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Discussion Starter #1
With all this talk about head gaskets lately I decided to write an article describing the various SOHC head gaskets. Below is the article I'm working on but I still have questions. Questions follow after the article.

Head Gasket Guide

There are two basic head gaskets used in the 2.2/2.5L SOHC family of vehicles. One being the non cross drilled style of head gasket, Mopar part number 5281064. This is the same style as the former Mopar Performance P4452005 head gasket.



The other style head gasket is the cross drilled style, Mopar part number 5281065. This is the same style as the former Mopar Performance P4452006 head gasket. The only difference between the standard production part is that the Mopar Performance version is double cross drilled. Notice in the below illustration how there is only one set of cross drilled holes (highlighted green) between the cylinders. The Mopar Performance gasket will have another set of matching holes towards the front of the block. No production vehicles came equipped with double cross drilled blocks.



Below is a list of head gasket part numbers for each year and engine combo. Part numbers highlighted in blue have been superseded to part number 5281064, non cross drilled style. Part numbers highlighted in red have been superseded to part number 5281065, cross drilled style.



Of interesting note is the application of the non cross drilled head gasket throughout the 1990s. Many online sources indicate cross drilled naturally aspirated blocks existed as early as 1990. The factory parts manual indicate non cross drilled head gaskets were still in use as of the 1993 model year. The factory service manual of the same model year contradicts this by omitting the illustration of the non cross drilled gasket.

Additionally, the factory parts manual lists the wrong application of the cross drilled head gasket in 1987. The above chart has been corrected to show that 1987 "EDR" code engines use head gasket part number 4387837.



Questions:

1) According to martymopar in this post, the cross drilled style head gasket 5281065 is NS1. Can someone confirm that and see if any are available.

2) Many have been lead to believe that pretty much all 1990 onward blocks have been cross drilled. This seems to not be the case as indicated from the FSM and parts manual. Any experience? I've been putting cross drilled MP head gaskets in my 1990 Omni and can't seem to ever remember even validating to make sure it has a cross drilled block.

3) Double cross drilled heads seem to be normal in Chinese after market heads, heck I have one myself. Did the factory ever double cross drill a head?

4) Are there any double cross drilled production blocks? I know a few pre-production Shelby cars, limited production performance blocks, and some user created blocks are double cross drilled. Did the factory do this to any production vehicle?

5) What are the benefits/drawbacks of using a cross drilled head gasket in a non cross drilled block/head combo?

6) What are the benefits/drawbacks of mixing a cross drilled block with a non cross drilled head or vice versa?
 

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There is actually a significant difference between the '005' style and the '006' style gasket. I'm using the word style here in the context of the location and presence (or not) of the cross drilling holes. In the early '005' style there are three large steam/water vents located on the distributor/front of the head gasket. These steam vents are NOT present on the '006' style. The reason is that if those steam vents were present, then there would be a reduction of water flow through the smaller cross drilled holes that run down at a 45* angle between the cylinders. By not including the 3 larger forward steam vents on the cross drilled '006' style gasket, there is additional pressure in the water jacket forcing more coolant through the cross drilled holes and further (in theory) reducing the temperature of the block between the cylinders. This is the actual purpose of the cross drilling, to reduce the temperature of the cylinders and the head near the sealing surfaces (the gasket).

What is not pictured here (yet) is the aftermarket one-size-fits-all gasket. I believe the Fel-Pro gasket (not sure which part number) falls into this category in that it has both the cross drilled holes (on both sides like the MP 006) as well as the three forward steam vents. So depending on the combination of early/late block and heads it is very possible to wind up with a cross drilled head, and block with a gasket that flows coolant up through both the available steam vents, those being the cross drilled holes (the small ones) and the larger three forward ones. This might not be a good combination and would result potentially in an engine that would run fine when cold/cool but be more susceptible to detonation once it warmed up.

I think the factory had it right by blocking the three larger forward steam vents on the 006 style head gasket.

From what I've read, the double cross drilled blocks were shipped only on the Shelby prep'd cars but that the practice was discontinued at some point due to the difficulty in getting the holes right on and the breakage of the drill bits used to accomplish the task. Speaking from personal experience, it's very easy to snap off a bit doing the second hole and not so easy to remove the broken piece out of the block when this happens. I documented this adventure a while back in my how to cross drill a block post...complete with pictures.

I have seem several virgin (true) T2 blocks opened that were double cross drilled, and several 90+ turbo I motors that were cross drilled on only one side. All my 86 GLHS cars were not cross drilled, nor were any of my 87 GLHS cars that still had the original engine in them. The cross drilling began in 87 and I'm guessing out loud here, would have first appeared in an 87 CSX T2 car...but that is at this point only theory. My 89 CSX, I just opened had a single cross drilled block, it's the original block/engine.
 

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Discussion Starter #3
Very good info.

I see where the dodge garage has quoted a former Chrysler engineer saying that cross drilling actually promotes head gasket life. It's beneficial effects on detonation may be secondary, although I think using a non cross drilled gasket (or an aftermarket gasket) in a cross drilled application may make the gasket more susceptible to damage under detonation on cylinders two and three. Any thoughts on this statement?

Also it would actually seem that the non cross drilled style head gasket will not impede the cross drill holes on a block or head. It just seems that it has open steam ports so water will not be flowing through the cross drill holes as vigorously as the cross drill style gasket. If this is the case, both gaskets can technically be used in any application right?
 

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"both gaskets can technically be used in any application right?"

No, not at all. The MP '005' gasket doesn't have the cross drilled holes in it. So if used on a cross drilled setup you loose the advantage of the cross drill. If you use an '006' on a non-cross drilled block, since there are none of the three larger steam vents present in the gasket, and the head/block has no cross-drilling, you'll have no, none, NADA cooling at the center of the head and it will get pretty hot, probably have detonation problems when warmed up, and eventually fail the gasket.
 

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Discussion Starter #5
So if we are to agree with the statement from thedodgegarage that states that cross drilling is to lower head gasket temperatures and promote head gasket life, would it be reasonable to assume that having an aftermarket gasket that has open cross drilled ports and open steam ports and non conjoined fire rings, that such a head gasket would be more prone to damage between the cylinders?
 

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I think that would be a reasonable assumption based on my observations if said gasket was installed on a cross drilled block/head combination. Almost all the blown head gaskets I have seen, have blown between cylinders. The conjoining of the metal seal between cylinders is to help prevent this. Having botht the three larger steam vents as well as the cross drill holes open will lower the flow through both, the coolant will simply take both paths and the flow will be reduced through each path. The same quantity of fluid will still move, but now there would be two paths so the speed of the flow through either path will be lower, so the volume of coolant moving through either will be lower. I personally believe the entire reason the factory engineers decided to block the three steam vents on the cross drilled applications was to create more pressure, one single path, and therefore move more coolant through the cross drill holes, between the cylinders.

My $.02, not gospel
 

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Discussion Starter #7
Excellent. I was thinking the same thought.

Any other comments out there about head gasket design or what the factory was thinking when designing these gaskets?
 

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It IS excellent news. I feel like I should run down to the ChryCo dealer and order a stash of them in case they run out again.
 

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Hate to revive an old thread, but received a 05281064AB head gasket today in place of another I had ordered. Sounds like I shouldn't use this on the 1989 TII Shelby Daytona at all. Is that a correct statement? Thanks guys, all feedback based on experience will be welcomed.
 

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Thanks. Looks like that crappy FelPro I've been trying to avoid is going into this car. Dammit I hate finding parts for this Turbo Twinky. Wasting money I could have put into the 07 Daytona and wasting time, and I'm all out of patience.
 

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The newer Felpro gaskets are supposedly a vast improvement over the old style, if that helps any.
 

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Decided not to start a new thread on this. Anybody tried a Magnum head gasket? American made, owned by Dana, looks like a high quality gasket. P/N for our cross drilled heads is HG10023.

It appears the Mopar gasket are unavailable again, not sure if I want to go Felpro, or try one of these???

The reviews I've found online for Magnum have been positive...:shrug:
 

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Never heard of Magnum HG. But I'll be keeping an eye out for feedback on them. Thanks for posting the info.
 

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Discussion Starter #18
Based on the pictures alone and one other forum member's post of the new batch of Mopar head gaskets, it appears that Magnum is the manufacturer of the new Mopar batch of head gaskets.

The only negative review that I have seen of the new Mopar head gaskets (and thus assuming that it is indeed a Magnum brand) is that it isn't as good as they once were. Again, this was based only on one member's experience with the new batch of Mopar gaskets. It is too early to tell really if they are a good brand or not.
 
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