318 block and I don't know

-
W

Wayne Rider

Active Member
Joined
Aug 6, 2022
Messages
42
Reaction score
7
Location
Beaver
I recently bought a 1975 Dodge Dart Sport with a lot of new parts but am lost on what needs done and why. I have a 1985 318 motor a scat pack 360 crank >.040 over flat top pistons performer rpm heads performer rpm intake and 532 lift 292 duration cam lunati voodoo. Why 360 crank ? Do mains need turned down ? Will rods work without any head work ? all Clevite main and rod bearings Are they okay for this ? I am not great at this but am not sure what previous guy had in mind. Any help greatly appreciated.
 
It sounds like you have a bunch of new parts, mismatched or otherwise, I would advise you to find a machinist in your area, Beaver Utah I’m guessing so salt lake might be your best resource, and bring them what you have with a goal in mind. If you find someone willing to work with you and you can trust they’ll be able to set you straight.
 
Welcome to Fabo Wayne. My first question would be, do those pistons have a part #? Might tell us if they are even compatible with a 318 bore and a 3.58 stroke. I agree with @TT5.9mag that you need some help finding out just what you have. I do believe you got some good parts, we just have figure out what will work with what?

My gut tells me you may be looking for a 360 block to build. We'll see?
 
Last edited:
TT5.9mag said:
It sounds like you have a bunch of new parts, mismatched or otherwise, I would advise you to find a machinist in your area, Beaver Utah I’m guessing so salt lake might be your best resource, and bring them what you have with a goal in mind. If you find someone willing to work with you and you can trust they’ll be able to set you straight.
Click to expand...
I am in Beaver Ohio sorry but I do have a machine shop close and I can talk to them
 
Another quick thought is to look the crank over well for a casting# or part# that may be on the counter weights. Not to say it hasn't been modded, but it gives us a starting point.
 
Wayne Rider said:
I am n Beaver Ohio sorry . but I do have machine shop I can talk to fairly close Thanks
Click to expand...
No apology necessary, I was assuming. Call and have a serious talk with the machinist and get to know him. Post some part numbers and casting numbers of what you have and we’ll be able to (with the help of your machinist) to set you down a good path.
 
Wayne Rider said:
I recently bought a 1975 Dodge Dart Sport with a lot of new parts but am lost on what needs done and why. I have a 1985 318 motor a scat pack 360 crank >.040 over flat top pistons performer rpm heads performer rpm intake and 532 lift 292 duration cam lunati voodoo. Why 360 crank ? Do mains need turned down ? Will rods work without any head work ? all Clevite main and rod bearings Are they okay for this ? I am not great at this but am not sure what previous guy had in mind. Any help greatly appreciated.
Click to expand...
Not too sure, but it looks like a stroker build was in the works. Pistons would need to be different than stock 318 specs to allow for the extra stroke. Could be shorter rods too but without all the info all any of us could do is guess. Cam specs are not really important until we figure out what the internals are.
 
318thunder said:
Not too sure, but it looks like a stroker build was in the works. Pistons would need to be different than stock 318 specs to allow for the extra stroke. Could be shorter rods too but without all the info all any of us could do is guess. Cam specs are not really important until we figure out what the internals are.
Click to expand...
Thanks I will get numbers and post . It is in my brothers garage so it may be a day or two
 
Just throwing this out there, but it sounds like the previous owner had been planning to build a 347 stroker. You use off the shelf pistons and mill the tops down a little, and then either mill the skirts to clear the counterweights on the crank or turn the counterweights down to miss the skirts of the pistons. Turning the counterweights down may also allow the rotating assembly to be internal balanced. If I live long enough to ever get the numbers matching 318 block back in my 71 Challenger conv, this is exactly the motor I will build.
 
JDMopar said:
Just throwing this out there, but it sounds like the previous owner had been planning to build a 347 stroker. You use off the shelf pistons and mill the tops down a little, and then either mill the skirts to clear the counterweights on the crank or turn the counterweights down to miss the skirts of the pistons. Turning the counterweights down may also allow the rotating assembly to be internal balanced. If I live long enough to ever get the numbers matching 318 block back in my 71 Challenger conv, this is exactly the motor I will build.
Click to expand...
I hope you get to . I have been wanting to try to builda nice street mopar for a long time. I have a lot of work to do but my brother is a big help. He is a big block guy though and wasn't sure where this was headed. thanks for your comment
 
Wayne Rider said:
I recently bought a 1975 Dodge Dart Sport with a lot of new parts but am lost on what needs done and why. I have a 1985 318 motor a scat pack 360 crank >.040 over flat top pistons performer rpm heads performer rpm intake and 532 lift 292 duration cam lunati voodoo. Why 360 crank ? Do mains need turned down ? Will rods work without any head work ? all Clevite main and rod bearings Are they okay for this ? I am not great at this but am not sure what previous guy had in mind. Any help greatly appreciated.
Click to expand...
Either there's no crank and you need to get one or the 360 crank has the main journals turned down and the Pistons have the proper pin height to accommodate the 3.58 stroke.
 
@Wayne Rider The idea of putting a 360’s crank into a 318 has been shown here once before. I wasn’t particularly fond of the route taken.

The build starts with cutting the 360 mains down to fit the 318 block. Stock rod length is used. Now comes the hard part and that’s pistons. There going to be a custom order if bought new. That equals expensive.

The other thing to do is modify a set of pistons. IIRC, *I Think* the builder modified a 318 piston to fit. Being there normally pretty far down in the hole, there workable for this. The builder had to cut valve reliefs in the piston.

I don’t find this particular build all the advantages or a big fruitful adventure myself self. However, since you seem to have a bunch of parts, this could be a fun build.

Displacement is 343 on a standard bore & 349 @ a .030 overbore.

Are your pistons notched?
 
I remember a thread here years ago about how to do it. About all it does is make the motor a little more torquey because of the longer arm on the crank. Supposedly, you use some Silvolite pistons with a 1.741 compression height, and mill .065 of the tops of the pistons, and then mill the skirts to clear the counterweights. I was talking to my machinist about it one day, and he said it would be easier to turn the counterweights down and neutral balance the motor than fool with the piston skirts. It would be ok for a stockish type build if you wanted a little more torque, but it's a lot of work just to say you did it! There's easier ways to make torque...lol.
 
Agreed. Not the route I’d take. A 360 or better yet, a 5.9 with a cam, header and a 4bbl. carb would be just fine. I’d ether build the 318 stone stock or a wacko balls to the wall build.
 
Thanks to all I am in search of 360 now. I think it would be a lot easier for a novice and I just want a good sounding , running street driver to play with
 
You must log in or register to reply here.
-

Back
Top