200 vs 250

[Bayrunner]

Hey Guys, here a question for you. Please.

Since I am building a new engine anyways, Head, rods, cam, pistons, the works. Would it be to my best interest to up to a 250 vs my 200? I read the other car mods needed to fit the 66 mustang. The car needs lots of other work anyways. Wouldn't the power difference be worth the few other modifications? Please let me know your thoughts.

Jack, What about the block/head mods for the crossflow? Do I still need to make those? Also, pushrods? Since cam location is difference, what happens there?

Thanks Fells.

 

[stevexysupersix]

Since I am building a new engine anyways, Head, rods, cam, pistons, the works. Would it be to my best interest to up to a 250 vs my 200? I read the other car mods needed to fit the 66 mustang.

Hey Bayrunner,
Please excuse my ignorance, what mods does the 'stang need for the 250 to fit?

 

[Bayrunner]

Look at the tech section that mustang six has provided for us all. Swaping a 250 into a 66 mustang. I am not good with links. Sorry. Hope this helps

 

[Lazy JW]

Hey Guys, here a question for you. Please.

Since I am building a new engine anyways, Head, rods, cam, pistons, the works. Would it be to my best interest to up to a 250 vs my 200?......

...... Wouldn't the power difference be worth the few other modifications?.....

If more power is your goal then yes, definitely upgrade to a 250. There is no easier way to gain power than simply bolting in an extra 50 cubic inches. Any modifications done afterwards will yield that much more power.
Go for it!
Joe

 

[Gene Fiore]

Hey Guys, here a question for you. Please.

Since I am building a new engine anyways, Head, rods, cam, pistons, the works. Would it be to my best interest to up to a 250 vs my 200?......

...... Wouldn't the power difference be worth the few other modifications?.....

If more power is your goal then yes, definitely upgrade to a 250. There is no easier way to gain power than simply bolting in an extra 50 cubic inches. Any modifications done afterwards will yield that much more power.
Go for it!
Joe

What he said!

 

[rocklord]

Hey Guys, here a question for you. Please.

Since I am building a new engine anyways, Head, rods, cam, pistons, the works. Would it be to my best interest to up to a 250 vs my 200? I read the other car mods needed to fit the 66 mustang. The car needs lots of other work anyways. Wouldn't the power difference be worth the few other modifications? Please let me know your thoughts.

Jack, What about the block/head mods for the crossflow? Do I still need to make those? Also, pushrods? Since cam location is difference, what happens there?

Thanks Fells.

George,
I posted an answer to your question on the XFalcon forum but here's a copy for those here:

I believe that it would be better to go with a US250 with the crossflow head instead of the US200 for several reasons:
1. The distributor clearance issue would be resolved.
2. The US250 uses the SBF bellhousing which allows more transmission options, including the AOD if you don't like to shift.
3. The cams and performance modifications that the Aussies do on their 4.1L crossflow should have the same benefit on the US250Xflow; no worry about overcamming the 200.
4. You can't beat cubic inches.

Several problems I see with this setup is:
1. The US250 has a low mount starter, whereas the OZ 4.1L has a high mount starter, so there may be interference with an extractor (header). This could be resolved by cutting the extractor back at the collector and rerouting the exhaust.
2. The EFI intake may interfere with a power brake master cylinder as MustangSix documented. His resolution was to switch back to a non boosted MC.
3. As for the modifications to the block and crossflow head, they still have to be made. You would need different pushrods than what Jack used in his 200Xflow, but I don't know if there is stock pushrods from other vehicles that can be used. One way to get the correct pushrods is to bolt everything up and measure the length, then have them custom made.

I installed a US 250 in my 65 Mustang back in 1978, and it went in fairly easy. The biggest problem I had was with the hood clearance, since I used the 200 motor mounts which raised the engine higher; Maverick 250 motor mounts will lower the engine in a Mustang. MustangSix (Jack) installed a crossflow 4.1L in his 66 Mustang and stated that the crossflow with the EFI manifold was not as tall as the US 250 with a carb and aircleaner; this may eliminate the clearance problem.

Hope this helps.

 

[Mustang_Geezer]

Since no one is speaking up for the 200 I will....

Relatively easy to bump up the compression using the 2.3 litre HSC flat top piston in the 200 where in the 250 you have to run 255 V8 pistons in it (getting hard to find) and deck the heck out of it.

Shorter stroke for the 200 means you can rpm it more and its less prone to grenade. (knock on wood) :mrgreen:

More header choices.

Double roller timing chain and gears are available for the 200. Nothing available for the 250.

Getting a custom convertor built for a 200 is no big deal and not any more expensive than a GOOD QUALITY V8 convertor costs.

Performance oil pans are available through Classic Inlines for the 200. Custom made only for the 250.

If you do decide someday to swap to a aluminum head there is some clearance problems that are easily addressed on a 200 but I cant think of anyone running a 250/aluminum head combo in a early Mustang.

Depending on your area a 250 can be next to impossible to find. I have NEVER seen one myself in my area in any salvage yards.

Plus there is the normal problems to fit a 250 in a early Mustang that are explained on the webpage. A 200 is a "bolt in".

Later,

Doug

 

[Bayrunner]

Everyone is so willing to share here. That is why I valie all of your input.

My thinking was as such.

Putting in a 250, which I have found a number in my area, CHEAP; will get me the extra cubic inches. The extra mods to get it to fit in the engine bay do not concern me. Since Jack has already paved the road, both on a US 250 and a AU Crossflow 250, I think I can muddle through the rest. Now, as far as the aluminum head, I will keep the 200 for that later.

On the 250, lower rpm's and higher torque will get me where I need to be on this project. The Crossflow head, Roller rockers, etc. should be able to get me some additional RPMs which I will self impose a limit anyways. I just did not want to modify the hood. I want the mustang looking stock. Possibly, down to the 4 lugs from the outside. If I can get the US250 and the Crossflow EFI to fit under the hood.....Well : Mission accomplished. As far as power assisted brakes, That is something that will suffer for now. Export brace, I can re-design and probably get better results anyways. The headers, well on a Crossflow head, I will have to modify anyways in order to get a turbo on them. Pistons, Expensive anyways. Pushrods.......Math, math, math. Compression...Math on that as well. Zero deck, I do not know how far I can get to zero yet. Any advise is welcomed here.

Thank you fellas.

 

[Bayrunner]

O.K. Dan

Here is what I have.

Measured the stock 200 ci from the top bolt of the engine mount to the log head valve cover. Actually the oil cap. it measured 13 1/4"

swaped the Crossflow with EFI and measured from the same place. 15 3/4" Now that is an extra 2 1/2" which the mustang can handle.

Thoughts. the US 250 is 2" taller than the 200. Right? I do not have one to compare where the extra 2" actually play in the equation. Suppose that it is from my same starting point. Don't you guys think I can cheat the 2" by fabricating new mounts or using the maverick mounts if I can find them? What about the tranny? I would need to fab thast mount as well, right?

 

[Bayrunner]

O.K. Guys,

Some simple math on the Mustang, I believe that we can get a 250US with Crossflow EFI setup to fit the 66 mustang engine bay with engine mount modifications.

Does anyone have access to any CAD files on the Mustang engine bay? If not, I will make a cad file and also PDF it if anyone else is interested. Let me know, It should take a few days but I will get one of my Cad guys on it.

Thanks

 

[rocklord]

George,

In regards to zero decking the 250, be careful. How much to deck the block should be the last thing to consider after porting and cc'ing the head, and selecting pistons. It's awful hard to put metal back onto a block. Use the CR calculator on the Falcon 6 Performance Handbook website to help you make decisions.

http://falconperformance.sundog.net/compcalculator.asp

I suggest, if you haven't already done it, is to purchase a copy of the Falcon 6 Performance Handbook. It is a great How-to and reference guide.

 

[Bayrunner]

Dan

Thanks for the info. I do have the book and looked at the calk on the website as well. I am waiting on Glen to send me some info on the gaskets he is sending me so I can compute. My only other question is now do I obtain the Dish valve relief dome volume as well as the volumetric effieciency?

 

[MustangSix]

The real reason that I took off the power booster was the hydraulic clutch. No room for both using a Tilton clutch master. Wtih a cable or a ford truck style clutch master it might all fit. The EFi should clear the stock or 4cyl Fox-Mustang booster.

 

[Bayrunner]

So, A us 250, an EFI Crossflow and Power brakes! Life is good.

Thanks Guys