Thread: Mount a 318 Oil Pump

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I am in a bit of a fix: The fellow that built my 318 sent it back to me with the oil pump in a box [not installed]. When I went to install the oil pump, I immediately noticed that one of the rear main studs was keeping me from mounting the pump correctly. I cut the stud down to the nut, almost, but it is still about 1/8" too long for the oil pump to set squarely in place. My dilemma: do I cut into the nut, or build a shim to fit under the pump?
This is a 93 318 with magnum heads, really about 325 right now with roller everything. It is going to be mated with a Torqueflight trans and the rearend from a 89 New Yorker and being put under my '38 [Sarnia built] Dodge 2 door touring.

Can we assume this is a new oil pump, provided by the fellow who built the engine? Lots of 273/318/360 parts interchange, but I think that there is something about the rear mains being smaller on the 360 than the 318 that prevents pans from swapping? Are you 100% sure that you have the right pump for your 318? Have you gone back to the "engine fellow" and asked about the interference? Simple questions, but something just doesn't seem right here.

IF---If the pump you have is all thats available---you can spotface down the main cap a small amount to get clearance for the nut----and maybe even clearance the pump body a little bit ----also a spacer can be made, but then you'll have issues with the drive shaft for the pump

360 mains are bigger than a 318, not smaller.
Pull the stud and put a bolt in that hole. The engine will never know the difference!

@ rpope: Won't that mess things up, The engine is built, everything is torqued down right and I cut the stud down right at the nut.

@ Jerry Clayton: Thanks, Yes I have thought of the pump housing thickness, afraid of making that thinner, the cap clearance isn't an issue, just the one stud on the pump body side.

@ rspears: Yes, pump from the Machine Shop. Chrisco Machine, Jeff Chrisco, he has a good rep, I will double check the pump again. I have matched it up with a 318 pump once awhile back but it never hurts to be certain. Thanks.

I like rpope's idea, pull that one stud and replace it with a bolt. As long as you torque it back to spec it shouldn't cause any concern. You should be able to get a pair of thin jam nuts, torque them together and use them to pull the stud, right?

When the engine was rebuilt were the OEM bolts used?

@ rspears: I believe I am going to do this! The first thing I thought to myself when I saw this problem was: "Why didn't he use a bolt in this position?" But I contacted a "expert" at Melling and was led to the idea of chopping the excess stud length.

Originally Posted by Inkitup

@ rspears: I believe I am going to do this! The first thing I thought to myself when I saw this problem was: "Why didn't he use a bolt in this position?" But I contacted a "expert" at Melling and was led to the idea of chopping the excess stud length.

Just get a good Grade 8 bolt and it'll be fine. Cutting the excess stud length is fine too, if it had given enough clearance. Kudo's to RPope for guiding the bolt idea!!

If you don't want to put a bolt in, you could notch the nut enough to clear, or find a thinner nut.
I don't see the advantage of studs on a street engine. Sure, they have more clamping action, but that's not an issue with a relatively mild engine. They just aren't worth the hassle on a streeter in my world.

Studs in street engines--------------Studs are a good idea in any engine, especially a used core or block that has been lying around getting rusty--A stud will pull evenly on all the threads instead of winding and twisting as a bolt is tightened-----They also allow you to use a quality nut as an economic way to rebuild and have new threads instead of reling on some questional threads of a bolt or block---


However, the choice of the proper length and thickness of the stud/nut/washer does get touchy under the oil pump /main cap of some engines that fasten the pump to the main cap-----------A late model hemi is the way to correctly remedy this particular case----------

@ Jerry: I appreciate the info. The remedy, however, I cannot comply to. I will continue with the engine I have. Thanks.