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318 LA overhaul


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33 replies to this topic

#1 JAB19

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Posted March 17, 2011 at 07:19 am

I have a 1990 Dodge D150 truck. It has a 318 LA with TBI and an EGR. i am planning on overhauling it this spring as it is smoking a little and has high mileage. I plan on pulling the motor. I did order the "Rebuilding mopar small blocks" book by HP. I have around a $1500 budget to upgrade any parts. I wont be swapping heads or sending out for any machine work. I'm just gonna pull the motor, clean it up, new gaskets, seals, rings, bearings. I have been researching alot and would like to know if putting in the following upgrades would work: keith black pistons, a cam upgrade in the .440 range, an msd distributor. Is there a manifold upgrade available for this motor? It does have the TBI and EGR and the smog pump. I would also like to install headers with a dual exhaust, but with the smog pump, I'm not sure I would be able to do that.
Thanks for any help and suggestions.

#2 ImperialCrown

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Posted March 17, 2011 at 07:33 am

An upgrade to a used/rebuilt '93 5.2L/5.9L Magnum SFI may be more cost effective per horsepower. You would want the engine compartment harness and PCM from the donor truck as well.
With the old engine you may find that you will need some machining done once you get into it. Reaming valve guides, honing cylinders for fresh rings and fresh cam brngs/center-lining for a new cam come to mind. Perform a compression test /cylinder leakdown test before you pull the old motor.
Keeping the EGR and smog pump would depend on the local emissions laws for your area.

#3 JAB19

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Posted March 17, 2011 at 07:40 am

An upgrade to a used/rebuilt '93 5.2L/5.9L Magnum SFI may be more cost effective per horsepower. You would want the engine compartment harness and PCM from the donor truck as well.
With the old engine you may find that you will need some machining done once you get into it. Reaming valve guides, honing cylinders for fresh rings and fresh cam brngs/center-lining for a new cam come to mind. Perform a compression test /cylinder leakdown test before you pull the old motor.
Keeping the EGR and smog pump would depend on the local emissions laws for your area.



#4 JAB19

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Posted March 17, 2011 at 07:57 am

I dont think I'm gonna go the motor swap route. I'm just gonna work with what I have. I am gonna replace the cam bearings, hone the cylinders for the rings. It seems you cant do much with the motor I have without doing machine work and head swaps etc. I'm not looking for major performance mods, just whatever I can to wake it up a bit. I'm in jersey and they are strict with the emissions testing, So i will probably have to stay with the egr and smog pump.
Thanks for your help.

#5 KOG

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Posted March 17, 2011 at 08:13 am

If you want more power you're far better off with several swap possibilities beginning with a 360LA. If you don't want more power you're probably better off finding another used 318. Rebuilding a 318 is an exercise in wasting money.

#6 JAB19

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Posted March 17, 2011 at 08:18 am

For example, If I install the keith black pistons, will that help with my compression, If I install an msd distributor, will that help with the air/fuel burn, if I install a mild cam how will it effect drivability or would any of these upgrades be a waste of time and wouldn't help much.

#7 dana44

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Posted March 17, 2011 at 10:34 am

Your cam swap is a good one and will increase power over stock. Keith Black pistons is fine, but there are less expensive ones out there, and if there are lots of miles there is a good chance you will have to bore the block, won't know for sure until you pull the heads. At a minimum the heads will need a simple valve grind and new valve stem seals (PC seals I believe) which are in the overhaul gasket set. A timing chain (double roller, there are ones out there under $40 and are just fine), a high volume oil pump (high volume never hurts, high pressure does), new bearings (ensure the crankshaft is checked, a .010 regrind is usually needed no matter what they look like with the naked eye since all the spinning and explosions hitting against them tends to oblong them over time just the tiniest bit), Simple dual exhaust will show an improvement over stock single exhaust, put an H pipe to tie the two pipes together, helps balance everything and run smoother. There should be an intake manifold, by this time the 318 and 360 is the same intake port size wise, and the only problem is the TBI bolting to it, being a 2bbl and computer controlled, smog pump and all that, keep what you have out of safety and smog numbers.

YOu have some unknowns with the engine being wear of the cylinders and heads themselves. Boring the block for new pistons is costly, having to replace valve guides and regrind the valves gets up there too, the rest of the parts are all in a simple kit to save money, and as far as the distributor goes, you can save the most money by keeping what you have, which is fine with a pretty stock engine and computer in the truck (do a good tune-up instead).

#8 ImperialCrown

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Posted March 17, 2011 at 10:46 am

Raising the compression ratio over stock with special pistons may require you to buy more than 87 octane pump gas to avoid detonation.
An old stock 360 Magnum EFI would still burn cheap(?) regular unleaded with a respectable torque output.

Edited by ImperialCrown, March 17, 2011 at 10:47 am.


#9 JAB19

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Posted March 17, 2011 at 10:49 am

Thank you for the suggestions.
The truck has 160,000 miles. Theres a little puff of smoke out the tailpipe after idling a bit, say like stuck in traffic, when I get going again a little smoke comes out. Its not smoking while I'm driving though. It does burn some oil. I like the truck, so I want to hang on to it and just refurb it.

#10 dana44

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Posted March 17, 2011 at 11:37 am

You can do some real easy and simple combustion chamber work to stop the possiblity of pinging with 87 octane, and you can get up to 10:1 by doing this, but you don't need to, a flat topped piston will get it up to 9:1 without difficulty. When you remove the heads you will see a carbon buildup on the head. Since the heads are dirty and will be cleaned before reinstalling, take a round file or sanding rolls and round all the sharp edges where there is a carbon build-up. It will improve the flow, and pinging is a result of these sharp edges remaining hotter than the rest of the surface, just like a burning board, the sharper edges remain the hottest, removing them removes the hot edge syndrome and allows the flame to travel better past them. Sharp edges tend to make a negative pressure spot on the other side of the combustion process, thus the carbon build-up on the opposite sides of them, which will be evident after you remove the heads and look at them. The greater you round them, the better the flame burn, the more power you will gain overall. If the heads are cleaned before you do this, use the head gasket as a guide to make sure you stay inside the head gasket, not past it.

#11 JAB19

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Posted March 17, 2011 at 11:59 am

If the valve seat doesn't appear to be in bad shape, would lapping the valves be an alternative to taking it to a shop for a valve grind?
I cannot find a manifold for this motor / year. I've called summit, jegs and talked to a mopar guy, nothing.

#12 dana44

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Posted March 17, 2011 at 12:31 pm

I don't think you will find a manifold being a TBI 2bbl. The option is to convert it to a 4bbl, but that removes the TBI and computer, which is probably not what you want for smog purposes. The other option for the manfold is to improve its flow by going in with some sanding rolls, the underside of the throttle body probably has plunge cuts straight down and a sharp edge at the bottom, something that does not promote good flow, making dead spots through the rpm range, rounding them a bunch will help. Look into the ports and see what lumps you can smooth out, most bolt bosses are large enough they can be removed without damaging threads. It may also be an aluminum intake, so easier to grind on. Unless you are going to port the heads and gasket match the whole thing, I would not try to open the intake more than removing visual mistakes in flow, like casting seams and the lumps.

Lapping the valves is fine, the puffs of smoke from sitting a bit may be the guides. The new PC seals will help, but a valve bouncing around inside and a seat mismatch can still cause problems, so verify the side play when the valve spring is off, pull the valve out of the head to the point the valve stem tip is even with the valve guide and move the valve side to side. They can move a tiny amount, but if it is excessive, looking at new valve guides to last longer. Look at the side of the valve stem and see if there is actual wear, like the tiniest step from scraping the valve guide so many times going up and down, which will require valve replacement and valve grind. The puff of smoke is from the guides and seals, how much wear there is determines whether rebuilding is needed.

When you have a smog motor, you have to work with what you have, and when you have smog requirements, all you can really do is improve the flow, thus the cleanliness of the burn, which can improve the power and longevity of the engine in question. Even non-aftermarket supported engines can be improved with a little detailing (called blueprinting) of the existing parts. How much time and money and experience you have in doing it are the keys to making it work.

#13 JAB19

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Posted March 17, 2011 at 01:35 pm

Thanks for your help and suggestions.

#14 KOG

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Posted March 17, 2011 at 07:34 pm

If your concern is slight oil smoke, replace the valve stem seals and you may have fixed it entirely.

#15 JAB19

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Posted March 17, 2011 at 07:46 pm

Hey KOG,
Yea, I'm gonna buy a rebuild kit and just overhaul the entire engine. Hopefully it is just the valve seals and not the guides causing the smoke.

#16 ImperialCrown

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Posted March 18, 2011 at 05:16 am

I would suspect valve guide wear (particularly the hot exhaust valve, the intake valve stays relatively cool) more than ring wear causing exhaust smoke. It would be a good idea to do some preliminary diagnosis before rebuilding it.
Marginally worn rings may not look bad on a compression test until you try a 'wet' compression test (squirt a couple of teaspoons of oil into the cylinder and repeat the compression test). If the compression reading goes significantly higher, the rings/cylinders may be worn. Internal engine blow-by from worn guides or rings can overwhelm the PCV and make for oily air cleaners and engine sludge build-up.
Oil smoke from an engine exhaust is much less common than it used to be because the catalytic converter is able to oxidize much of it as it passes through the element and you won't see it at the tailpipe. It is also possible that your cat isn't functioning. In NY state safety/emission inspection on 1984-1995, the cat just has to be there but may not work. On OBD II (1996-up) the cat monitor has to pass.

#17 patricklynch

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Posted March 18, 2011 at 09:34 am

If your concern is slight oil smoke, replace the valve stem seals and you may have fixed it entirely.

I would completely agree with that. Did this to the 318 in my St. Regis a few years ago. No more smoke at start up. My '68 VIP does this sometimes at startup and it has the original valve stem seals which by now have to be very brittle..

#18 JAB19

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Posted March 18, 2011 at 01:12 pm

I'm about to order parts for my overhaul job and just want to run this through some of you more experienced guys. I do want to replace the cam. Right now the truck comes with a hydraulic roller set up. The cam I'm thinking about getting is a mopar purple cam hydraulic flat tappet one. The application chart on the part has my year and style motor listed for it, so it should work correct? Here is the link for the part: http://www.summitrac...ts/DCC-4452782/
As suggested in one of the allpar sections on upgrading the performance on an LA motor, the article suggests staying in the .440 range for a 318 motor. I will get the necessary springs for it also.

#19 JAB19

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Posted March 18, 2011 at 01:34 pm

interesting, I thought this year/motor had the hydraulic roller set up. I called RPM Machine to order my re-ring kit and they told me the LA motors do not have a hydraulic roller set up. My repair manual (haynes) says a hydraulic roller set up also. I guess I won't know for sure until I pull the heads.

#20 JAB19

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Posted March 18, 2011 at 02:38 pm

ok, heres the casting numbers on my block, on the drivers side I have: 4387530-31828, on the pass side of the block I have the date: 7.10.89. Of course I cant find this cast number anywhere on the web, maybe one of you guys can tell me?
Thanks.


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