Greenhorn Builder Looking For Some Direction from the Sages

Alright, first off, thank you and hello to whomever reads this post and gives giving me your advice and guidance your best try.

Ive had my 1973 Mustang for close to 4 years now, and she's a great car, I built it with my dad and I'm probably never going to part with her. That being said, as you all know, a semi-stock, improperly tuned 250ci I6 doesnt exactly do much except sound kindof 'cool' to people who don't know jack about muscle cars or engines. Up until now I havent really been interested in extensive modding of my I6 because I did in fact want to throw a 429 cobra jet into her. Obviously that is no longer happening, mostly because I'd like to keep the same engine me and my dad worked on together.

Ive done some research on classic inlines as well as a bit of other reading about I6's and ive definitely caught the bug to build her up into something unique.

as of now, this is my current engine configuration that I'm aware:

-Stock head
-stock log
-stock internals (decided to just say what I know rather than sound like a moron)
-exhaust manifod
-1-v 1100 Autolite Carb
-Pertronix Ignition & 40,000v ignition coil w/aftermarket wiring
-split exhaust (yeah, I was in High school with $500, didnt really realize that you need a COMPLETE system)

I DID rip out all of the emissions stuff because it is no longer required and did upgrade to an open air filter.

Putting it bluntly, I know theres ALOT of work to be done to break that depressing 88hp rating that was given to my car in 1973. I want to build a Motor that gets close to or breaks 200hp, lives up to the idea of the 'reliable 6', while retaining drive ability(Not looking for 40MPG, just something decent), an engine that in essence is something that will cause the people who think the straight 6 to do a double take. I'm a pretty inexperienced mechanic looking to gain some knowledge and some insight from y'all. Thank you.
 
:unsure: In order to better help you, it would be helpful to know how much you plain to invest in this build and the trans that you plain on using. Getting a 250 built and tuned to 200 or more HP and still be a good street car is a tall order. One way could be with a turbo install and the 250 with its low compression is made to order, but it will take some upgrades to the short block. That said its not so hard to get to 125 to 150 HP range on a modest budget, in my Opin HP is not as important as Torque on a street car. Good luck on the build :nod:
 
Honestly right now budget isn't an issue. I know hitting the 200hp mark is a far ways off, thank the lord I'm not that deluded. Right now, to put it into perspective, I have no issue buying a Saginaw Power Steering pump w/a complete DUI ignition system as well as properly doing the exhaust and maybe sending the stock head in to get machined to take a 2v Carb.

Part of my curiosity is which direction (side of the engine) should I really Invest in first? Or should I skip both and just save for the AL head?
 
Howdy MM73:

And welcome to the forum. Your car sounds like a nice ride. Keep it straight. Is it an auto trans? Is the rear gear stock? What ratio? What type of driving will you mostly do with this car? Do you need to keep it as a daily driver or can you afford to have it down for a length of time?

Take a look around on this forum. You'll find some Dyno tests of similar builds with pretty impressive results.

FYI- a '73 with a 250 should have a Carter RBS carb. Does it really have an Autolite 1100 on it? An RBS is rated at 210 cfm. An 1100, up to '67, is rated at 185 cfm and have a SCV. "68 and '69 1100s do not have a SCV but are rated at 150 cfm.

My recommend to you is to find a '78 an later head to rebuild and modify. The point of the rebuild will be to resolve several of the current limitations; namely low compression and cfm. The head build will also increase flow reduce the chance of ping. The build would include larger exhaust valves, back cutting the intake valves, modifying the log to adapt a wide based two barrel, milling to increase the compression ratio, a general clean up of the Valve pockets, ports and combustion chambers and a three angle (At least) valve seat. Details like adjustable rocker arms and valve train pieces too.

Add to it a Holley 2300 350 cfm or an Autolite 2100 1.21 or 1.23 (both are near 350 cfm), a performance exhaust and an ignition system with an appropriate advance curve and you'll be on your way.

The only thing not addressed with this step is the cam timing. IF you are planning on a performance cam upgrade, you might as well plan for a complete block rebuild as well, including balancing. That will be down time, unless you can find a core engine to build and then swap out when it's ready. building a bottom opens the door for many other discussions such as reducing deck height, piston selection, and others.

So, what do you think. Budget is always a factor, and remember Murphy's Law about engine building- What ever it costs it will cost more. And, How ever long it takes, it will take longer. Let us know what you think.

I love the relationship you have with a car and your father. Keep the memories.

Adios, David
 
You should know that Moses of the Ford just answered your question. David and his brother wrote the bible of this site: The Falcon Performance Handbook.

He is too humble to sell it himself (really), but if you want to know the TRUTH about your gutsy little engine, you need to get his book. Usually we say you can order it from Mike at Classics Inline, but that is out of the question now with his passing. Order the book directly from David using the link at the bottom of his signature. The best sawbuck you will ever spend.
 
Its your car, you'll do it justice, and everyone will love it. They are my all time favorite.



Just a word on where I have found the 250 to fit in to the Mustang line, a line mist call the FatStang. I use the term with the utmost reverance.

They and the Foxes were Mass Produced Italian Supercar rip offs, the Fatstang SportsRoof
1305-gone-in-60-seconds-1973-mustang-sportsroof-on-set.jpg


to me is a Lamborghini Espada,

Intro21-620x349.jpg


The Fat Stang Notch is Lamborghini Jarama.

the Foxstang a DeTomaso LongChamps/Maserati Kylami.

It just needed some American subtly to bring out the best of the designs...they lost there way with the details IMHO. Those 351 Boss needed 1969/1970 Shelby Mustang type divergance, but all it got was paint. Clinics have proven it again and again, halo models have to build sales volume, but I'm pretty sure the same negative response to the Mavi GT was perpetuated in the specialty 351's.

70mavigt_zps076cd7fd.jpg


That's sad, becasue the same thing happened in Australia, the GT versions of the Falcon sold worse than any other GT in a 9 year period, even after winning the every motor race but the sales volume from the step up 250 and 250 2V and a really sweet 2-bbl 240 hp 302 was huge. They tomed the package down, and the underling cars sold the best volume they ever did.


The 250 is much more responsive to the right gear than the 200. Big x-shell Fords (pre 1973 Torinos, the Granada, the Monarch, the Versaillies) were fat unibodies, but the Mustang six cylinder was still in touch with the frugality the gas crunch years required. The bigger, raunchier 302's and 351's were just too much of the 68-69-70-71 Shinoda era excess when dollied up with war paint. A Sportroof is just the most killer Ford ever, it needed nothing like the Mach I or Boss stripes. The stock 250 notch was such an honest car, that just lacked some gradational options. You got stuck with a really bad F code 302 as a step up. Then there was the 'matte black' or 'argent' stripes, on a car with a hood longer than an F100's tray.

The L code engine was a pivotal swing to making all the little x-shells (the Comete and Maverick) sales charters.

People liked the Boss 302 and Boss 351 and March I but the whole ride smacked of try hard De Tomaso Pantera GTS...the blackouts and the expansive toned down NACA ducts didn't turn people on like the clean lines of the 64.5-66 Mustangs.


Ford was out of step on those details, and that's why the little Mustang II sold so well without a V8 for a year. The V6 Capri import and Mustang II were standout sales sucesses...it was Ford USA's non 2V and Fuel Injection follow through that made these cars sell less than 138000 units per year; people shied away becasue Ford had left them no elegant intermediate step.

When I6's got wacky air scoops and attempted to become Grabber 302'S with 250's, like the Mavi GT did in 1971, they turned people off even more. All over the world, it became okay to drive a Benz, but frowned on to drive a hot Ford unless it was a Starsky and Hurch Torino. Somw how, the big, flat, Pontiac like or early Z-28 like Shinoda embelishments siad try hard.

The truth is, the Mustang had it all, and really needed to tone down the visuals, and tone up the base, like Muhammad Ali...Like him, the Mustang was an Undisputed Heavyweight Boxing Champion. It had all the cred, but didn't need the tatoos. The warpaint was what differentiated the base to topline. On the little Mustang II, Pinto or Maverick, it was okay to paint your wagon. On the Fatstangs, it needed some restraint that it never got. The monent you stood on even the emasculated the 248 and 255 hp 351 4v packages, you knew you had a runner. Nothing else was required, the 429 wasn't even needed.


The gap filler in Australia was the GS 2V 250, an M code with 170 hp gross, up 15 hp on the still 155 hp gross 250 1v, same rating ad the 1969 US 250. If the US had one, it would have made 97 hp.The later 250's climbed back up to 99 hp by the last C code 4.1, so if a 2-BBL 4.1 was made, it would have ended up a 110 hp net engine. If it had been given port injection as Jaques Passino promiesd in 1969, it would have made the same power as a 302, 122 to 140 hp.



Where the little I6 came in is that there was no step up V6 like intermediate Mustang II's had. They needed to add a 2-bbl to it, and cut the engine block down to 9.38" from 9.469", and use a 250 specific deap dish piston like the Aussie 250's used. The little M code 250 4-speed could do 16.9 second quater miles all day with 170 hp, while the 240 hp 302C 2-bbl with the same carb would do 16.4's with a four speed, and that shows that there wasn't 70 hp difference!


With a little planning, I'd follow Faron's (Falcon Sedan Delivery)'s lead, he copied the Ak Miller build on the biggest cam you can use on a 250 in terms of lift and use the same cam but and try track down a 1.23 2150 carb, and turbo it like this one.

http://mmb.maverick.to/threads/did-i-ow ... ick.35295/

Everything else can remain stock, although your better off with a Yellow strain relief Duraspark II distributor spark conroller off a Carb Turbo Mustang, and follow Powerband, Lincs 200 or FirstFoxes engine builds.

I have a good buddy who has a 301 Firebird Turbo, and those old GM turbos with a 4-bbl Q jet are a good set up...1972 429's ran a factory Ford Qjet too.

See viewtopic.php?f=1&t=72632

for full historic i6 details that will help you out
 
MM73 I just completed such a build. See 250 Freshen Up. I had burnt a piston in the 250 in my 62 Falcon. I purchased a 250 out of a wrecked 73 stang and rebuilt it. I'm very happy with the result. My goal was a daily driver that will live on 87 octane and still do a burnout. My budget was around $1000 - $1500. I met that goal. The biggest challenge was finding a timing chain and gears. I actually ended up running the old one from the 69 engine. It was within usable spec and the order I had placed with CI was not completed because of the transition they are going through. I can always do the timing chain later when CI reopens.
 
MM73,

Welcome to the forum. A little bit more information about your 73 would be helpful.
C4 auto or standard? Rear end gearing (look on the door frame tag for the code)?
Axle Code - Axle
2 - 2.75
3 - 2.79
6 - 3.00
7 - 3.40
9 - 3.25
A - 3.50
G - 3.55
Switch out to a set of 3.55s, then go with an AOD 4spd automatic or a T-5 standard for better cruising and MPG.

You need to get the engine to breathe, a stock engine wheezes above 4300rpm.
Do what CZLN6 suggests. Also upgrade to a header with better exhaust.
 
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