37 truck with a 8RT

Gary-UK

Gary-UK

Senior Member
I've just dropped a freshly built 8RT engine in to my truck, foolishly thinking that this is a bolt in deal, only to find I've interference 'between the drag link and oil pan.

I don't think I am breaking new ground here so am wondering if my pitman arm is incorrect. I see listings for a 51-3590 pitman arm for 35-37 trucks but also see 78-3590 for 37-41 trucks, is there a difference? I have the 78-3590 but it looks like if I tapered the end of the pitman arm from the opposite side my problem may go away.

For clarity it's a 8RT block and oil pan with the clean out plate, everything on the front of the engine is early, pumps, ignition etc. Cast truck bellhousing adaptor with stock 37 trans, all sat on stock engine and trans mounts. Very mildly lowered with a de arched front spring with a reversed eye. Oh, it's RHD too.
 
It's not uncommon to have clearance problems on a swap like this. The 8RT truck pans are deeper than any of the other 8BA family of engines but mostly at the rear. The Mercury pan is a bit better on the front but there is no clean out. The 8RT pumps boost the engine up a bit taller but a person may be able to put spacers on the mount pads if there is room to do that. You may have to find the spacing anywhere you can get it to get the clearance you need.

When you mention truck, is that a large truck or a commercial pickup?
 
Don't know about your particular swap but its pretty common to heat and bend pitman arms to help with clearance issues.
 
I've also seen folks put a U shaped drop in the middle of the tie rod to lower the middle of it down to clear a pan. A person might be able to do this with the drag link. Usually this stuff happens with a deep dropped axle but it sounds like just a pan clearance thing instead of a wishbone and pan clearance thing. Bending the pitman arm might work too but it just depends on how much clearance you need. I wouldn't want to bend it too much.
 
I have installed two 8BA (49-53) style engines into '37 Ford 1/2 tons with no problems..
Did you use the '49-50 Merc motor mount spacer blocks under the water pumps with the truck pumps, in lieu of passenger car pumps.
See attached pix of the most recent installation.
 

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That one appears to have the 50/51 Mercury pumps too but it looks like they fit good with the Merc spacers in there.
 
Thanks for the replies, I wanted to double check I didn't have the wrong pitman arm, which i don't, so I will make it work by tapering the hole from the opposite side and tweaking the pitman arm and drag link to suit.

I've tig welded the clean out plate shut, so hopefully no leaks! Will post some pics when done. Thanks again.
 
[B The pan needed is the 49-51 Merc oil pan and short body 8RT oil pump. It has the rear sump and will "clear" tie rods and drag link.[/B]
 

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I have always been under the impression that the '49-50 Merc motor mount spacers under the water pumps is a must have item when putting an 8BA/8CM, etc., engine in an early V8 chassis. The truck pumps usually work well as do the '49-50 pumps. The truck pumps generally have the wide belts in lieu of the narrow passenger car type. The Merc spacers also compensate for the slight off-set of the holes in the later model motor mounts, matching up to the early frame holes.
It could be that the pan on the 8RT should have been changed to an earlier pan.. I would not have used a "truck" pan on a light 1/2 ton. Of course hind sight is 20/20.
 

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They made some spacers just for that purpose that are a bit different than the ones used on the L49/51 Mercs. I think Drake or one of the other restoration supply places carry them.

The early 1949 Mercs used a different motor mount cushion set up than the later ones and used the early 21A style fan set up. The water pumps were set up for both water pumps & generator belt (wide belt) with just a short belt for fan and had oil cups for the bushings in the pumps. Somewhere in late 49, they changed over to the set up used through 1951 with offset spacers. The later set up might be preferred for pump reliability but the wide belts & 21A fan could still be used in those early Fords.
 
As I understand it when using the the Merc pumps to install an 8BA in an early chassis you need to use the Merc spacers.
When using the wide belt 8RT pumps you don't have to.
Reason: The height of the bolting flanges for the Merc and truck pumps is different. Easily seen if you put the pumps side by side. These are 8RT pumps in a 40 with an 8BA.
 

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Closely reviewing the pix attached to response #16, showing 8RT pumps on an 8BA engine it appears the bolts in the motor mounts are off set from center within the mount.
If they are off set, that is what the 49-50 Merc spacers compensate for, making the installation much easier.
The Merc spacers bolt to the stock motor mount, then an additional bolt attaches the spacer to the pump, correcting the off-set.
I might add, pretty nifty plumbing job on the water pumps to the radiator.
 
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