im new here so please forgive me if im in the wrong spot.

i have an 85 w150 with a 360 3sp auto and 35's. the motor is knocking bad in the bottom end and i have access to a 70 something 318 out of a dart i believe.

i figure instead of spending the money to replace the bottom end ill get the 318 and build it up for less than it will cost me to get the 360 fixed.

i use the truck mainly as a daily driver in the winter and a toy in the summer so i dont want to go radical and watch the gas go completely out the window. only getting 9mpg right now.

what can i take off the 360 to put onto the 318 to help it out and what size cam should i go with since it will be going into a truck and not a car?

and i want to keep this as cheap as possible to do and need to replace the motor soon before my only running vehicle right now goes to hell too.

thank you

 

You can put the heads and intake from the 360 on it. You would probably want to have the heads milled to keep the compression from dropping.

 

In my opinion the 318 has more potential then a 360 from my experience with them, my brother has an 85 ram With the 318 when we sent his to be rebuilt, they bored it out, and surfaced the heads the minimum amounts, but what I seriously recommend is to get it what they call blueprinted, what they do is completely balance the motor so that you could run them however fast you wanted, my brother got his blueprinted and its rated to go to 6000rpm and never hurt it, cost $200 to do it at our local shop, another thing I recommend is if you beef up your motor to do the same to your transmission as well

 

Please enlighten us as to how an engine that starts with 42 less cu in has more potential than a 360?

If your brother had the same work done on a 360 he would would have been that much further ahead. Do you know what blue printing and engine is? It isn't balancing the rotating assembly.


To the OP:
Either rebuild your 360 or find a replacement. With your 35's you will want the additional torque from the 360 to get it moving. You will also probably find that going down in engine size; i.e. lower torque from the 318 your mileage will suffer more.

My truck with 35's had a 318 which was getting 11 mpg, I replaced with with a stock 360 (both engines were fuel injected) and I'm now getting 12.5 mpg. It isn't much but I drive it 66 miles a day.

 

The blue printing that our machine shop does is what they say balancing everything within the motor to enable you to run them at higher rpms, different people may call them different things, as for the 318 vs 360 I've never personally owned one but with the many people I knew who did own one thought that the 360 didn't have enough power to get the fuel economy It did and nor have the power of the 318, just because the cubic inches is smaller doesnt mean the motor doesn't have as much potential, the TBI and magnum 360s were much better then the older ones, ill always stick with the 318, everybody is going to think differently and like different things is the fact of the matter, personal preference.

 

Well I can tell you that a "quality" blueprinting job will cost much more than most folks are willing to spend especially for a daily driver.

• Position & alignment of main bores in every axis, relative to the block casting
• Correction of the crankshaft’s main journal alignment and spacing, end play, rod journal alignment and spacing, stroke throw length and clock position of each throw
• Size\alignment of each cylinder bore relative to the corrected centerline of the crankshaft
• The plane and height of each deck relative to the corrected centerline of the crankshaft
• Diameter sizing of main and rod journals
• Bore sizing and equalization of each connecting rod in terms of center-to-center length, squareness and balance
• Piston skirt sizing, pin-centerline-to-dome *verification and weight equalization
• Camshaft check/correction for shaft straightness, alignment, lobe spacing, clock position, ramp angles, lift heights, etc.
• pushrods, lifters for length, diameter
• qualization of cylinder head combustion chamber volume (modifications to chamber and/or dome required to achieve a specific total volume and compression ratio)
• Possible equalization of all intake valve and *exhaust valve stem lengths, head diameters, weight
• Achieving a specific (and equal) valve seating depth at each valve
• Centerline-positioning, aligning and sizing each valve guide
• Achieving desired valve seat pressure
• Checking/achieving specific valvetrain geometry
• Improving efficiency of oiling system and cooling system
• Magnafuxl of all parts and shot peening for strength.
• Checking all operation clearances (piston-skirt-to-crank counterweights, piston-to-wall, etc.)
• Checking and achieving a specific desired *compression ratio
• Alignment of intake ports (head-to-manifold)

Balancing as performed my most machine shops is generally inexpensive unless you need to add extra weight (mallory) as it is very expensive. Proper balancing will include both ends of each rod the match the weight of each rod in relation to the others, each crank throw and bob weight. You should also include the flywheel and dampener.


Onto 318\360 debate:
Both 318's and 360's (LA) suffer from low compression and poor flow characteristics out of the box. Now I'm referring to 80's smog era engines in our trucks. So in this context if a person such as the OP with a truck and 35's finds that their 360 needs to be replaced and goes down to a smog era 318 (stock) they will notice a loss in power\torque (this is provided that their 360 was in reasonable condition other than the knock)

For someone with a truck such as the OP's that was equipped with a 318 and they switched to a stock 360 they would notice the improvement in power and possibly economy due to the increased torque that the 360 provides.

But to make a blanket statement that a 318 has more potential than a 360 has no basis in fact. If you took the same work you put into a 318 and put it into a 360 you would still have more power and torque simply due to the better potential of the 360. If you are building a race car and want a short stroke then you might want a 318 but most people use their trucks as daily drivers, towing, off-roading etc so they are far better off with the longer stroke of the 360 i.e. additional torque.

1 last thought...just because your engine can rev to 6k what have you done to be able to utilize that RPM? Did you buy Indy, Edelbrock, Mopar heads that have been ported to flow to the max at that RPM? Is your intake properly ported and matched to the heads to flow at that rate? Is your cam spec'ed to kill all your low end power to only deliver high RPM power?

To the OP:
What do you intend to do with the truck?
Daily Driver \ Mild Off-Road use - then you need an engine that delivers high torque at low RPM - then you want a 360 based engine, mild build, RV type cam, 9.0 - 9.5 compression ratio, 500 cfm 4bbl carb.

 

What started out as a "budget build" for me cost about a grand more then I wanted it to. Just because you think it will be a cheap build it most likely won't be. Also check the quality of the rebuild kit that you get. The one that my shop ordered in had the wrong piston heads...3 times.

 

who would have thought people would get so technical in a thread started by a guy that just joined the forum and has not responded. there must be something going around the web that is making people so argumentative.

 

I agree. Must be the holidays that has everyone in such a cheery mood.

To the OP, (if you aren't scared off by now), If you are looking for the most bang for your buck, I would probably swap out to another 360. They are cheap and plentiful. I would look for the magnum version though. They flow much better and produce more power than the old smog monster 360 LA's. Its pretty easy to carb a Magnum engine now, as there are a few companies that make carb intakes for them. Good luck, and please dont be afraid to ask another question, even though the first time around wasnt the best welcoming ceremony. - Scooter

 

You like the 500 CFM for that much motor? I think I have been accused of undercarbing an engine or two, and that seems a little light, even for me. I was under the mindset of using a 500 on a smaller engine range. 283,289,302,...340. Of coarse that all depends on how built the engine is and altitude. (I recently left 9000 ft and moved to nearly sea level.) I have always used 600s on 350ci and up. Im no expert, and you seem to know more than I do, but thats what I have always thought.
I know Im posting this on what is most likely a dead thread, but you got my gears turning.