Sorting Out: Chrysler’s 238, 318, 360 Engines, Doug Anderson, Automotive Rebuilder, April 2000

The Chrysler 90 degree V6s and V8s have been as predictable as death and taxes over the years. Not long ago you could catalog two or three of each and cover everything for more than 15 years, but all of that has changed since the early ’90s. Now it takes four 238s, nine 318s, and seven 360s to cover all the combinations.

Some of the changes are very apparent, but others are pretty subtle. With all that in mind, we went back to the source and asked Bruce Chapman at Ontario Reman, Toronto, Canada, an authorized Chrysler remanufacturer, to find out what has changed over the years. Here’s a year-by-year synopsis of each engine:

The 238 V6 is basically a 318 without two cylinders. The original engine shared most of its internal parts with the 318 except for the split pin crank, the narrowed rods and different rod bearings. The block itself had one distinctive difference; there were three flat, drilled pads on both sides for the motor mounts instead of the traditional "ears" that Chrysler had always used in the past.

This engine has gone through several changes since it was first introduced in 1986. Here’s the chronology on the short blocks:

When the 238 was initially introduced, it used a flat tappet cam in the 4323730 block casting, but the two bolt bosses for the lifter holddowns were cast in the block from day one.

Chrysler continued to use the original 4323730 block casting, but switched to a roller cam, so the two extra bolt holes in the valley were now used for the lifter holddowns. There were two roller cams, one with a long snout (0.960˝) that had room for a fuel pump eccentric and the other with a short snout (0.635˝) and no room for the eccentric. All the 238s had fuel injection and electric fuel pumps after ’88, so there was no need for the eccentric, but Chrysler continued to install it as a spacer because the cam with a short snout wasn’t available until ’89. Now the engine offers a special cup-style washer (p/n 4483054) to hold the gear in place without using the eccentric.

This was the year that Chrysler standardized all of its oil filters, so it made some very subtle changes to the block, along with a few other related parts:

•The threaded boss that the oil filter adapter screws into was shortened by about .250". It was now even with the machined surface on the inside diameter of the filter casting instead of being flush with the cast surface on the block.

•The threaded oil filter adapter was about 0.250" longer. It measured 1.460" in overall length instead of 1.240"

•The arch of the adapter plate was changed to match the shorter length of the boss. The new plate (p/n 53009219) can be easily identified because it has six holes instead of the four that were used on the earlier plate.

The only other notable change was the introduction of a new rod (c/n 53005798). It’s very similar to the old casting except that it is narrower on the small end and it uses an oval pad instead of a round one for balance. There are two versions of this casting, but it’s easy to tell them apart because the V6 rod has a narrow big end (0.862") to accommodate the split-pin crank. The early and late rods are interchangeable, however, the best idea is to keep them in sets.

This is all pretty straightforward except that there were two different block castings used during the year, and both of them were unique to ’91. The first one was a carry-over from ’90 (c/n 4323730), so you have to check the length of the filter boss on it to be sure if the block is the older version or for a ’91. Using the wrong block will cause a serious oil leak, so it’s important to get it right.

The second block used in ’91 was the new casting (c/n 53006711) that was used through 1994. It’s identical to the earlier block except that it has a dowel pin to align the rear cap, and it may or may not have a relief machined in the block under the rear main cap for an o-ring seal.

This block was unique to ’91 because it still had the oil feed holes in both decks to provide oil to the rockers. When this same casting was used in ’92, it didn’t have the oil holes in the decks, so the later blocks can’t be used to build a ’91 engine.

1992- ‘97
Chrysler introduced the Magnum version of the V6 in 1992. The changes to the head and induction system increased the output from 125 hp to 180 hp and made the V6 into a much healthier engine. There were several differences:

•The same 53006711 block casting that showed up in ’91 was used from ’92 through ’97, but now the rear cap was grooved for the pan seal. It may or may not have the relief for the o-ring under the rear main cap. There is also a 4772988 casting that has been used in later years.

•The pistons were the same except for a slight difference in the alloy and a small change in the location of the top ring groove. It was moved up 1.20mm to help reduce crevice volume and hydrocarbon emissions. The earlier pistons and rings can be used.

•The Magnum engines used a roller cam that was very similar to the earlier cams. The ’94 version was slightly different than the original Magnum cam, but it appears that all of them can be used interchangeably. However, none of the Magnum cams can be used in the earlier roller cam engines because they don’t have the oil holes in the two center cam bearings that are needed to meter the oil up through the decks for the rocker shafts.

•All the V6 crankshafts were the same, but the Magnum engines used a sleeve and bearing instead of a sleeve and bushing for the pilot bearing. This sleeve and bearing assembly is p/n 53009180; the bearing itself is p/n 53009181. A new, two-piece fluorocarbon rear main seal was used instead of the old-fashioned rope seal.

•The big difference in the Magnum engine was primarily topside. The Magnum heads replaced the original castings that were used from ’86 through ’91. They were all new with revised chambers, bigger valves and better ports for improved breathing. The intake valves were 1.92" versus 1.77", and the exhaust valves were 1.62" instead of 1.50". Both had 5/16" stems instead of the 3/8" stems that had been used in the past. The stamped steel rockers pivot on individual fulcrums that are bolted to machined pads on the heads and positioned with guide rails. The Magnum head is a 53006680 casting.

•The rockers were oiled through the pushrods, so the lifters were modified to meter the flow of oil topside. The Magnum pushrods are .120" longer than the earlier ones, so they are easy to identify if you hold them side by side.

So, that’s the story on the 238. It has basically evolved from flat tappet to roller tappet to Magnum with some changes to the oil filter boss along the way. This same pattern repeats itself in many ways for the 318.

The original 318 engine was used way back in the early ’60s. It featured "polyspherical" chambers and "sawtooth" rocker covers. This venerable classic was replaced in 1968 by the updated "LA" engine. The latter engine was originally introduced as the 273 in 1964. Here’s how it has evolved:

The original block came with two ears on each side of the block for the motor mounts. Both of the ears were narrow and they each had two bolt holes for a total of four per side. There were also bolt holes on both sides of the block nine inches forward of the bell housing and just above the pan rail; the one on the left was used for a brace that helped reinforce the transmission. The only block was a 2536030 casting.

After 1976, the ear in the front was wider on both sides of the block and there were only three bolt holes instead of four on the right side. The bolt holes on both sides were still nine inches forward of the bell housing. The most common castings were the 4006730 and 4179730.

1981-’84 CAR AND TRUCK
This block was identical to the earlier one except that the hole for the brace on the left side was moved forward one inch (to 10˝) so that it would clear the bigger starter motor. Most of these blocks had a boss with room for both holes, but they were not always drilled. These engines all came with flat tappet cams. Look for casting number 4104230 or 4179730.

1985-’89 CAR AND 1985-’90 TRUCK
Chrysler changed the block in ’85 to accommodate roller lifters by adding three bosses in the lifter valley for the lifter holddowns. Roller lifters were used from 1985-’89 in all domestic cars, except police cars (’89 was the last year for the RWD car) and from ’88 on up in domestic trucks. Canadian cars and trucks both got rollers in’88.

There were two versions of the roller cam, just as there were with the V6. One had the long snout (0.960") with room for the fuel pump eccentric, and the other had the short snout (0.635") and no room for the eccentric. The 1985-’89 cars were all carbureted so they needed the eccentric. In 1988, the trucks all got fuel injection along with the roller cam, so they didn’t need the cam with the long snout, but they continued to use it with the eccentric as a spacer until 1990 when the shorter cam was finally introduced.

Most rebuilders use the long cam with either the eccentric or the cup style washer (p/n 4483054) for these engines because cores are more readily available. Both of the cams had oil holes in the two intermediate cam journals.

In 1990, Chrysler stopped machining the hole for the pilot bearing in the cranks that were to be used with manual transmissions and switched to a sleeve and bushing that fit inside the hole for the convertor hub. The sleeve and bushing assembly number is p/n 4338876; the re-placement bushing is p/n 4338859. The common block castings were 4387530 and 4323330.

There were a couple significant changes in ’91. The 318 used the new corporate oil filter, just like the 238, so the threaded boss on the block was shortened by 0.250˝ and both the plate and adapter were modified accordingly. A new block (c/n 53006657) was introduced. It had the three flat, threaded pads on both sides for the motor mounts, in addition to the conventional ears, so it could be used in the Dakota chassis.

The engine still had rocker shafts, so it had oil holes in both deck surfaces. The rear main cap was still smooth, not grooved, but it did have a dowel pin to help provide better alignment during assembly. There are two catches to all of this: 1) This new block casting may also show up in ’92 without the oil holes and with a grooved cap; and 2) There appear to have been some earlier blocks that were carried over from ’90 that are identical to the earlier versions except for the change to the oil filter boss.

So, the only way to be absolutely sure that you have a ’91 block is to physically check the length of the oil filter boss, look at the rear cap, and double check the deck surfaces to see if the oil holes are drilled.

The roller cam used in ’91 had the oil holes in the intermediate cam journals along with the short snout. The long cam will work for everything but the Dakota; it has to have the short snout to go with the thin front cover needed to get the V8 into the smaller engine compartment.

The Magnum engine was introduced in ’92, so there were several changes: The ’91 block (c/n 53006657) was carried over in ’92 and used along with a new block (c/n 53006714). All of the blocks had a grooved rear cap with the dowel pin and most of them had the recess for the o-ring under the rear main cap. All of them had three pads plus two ears on both sides for the motor mounts. None of them were drilled for oil to the rockers.

The 318 Magnums had to have the shorter cam to clear the narrow front cover that was used with the serpentine belt. There were no oil holes in the intermediate cam journals because the rockers were oiled through the pushrods instead of through the rocker shafts.

Once again, the major difference was topside with the better heads and the individual bolt down rockers. Everything, including the valvetrain, is the same as the 238 Magnum, so the metered lifters must be used in the 318 Magnum, too

That’s the story on the 318 short blocks. Now let’s look at the heads:

The original heads came with 14mm plugs and small, almost square exhaust ports. There was no provision for AIR. The most common castings are 2658920, 2684675 and 2843675.

The original heads were replaced by a casting that had big, elongated pads with room for an AIR (smog pump) hole under each exhaust port. Some were drilled for AIR, others were blank (they can be converted). The common castings are 3769973, 4027163 and 4027593. Just for the record, the 360 heads were used for the 318 police car engines starting in 1980.

Chrysler made two changes in ’85. First, the pushrod holes were enlarged to 0.660" to accommodate the difference in the angle of the pushrods due to the longer roller lifters. Don’t try to use the early heads on an engine with a roller cam; they’ll interfere with the pushrods. Second, the chambers were now heart-shaped to reduce emissions. See photo. All of these heads were drilled for AIR. The common castings are 4343646 and 4323302. The 360 heads were still used on the 318 police car engines through 1989.

The Magnum heads with revised chambers, big valves with 5/16" stems and better ports were introduced in ’92. Stamped steel rockers are individually mounted on machined pads and aligned with guide rails. The original casting was a 53006671 that has been replaced by a 53020466 casting that is identical.

That’s the story for the 318. It has gone through several changes, but there’s a predictable pattern once you begin to look for it. With that in mind, let’s take a look at the 360. There are some familiar patterns that will become very obvious:

The original 360 was just a bored and stroked 318. It had the same ear style motor mounts, the same oiling system and the same valvetrain. The hole for the transmission brace was 9" up from the bell housing. In fact, the only noticeable differences between the 318 and 360 blocks were the bigger mains and the groove in the cap for the rear pan seal. The common castings were 3418496 and 3870230.

Chrysler installed the bigger starter on the 360 in ’76, so the bolt boss for the transmission brace on the left side was moved forward one inch to provide more clearance for the starter. These engines all had flat tappet cams. The castings were 4179930, 4006830 and 4045610.

The 360 got a new block with three cast bosses in the valley for the roller lifter holddowns. Although all of these engines had fuel injection, they continued to use the cam with the long snout along with either the eccentric or the special cup-shaped washer. Both intermediate cam journals had holes to meter oil topside. The 318 and 360 cams are different and shouldn’t be interchanged. The most common block castings are 4315830 and 53006921. The later block (53006921) was used in ’91, too, so check the oil filter boss to see whether it’s a ’89-’90 or ’91 before using it for either application.

This was the year of the corporate oil filter, so the 360 block was changed along with the 238 and the 318. The oil filter boss was 0.250" shorter so both the plate and adapter were modified accordingly. The rear main cap had a dowel pin and may or may not have the recess for the o-ring. The cap was still grooved for the rear pan seal. It had the old style ears for the motor mounts. The block was the 53006921 casting that was carried over from ’90, so once again you have to physically check the length of the filter boss to be sure if it fits a ’90 or ’91.

This is a transition year with a rather unusual 360 block. It looked like a Magnum on the outside with the three flat, drilled pads along with the old style ears, but it was still the early engine on the inside with the oil holes in the cam and block. It’s a 53020006 casting.

The 360 Magnum came out in ’93, one year after both the 238 and 318 Magnum engines were introduced. It used the 53020006 block that came with the three flat, drilled pads and the oil style ears. It still had the oil holes in both deck surfaces, but they were not used because the rockers were oiled through the pushrods.

The best guess is that they were drilled so that the block could be used as a "fits-all" replacement; the cam without the holes blocked the flow of oil topside on the Magnums. This engine had the grooved rear cap with the dowel pin as well as the recess for the o-ring. The Magnum cams all came with the short snout, but without the oil holes in the two intermediate cam journals.

The 360 Magnum pistons have a unique rectangular dish that gives a 9.1:1 compression ratio with the new chambers. The rings are a nominal 1/16", 1/16" and 3/16" wide. The crank itself was carried over from the past, but the amount of external weight used for balance is different, so both the stick flywheel and the torque convertor are different than the earlier versions.

The non-Magnum engines required 19.79 in.oz. and the Magnums need 14.65 in.oz. in order to be properly balanced. The rear seal was the same two-piece fluorocarbon design used in other Magnum engines. The 360 cams have different timing, so it’s best to keep the 318 and 360 Magnum cams separate.

That’s all there is to the 360 short blocks. They follow a pretty predictable pattern except for the oddball block in ’92.

The 360 heads are just as predictable.

The first 360 head was similar to the early 318. It had small, almost square pads around the exhaust ports with no room for AIR. The only common casting was a 3418915.

These heads had the big, elongated pads below the exhaust ports with room for the AIR hole, which may or may not have been drilled. They had the small pushrod hole (0.500") used with the flat tappet cam. Typical castings are 3671587, 3769974, 4027596, 4071051 and 4323345.

When Chrysler switched to roller lifters in the 360 in ’89, the pushrod hole was enlarged to 0.660" to handle the difference in the angle of the pushrod. These heads appear identical to the earlier smog heads, actually sharing one common casting; so it’s easy – and expensive – to mix them up. There are two castings, a 4323345 and a 4448308.

Chrysler put Magnum heads on the 360 in ’93. They are identical to the ones that are used on the 318 Magnum. It’s either a 53006671 or a 53020466 casting.

The 90 degree V6s and V8s have evolved and been upgraded to meet changing performance and emissions goals. Through continuous improvement, Chrysler has taken an engine family now more than 30 years old and kept it current. But, they have created some confusion for the rebuilder who hasn’t taken the time to look for the patterns and see how they apply to each engine.