Changing from a 4 to a 6 cylinder

[Quadromaniac]

My car has a 4 cylinder in it now. I believe the valves are burnt. I just bought a 6 cylinder that runs great. Can I just pull the motor and bolt the 6 up to the 4 's transmission, or do I have to replace the transmission with it. The motor came with a transmission bolted to it already. And are their going to be any other issues going to the 6 cylinder motor. Both the car  and the 6, I just bought are 1953 models.

[pnw_oldmags]

I would swap out the differential and driveline as well. 

[joefrazer]

The exhaust pipe...from the manifold to the muffler differs between the 4 and 6; the accelerator linkage is also different, as is the fuel line routing. The motor mounts stands...the part that attaches to the frame may differ also. You may also have to do some work on the wiring to the engine.

[Corsairdeluxe]

Was this the one on ebay in Kentucky? You will need the two pieces that bolt below the engine mounts to the frame .They are different from 4 to 6 . Lowell can give you the part numbers for the radiator hoses. You will be glad you made the change.I would not bother to change out the rear end if your current one is in good shape or unless you plan to do a lot of freeway driving.

[Quadromaniac]

This came from E Bay, but I bought it in Paulden Arizona. The 6 runs great. He started it on a wooden frame before I said yes.It has the complete overdrive transmission, driveline, minus the u joints, rear differental, complete with break hardware, and oil bath air filter. It has been converted to an alterenator and pointless distributor, 12 volt. I think I will be changing that back to 6 volt. Not willing to change the rest of the electrical.I am not sure now if doing this or just doing a valve job to the old 4 is the right choice. I am actually having 2nd thoughts.

[Fid]

If the car is a 1951 and the six cylinder engine has an overdrive transmission with it, you are good to go. If you didn't have overdrive, then you would need to either add overdrive or change the rearend but if you have overdrive all you need to do is install the different exhaust header pipe and change the motor mount supports (two pieces that bolt to the cross member) and the throttle linkage.  The fuel line routing is slightly different, but all you have to change is the neoprene hose that goes from the pump to the line - NAPA still sells it.
I speak from experience, having done it several times.
The four cylinder is an anemic, under-powered engine which is prone to throwing rods (I never heard of one that didn't throw a rod). If you can put a six in the car you will like it much better but be aware if you have it judged at a KFOC event there will be point deductions because there are other differences than just the engine between the standard and deluxe models. The six cylinder cars had bumper gaurds standard (many restorers have added them to the four cylinder cars as they do look better). The 1951 four cylinder cars had painted grill moulding on the hood but again, many restorers have added the chrome moulding that the six cylinder cars have (this is probably the most common modification I see on Henry Js). The six cylinder cars have stainless steel brightwork around the windsheild and rear window which the four cyls don't. The six cyl cars have two horns, the fours have only one. There are other changes too but when it comes to the engine, as long as the car has the correct rearend, the 1951 four cylinder cars all used the 41/9 (4.55:1) which is the same one used on the 6 with overdrive, it will work fine.
If the car is a 1952-53 four cylinder without overdrive, then it would have the 47/11 (4.27:1) rearend which would have to be changed.   
I have a set of motor mount supports and the throttle linkage which I am willing to sell. Let me know if you're interested.

[Corsairdeluxe]

From your photos I think you have most everything you need except the throttle linkage . I would grab it.I also do not advise putting a lot  of work into the 4 cyl.,especially if you intend to do a lot of driving.Where are you?

[Quadromaniac]

I live in Surprise AZ. There is linkage to the carburator all the way down to the oil pan and a small bracket on the end of that. There are 2 mounts that look like they bolt on to the front of the motor to the frame possibley with broken motor mounts on top o them. You can see one in the photo and the other side looks like the mate to it. My car is a 1953 Allstate and I was told that this motor is from a 1953 Henry J. I am not trying to build a *points car* I would just like to be able to drive it on a regular basis. There will be no freeway driving just around town and to the club meetings.

[Fid]

I see the motor mount support brackets in the photo so you have those! I do have the throttle linkage - from foot-feed to bellcrank, that's what's different.

[AZ_HJ]

Bill of Surprise, AZ

Remember you can always come over to my house and look at my 6 cly in my Henry J. I think I have some extra throttle linkage for a 6 as well. We could also go by Larry Braker's house and round up any parts you might need to do the change over.



Mark in Sun City, AZ

[Fid]

Another note - the photos posted reveal the water outlet (thermostat housing) is not the original Henry J part.  The one on the engine in the photo is at a 90 degree offset toward the passenger side. The original is straight up like this -

Larry may be able to help you get that piece too as putting hoses on may be trickey with the other one. Also note, the 4 and 6 cylinder cars used the same radiator so no changes needed there. The carburettors are different though, even though they look identical they are different inside.

[kaiserfrazerlibrary]

One of the reasons the 4 cylinder engine can have problems is that it was never intended for today's driving.  Willys-Overland unofficially rated the top road speed of the 134 cu in 4 in the L-head configuration at 45-55 MPH tops and even then, it was not intended for road trips (say, Chicago to Cleveland) without the occasional stops.  The government said the HJ only had to do 50 MPH on the road to meet the speed mandate for the car.

[Jim B PEI]

Question: was that unofficial speed rating for the 4 cylinder 45 for straight shift and 55 with overdrive? Or just 45-55 range with straight shift--making the require "50 mph" without the definition of 'how long at 50' set in stone?

[kaiserfrazerlibrary]

I was not allowed to make a copy of it, but the document from Ford Motor Company gave more detail than the AMA Questionaire Willys-Overland submitted for the 1952 Aero Lark.  Ford's engineers indicated that the speed range was determined by:

1.  Overdrive engaged (so there was a slighly lower rear axle ratio than 4.27:1 or 4.55:1)

2.  Fairly straight, level road rather than lots of hills or higher elevations (like the spot on I-80 in Western PA).

Perhaps some 4- cylinder HJ owners may want to comment on their own experiences to get a really good picture on this.

[Corsairdeluxe]

I have paid my dues in this club,con rod through the oil pan. It's rpm under load that limits this engine. It has a long stroke,lots of reciprocating parts and beats itself to death at sustained periods under load over 2,000 rpm.Shorter periods at higher rpm just hasten the deal.Rember this is a 1938 design.

Did the ALLSTATE swith to Delco along with the J?