TimC wrote:

MS has probably done it 100 times for himself or other customers....

Dayum. Between a hunnert V8 conversions and the innumerable 5.0 builds, and the MS online thing, how did MS ever have time for a real job?
Holy smokes....

MS wrote:

Amazes me, too. I got more done when I had a full time job.
I used to have a very comprehensive parts list of required items for the swap on the web site. Like so much other valuable information, it was discarded after I sold MustangSteve.
It is a very worthwhile swap. The last one I did was about three years ago when I did Jose’s 65 fastback. It took three weeks of work and around $9,000 to buy and build all the stuff. It got a Explorer 5.0 roller cam
engine and a Summit 500 cfm carb with 289 hipo exhaust manifolds and Duraspark ignition. Added borgeson p/s, vintage air, disc brakes and a Maverick 8” rear. 15x7 Torque thrusts in back and 15x6 in front. Shelby drop, new lowering springs and trumpet exhaust through the rear valance. Turned out very nice. He now drives it every chance he gets.

Thats what I should have did.
 

rpm wrote:

I've often thought having a 250 six cylinder with a 5 speed would be a cool power train in a classic Mustang. I'm fact I have a 250 from a 69 on a stand in my shop. Butt...after running RCodePaul's 5.0 for a bit while the 393 undergoes a rebuild, I'm not sure I could live with so little torque. The torque drop from the 393 to the 5.0 is astounding, and very much missed.

The little six with a 5 speed would be kinda fun ifn you lived in the city and only went to the grocery store and library. A cool little put-put grocery getter.

 

MS wrote:

Cara’s 65 had a 250 and a C4 when we got it.
Still sounded like a six, not matter what.

It had a 250? In a 65? I made the mistake of putting a 250/C4 out of a 1975 Mercury Monarch in my 68. A LOT of work and "engineering" to make it  work.  Engine sat too far forward for a fan on the water pump. Put an electric fan in front of the radiator. Thank God that it spun a rod bearing after 600 miles. Pulled it and dropped in the 351W. Much happier after that.
Did you mean it had a 200?

It was a 250 out of a 70 Mustang.  There was no issue with the fan or anything else. Just had to use a later C4 that had the 250/V8 bolt pattern.  My 69 coupe also had a 250 in it when I bought it.

Last edited by MS (12/14/2025 2:38 PM)

I started searching around, but I do not see a swap parts list. https://web.archive.org/web/20110213025627/http://www.mustangsteve.com/index.html

Edit: Found it! Scroll down about mid way.

https://web.archive.org/web/20050531005146/http://www.mustangsteve.com/MustangSteveFAQ.html

Last edited by Raymond_B (12/15/2025 4:24 PM)

rpm wrote:

I've often thought having a 250 six cylinder with a 5 speed would be a cool power train in a classic Mustang. I'm fact I have a 250 from a 69 on a stand in my shop. Butt...after running RCodePaul's 5.0 for a bit while the 393 undergoes a rebuild, I'm not sure I could live with so little torque. The torque drop from the 393 to the 5.0 is astounding, and very much missed.

You could build an LS-headed Ferd 300 inline six...

https://www.hotrod.com/how-to-and-engine-builds/300-ford-inline-straight-six-with-ls-head-engine-build-part-2/photos
 

Last edited by RCodePaul (12/15/2025 7:39 PM)

RCodePaul wrote:

Converting a 6 Cylinder 65-66 Mustang To V-8 Engine by MS
    There are a lot of variables involved in that swap.  DO you already own an engine and tranny for it?  What level of buildup do you want for the engine, as-is, stock rebuilt or performance rebuilt, or full boogie?

At any rate, figure a minimum of:
     200 to buy a worn out 289
     1,000 to rebuild the engine
     200 for a junkyard c-4 automatic transmission
     200 for exhaust work
     100 for motor mounts
     250 for front end steering parts
     100 for a used 8" rear axle
     150 for a drive shaft and u-joints
     100 for used front brakes with 5 lugs
     200 for brake rebuild
     100 for some used 5 lug wheels
     new tires are extra if you don't have 14" wheels now
     30 for a used v-8 accelerator rod/auto transmission kickdown
     150 for hoses, filters and oil and coolant
     300 for all the little miscellaneous stuff you will want/need to change "while you are in there"
     200 for a new radiator  
_____________

Pretty good idea of the scope of things. Thanks MS for writing it and Raymond_B for finding it. That's a $3200 shopping list and skinny as can be by most measures. Even if you are a super deal finder like MS. Probably similar outlay if you bought an Explorer and used the 5.0 and some of those bits and/or went 8.8" instead of the 8". I already have an 8" diff and some SBFs lying around. Doesn't really change the cost or scope of work much. 

Hmmmmm. 



   

Probably need to double those 20+ year-old prices!

TKOPerformance wrote:

Also, I wouldn't waste dollar one buying a 289 when you can get a 5.0 for the same price and immediately get an engine with a roller cam and better heads (even the E7TEs are better than the '60s era castings on a 289).  

Fair enough but given the year that was posted it was on point. 

The 5.0 supply around here is plentiful and prices seem quite reasonable. On the SBF head flow, admittedly these are just at 0.500" of lift,  not the entire area under the curve, but E7TEs are close to the bottom of the heap flow wise. Explorer GT40p heads are near the top. And of course the old school 351W, ported with Shivvy valves in it is king of the 60's era Windsor castings. 

RCodePaul wrote:

TKOPerformance wrote:

Also, I wouldn't waste dollar one buying a 289 when you can get a 5.0 for the same price and immediately get an engine with a roller cam and better heads (even the E7TEs are better than the '60s era castings on a 289).  

Fair enough but given the year that was posted it was on point. 

The 5.0 supply around here is plentiful and prices seem quite reasonable. On the SBF head flow, admittedly these are just at 0.500" of lift,  not the entire area under the curve, but E7TEs are close to the bottom of the heap flow wise. Explorer GT40p heads are near the top. And of course the old school 351W, ported with Shivvy valves in it is king of the 60's era Windsor castings. 

RCode:  Thanks for the info.  I have wondered about the flow characteristics of all those heads.  I see a lot of stuff about the E7 heads and not much about the others.

I have D0OE's on my 351 and am happy with them.  I have port matched and removed the Thermactor hump in the exhaust.  My mechanic also installed screw-in mounting studs for longevity.  Cam is 218/224 -  ,.512 lift retro rollers with roller rockers.  Looking at the numbers, my heads would probably do even better in your list.  I have been looking at the AFR165' as a useful upgrade, but I'm not sure of the gains would be worthwhile. (Looks and weight reduction are my justification.)  I don't need more than 5000RPM. My hot rodding days are now limited to punching it on freeway on-ramps.
 

Ron68 wrote:

Do you have any stats on the GT40 heads (not the P) heads? I have them on my351W.

Hey Ron - sorry, no. I did a somewhat over the top amount of research on stock heads when I was thinking of running early 351W heads on the 422. When the AFRs came out 25 years ago I pounced on a set of those. A common opinion was to just run GT40P heads and be done with it, but a bit of research showed what that info was worth. 

lowercasesteve wrote:

RCode:  Thanks for the info.  I have wondered about the flow characteristics of all those heads.  I see a lot of stuff about the E7 heads and not much about the others.
I have D0OE's on my 351 and am happy with them.  I have port matched and removed the Thermactor hump in the exhaust.  My mechanic also installed screw-in mounting studs for longevity.  Cam is 218/224 -  ,.512 lift retro rollers with roller rockers.  Looking at the numbers, my heads would probably do even better in your list.  I have been looking at the AFR165' as a useful upgrade, but I'm not sure of the gains would be worthwhile. (Looks and weight reduction are my justification.)  I don't need more than 5000RPM. My hot rodding days are now limited to punching it on freeway on-ramps.
 

Most welcome. I appreciate your comment.
I think the 165s (assuming the heads are your weakest link and not intake/exhaust) would be a nice bump. They flow (reportedly) 250 and 208 at .500 so a significant percentage better. If you want to research it a bit, look at Richard Holdener's YT channel. He dynos everything and I think he does an exhaustive 5.0 head comparison. I've revved my 4.140" stroke 422W to 5500 a zillion times. It has a Ford 400 crank and Chrysler 340 rods. If it were me, I would rev a 3.5" stroke 351W to 6500 without a thought. But that's me.  
Thanks again...

Ron68 wrote:

Do you have any stats on the GT40 heads (not the P) heads? I have them on my351W.
 

TKOPerformance wrote:

IMO 165s would be too small for a 351 with a decent cam and free flowing intake/exhaust.  IMO if you're going to spend north of $2,200 on a set of heads get a set of 185s.  I have the 185 renegades on the 331 that's going in my '89 GT.  That engine combination was the result of voluminous research, including talking to AFR and Crane Cams tech departments.  I absolutely 100% did not want (an was adamant about this) an engine that was soggy down low and made a bunch of power on top.  My previous experience led me to believe that a 180-190 head was a good option on a 350-390 CID engine, and might be too big on a smaller engine.  What I was told was that the low lift flow in the AFRs was so good that I would not be sacrificing anything on the low end (and there was nothing to be gained from running a smaller head on the low end either), but the 185s would outperform the smaller heads once max flow mattered.  

As far as how high you could rev that 351; it depends on the rods.  Assuming you are not going to run into valve float, the limiting factor is piston speed.  I've spun a 383 Chevy stroker to 6,000 RPM all day long, and it has a longer stroke (3.750"), BUT that engine has 4340 rods with ARP capscrew bolts.  We used to spin LS6 454s to 6,000 under high load with factory bottom ends in speed boats and never had an issue, though the factory rods are forged and they use 7/16" bolts.  So, in part its stroke length, but its also part material.  I don't think I'd spin a stock rod 351 past 6,000; at least not very often.  Now, if it had even entry level aftermarket rods, or a worked over set of stockers with good bolts?  I'd probably give it a go.  

I know that 185's are better than 165's.  I only looked into them with a 'dare to be different' attitude.  They are still better than my iron heads.  My current engine has more than enough power for me.  With age I have slowed so much that I let my wife do most of the driving (not the '66!).  Canyon carving is a long past joy.  I5 from ~5 miles north of the grape vine to the coast thru the coast range was my favorite route.

Anyone else have a favorite route?  Or maybe we should start a new thread.
 

Last edited by lowercasesteve (12/21/2025 9:55 PM)