check the integrity of internal components, it was last run 2 years ago and was good then.

After sitting for 2 years the crank, rod, and cam bearing faces are all good... but rust had started to form on the cam lobes. I used a little naval jelly to remove the rust and there is some very slight pitting of the surface.

Now for the questions:

1. Would I be better off using the head from my 81' 200, it's in much better condition and only has about 40k miles on it? Or should I stick with the 76' 250 head, milage unknown... ?

2. Does the 76' head have hardened valve seats?

3. Are the log CC and intake valve sizes the same on these 2 engines at 1.750 and 1345cc? Or does the 76' 250 have smaller intake valves 1.649 and 1240cc log like the 74'?

4. Can I use the cam from the 81' 200 in the 76' 250? Are the specs the same?

There is no information on the general specs chart on the Classic Inlines page about 250's from 1975 and 76'... also no information about post 1980 200's. As far as I know the chamber size for both 200 and 250 has remained the same from 69' up at 62cc. But the intake sizes changed as well as valve sizes throughout the years.

Thanks for any info or thoughts anyone has on this...

 

[bubba22349]

1. The head from the 81' 200 would have the biggest log of the two.

2. Yes 75 up were designed for unleaded fuel use.

3. A slight difference in log size 1420 cc for an 81 head not sure on the 75 or 76 heads but think they might be close to the 77 up 1345 cc log same size valves for both. Don’t think there would be a significant difference in performance of one over the other. Had both a 75 and still have a 77 250 equipped the same and same body style. Had the 77 apart but not the 75 the stock performance on both cars was very close.

4. Maybe but don’t think the specs would be the same you might lose some power though again is probably not a big difference.

As to whether you should use parts from your 200 on the 250 I guess it all depends on if the 200 still runs good and you want to take it apart. Than you are also going to need to mod the oil pan and pickup to fit the 250 into your chassis.

 

[hellcat81]

Thank you for the information it really helps.

I will definitely be using the 200 head now, the 250 head needs rebuilt badly but the 200 head just needs new valve seals for now.

As far as the camshaft goes I can't afford to buy a new one anytime soon and the 250 cam has some pitted lobes and I don't want to chance using it. As long as I can make the 250 run well enough to drive with the 200 cam I will be happy for now. I plan on completely rebuilding the 250 for street performance later on, after I find a job first...
Edit: After searching for stock cams from online parts stores I discovered that the stock cams for both engines have the same part number. Looks like I may have just gotten lucky and will be able to use the good cam from the 200 without any problems.

I have no problems taking the 200 apart to swap parts, it needs a full gasket kit anyway. The main reason I am swapping a 250 into the car is because I can't find a bellhousing that will fit a C4 to my 200. It currently has a crap C3 that I can't find parts for that needs to go... I already have a mated 250/C4 combo, just need to make it work now.

To give you an idea of my budget, this is the only car I own and I have a wife and 2 young kids and no job right now. I'm not looking forward to doing the oil pan mod but I have to make this work on the cheap with the parts I have now. Is there any more information on the oil pickup mod? I'm not sure what the best thing to do about that is. Does it need a dual pickup? If so what is the best way to make it work?

Again thanks for any help offered.

 

[chad]

any help offered
Not sure if this is - but there's some threads of puttin a 250 in a bronco (not oem). Some talk there on mods to the pan/oil p/u due to non-oem app. The front chunk (a D44) is close to the oil pan and some have had to mod the motor there.
Wish I had some time to do a whole archive search and consolidation for a stickie here (250 into a bronk), but like yerself - all my time goin into job search.

They ((1s who've swapped a 250 into the bronk) put a frnt pan from 170/200 brazed onto back 1/2 of a 250 and move the p/u around to the back (or is it vise versa?). Never had 1 off to look there. Hope this is enuff AND the right idea 4 U.

 

[bubba22349]

As far as the camshaft goes I can't afford to buy a new one anytime soon and the 250 cam has some pitted lobes and I don't want to chance using it. As long as I can make the 250 run well enough to drive with the 200 cam I will be happy for now.

I hear yeah in the same spot, not much money makes it hard but it sounds like you have good parts usable and some time. I have no problems with using a cam and lifters over or any other part that check's out good. Done it many times when that’s the plan will make a 2x4 block layout and drill holes part way to keep all the lifters in order. It's very important to keep them on the same cam lobe.

I'm not looking forward to doing the oil pan mod but I have to make this work on the cheap with the parts I have now. Is there any more information on the oil pickup mod? I'm not sure what the best thing to do about that is. Does it need a dual pickup? If so what is the best way to make it work?

Have not done a 250 pan in your chassis but have built a number of oil pans for other engines is all the same idea. If you can weld sheet metal or have a friend etc. than that’s 1/4 of it. Since you have the 200 pan that fits the car you got the biggest part “what it needs to look like”, the pan rails on a 250 are the difference. Number of ways to do it slice the pan rails off at about 1 to 1 ½ inches and swap them clamping them to a good flat steel table or bolt down to the engine block helps keep it straight. Another is to just cut the sumps off the 200 pan and add them to correct location height on the 250 pan than make patches to fill in. In this case if you keep the sump locations and heights the same as the 200 than the 200 oil pickup tube should bolt right on without any mods. Last you can also go further too from the pan rail up make a custom fit all new sump and or add more capacity baffling etc. not really needed for a mild street car but if you plan any racing than … Which ever way you decide to prep for welding clean pan and parts good last test pan for leaks afterwards. Good Luck

 

[rocklord]

1. Would I be better off using the head from my 81' 200, it's in much better condition and only has about 40k miles on it? Or should I stick with the 76' 250 head, milage unknown... ?

2. Does the 76' head have hardened valve seats?

3. Are the log CC and intake valve sizes the same on these 2 engines at 1.750 and 1345cc? Or does the 76' 250 have smaller intake valves 1.649 and 1240cc log like the 74'?

4. Can I use the cam from the 81' 200 in the 76' 250? Are the specs the same?

1. You would be better off using the 81 200 head, intake log is larger. The combustion chamber size on both heads should be the same, so you shouldn't loose compression.

2. The 76 may have hardened valve seats, but since you are using your 81 head, not a problem.

3. The 81 head should have a larger intake volume than the 76, along with larger intake valves (1.750 vs 1.649).

4. The 76 cam is the better choice. The 81 200 cam is set up for emissions.

One problem that I forsee in your swap is hood clearance. If I remember correctly the 81 Cougar is based on the Fairmont (Fox) platform, which is a tight fit for the taller 250. Of course, if you install a hood scoop, that might help.

 

[CZLN6]

Howdy Cougar and All:

FYI; "Edit: After searching for stock cams from online parts stores I discovered that the stock cams for both engines have the same part number."

While this may be true of aftermarket cams, it is not true of OEM factory cams. The '81 200 cam is ground with a significant advance built into it. The forward bias was an effort to off set lower compression, higher gear ratio, less emission and higher mpg. The duration of 256 is the same as the 250s. THe late 200 cam does have a slight advantage in lift at .372". The change was in the cam grind and not in the timing gear. All 200s used the same timing gear.

The 250 cams were all the same. Timing gears changed for the '73 and later 250s- again to advance the cam timing to favor low end torque. The lift on the 250 cams is .368". The 250 cam was raised in the block as well as scalloped to clear the rod journals. Some factory 200 cams are scalloped, but not all. Take note and compare the 200 cam to the 250 to make sure it has the scallops or you will have interference.

IF the 200 cam has clearance scallops you can use it in the 250. The specs are not the same.

The only criteria you listed is cost- to get it running as cheaply as possible. If that's the case, I'd use the 250 block stuff all the way with the later head. I would use the '76 exhaust manifold too.

Also You may want to check for hood clearance before deciding the 250 is about 2" taller then a 200. You could swap the Carter YF carb for the earlier and shorter Carter RBS for a little more clearance.

Keep us posted on your progress.

Adios, David

 

[chad]

clearance before deciding the 250 is about 2" taller then a 200. You could swap the Carter YF carb for the earlier and shorter Carter RBS for a little more clearance.

I could stand corrected (have a suposition re: it for my own app) that the Autolite is even shorter/lower.
Also
Several who've placed the 250 in a Bronk have "sloted" the motor mounts (actually the "towers") to have the entire motor sit lower (don't wanna hood scoop). Gotta look @ the clearence below tho...

 

[hellcat81]

Thanks all for the input, it will definitely help me get this project going.

Lots of thanks to CZLN6 for the camshaft specs, but now I'm confused about the timings.

The '81 200 cam is ground with a significant advance built into it.

The 250 cams were all the same. Timing gears changed for the '73 and later 250s- again to advance the cam timing to favor low end torque.

I thought that most cars built after 1971 had severely retarded camshaft timing to reduce emissions.

According to Classic Inlines the later 250 timing gears were retarded to reduce emissions. They only sell one timing set for the 250 and this is what they say about it.

"Note: These are the early (69-71) timing chain sets, which offered more low end power."
"NOTE: Later timing chain sets were retarded at the factory to reduce emmisions. As such, we only sell the early timing chain sets, which offer increased low end power for optimum performance."

As far as hood clearance goes, I have known all along that it would be an issue. Not sure what route I am gong to take to remedy that problem yet, might just install a hood scoop if I have to.... I had planned on using 1971 Maverick mounts as I have read they lower the block a bit but not sure if it will be enough...

 

[MustangSix]

I believe the later timing sets were retarded to reduce cylinder pressure to reduce NOx emissions. The early timing sets restored a lot of the lower end power. The cams all seem to measure about the same, but the 250 cam has a tad more duration. Not enough to notice.

The late 200 head and cam, along with the early 250 timing set will work fine.

I think the best performance mod you can do on an otherwise stock 250, if its in the budget, is to have the block decked to raise the compression a bit. The stock pistons along with the abysmal low deck clearance only give you a true static CR of about 7.5:1 with most composite gaskets. Cutting the deck helps get that back to a more reasonable CR. Just getting it back to 8 or 8.5 would net you a pretty good bump in power and mileage while still allowing regular gas.

At TDC, the pistons could be down in the bore as much as .140" and shaving the block helps fix that. Assemble the crank and one piston (rings not needed at this point) and measure the compression height (top of piston to deck) to see where your engine is. Then measure your gasket thickness and run a CR calculator to see where you are. Most dished 250 pistons are about -7cc's and I think the late 200 head should be about 66 or 68 cc's. I'm sure someone here can verify. If your piston is .140 down, a .060" cut gets you back to about 8:1 and the engine will be more responsive.

But measure first!

 

[CZLN6]

Howdy all:

Late model 200 (AKA 3.3) cam specs-
Duration Intake open Int. Close Exh open Exh close Overlap Lift
256 28btc 48abc 76bbc 0atc 28 degrees .372"
Early 200 cam specs
252/256 7btc 65 abc 55 bbc 21 atc 28 degrees .348"
Early 250 (with straight up timing gears)
256 10 btc 66abc 58bbc 18atc 28 degrees .368"

Seeing as how the late 200 cam favors the earlier opening on both the intake and exhaust valves I think of this as advancing the cam timing. The late 93.3) 200 cam timing is significantly earlier that the early 200 cam timing. Retarding the cams timing moves the rpm power range higher. Advancing moves the power range lower.

What ever you call it the later cams were designed for more low end power and lower emissions. Earlier cams had a little more top end.

I know that there has been alot of cussing and discussing on this subject, but this is my story and I'm sticking to it- for what it's worth.

Chad- the Autolite would not be compatible (Except for a '69 250 with an 1101 Autolite) with the DSII distributor in an '81 Cougar. And changing away from a DS II would not make sense in my mind.

Adios, David

 

[xctasy]

With a few modifications, some 70's to 82 F100 offset 4.9/300 ci Truck air cleaners (1974-1982 esp) can be made to suit a Fox Fords nice low hood.

http://www.supermotors.net/getfile/7167 ... ne-bay.jpg
http://www.ford-trucks.com/user_gallery ... 4798&.jpg=
http://www.ford-trucks.com/user_gallery ... 4800&.jpg=

Some L-code 1969-1970 250 air cleaners for some non Mustang applications or Mustang 428/390 FE air cleaner has a 2100 series goose neck (carb bonnet to remote air cleaner). They are perfect for fitting the 250 engines carb under the very moderate hood bulge Fox Fords have. Non US market Toyota SR5 Hilux RN 85 with 22r carb 2.4 or early non EFI Landcruiser FJ40 series have similar pressed steel goosenecks which look like a poor mans Classic Inlines Turbo carb bonnet.

http://i260.photobucket.com/albums/ii10 ... 230109.jpg

Or just get CI carb hat

http://i1215.photobucket.com/albums/cc5 ... Gen2_5.jpg

I've got a photo of a 390 FE California spec one somewhere which used the offset air cleaner...and one guy posted a blue 250 1970 engine picture from his barn a few years back...the stock remote air cleaner on each of those was really good.

Oh yeah, and the first 1970 to 1977 compact Bronco might have had one when using the 170/200 engines.

Another option, as used on 1972-1977 2V Australian Cortinas such as this New South Wales 1976 TD Cortina 250 2V, is to use the stock power bulge hood scoop (Mustang Cobra/GT or Turbo or Indy Pacecar would be an option for your Fox), and add another offset glass fibre lid as an integrated insert. Pretty simple way of getting clearance without too much interferance. Often, fibre glass shapes like the one below can be picked up from outher RV or motorhome or trailer applications without any major cost.



LC Redline make them too

http://image.4wheeloffroad.com/f/880419 ... y_08_z.jpg

 

[MustangSix]

Thanks David,
That clears up the cam timing questions for me. Given the specs you posted, I'd lean toward the late 200 cam as the one to use.

For a short air intake, you could look at using something like a Spectre 98499 with an adapter.

 

[chad]

'66 - '77 Bronco might have had one when using the 170.
(Close yrs to check '66-'73 or 4 - ie the 6 cyl 'run').
Yes...it sits down, off to the pass. side on a arm that comes offa a nut on the block (supports the bottom of the air cleaner in same style as if on top of the carb). The traditional wing nut is there on top of the carb fastening a sheet metal top that stretches all the way over to the air filter canister an inch or so below the hight of the top of the valve cover. The hole thing is about 18 inches viewed from above as an ellipse ( sm. circle over carb, lrg circle, a traditional a/c w/it's standard szed air filter inside, on other end). I love pic and would put 1 up if I knew how. (PM w/personal e-mail, I CAN post pics there),

It's a good work around system for this problem, nice and stock looking (cuz it is).
28 yrs. ago B 4 I acquired the bronk some 1 put a car 170 in 'er. Even with this "low riser" system & a stock carter YF the hood hits the wing nut. I will have to find a "lower riser" carb when putting in the 250, see if I can keep this a/c system, 'slot' the towers on the motor, consider a 1 inch body lift (and may be modify the pan due to a frnt 'chunk' being there in a 4 wd vehicle).

Hope I haven't taken this too far off topic, thanks (4 more ideas) xctasy. Now just send me 1 a those x-flow heads 4 my '69 n I'll B real happy!
8^0