Downsize my flat 8 to flat 6

S

santino2010

Member
Hello all I just bought a H series straight 6 and want to swap it on my 49 coupe,I have a flathead v8 on it right now but the engine is toasted can't afford to rebuild it ,as for the flat 6 are the motor mounts similar and is it a straight bolt in with my 3 speed column shifter, also can I interchange parts off a G series flathead 41-47
Thanks
 
You have to move the radiator forward to accommodate the extra length. The front splash pan is also different to accommodate the radiator move. Not many G and H parts interchange.
 
From what i am finding i know of few parts of the G that swap to the H. The head may but don't know for sure. The gen won't. G uses double pulley up front H uses single pulley. I know the and H had gaskets are slightly different. Distributors are located different.
 
Motormounts bolts up so does the trans...after that it gets harder...
Radiator as mentioned above.
Wiring harness needs to be tweeked.
Solenoid and cables has to be moved.
Battery tray sometimes needs to change side...atleast on pickups.
Sheetmetal above radiator has to be changed since lenght is different when moved backwards.
Accelerator linkage and choke wire needs to be adressed.
Front exhaust pipe needs to be changed.
If you want to go back to V-8 again i would think twice before doing the swap...othervise the 6 are good engines.
 
If I had it to do over, V8 but then I have the G 226. Some parts are getting really hard to find.
 
Hello all thanks for all your input, I have been doing a bit of research and yes the radiator is gonna be the fun part
I have heard there is a center mount that I am not firmiliar with,what mount is this?????
 
In addition to the radiator, the shroud is different - and important. The V8 radiator also has too many inlets/outlets for the I6 - either needs to be modified or replaced.
 
The bell housing and flywheel are different also 6cyl requires a spacer between the engine and bell housing. Contact Chris at Shoebox central. He may have these parts.
Rob
 
Are you sure this is cheaper/easier that just rebuilding the V8? Also keep in mind it will lower the value of the vehicle.
 
If you really want a 6, look for the 'M' series from 1 1/2-2 ton trucks of the day. They are 254 cu. in. and will outrun even a warmed up V8.
 
Thanks robz51 I talked to chris and he's got me covered on what I'm gonna need
The reason I'm going to downsize to a 6 is because I cannot afford to rebuild the v8 , I'll keep the flatty stashed away till the time comes
 
Is the radiator support different between the 6 and the V8. My radiator support will only mount in one location because of the fender support holes. the holes in the inner fenders only allow for this support to be located in one place.
 
Just how "toasted" is your V8? Unless a rod is hanging out the side or a wrist pin ate a cylinder wall, chances are a "back in the day" overhaul (or "ring and valve job") will fix 'er right up. Since you're planning on pulling the engine anyway, it'll be easy to clean it up and Plasti-gage the bearings and visually inspect the crank,pistons, cylinders and valves (and look for cracks). Don't worry about a little cylinder wear at the top. .012-.015" taper is not a problem. Parts stores like Auto Zone or O'Reilly's have a free tool loan program for things like a ridge reamer, cylinder hone and torque wrench. A can of valve grinding compound and a suction cup stick will take care of the valves. Just keep them in order and you won't even need to readjust. If one is burned, used ones are easily found (which you may need to readjust).
This would be a lot easier than adapting the 6 and will run well for many miles. Then start throwing your spare change and loose bills in a jar for the future complete rebuild.
 
Just checked NAPA online. They have re-ring kits (gaskets, rings and rod bearings for $130 and up. A kit that also includes main bearings is $292. So it may be possible to fix your V8 for less than converting to the 6.
 
Hey thanks for that info 40deluxe the history behind my flatty 8 is that the rings were bad so what I did is I took out the engine and cleaned it up as best as I could have ,changed out the gaskets but I didn't wanna proceed with just replacing the rings cause a machinist that i know who is experienced in flatheads recommended is I'm gonna replace the rings I might as well bore it 1 over and that's where the big $$$$$ come in, so I stopped there with it . That info you gave me sounds very interesting but I don't think I can be capable of doing that cause I have no experience what so ever on flatheads unless someone walked me through it ,I wouldn't wanna break something and there I go again spending for money I don't have ,
 
Not sure where you are located...but maybe someone close by can give you a hand and some good advice.
Burgers and beer gets you a lot of help sometimes...
 
"Back in the day", I would bet there were many thousands of these backyard "ring 'n valve" jobs done with good results. I did a couple of them myself. I remember one I did where I wanted to take out as much taper from the cylinders as I could, and ended up completely "wearing out" the hone I rented. Suffice it to say, the owner of the rental place was NOT pleased. It did the job, though. I drove that one to college for three more years and sold it to a guy who wanted it because it ran so well.:rolleyes:

In addition, it'll be a good experience to get under your belt; there's nothing better than being able to say, "Oh yeah, I rebuilt that!".
 
Another thought : There may not be many people out there who want a good runnin' "H" motor, but if you could find one, you might be surprised at how much they'll pay. Plus if you're going to go with the messing around to get a six in there, the 254" truck engine sounds intriguing.
 
tubman said:
"Back in the day", I would bet there were many thousands of these backyard "ring 'n valve" jobs done with good results. I did a couple of them myself. I remember one I did where I wanted to take out as much taper from the cylinders as I could, and ended up completely "wearing out" the hone I rented. Suffice it to say, the owner of the rental place was NOT pleased. It did the job, though. I drove that one to college for three more years and sold it to a guy who wanted it because it ran so well.:rolleyes:

In addition, it'll be a good experience to get under your belt; there's nothing better than being able to say, "Oh yeah, I rebuilt that!".
Click to expand...

I enjoyed reading this Tubman. I believe you are right. My grandfather drove these cars when they were in everyday use and I'd bet he'd fall over dead again if he knew what all I did to my recent engine rebuild. He'd consider it "overkill".
 
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