4BT / 4BTA Modifications

[WM-300]

I am running 4BTA (CPL 857) 120 hp at 2500 R's, aftercooled (water Jacket) engines in my Dodge Power Wagons and M37. I just bought 2 4BT's CPL 767 and 2 4BTA's CPL 1260 for my Power Wagons. The 4BTA's are Charge Air Cooled. The 4BT (CPL 767) and the 4BTA's (CPL 1260) are both rated 105 hp at 2500 R's, per my Cummins Shop Manual.



I would like to convert these latest engines to CPL-857's 120 hp at 2500 R's water jacket aftercooled. The Charge Air Cooled aftercoolers are awkward to use in my application.



When changing to the Water Cooler aftercoolers, the water return line goes to a port towards the front of the head. This port has a plug driven which I removed. It is not threaded to accept any type of connection pipe for the water return. How does the water return line fasten into the head ?



I also note reading about the injection pump timing that the letter on the injection pump drive gear needs to be matched to the mark on the camshaft gear. The manual shows using the

B letter for 1986 & 1987 EPA, and all pre 86 noncertified, and using the F letter for 1986 thru 1992 EPA. How do you determine if the engine is EPA or Noncertified ?



What other changes are required to convert these engines to CPL 857, 120 HP with Liquid cooled aftercooler.



Thanks WM300

 

[bgilbert]

When changing to the Water Cooler aftercoolers, the water return line goes to a port towards the front of the head. This port has a plug driven which I removed. It is not threaded to accept any type of connection pipe for the water return. How does the water return line fasten into the head ?

The return line should go to the block right below the alternator, t-stat housing and cylinder head. The supply came from the port you are talking about. I would check closer for pipe plugs/ports. Could you tap the plugged port for 1/2"npt to accept a water pipe/neck?

I also note reading about the injection pump timing that the letter on the injection pump drive gear needs to be matched to the mark on the camshaft gear. The manual shows using the

B letter for 1986 & 1987 EPA, and all pre 86 noncertified, and using the F letter for 1986 thru 1992 EPA. How do you determine if the engine is EPA or Noncertified ?

Who know, who cares? Why would it matter, I wouldn't be too concerned. What's the book say? I suppose the engine serial number could be given to Cummins and see if they could tell you any of that info.

What other changes are required to convert these engines to CPL 857, 120 HP with Liquid cooled aftercooler.

Most likely you could simply slap a water aftercooler on, matching injection lines that route around the cooler, and be done with it. But I would guess the difference in HP between the CPL's could be explained from the injectors, cylinder heads, timing, and possibly the pistons. The injectors on the cpl 857 might be 9mm tipped, vs. 7mm tipped in the air to air cooled engines injectors. The bigger tipped injectors would be of greater HP, same as the 6bt vs. 6bta. The cylinder heads would be difference as well to accept the big injector. You already mentioned the timing being differenct between them. Timing with rotary pumps is simply adjusted by moving the injection pump towards the cylinder head to advance or away to retard. Piston bowls could be different to match the spray of the injectors.



Ok I just reread your epa, non-certified question. The data ID tag on the timing cover should give some info. Either way it's only important if you were to remove the pump gear or camshaft (gear).

 

[WM-300]

Bill;

Thanks for the reply.



Yes, the supply port could be tapped for a 1/2" npt fitting. On my CPL 857 engines, that port is not a pipe fitting. It sort of looks like the tube is pressed into the port, much like the plug that was in there.



I re- ead the shop manual part on timing the pump ie Letter on pump gear. Engines 4BT and 4BTA use the same letter, the letter only changes between EPA and noncertified engines. So what ever letter its timed to now would be correct and not need to be changed.



I understand what your saying regarding the injectors. If with some research different injectors are needed to up the HP and if they require a different head, I will stay with the 105HP.



My Cummins Parts Catalog is for CPL 857 engines. I have to make a run to Cummins NorthEast and get a Parts catalog for CPL 767 engines. Then I can compare all part numbers that would influence the HP difference.



The water aftercooler is really a must when putting the 4BTA's in the Dodge Power Wagons. There is no room to route the Charge Air Cooler hoses either along side the radiator or over the top.



I wonder in operation, if one would ever see the 15 hp difference between the CPL 857 and the CPL 767 engines. The CPL 857 in my 1943 Dodge Carryall is getting 26 mpg over a 3411 mile trip. The CPL 857 drives a NV-4500 married to a NP-205 turning stock 4,89 ring and pinions and 36 inch tires. Now the search begins to find (2) used water aftercoolers.



wm300

 

[PToombs]

Do an internet search for heavy equipment salvage yards. Backhoes and mid size excavators have water aftercoolers. ex; samsung lc130, darn, I can't think of any others right now!

 

[WM-300]

Thanks Pete, good tip for water aftercoolers.



WM300

 

[Matt S]

I understand what your saying regarding the injectors. If with some research different injectors are needed to up the HP and if they require a different head, I will stay with the 105HP.

If it's anything like the 1st Gens then they have a sort of copper sleave that goes over the 7mm injectors to make them 9mm to fit the head.

 

[PKroll]

You can also go to a smaller sized hot housing for more power like the industrial versions run.