318 Rebuild suggestions?

-

knote72

Stupidity is not unilateral, we all pay the price
Joined
Aug 23, 2016
Messages
200
Reaction score
24
Location
Marcola, Oregon
As the title says, I'm planning to rebuild a LA 318 in the near future (from my 91 Dakota). I got it from a relative over 8 years ago but so far as I know from her it's all stock, hasn't been rebuilt ever. I know that it burns oil and has low compression (60psi) on cylinder 8, a couple years ago we popped off the head and saw that a)the ring was cracked and b)there was scoring on the cylinder wall (may have to see how it is now but at the time it was minor enough that we agreed a 0.030" bore would fix it). We didn't have the means to work on it then and it still ran ok so we just put it back together. Soon I may have the funds and time to have it worked on and I also got me a book https://www.amazon.com/dp/1613250584/?tag=joeychgo-20

I talked to a friend of mine's dad about it, he doesn't have experience with mopars and he hasn't done a rebuild in a while but he does have some experience (helps since I still don't have the best of experience). He recommended a machine shop to me and that I get from them a quote for:
  • Short block vs long block rebuild costs
  • In house oem parts cost (vs cost of finding the parts myself)
  • Getting new pistons/rods and having them fitted
  • Having heads, machined and magnafluxed for cracks
  • Having valves and seals machined and fitted
  • Price for full gasket set (suggested felpro permatorque)
  • New cam and lifters
  • See if crank needs turned and polished
  • Opt for high volume oil pump
I want to double check with some of you guys to see if I'm missing anything, or if there's anything I should know before I go forward with this
 
I am curious, why rebuild a 318 when you can get a 360 dirt cheap? Or better yet a 360 magnum?
 
The high volume pump isn't necessary and most shops will run you off if you try to buy your own parts since they can make a good amount of markup on them.
If anything have the shop do the machine work and do the rest yourself.
If you can't do that look for a crate motor long block as a direct swap.

Just recently did a long block in a friends truck with a performance (315hp) for under 2,500 so all the time having yours down and the cost of machining and parts along with your own abilities needs to be weighed there.
Long blocks have a warrantee also.
 
I am curious, why rebuild a 318 when you can get a 360 dirt cheap? Or better yet a 360 magnum?
I don't need a 360, 318 is already overkill for a Dakota and would just be even less gas mileage. "Go all out" mentality need not apply here. Also, odds are any engine I'll find "dirt cheap" will probably also be in line for a rebuild down the road

The high volume pump isn't necessary and most shops will run you off if you try to buy your own parts since they can make a good amount of markup on them.
If anything have the shop do the machine work and do the rest yourself.
If you can't do that look for a crate motor long block as a direct swap.

Just recently did a long block in a friends truck with a performance (315hp) for under 2,500 so all the time having yours down and the cost of machining and parts along with your own abilities needs to be weighed there.
Long blocks have a warrantee also.
He seems to know this shop pretty well, vouching for them with some work he had done there plus this shop has almost perfect 5 star rating so I guess I can take his word for it. Time down for maintenance isn't a huge factor, I have a Ranger to drive in the meantime. At best I'd prefer to have it ready for January, since the Dakota can hold its own on ice.

The important thing here, I probably should have detailed, is that I'm not going for some all-out project. I just want to get the engine in my pickup rebuilt and running PROPERLY for the best price I can (money is a factor here). I can do some of the assembly work myself where needed, and of course the machining I'll leave up to the shop
 
Looks like you've got a pretty good handle on what you want/think needs to be done.

I agree with Trailbeast about the need for/use of a high volume oil pump, I don't think it's needed........however as an out to your preference/peace of mind, wait till the lower end is assembled and you know your clearances, then buy your pump. Two thousands and tighter (just to pick a number) does not need an HV pump........if, IF, you go with an HV pump buy a heavy duty pump drive shaft.

Good luck with your build.
 
Yeah he is a trusted source on my auto work but I did question his suggestion for a HV pump. Every now & then when I stop at a light the oil pressure gauage dips, a quick rev brings it back up, I know it's good on oil so I figured that can be addressed during the rebuild. I figured this timeframe during December, right before the icy weather sets in (when I'd like to have the Dakota ready for) but it'll be a whole month I have free until winter term in January
 
Option #3 - Get a rebuilt long block from your local Autozone. Part #DD67 - $1652.99 + core charge. Change out the crappy timing chain and you're good...Maybe add a little hotter cam.

But...if you have never rebuilt an engine before, it's a good experience.
 
The only way I'm gonna consider a brand new engine is if it was somehow cheaper than basic machine work and I had that kind of money
 
Add up all your parts and machining costs then add another 25-50% and compare it. Unless you only get the most basic of overhauls (reusing pistons) a warranted long block will be a better deal in most cases. If we're wrong, I'll be pleasantly surprised and overjoyed for you and wholeheartedly recommend you rebuild it for the experience.

But by saying the only way you'd consider a new engine is if you had the money and if its cheaper tells me you've pretty much already made up your mind and until you see the costs for yourself, anything you read on this forum is non-value added.

Either way, have fun
 
MABBCO® MOTORS Online Catalog - <a href="/catalog/Auto">Auto</a> - <a href="/catalog/Auto/National_Long_Block_Program_-_NO_CORE_REQUIRED_">National Long Block Program - NO CORE REQUIRED </a> - <a href="/catalog/Auto/National_Long_Block_Program_-_NO_CORE_REQUIRED_/Chrysler">Chrysler</a> - Dodge Chrysler 360 5.9 Premium Long Block 1989-1992 Roller - NO CORE REQUIRED - 1 Year Limited Warranty

No Core, Roller 360, 1 year warranty - $1500... upgrades available.

Non-roller La360 - 1450
Magnum 360 - 1650

upload_2016-10-20_21-13-55.png
 
I tell you what; if you are forfeiting a 360 for fuel mileage, that would be a false economy.
The long stroker can make more torque,more horsepower a AND better fuel mileage. Unfortunately, if you drive it to take advantage of the power, well, there goes the economy.
I have a 360 that at one time was tuned to get over 32mpgUS with a 223*cam, so I know it's possible. IMO, I wouldn't waste my time with a teener;it's just too small for a Dakota.
The Dak does OK in first gear with 3.91s. But it's really fooling you.The MPI injected engines like in my 92,were a little better, but it worked awful hard to keep up. It was a 4x4 tho.....I think it scaled at 7 million pounds,lol. Awful heavy for such a little truck.
 
I'll double check with my friend about what really needs to be changed out, see what's really necessary to swap out and what can stay. His only mention of getting a new block was worst case scenario like if the machine shop screwed it up. I just find the idea of scrapping a good engine for a brand new one being cheaper a little hard to follow. Especially since this one is only down a little on power and mpg (yet still hauls better than our perfectly good Ranger lol). It averages 16 right now, at peak I've had it up to 21mpg (which is why I find AJ/FormS's claim of 32mpg with a 360 a little hard to believe since I've never heard of that out of anything stock over 4 cylinders other than a Feather Duster). So far from what I've seen, a 318 makes light work of a Dakota, if it was a full size Ram then sure the 360 might have a mileage advantage but for a Dakota the 360 only comes close (12-14 reportedly vs the 16-21 I've noted with mine). It might match that with expert tuning but that sounds like a bit of effort and $$$.
 
Last edited:
AJ has done a lot of tuning and has the engine set up a certain way that can optimize mileage.

But, you will be fine IMO with the 318 and with economy. Smaller engines mean lower pumping losses. You can improve mileage with cam and carb selection; for example, the old Holley 6619 was an emissions and mileage 4 BBL carb from the 70's and can be found, or the new equivalent. Any headers will help mileage too; stick with smaller tube ones.

Mileage/hi-torque cam are out there to be bought readily. Keep the lift under about .450" to keep from having to modify the retainers and guides for higher lift. If this is just for driving around, I would refresh the valve springs with new ones; what will be adequate depends on if you are just low RPM cruising all the time, or will rev it from time to time; please let us know.

A modest compression ratio increase will help mileage too; moving up to around 9:1 true SCR will do the trick for a mild application like this. (Real 318 LA SCR's were low 8s to mid 7's). The hard part is finding cheap pistons for the 318 in that SCR range. The Speed Pro H814CP would get there with some head surfacing, but they are lighter than stock and so would require a rebalance of the crank. (You could probably not worry about the rods for stock, low RPM use.) Sealed Power 526AP's are cast and should be stock weight. They will give you right at 9:1 SCR with .028" thick head gaskets (Mr Gasket 1121G), AND shaving the heads .025-.030" to get the cumbustion chamber volumes down around 63 or 64 cc. (This assumes typical 318 LA heads, like the 675 casting ones.) Note that the the standard Felpro Permatorque head gaskets as thicker and will cost you almost 0.5 point of SCR.

BTW, add valve guides to be checked and replaced if worn. You don't want to do a quality rebuild without getting the valve-to-guide fit back to new spec.

And agreed on the oil pump; a new standard pump and good internal bearing clearances will get you all the pressure you need for this application. A SBM HV pump actually only shows any advantage at low RPM flow and pressures anyway.

Of course new timing chains, cam bearings, and so forth. There is NO need for new rods.

I personally like doing my own work for quality control versus a bought assembly. And you can control the parts selection too.
 
I said 32 was possible.
Built right, for torque, which is what a Dak needs, the long-stroke 360 can build more torque at lower rpms. That means you don't have to open the butterflies as far to achieve the same acceleration as with the teener.Less butterfly opening can mean less fuel being burned, and that leads to less money spent on gas.
A hi-compression crate 360(5.9) will likely cost a few bucks more than a custom built 5.2, but the fuel savings over the life of the engine can more than make up for the initial outlay; if you drive it conservatively.And the extra power comes in real handy from time to time.
But to each, his own. Do the math,satisfy your needs .

Having worked with 3.58stroke 360s for so many years, I just know a bit about their potential,and have no interest in the smaller Mopar offerings, in a 3650 pound (like mine) chassis.If I had a lightweight chassis, I might consider a smaller engine.
If I still had a Dak, Ima thinking a 3.58stroke 318. A guy could put a longer period cam in that sucker and still have some good Dcr left over. That would make about 349 cubes. Yeah, a stroker-teener! Torque and mpgs;Best of both worlds?
 
Last edited:
I'm not saying AJ's case is entirely impossible, it just sounds to me at best a rare exception. I like to stick with the general concensus for these engines, which is blocks around 318 size can get mileage in the upper teens and 360 gets in the lower teens. These are real world numbers I believe because I've seen (my friend has the old 70s Chevy Cheyenne with a 350, that thing gets consistently 11mpg). My 21mpg figure was at a time before the power loss issue when I was running a K&N filter (got me an extra couple mpgs) and I had just scrapped my cat converter for issues it caused. That's also given my commute, level all the way to/from town, and I'm always soft with the pedal. As for my friend's suggestions, I'll see if I can challenge him on what really needs to be replaced and what all should be left up to the machine shop, but for the most part he's helped with all sorts of auto work so I trust his judgement. While he trusts this shop, he has had another shop screw up a 350 he was gonna put in his camaro. Something wasn't done right, crank seized and snapped in half first turnover

Remember this is a stock 318 from a 91 Dakota. All stock, simple TBI EFI so no carb
 
the 318 can be an efficient engine with good power.
Search the web for Hot Rod Daves Super Duper Mileage Master 273 / 318.It's a well documented 318
build step by step ending at i believe 28 mpg and excellent performance.Dave tried numerous
pieces and selected those that suited the project best.Been awhile but i think the cam was very critical and was an early 273 piece.
 
Yes on the cam... my 351C would get 18.5-19 mpg all day long at 65-70 mph (3.08 rear axle and stock non-locking TC) and yet make 350-375 ftlbs torque and 325-ish HP. It used a 70's Crane HE series cam.... 'hydraulic efficiency'.... generated when the Arab oil embargo hit. It had narrow .050" durations, but pretty wide .005" numbers to be able to use in a higher SCR engine to keep DCR from getting too high, and wide LSA (114*), and high lift. So slow ramps at first and then steep ramps around the peak of the lobe.
 
Some of the reasons factory LA360s in factory applications,don't usually make the numbers are;
very low compression, chamber shape,lack of timing cuz of the former two, bigger cam and bigger carb than a 318,usually stuck in a heavier chassis often with lower number gears,and, since they make more torque, we tend to drive them harder. And finally, if they come with a 4bbl they make this wonderful moaning wail when the secondaries open, which is terribly addictive!
So the first step,IMO, is bringing the chambers into the 21st century.And the second would be gearing and overdrive.
Reducing the cruise rpm, and increasing the take-off torque through gear multiplication should not be underestimated. I found my Hi-Comp.LA360 would easily cruise my 3650 pound chassis down to 1450 rpm,and less.Of course, the 292/508cam won't make fuel mileage down there.So, if you are gonna use the A500, with its 2.74 1st gear and .69o/d, just gear it for your tires to hit sub-2000rpm,cam it to run down there, and; voila. My '92 teener4x4 had 3.91s and 235/75-15s(29s). With these; 65 = 2035rpm.I believe it had the A518 with a 2.45 low. But with an A500 the starter gear would be 3.91x2.74=10.71. Ima thinking a well-thought out 360 could pull 3.55s, even with the 29s. That would pull the hiway rpm down to 3.55/3.91 x2035=1848;about a 10% reduction. Between the increase in engine efficiency through a modern tight-squish design, optimized timing, a triple-booster carb, and the 10% rpm reduction,hmmmmm;IMO, it should be possible to at least match what the teener made when new.But Ima thinking an improvement of perhaps20% over the teener,should be possible.This is about 3mpgs.All the while, you have the extra 360 torque.And when you need it, an extra 500 to 1000 or more pulling rpm at the top;depending on chosen cam.
Then again, if you don't need the rpm,or the torque, or if you applied the same principles to the teener...............well,you can see where this is going. Boost the Dcr,increase the breathing, reduce the gearing, and you are back in the game; leave the 5th wheel to the other guy.lol
In any case, it's fun to explore the what-ifs.
 
Yes on the cam... my 351C would get 18.5-19 mpg all day long at 65-70 mph (3.08 rear axle and stock non-locking TC) and yet make 350-375 ftlbs torque and 325-ish HP. It used a 70's Crane HE series cam.... 'hydraulic efficiency'.... generated when the Arab oil embargo hit. It had narrow .050" durations, but pretty wide .005" numbers to be able to use in a higher SCR engine to keep DCR from getting too high, and wide LSA (114*), and high lift. So slow ramps at first and then steep ramps around the peak of the lobe.
Kindof like a thumper cam.............lol
 
I assume the 'LOL' means you're joking....! Not at all... the LSA was muuuch wider and durations much shorter. Idled very smooth with high vacuum, and met the Federal emissions for the mid 70's for HC and CO. So no relation to the Thumpr's at all, really.
 
Just getting back to this thread now, been busy all weekend dealing with a midterm quiz

So I talked with my friend and, well, he helped me get a better idea of what price I'm looking at for my rebuild (as opposed to what numbers my research turned up). Given this development, and the info I shared with him, he said the best course of action is to either have them machine the block/heads and fit valves and we can do the rest of the assembly, or "$1650 & 3 year no-mileage-cap warranty ain't bad for a new crate motor". In the meantime, he said to try and research a good small duration cam to use with a 318 block. Any ideas?
 
Last edited:
It ain't a bad price but it is a good engine? The low price should be a BIG clue. Sorry, I would not ever consider a rebuilt engine from Autozone. If it goes, then the warranty won't look so good when you have to do the labor of R&R. I would not expect any particular quality from them at that price; IMHO it will b quite a crapshoot. Seriously, I would go to the boneyard and pull a running engine for a lot less $$ before going that route.

I also know how it is to be in school and poor. I only skimped on one engine rebuild and the results were as expected for what I started with. It ran.....
 
-
Back
Top