You'll need to replace the bell housing. You'll need to upgrade the front suspension. And you'll need to replace the motor mounts. The clutch linkage (I'm pretty sure) would need to be changed as well.

 

...and the front brakes, and the front steering, and the rear axle... it can be a LOT of work and expense. If the super 6 was enough before, a good rebuild OR a replacement 250 will bolt right in, and when properly cared for the 6 can run virtually forever. There are lots of power enhancers for the 6 now, but it's hard to beat adding 50 cubic inches then adding the power enhancers ! ! You can always add the V8. It's just a lot more involved.

 

It all depends on what you are comfortable doing. You can pull the six for a rebuild or purchase a remanufactured short block and reinstall your cylinder head.

You can also remove the six and install any of the Ford small block (221-260-289-302-351W-351C-400) or FE (332-352-390-406-427-428) V8 engines as well as the 385-series (429-460) with a bit of modification.

Note that the swap from the six to ANY of the V8's is going to mean substantial expense and work in the area of radiator, radiator brackets, engine frame mounts, throttle, clutch and shift linkages, fuel lines, front and rear brakes, springs and shocks, rear axle housing and differential, underhood wiring, starter motor, accessories and brackets (alternator, power steering pump , etc.).

As far as transmissions, you'll need the appropriate manual transmission bellhousing and the '67 3.03" 3-speed will be satisfactory for most any of the V8's, provided the correct size input shaft is used for the engine application.

In short.... unless you have lots of time AND money, stick with the six. If you're looking down the road to doing any further modifications you can look to swap in a later 200 six (aka 3.3 liter) from a late seventies/early eighties Fairmont, Zephyr, Mustang and a few other models.. they have bellhousing pattern compatible with the small block V8's so transmission choices are much greater, including the T-5 without as much "fuss" as behind the small six bell, larger clutches, better starter motor choices, larger diameter intake manifold, etc.

Visit fordsix.com to get "into" the six bangers more.

 

Let’s cover a few terms first. You don't have a V6. You have a staight six often called a L6 or I6. When you remove the head the remaining engine is called the Short Block. The V8 engines are referred to as Small block or Large Block depend8ng on the family.

260/289/302/351. Small Block
427/428/390/429 Large Block.

Your car can fit either a small block or large block. In 67 you could order the car with a 200, 289 or 390.

To move to a V8 though you need to replace A LOT. The transmission, rear end, front suspension, steering, wheels, etc. All doable, but if you don’t have a donor car it gets expensive fast.

The 6 cyl engines are easy to find and often cheap. There is one for sale on VMF that is a fresh rebuild. Look on Craigslist people upgrade to V8s sell them all the time.

As for your current engine. Do you know it’s bad? It could be something as simple a blown head gasket.

 

260/289/302/351. Small Block
427/428/390/429 Large Block.

Your car can fit either a small block or large block.

I have never heard a big block referred to as a “large” block before.

It sounds like the swap from a V6 to V8 is a much bigger deal than I am thinking.

By continuing to refer to your straight 6 as a “V6”, you make it seem like you aren’t listening to our advice.

Should I pull the engine and do a total rebuild of the short block or try to remove one single piston and check the rings.

thoughts ?

Neither. As previously mentioned, good running 6 cylinder engines are cheap or free if you look for them.

 

I knew they'd be more... just wanted to hurry up and get the first word in on this one At least, nothing I said was incorrect. Chalk one up for "the kid"

 

V6 :shrug:
Your local pick a part has a GT40P 5.0 waiting for you . But you'll need different brakes ,suspension ,transmission ,rear axle and various other V8 tidbits

 

Stay away from a 250, its a lot of work, more work than a V8 swap.

I have a 67 with a 200/C4. Swapping to 5 lugs is pretty simple. No spindle or steering swap required. Driveshaft and u-joints work.

Upgrading to front disc brakes with Ford parts is simple.

A mild cam, more compression, a 68+ carb and distributor and a better flowing exhaust will really wake up a 200 in a 67, especially with a 3 speed.

200s are light, making power steering unnecessary.

Buy the Falcon Six Handbook. A comp Cams kit from Summit, flat top pistons, header and a 2V adapter with a Weber will almost double your rear wheel hp. The Weber will not give you much in the hp department, but the car will idle and run better and tune much easier.



1967-68 Mustang 6cyl to V8 Conversion - Average Joe Restoration

 

Thanks everyone for the input. It sounds like the swap from a V6 to V8 is a much bigger deal than I am thinking. I just want to get this car running again with no issues. I am not looking for more power.

Here is my issue. Low compression in my third cylinder and oil blowback out of my breather cap. This was causing oil to drip on the engine and smoke me out inside the car.
I checked the PCV valve, no issues.
I ended up removing the head and had it checked out. No cracks and seals are all good.

I am not sure what is wrong at this point. I think it could be a bad piston or ring.

Should I pull the engine and do a total rebuild of the short block or try to remove one single piston and check the rings.

thoughts ?

 

Yeah, the V8 and Inline 6 Mustangs were very different cars.

A fresh and well-tuned I-6 will pull like a mule and cruise at 80 MPH all day. Install and overdrive trans and it will do it effortlessly, quietly and use less gas doing it. Great cross-country cruiser!

As mentioned, you can even wake up the 6 a bit. Deck the block and mill the head to boost compression. Install a better cam. Calibrate the distributor. Install headers and nice dual exhaust. Find a better carburetor. This will be much easier, much cheaper and much more fun than PROPERLY converting an I-6 Mustang to a V8 Mustang.

My take is if you want a V8 Mustang, buy a factory V8 Mustang. It's not like they're in short supply. One exception would be if you're building a very high end custom Mustang will all aftermarket parts. In that case, you'll be replacing everything anyway, so starting with an I-6 Mustang doesn't make any difference.

Have fun!

 

CL, Facebook marketplace and VMF classifieds turn up good running 200s pretty often. Lots of V8 swaps still going on.

 

A lot of these swaps aren't being done properly. One of my coworkers bought an I-6 Mustang with a V8 a few years ago. The PO had installed a V8 and C4 into the car and had done NO OTHER CHANGES. My coworker said he bought it for his wife. I politely recommended he properly convert the car before he let his wife drive it. Apparently, he eventually figured out the issues because he soon sold it.

 

Your answer is waiting right here..

https://forums.vintage-mustang.com/engine-drivetrain-parts-sale/1163834-rebuilt-6-cylinder-engine-complete-cheap.html

 

I say rebuild your six and get back out there cruisin' and think about the V8 swap later. A V8 swap is doable but it is involved - no matter which way ( stock or hightly modified) you want to go. Plan that out well if you are going there. If you are going to rebuild your existing block, might I suggest you look at VINTAGE INLINES https://www.vintageinlines.com/ for a new head and intake manifold. There was an interesting article in MM a short while back although I'm not sure I have seen the dyno results on their I6 rebuild. Vintage Inlines' head setup seems light years ahead of the OE head with cast-in manifold. GOOD LUCK no matter which way you go!

 

You probably just need new piston rings.

I've seen them break on this engine and you'll lose some compression and it will cause lots of blow-by but it'll just keep driving along.

Drop the sway bar and the oil pan and you can start taking pistons out. Just remove the caps, be careful with the bearings, and pop the pistons right out the top.

Since you haven't noticed any huge gouges in the cylinder walls or holes in the pistons the rings are likely your problem. You've almost got the engine torn apart enough to replace them so it should be a quick and easy fix.

Once it's back together check your timing too. It could be that the rings failed just because they're old, but if you're running the wrong carb/dizzy combo or pinging all the time that could be contributing to their early failure.

 

'By continuing to refer to your straight 6 as a “V6”, you make it seem like you aren’t listening to our advice.'


if he keeps doing that he has no business trying an engine swap.

 

Does anyone have a video or more information on how to remove the Pistons without taking out the engine. In theory, I understand what you are saying, dropping the sway bar and pan and going in that way. I am not clear on how to remove the pistons and rings from the top. Any information would be great.

I think this makes a lot of sense to start off. If I don't see any issues with one of the pistons, I could then go to a full engine rebuild.

 

Not the sway bar, the removable crossmember under the engine.

 

Guys, there is a lot to learn as a newbie to car work. I have been doing this for 2 years now. I understand that I have a straight 6 and know the difference. I am a little overwhelmed by the thought of rebuilding an engine or doing a swap. I have been coming to this forum for advice for the past two years and appreciate all the insight you guys have. That is why I keep coming back. If there was a mustang engine school, I would be the first one to sign up and attend. Each project I do, I am learning the terminology and workings of the car.
Again, thank you for the insight and bear with me on using the wrong names for parts.
thanks

 

All of these projects seem overwhelming at first. But do your research, gets books, watch videos and keep asking questions. I’ve taken on task I never thought I could or would attempt. None have proven too tough once you have the proper tools and knowledge.

That said, an engine swap is pretty darn easy, especially on a straight 6. Much easier than rebuilding it yourself. Disconnect some wires and hoses. Unbolt a bunch of stuff and hoist it right out. An easy weekend job.

 

Not the best video but I think it shows the basics. Theyre working on a v engine instead of the straight 6 you have, but the basics are the same.

 

With the head off and oil pan removed; find the connecting rods that are pretty much oriented in a straight up and down position. all the way down is good. remove the two nuts from the rod at the bottom that holds the rod cap on, and remove the rod cap. now push the rod with piston straight out the top of the motor. The way to do it is put a couple hoses on the rod bolts to keep from scarring the crank bearing surface, place a wooden dowel/broom stick up the bore against the bottom of the piston, and push it out. If it hangs up just before coming out the top don't force it. Push it back down the bore and you will feel a ridge at the top of the cylinder. this ridge needs to be cut down before removing the piston. they make a tool, ridge removal tool, for cutting this down. Take care of the bearings and keep them in the correct order.

 

One other tip, mark the rods and caps and make certain the caps go back on the way they came out on the rod they came off of.

 

I would lean towards a fresh 6 cylinder install.
Second choice would be a mild V8 transplant, and here is where I will have to soundly disagree with some of the advice given. A full conversion to 5 lug etc. is NOT mandatory.

It sounds like you have no high performance aspirations and if all you plan to do is leisure trips the stock suspension and brakes will get you by. Believe it on not it takes you the same braking power to go from 65-0 mph in a 4 cylinder car as it does a V8 unless there is a great weight difference, which there isn't between a 200 and a 289. I know of several V8 swaps into I6 cars that were driven for many years without any problems. I also know of some six bangers that had been seriously warmed over and were pushing more horsepower than the original 289 ever did and the owners preferred to keep the original running gear. The car won't suddenly stop functioning because of more horsepower.

NOW, if you have any thoughts of canyon carving or you intend to pass the car to the soon to be 16 year old son, scratch all that..ha ha. If you do go the V8 swap and decide to go updated suspension, skip the factory stuff and go straight to a more modern up to date setup while you are at it. Other wise, you may well end up tearing out your newly installed stuff to upgrade it....performance is a slippery slop: one upgrade leads to another.

 

Second choice would be a mild V8 transplant, and here is where I will have to soundly disagree with some of the advice given. A full conversion to 5 lug etc. is NOT mandatory.

I'm on the same page, but I think some clarification is needed for owners of 1965/66 I6 cars who might be reading this thread.

All base line 1967 and later cars have the same front spindles and an 8" rear end. Obviously, the hi-po cars got upgrades, but that's irrelevant to this topic. So besides new springs front and rear, there's not a lot to "convert" when swapping a 1967 or later car from an I6 to a mild V8.

The 1966 and earlier I6 cars are another matter...

Since the 1980s, I've heard many horror stories about the weak 64 through 66 I6 spindles failing while driving and eventually being recalled by Ford. To this day, I'm not a fan of daily drivers using those original I6 spindles. Don't even get me started on people still driving around with the original single-reservoir master cylinders!

I also know from personal (scary) experiences how badly those tiny 9" 4-lug drums stink. Once you hit 50+ mph, you better think way ahead when it comes time to stop.

Finally, the 7.25" rear end the 65/66 I6 manual cars got is just truly awful. Dumping a true 200 lb/ft of torque into that weak rear end will likely just spin the rear tire, but the rear end will break eventually. How and when it breaks can get ugly. Maybe you'll get lucky and just snap an axle, but locking up a rear diff at highway speeds is bad.

 

Thanks everyone for your feedback. It is much appreciated. Lot's of good conversations about 6 v 8. Here is my plan

I am going to stay with the Inline 6 motor for now and try to fix the problems that I have.
I am going to drop the oil pan and the support bar underneath and push out the piston from below
Hopefully I will see an issue with the rings and be able to replace them and go from there

If that does not work, I will then consider pulling the engine so I can get better access to the entire engine.
I can then decide to do an engine overhaul myself or to find a V8 and drop that in. I don't think that is with I want to do after reading what is involved.
Thanks again and I am sure to be back with more questions

 

Where are you located?

 

You’re ignoring good advice. Find a running six cylinder. They’re fairly common due to V8 swaps and practically free. That would cost a small fraction of what a rebuild would cost.

 

I pulled the engine out of my wife's Mustang just to change the oil pan gasket. Because I didn't feel like crawling around under the car too much. These days I do such things but I didn't star tout that way or with the proper equipment. That said, your life will be ever so much easier if you just take the engine out. It's a fairly heavy little booger but once you solve the problem of how in particular you are going to lift the engine out of the car, the rest is really just turning nuts and bolts. Pulling the crankshaft, rods, and even just one piston from under the car is just miserable work.

The very easiest thing to do would be just swap the engine out for a used one. Then you have your original to rebuild or do what you want with and a running car at the same time. 200's can be had cheap , if you look. It always helps a WHOLE lot is you put your general location under your avatar. That way someone might say "Hey that guy's near me and I have some parts he might want/need free or giveaway cheap." That has in fact happened to me. Twice so far.

 

Changed the "V6" in this thread's title to "I6". Sorry, I just couldn't take it anymore.

 

Swapping from an I6 to a V8 is VERY expensive if you want to do it right. For 67 and upwards cars, its a little cheaper, but still pretty expensive. 65-66 cars are the ones where you have to spend a small fortune to convert one from I6 to V8. If your not after power, and just want the car running, id suggest you either rebuild the engine you have, or find another 200ci 6 banger that someone is getting rid of locally, and swap that in. My 66 mustang is a 6 cylinder, and im currently in the process of upgrading it to a V8. You basically have to redo the whole car if you want to swap a V8. Some people have gotten away with just shoehorning in a used junkyard 302 from some truck or free candy van, but i can guarantee you that the 6 cylinder parts on the car wont last very long behind a V8.

 

Since you've got the head off, your engine bay now looks something like this:

As long as the cylinder walls all look ok (especially #3 since that's your problem) leave the engine in the car and climb up underneath.

You don't have to take the big heavy crossmember off, but you do need to remove the sway bar and if you've got them you'll probably want to take the transmission cooling lines loose. Taking the crossmember off might give you a little more room, but the steering linkage is still in the way so it's not going to make much difference. The oil pan just unbolts and you can drop it down and slide it forward and off.

The only thing you have to worry about hitting is the oil pump pickup. It hangs down about where the drain plug is on the pan.

Has anyone mentioned safety goggles? Aside from 50 years worth of dirt and crud you're now going to have oil and transmission fluid just constantly dripping in your face.

At this point you'll have a nice view of the bottom of your engine.

You can take the nuts off the pistons and pull the bottom cap off keeping track of the bearing and how it was sitting. Then put some old fuel hose on the bolts and shove the piston up by hand if you can and take out the upper part of the bearing. Then just push the piston up and out the top. If the piston gets stuck you can tap it with a wooden handle to help it along. Don't use anything harder than wood though since you don't want to accidentally scratch anything important.

Once you've got the pistons out you can look them over and see how the rings look and the bearings and decide where to go from there. After posting pics here of course.

Re-assembly is reverse of removal (though it will require a piston ring compressor or something similar and a torque wrench in addition to the tools you used to take it apart.)