8BA & 8RT engines in LP Bren Gun Carriers
 

Hi, over the years I have looked at and thought about placing a 8BA (car) or 8RT (truck) Ford side valve engine into my Bren Gun Carrier.
My question is, has anyone done this? if so what problems did you encouter and what advice can you pass on?

The WW2 Ford V8 engine is 85hp and is 221ci.
What I have read, the 8BA or 8RT engine is 100hp and is 239ci. The main differences are (apart from the exta horsepower) a bolt on bell housing, water outlets on the heads are to the front, distributor is more conventional and mounted at the right front of the block/head area, bolts to secure the heads to the block (both are 24 stud).

specific questions/concerns are:
will a ford truck/carrier gear box bolt on to the different bell housing?
will bren gun carrier manifolds bolts to the 8BA block?
are the water pumps the same on both engines?
will 221 heads bolt onto the 239 block (this would give the appearance of a 221 engine) compression ratios are the same for both engines.

thoughts and feedback appreciated.
I would assume that the same idea/logic would also apply to those who have Universal carriers.

There isn't a lot of point really.

Get a wartime 81 or a 59AB, these are the wartime 239ci and the postwar 239ci, externally they look identical, centre water outlet, same water pump castings, same bell housing and cam mounted distributor, the 59AB has an slightly higher CR and modified block casting internals for improved cooling, but only a little I think.
An 8BA did have improved cooling passages and modern rod bearings, but most of the redesign was a cost down rather than improvement. If you use one, you can get an adaptor plate to use the wartime gearbox, you will need wartime water pumps as the pump casting is different on the 8BA putting the engine mounts in the wrong place. You would need pre 8BA heads (24 stud) and an earlier front cover to use the original wartime distributor, which would mean changing the cam as I think the nose I'd different...in the end you would only be using the short block.
The 'best' engine would be a French 1990s flathead with pre 8BA everything else. When I say short block I include the valve train, 8BA valve gear is much better than pre 8BA as far as fitting and service goes.
All flathead distributors are terrible compared to the last of the line of distributors before full management came in, so having the side mounted unit would not be any better than the front unit, best would be to replace with a later chev or something that has both centrifugal advance and vacuum advance for better combustion at part load.

Engine
 

An excellent explanation. Clear, concise and professional.

Peter S

The Sidevalve engine used in Aust LP carriers and all Ford Blitzes is already a 239 engine (the 99A, or Mercury engine) with identical bore and stroke as the 8BA engine. The wartime V8 was rated at 95hp, while the same engine was rated as 100hp only due to the advances in fuel quality post-war. It is only UK/Canadian carriers and Ford Commercial Trucks (Incl Marmon-Herringtons) that used the 85hp 221.

As far as fitting an 8BA into an LP Carrier goes, it can be done but there are some issues. The 8BA/8RT engines use a conventional bolt-on bellhousing. For applications in Ford and Mercury Utes and Trucks (which still used the old 4 speed gearbox with integral b/housing), there were 2 types of adapter bellhousing made, a cast-steel and a stamped steel. The cast steel one was made for trucks and will clear an 11" clutch, while the stamped steel was for 1/2 ton utes and will only clear a 9 1/2" clutch (Carriers and CMPs use an 11" clutch). You will need to replace the clutch disc on the 8BA to one with a 10 spl 1 3/8" hub to match the carrier gearbox, to replace the 10 spl 1" hub it probably has fitted.

The earlier 24 stud heads will fit onto an 8BA block and will function, but the water passages through the head gasket are different and will lead to overheating! The 8BA heads have the water outlets and thermostats at the front of the head, and if using the generator-mounted fan of the wartime engines, the fan diameter will have to be reduced to clear the hoses. The 8BA fan is mounted lower on a bearing approximately where the dizzy is on the early engine and with the fan in this position it won't clear the shroud on the radiator. The frontal position of the thermostats and dizzy also interfere with the accelerator linkage in a CMP, but not a Carrier.

There is also an issue with the water pumps. The 8BA used in Ford cars has a different front engine mount set up from the early engines. However, the Ford and Mercury Truck pumps have the proper foot arrangement for fitting into an earlier chassis. You cannot use an early waterpump on the 8BA block because the water passages to the block are slightly different and also because the pulleys are set further out away from the block so the belts clear the angled distributor. For many years, these pumps were fairly hard to find, but they are now being reproduced as new castings in either steel or aluminium from Flatattack Racing

The starter on an 8BA engine has a different design Bendix drive which makes the starter non-interchangable with the early starter, and they were only available in 12v. This isn't an issue of course if you've changed your electrical system to 12v, but a problem if you're still running 6v.

And finally, the sump. The most common (Car) versions of the 8BA sump have the lowest part (ie drain plug) centred on the engine, while the early engines have it positioned toward the rear. In a carrier, this won't cause any clearance issues, but you will need to cut another access hole further forward to drain the oil. On a CMP, this sump will be foul of the front diff and disaster awaits! There is a version of truck sump that has a rear reserviour and drain plug, but these are rare and highly sought after (read: expensive). An early engine pan won't fit an 8BA engine due to the integral bellhousing on the early engines fouling the 8BA bellhousing adapter.

But the good news! The exhaust manifolds will bolt straight up without modifying the system. The carb is in the same place and the air inlet or filter will fit exactly the same way as on the original engine.

In light of the issues, you'd have to ask yourself why you'd want to put in an 8BA for negligible benefit, when your 99A engine can be "Built" to perform just as well as any 8BA, or better!

Top thread
 

Thanks to all involved for a top class thread with plenty of details

cheers

Phill

I put an 8BA truck engine into my carrier as a temporary until I rebuild my carrier engine. In hindsight I should have just rebuilt the carrier engine.

I was able to overcome the oil pan problem by cutting the bottom off the pan and welding a flat plate on. At the same time I was able to relocate the drain plug to the right position.

No problem on the tranny to bellhousing except that the bottom ears of the bellhousing stuck down to the floor and had to be ground off.

You can change the entire front cover over to the early style with the distributor down under, and the water pumps can also be swapped but you will have to plug one extra hole on the block for each water pump. That is as simple as threading the hole and putting in a small slotted pipe plug. That would allow the normal carrier generator to be used.

I think I had to do a little bit of grinding around the starter to get that to fit as well.

So it can be done, but you might be just as well off to keep searching for an early engine.

was going to suggest that the 239 99A (or T) lump was not post war... mine is a 1939 unit..

it is possible to fit a trigger wheel behind the crank damper with a VR sensor and go mapped ignition (over the naff dizzy)...it will run much better however....not exactly wartime or original for that matter.... the coil pack could be hidden away out of sight too, the megajolt style systems i have seen have USB dock to plug in and get the most out of an engine...

Go French!
 

I have a French engine in my Universal and boy does she fly! Last Race to the Bridge in Arnhem we were clocked at 40 Mph trying to keep up with the rest, mainly Jeeps. Had a crew of 10 and a 6 Pounder on tow. Mind you, I did blow a gasket and spray engine coulant all over. My own fault off course. Still need to get my speedo and temperature gauge working..... :doh:

Cheers,

Yes Marc, I noticed you had a French unit in a photo you posted a few days ago. Looked good :salute:

For the "best" forties flattie with all stock parts start with a 46 to 48 Canadian truck engine. They had higher compression and a better camshaft for operating at our higher altitude. Then get a 49 or up 255 Merc engine and put the crank and pistons in the truck engine. You need to change to the 239 crank gear so it'll work with the 48 camshaft since the gears are cut the opposite way. Bolt all the older accessories on and you'll have a 140 hp flattie that looks and sounds original. Oh, and Ford didn't use a 12 volt system until 1956 so flatties wouldn't have got them.

Just put the merc 100 hp in and tune it and it will get at least 40 plu Leave every thing original but the cam.
With the cam and tuned you will get the horses and the RPM
Take it from a guy who has done it
and no one only you will know it is not original

Stew

Except the wartime British Ford WOT series of military trucks, the full 12 volts on their flatheads !

I thought the speed was limited by the gearing not the engine ? if you want to go faster put a taller final drive in the gearbox... or a taller crown wheel in the diff...simple...your gauge will no longer be accurate but hey ho......... remember folks the speed limit in the UK for carriers is now 20mph.... would hate to stop one in a hurry at 40...it just wont happen. personally if i was going to build a modded unit for a carrier i would aim for something that has plenty of bottom end grunt and plenty of torque for static neutral turns etc..... thats just me though :)

Thank you all for the wealth of information.
It has shown me that I still have a lot to learn.
It is a bit hard to find info on wartime vehicles and engines, I had a thought that the V8 in the carriers was 100hp but could not find a reference to/for it.

In hindsight I should have mentioned why I was looking at the later engines. I thought a little more hp would really help the carrier, I also wanted something that was more maintainable with the distributor easily got to for timing and adjustments.

I think my way forward is to get a 100hp wartime engine (whick my Dad has several) and rebuild it with some internal improvements from Flatattack racing (adjustable cam followers/lifters, modern water pumps, thermostats) and also an electronic distributor (Pertronix electronic ignition is one of many out there). Also an upgrade to a 12 volt system for starting and lighting would assist.

Thanks

I fully agree with Richie, I dont see what the need for speed is with carriers, power and torque to pull you through the mud and up hills yes !!! but carriers are not good at speed things soon get out of control, as my old father says "any fool can drive a big car fast in a straight line" . may as well chrome the heads at the same time. ive probably said to much :doh:

if you want adjustable followers i think you need to strip the block back to bare bones as the block needs a hole drilled where the followers sit (or so i have read) if you want cheap and easy oomph then i would suggest the following:-

1) port and polish the head and block around the valves (just slight relief not full flow or it gets pricey... you can do this yourself with a die grinder and stone mandrels)

2) change out the cast exhaust manifolds for stainless ones (with better flow) OR port the cast ones out with a die grinder to match the exhaust ports on the block

3) centre main strap (stops blowing out the centre main when you over rev)

4) change the carb.


should point out that none of the above should even be attempted until you know the port velocity limits etc for the unit ! otherwise you take too much out and jigger the engine.

when you get into the realms of adjustable followers and cams it gets pricey you then need to consider high flow oil pumps etc etc... then its a case of why stop here i might aswell lighten cross drill and balance the crank and rods, and pop a lightened flywheel on whilst i am there.... KACHIIIIING !

if you want more CR then simply facing the head and deck will achieve this.. now remember when the CR goes up the quality of fuel or octane should go up too otherwise you blow holes in pistons.


from my own meager experiences in a carrier i have driven 60hp and 85hp units.... even the lowly 60hp unit was more than enough ! and the 85hp unit was very good more than enough to do what you need. so if you get a 24 stud 99a (100hp) you will have more than required...


i am afraid I have the "BHP" T shirt i spent just sickening money getting a 1300cc mini engine to exceed 200 BHP.... i got there in the end but my was it costly :)



and finally whilst i ramble on... you need to consider the tollerences of the running gear.. will it take greater BHP and torque... and if so how much ? i have seen diffs stripped clean of teeth and they never go quietly something always gets taken out at the same time...

That 255 Merc with the longer stroke gives lots of bottom end torque where you need it but the engine won't rev any higher than any other flattie. You don't want much more speed out of a carrier anyway. Think about how long those tracks would last at 50 mph!

Darrin,

I built up a 99A 239ci engine with (1) late pattern crank with two oil holes per journal, and (2) 8BA rods with fixed shell bearings and 4 ring pistons. Had it balanced. Everything else was standard. Worked fine: it's still in my (former) Blitz 15cwt. From the outside it looks the same as standard.

Mike C

Some extra cubes give some low end gain. better breathing is for the higher end of the rpm range, and is not what you'll want. Save that one for your hot rod.
Being able to turn the thing, and get it rolling is where the problems lay.
Not much point in making it breath better (stainless manifolds, port job, cam etc.) wont help if its still restricted at the exhaust elbows.(and what else are you going to mod?)
The truck cam is probably as good as it gets, as cams go. The adjustable tappets will work with std cams, and the extra cost here is somewhat offset by the extra labour costs of the standard setup.
With an oversize set of pistons to increase the cubes, I'd say the last two posts have completely covered what is nessesary, for a great performing carrier power unit.
As with any motor job, just do it all well. (and yes Rich you do have to drill the block to use adjustable tappets, but it is also easy to make a minor adjustment later)

On some of the adjustable lifters you can get a special wrench to do the adjusting without drilling any holes. It sort of looks like a 90 degree snap ring plier that goes down from the top to hold the lifter body while you tighten the adjusting nuts.

My 2cents
 

Hey guys,

Don't get me wrong, I can see the merits of many suggestions on this thread and I know the satisfaction of modifying and improving the performance of collectible vehicles (when I used to restore Model T and A Fords I had all the cool accessories)

But I thought the point of most Military Vehicle restorations is to preserve the vehicles as they were during the world's most devastating conflict. My hope for the Scout Carrier is that it will eventually look, sound, smell and feel just as it woukd have for the hapless RAC troopers who crewed them in France and Belguim with the BEF, or with British and Australian forces in the Middle East and North Africe.

I'm not criticising those modified carriers - they are yours to do as you please, but how noble an ideal it would be to demonstrate to my grandson in years to come what his great grand father and might have experienced all those years ago...

The old gutless late 30's English spec engine is what my carrier had and what I hope it will have again.

Cheers

Here's an example of an 8BA engine all set up to go into an earlier vehicle:

http://www.ebay.com.au/itm/1946-Ford...item1c20ef73a8

Call sacrilege if you will, but my carrier has a chevy 350 four bolt with a single barrel rochester carb, and boy does she move...I could pull stumps all day long. Flamesuit on.

Whatever works for you, but just don't paint it bright yellow.