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Discussion Starter #1
I have a some questions from the experts. I have a 67 Mustang inline 6 200. I have done a bunch of restoration work and I am dealing with engine issues now. I decided that I would pull the engine and do a full engine overhaul on the inline 6. I am now into the project an am questioning if this is a good idea.

My basic question is should I spend the money to rebuild the inline 6 motor or spend a little more and convert to a V8

If I keep the inline 6, I am looking at about $2,000 in parts and machining. Once I do that the car is in great shape with no other real issues. That seems like a lot to spend on a inline 6


If I were to convert the car to a V8, I would spend more for sure, but then I would have a much more appealing car
What type of V8 motor would you recommend, Coyote ?
Do I need to change out my 4 post wheel lugs ? I recently upgrade the suspension and added disc brakes in the front
Do I need to upgrade the rear differential ?
I have a 3 speed manual transmission, I assume I would need to change that out as well ?

Any advise here would be great. The V8 road seems way more complicated and expensive.
 

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The change is more than just the engine. The entire suspension should be changed too. You are looking at a new rear end housing with stronger gears and 5 lug axles & brakes. New springs, sway bar, spindles and 5 lug brakes in the front. Add in exhaust system and some wiring mods too.

Coyote? Now you are talking some real work and $$$.

When I bought my car someone had taken out the 6 and put in a 289. As a college kid it took me years to get it converted to a V8 car.
 

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Fix the six. Can't ask for a more reliable motor. Brian
 

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i say keep the six. nothing is more fun than surprising someone, and then popping the hood to show off an inline six.there are fun upgrades you can do to the six that are cheap to do, and give you more power and fuel economy. things like a cam upgrade, since you are replacing the cam anyway. do a direct mount 2bbl conversion as well, since the head is at the machine shop, the cost drops somewhat compared to having it done later on.
 

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i say keep the six. nothing is more fun than surprising someone, and then popping the hood to show off an inline six.there are fun upgrades you can do to the six that are cheap to do, and give you more power and fuel economy. things like a cam upgrade, since you are replacing the cam anyway. do a direct mount 2bbl conversion as well, since the head is at the machine shop, the cost drops somewhat compared to having it done later on.
WOW!!!!
This is the exact thing. We built many Mustangs, My dream (never accomplish) was to find a 6 cylinder car, No added luxuries, bare bones car. Then build it to concourse or nice, then as rbohm has related be proud. It would be a real head turner.
 

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You do know the amount of work to put a Coyote in there, don't you? It doesn't seem like you might if you casually threw out that option.

I'm definitely going to put a V-8 in my 6 cylinder car.

For a simple V-8 (289/302) here's what I'm planning:

Front end: Complete rebuild and new parts, 5 lug disk brakes, new springs to handle the increased weight of the V-8)
Tranny: Hopefully keeping the automatic, so far I haven't heard you need to change it.
Rear end: Different rear end with 5 lugs.
Exhaust

I've found 289s that were reportedly removed from running cars for less than $500. I should be able to get all of the rest of the V-8 specific parts for less than $500. If I do the math correctly I should have a running V-8 for $5000 because that just how the math works out... it always costs you 10x as much as you budget. So the key is not to budget! Problem solved.

I think that's the minimum you need to do. After that it's all upgrades. Like power brakes, etc.
 

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The spindles do not need to be changed. The brake backing plates, yes, but not the spindles.

I have 2 sets of basically brand new shoes, cylinders, springs, freshly turned drums, etc. on 5 lug backing plates, for 67 - 69, sitting on the floor of my garage, from people converting to disk brakes. If I cannot find a home, they will go to scrap pretty soon.
 

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Converting a 6 to an 8 in a 67 is much simpler than doing the same on a 65/66.

I converted my 67 from 4 to 5 lug by buying used parts and rebuilding them.

There are plenty of sixes being pulled for V8 conversions that can be had pretty cheaply. Just make sure its a 200 with 5 freeze plugs vs a 170 or early 200.

Im putting a 250 in my 67, I bought a newly rebuilt 250 shortblock for $350 and a 250 out of a 74 Comet for $25 for all the other parts I need.

My 02 is to put a used 200 in it to keep it on the road and plan out what you want to do in the future.
 

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Discussion Starter #11
Thanks everyone for all your opinions here. It seems like keeping a 6 is a simple option. I could get that up and running for sure
Where do you find a working V6 engine ?

I have a few more questions about the V8 upgrade
Where do you find a 289 or 250 short block ? Craiglist, eBay ? How do you know what you are getting.
I would need a new transmission as well, same question

I am leaning toward keeping my inline 6, cleaning it up and making it run great. Thanks for the direct mount 2bbl conversion as well. That's a great idea
 

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289s are getting hard to come by. But the later version, the 5.0 motor, was made all the way to 2001. You can find a '98-2001 Explorer, bolt up the engine with a few changes, and it works great.


The other end of that, of course, is having to convert all of your suspension and brakes to handle it. Rear end, front spindles, steering stuff, the works.
 

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Discussion Starter #13
One more question. I have the engine pulled out of the car for a rebuild. I removed the flywheel and clutch. I am going to remove the bell housing and replace the rear main seal. What else would you recommend doing to the transmission and clutch before putting the engine back in place ??
 

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Thanks everyone for all your opinions here. It seems like keeping a 6 is a simple option. I could get that up and running for sure
Where do you find a working V6 engine ?

I have a few more questions about the V8 upgrade
Where do you find a 289 or 250 short block ? Craiglist, eBay ? How do you know what you are getting.
I would need a new transmission as well, same question

I am leaning toward keeping my inline 6, cleaning it up and making it run great. Thanks for the direct mount 2bbl conversion as well. That's a great idea
while the 289 is a V8, the 250 is an inline six. as for finding sixes, find someone doing a V8 swap and garb the six from them. often times you can get them cheap since no one really wants them.
 

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I have a some questions from the experts. I have a 67 Mustang inline 6 200. I have done a bunch of restoration work and I am dealing with engine issues now. I decided that I would pull the engine and do a full engine overhaul on the inline 6. I am now into the project an am questioning if this is a good idea.

My basic question is should I spend the money to rebuild the inline 6 motor or spend a little more and convert to a V8

If I keep the inline 6, I am looking at about $2,000 in parts and machining. Once I do that the car is in great shape with no other real issues. That seems like a lot to spend on a inline 6


If I were to convert the car to a V8, I would spend more for sure, but then I would have a much more appealing car
What type of V8 motor would you recommend, Coyote ?
Do I need to change out my 4 post wheel lugs ? I recently upgrade the suspension and added disc brakes in the front
Do I need to upgrade the rear differential ?
I have a 3 speed manual transmission, I assume I would need to change that out as well ?

Any advise here would be great. The V8 road seems way more complicated and expensive.
I am not sure that our opinions are worth anything to this question. Its about what you want...do you want a v8? So you want a stock I6? Do you want a modified I6? The I6 is more than capable of making power depending on how deep down the rabbit hole you want to go, but to do so you will spend more than a v8. The choice in the end is yours...as are the reasons for it.

I am going with a 3.7L v6 myself....the reasons driving that choice were that I already have the engine, its lighter than even the 200ci I6, and makes more HP than a 289 HiPo...the downsides are that engine making a new engine like that work and fit the old chassis is going to be a headache and the time involved in getting the car back on the road go up dramatically.

Make the choice that makes the most sense to you and meets your goals for the car the best, but above all don't bite off more than you can chew...that's the path to losing interest in a car and it being sold on craigslist as a "project car"
 

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Discussion Starter #16
Thanks everyone for the great feedback. You have helped me to make my decision for now. I am going to clean up my inline 6 and do some modifications to get some more performance out of it. I am looking to make this a great weekend driver car that mechanically is dependent and ideally doesn't leak all over my garage. With the car apart, I will replace all the seals, rebuild the engine and get the car back running for next spring. I look at this as a lesson in how to build an engine. Great knowledge for future projects.

In terms of increasing the performance of the inline 6. What recommendations do you have.
one suggestion was " cam upgrade, since you are replacing the cam anyway. do a direct mount 2bbl conversion"
any other upgrades as I am rebuilding ?
Carburetor change ? I have a simple single barrel carb right now

thoughts ?
 

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I'm a bit late to this conversation, but I figured I'd throw my 2 cents in anyway because I've done this conversion. As others have pointed out, it's not just the engine. You need to basically swap the entire drivetrain as well as most of the suspension. If you're going to do the conversion starting with a '67 makes your life much easier as more parts are shared between the I6 and V8 cars than the earlier cars.
If attention at shows is what you're after I would keep the six. Popping the hood to reveal a little I6 always attracted more attention to my car then the 302 ever has. I think this is because people aren't used to seeing them vs. the V8 cars which are everywhere. Unless you do something unique with your car or engine, a small block V8 will make you just another member of the crowd.
I do not regret my conversion one bit. The additional power is great, and I now have a MUCH better base to start modifying stuff from. Making power with a six is possible, but it is harder and more expensive than with a V8. I may get another I6 car in the future to have fun with, but I would never take my car back to what it was before. Depending on what you want out of the car your experience may vary.
If you aren't wanting for more power or a better rumble right now I would say fix the six. If you feel the car is missing something right now a rebuilt six probably won't cure that.
 

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In terms of increasing the performance of the inline 6. What recommendations do you have.
one suggestion was " cam upgrade, since you are replacing the cam anyway. do a direct mount 2bbl conversion"
any other upgrades as I am rebuilding ?
Carburetor change ? I have a simple single barrel carb right now

thoughts ?
My thoughts on the direct mount 2bbl - if you keep the same intake, you're trying to push more fuel/air through the same sized hole; I don't think (my opinion) that you'll see huge performance gains. The intake and the head are cast as one part. You can't get a more free flowing intake without changing the head or doing major machine work. To get any appreciable amount of performance from a six, you're going to spend some cash.

Someone on the forum has a tri-power setup with three 1bbl carbs. Pretty nice once it's paid for and up and running.

You could consider headers and improve the exhaust side of things.

https://www.summitracing.com/parts/...o4TAGnIWLlUCfsO3y6IpbtTDdqLbNRN0aAuZAEALw_wcB
 

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Thanks everyone for the great feedback. You have helped me to make my decision for now. I am going to clean up my inline 6 and do some modifications to get some more performance out of it. I am looking to make this a great weekend driver car that mechanically is dependent and ideally doesn't leak all over my garage. With the car apart, I will replace all the seals, rebuild the engine and get the car back running for next spring. I look at this as a lesson in how to build an engine. Great knowledge for future projects.

In terms of increasing the performance of the inline 6. What recommendations do you have.
one suggestion was " cam upgrade, since you are replacing the cam anyway. do a direct mount 2bbl conversion"
any other upgrades as I am rebuilding ?
Carburetor change ? I have a simple single barrel carb right now

thoughts ?
Again, this is a question of how far down the rabbit hole you want to go:

https://fordsix.com/archive/www.classicinlines.com/AlumDevelop-2.html

These guys make an aluminum cylinder head that significantly bumps power and is great for a design that retains the ability to use existing header designs. Another route you could go as far as heads is the Australian crossflow aluminum cylinder head which places intake and exhaust manifolds on opposite sides of the head...but unfortunately since they were made only in Australia, getting your hands on the needed parts can be tricky and cost a lot in shipping(this is the best option for an aluminum cylinder head though).

You can also do things like turbocharging, which will also significantly increase power with the right setup...though if you were to go that route, an EFI conversion would be highly recommended(though not required) for better tunability.

There are of course many things you can do that will result in lower power gains, like electrnic ignition, headers, port work for the iron head, etc.


I should also mention that as far as cylinder heads go...people have also cut up Chevy LS1 cylinder heads and welded them together and bolted them to I6 blocks like this:

https://bangshift.com/bangshift1320...gether-and-mounted-them-on-a-ford-inline-six/

This guy was the pioneer, but this particular modification is becoming more commonplace(as commonplace as as grafting multiple heads together ever can be) as time goes on, some with better results than others. The advantage of using the LS1 head over say a couple of SBF aluminum cylinder heads is that you can use any normal or aftermarket Ford I6 cam to run things...whereas using Ford heads for this type of modification would require a custom cam.


Since you have the engine out for a rebuild anyway...I would consider doing something with the horrid head design....it has the manifold cast into the head obviously....but if it were me...that would have to change, its way too limiting for induction. I would cut/mill off the existing intake manifold and build one from sheet metal(I think Clifford will do this for those so inclined) and my choice for induction would be triple Weber sidedraft carbs once the factory manifold was gone.

Unfortunately to get real power out of the I6, you have to make some real(expensive and/or time consuming) modifications
 

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My take, if I owned a '67 Mustang hardtop 200 six....

I'd want to drive it as much as possible during "good" weather. I'd first make sure it's a) safe and b) comfortable. My next steps would be to make it perform better. Knowing that the drivetrain would need a "refresh" anyway, I think I'd do the following:

a) EFI/Dual-advance distributor conversion. Better fuel management and spark advance curve. Would involve modifying the existing log manifold for a TBI unit.

b) Camshaft swap to a custom grind for low-end torque and decent power through 5,000 rpm.

c) Transmission swap to a T170F-RUG 'SMOD' overdrive transmission. People will ask "Why not a T-5?". Well, I believe the T170 gear ratios are more evenly spaced and that the nature of the 200 six lends itself better to a wider ratio 4 speed transmission than the 5 speed with its "short" 1st and "tall" 5th gears. Also, it's not a "high demand" transmission and not, typically, abused so good examples can still be found.

That's about it.... then just sit back and cruise....
 
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