I have been starting to get back into my project 1966 mustang coupe from high school and have been tossing around the idea of swapping the 200 ci for a 300. I rebuilt the 200 in 2005 but cannot remember what all was done for specifics. I know they put a mild cam in but not sure if anything else was really done to it. I just know that it lacks the up and go that I fell safe getting on highways and freeways. I want to keep the inline six but to upgrade the 200 seems really expensive with the new VI head. My wonder is if swapping a 300ci in would be a better option with its ability to be upgraded easier? Of If I did go with a 300 swap, I would want to swap the C4 trans as well. I would love to have a manual in it if I could. This is going to be a car that gets driven a lot. So a 5 speed would be nice. I have been searching posts on this forum for ideas but still cannot decide if a 300 is the better option for my car. This is going to be a project that I work on with my son over time so I don’t mind piecing together things as I go. Any help or ideas would be greatly appreciated.
All Small Six 200 vs 300?
- Thread starter Grinndal
- Start date
This relates to all small sixes
300 six a big heavy thing. IMO a better option would be your USA 250 with a T5 transmission. A 250-2v head would really improve things, but expensive. You could use the cam from the 200 (making sure the conrods will clear the cam) run better carb, small weber?
Hi, the Big Block 240 and 300's are truck engines, a different Ford engine family. The bigger engine is not an easy swap. There is plenty of upgrade information here to increase the performance of your original engine. Start with a compression test. Often times, a good tuneup will help in a big way. If the aftermarket cam was not set up with a degree wheel, there is a good chance the cam timing is way off, leading to a lazy engine. That being said, the usual hot rod upgrades will wake up your engine. Good luck
I think your 200 will be fine. Why not get it running and driving and see what you think then?
If you want more acceleration, you can always change the differential ratio. It's relatively easy and inexpensive to do and can make your car feel very sporty.
Also, speaking from experience about the 5 speed, I wouldn't bother unless you do a lot of freeway-speed driving. Even then, the conversion for a 200 is expensive and complicated, and the difference in fuel economy minimal.
On Fathers day, my son and I got it running. The engine runs and sounds strong. From the rebuild that I had done back in 2004-05, the engine has maybe 20K miles on it since then. This included a full rebuild on the C4 transmission as well. I know that I want to get some higher gears in the differential and was thinking of doing the explorer rear end swap to get 3.73 ratio with disk brakes. I want to swap to 5 lug in the future as well so this will be the first step in going that direction. The T5 transmission is also wanted as most of my driving is at highway speeds.
I have done some digging around here and have seen some great builds with the 200 and that is why I was not fully set on swapping out the engine for another at this time. The engine itself is strong with no mechanical issues that I can find. I did upgrade the ignition to a pertronix system but it is still in the old distributor. I have all the paperwork from the builder on my engine in a box somewhere in my storage so I might be able to see what cam and other specs they set it all to.
This is going to be a learning project for both of us and I want to do it right this time around. Being able to teach my son and foster his growing love for cars is something that this project can do. Near where we live there are plenty of junk yards that we can go searching for parts and get them at a fairly good price still. So if I can get things that way I will as well. Rebuilding axles, transmissions, or fabricating is something that I can do.
I have done some digging around here and have seen some great builds with the 200 and that is why I was not fully set on swapping out the engine for another at this time. The engine itself is strong with no mechanical issues that I can find. I did upgrade the ignition to a pertronix system but it is still in the old distributor. I have all the paperwork from the builder on my engine in a box somewhere in my storage so I might be able to see what cam and other specs they set it all to.
This is going to be a learning project for both of us and I want to do it right this time around. Being able to teach my son and foster his growing love for cars is something that this project can do. Near where we live there are plenty of junk yards that we can go searching for parts and get them at a fairly good price still. So if I can get things that way I will as well. Rebuilding axles, transmissions, or fabricating is something that I can do.
frozenrabbit
Well-known member
302 v8 swap would be WAY easier than a 300.
I’m not a fan of hacking up a classic first generation Mustang. The 200 inline six is an easy to work on in the engine compartment. It can be made to scoot along nicely.
If your looking for extreme performance, stroke a 302 to 347. It would be much cheaper and easier to get performance parts. It will fit in the engine compartment without any hacking. But you would have upgrade the inline six C4 automatic to one that is spec’d for the V8. The complete drivetrain and rolling assembly should be upgraded the V8 spec’d setup. It’s not a cheap process.
A 300 inline six installed in a mustang has been done. But… why hack apart a classic car to install one? Personally I wouldn’t consider a 300 install when the car originally was designed to handle a 289 V8.
Just to let members know:
I always loved the nervous high winding stock 2.87 stroke 289 K code high performance V8. It will make a first generation Mustang a very fun car to drive. To me, it was the best engine option for the first generation Mustang. Out of all the engines I bought, I should have kept the 289 K code engine. Back in 1976 or 77, I put it in a 1967 mustang convertible then sold it.
(I sold it to help with the 428 SCJ rebuild for my 1969 Torino Cobra. Yes the car had the drag pack option with C6 automatic and 4:10 rear. That car had to be driven with respect, otherwise it could have been my last day.) Back to the 289. You don’t need an original 289 K code engine to achieve good performance. A 289 2 barrel engine can be livened up very easily at a reasonable price.
I guess, the best advice I can give you is think it over before starting.
If your looking for extreme performance, stroke a 302 to 347. It would be much cheaper and easier to get performance parts. It will fit in the engine compartment without any hacking. But you would have upgrade the inline six C4 automatic to one that is spec’d for the V8. The complete drivetrain and rolling assembly should be upgraded the V8 spec’d setup. It’s not a cheap process.
A 300 inline six installed in a mustang has been done. But… why hack apart a classic car to install one? Personally I wouldn’t consider a 300 install when the car originally was designed to handle a 289 V8.
Just to let members know:
I always loved the nervous high winding stock 2.87 stroke 289 K code high performance V8. It will make a first generation Mustang a very fun car to drive. To me, it was the best engine option for the first generation Mustang. Out of all the engines I bought, I should have kept the 289 K code engine. Back in 1976 or 77, I put it in a 1967 mustang convertible then sold it.
(I sold it to help with the 428 SCJ rebuild for my 1969 Torino Cobra. Yes the car had the drag pack option with C6 automatic and 4:10 rear. That car had to be driven with respect, otherwise it could have been my last day.) Back to the 289. You don’t need an original 289 K code engine to achieve good performance. A 289 2 barrel engine can be livened up very easily at a reasonable price.I guess, the best advice I can give you is think it over before starting.
Last edited:
I put a 5-speed in my 66 Mustang Sprint with the inline 200 and it has absolutely zero problems keeping up with traffic, getting up to speed on the on-ramps or anything. It cruises at 60 MPH at just below 2,000 RPM in 5th. It’s got jackrabbit acceleration off the line. I have it in 2nd for slow driving (school zones and congestion) or 3rd for regular 30 MPH traffic.
Mine had a top loader 3-speed and might have been geared differently (rear end) than the C4 automatic cars.
I’ve got a mild build. Normal compression, a little under 9:1, clay smith 6474 cam which is probably a little hot for the stock head and log intake, header, 2-1/4 single to the back with a 1 in 2 out 4th gen Camaro muffler, Weber 38/38 carb and HEI electronic ignition.
The recipe with the 5-speed has the makings to be pretty much perfect. It doesn’t use a whole lot of gas either. I’m on a little holiday and we took the the Mustang and put about 100 miles on the car since Friday. The gas gauge hasn’t really moved much past the half way mark which is where it was when we left. It does have a lot of wind noise and road noise when you’re tooling down the highway at 70 MPH though.
Mine had a top loader 3-speed and might have been geared differently (rear end) than the C4 automatic cars.
I’ve got a mild build. Normal compression, a little under 9:1, clay smith 6474 cam which is probably a little hot for the stock head and log intake, header, 2-1/4 single to the back with a 1 in 2 out 4th gen Camaro muffler, Weber 38/38 carb and HEI electronic ignition.
The recipe with the 5-speed has the makings to be pretty much perfect. It doesn’t use a whole lot of gas either. I’m on a little holiday and we took the the Mustang and put about 100 miles on the car since Friday. The gas gauge hasn’t really moved much past the half way mark which is where it was when we left. It does have a lot of wind noise and road noise when you’re tooling down the highway at 70 MPH though.
I really enjoy hearing detailed driving experiences on early Mustangs with modifications like your 66. If I was fortunate to have a Mustang I would have a similar to yours mild to medium 200 build and the T5.
One reason to have the T5 od gear is to cut down on engine roar at freeway cruising speeds as you have accomplished. You mention wind and road noise are evident. Is most of the wind noise likely from the design of the vehicle itself? Are leaking door seals a big factor? From what I have read about road noise there are many options available to reduce that as I am sure you know about and reducing noise in the cabin is a worthwhile endeavor.
I have a sound level meter app on my phone that I use for work which could be helpful to see how each noise reduction mod you try reduces noise.
If I have not sent this to you yet this has a lot of good info for early Mustang mods.
Similar threads
