the pic of the new mopar gasket NAJ posted last week or the week before seemed to have only the cross drilled holes in it
the 6 or so triangluar holes that usually are between the cylinders seem to be missing
I thought I'd saved it - I would have reposted it if I had
Is it worth it to add the cross drilling to an early block in a high end built street motor? I'm going to be running a stage 5 cal w/15-20lbs of boost and its fully ported head and manifolds, beehive springs, forged venolias, yada yada yada....
I'm looking for actual information on the angle of the hole required, their depth, where they lead/go and how long and big a hole we are talking about.
Thanks Donnie...I've got a lot invested in this block already. I'm just curious to know what it would take. If it's not a huge hassle, I'd like to see if it can be done and of course document the process for the benefit of others here as well.
I have been reading that the 87-88 Turbo II blocks may be the only ones that were cross drilled from both sides (crisscross), so for those there are 6 holes. Later blocks and heads were drilled only on one side, so for those there are only 3 holes.
See the Mopar Performance 'P4452006' head gasket pictured below on the far left, it has the 6 cross-drill holes necessary to make it compatible with either the 3 or 6 hole setups. It does have the steam vent holes.
The 'P4452005' is pictured in the middle, it does NOT have the holes for the cross drilled block/head. It does have the steam vent holes.
The Fel-Pro 9296PT Gasket is pictured on the far right. I'm not advocating the use of this gasket, but it is an illustration of a gasket that could be used with either the non-cross drilled or cross drilled head/blocks.
To use the '006' gasket on a non cross drilled block/head combo, you would need to add the holes that are missing from the '005' gasket. The same would be true for using the '005' gasket on the cross drilled block/head, you would need to add the holes for the cross drilled holes in the head and block.
I was under the impression that the MP '006' could be used on either block (cross drilled or not) and w/either head (cross drilled or not) but after reading this and comparing pictures....I'm not sure that statement is at all true! In fact, it looks like its totally bogus!
I'm totally going to have to pull the actual head and check the block. I know the block is not cross drilled....the head Im not so sure right now...and I know I have a MP 006 head gasket that I had PLANNED to use.
9/64 seems to be the size of the hole - at least the size of the bit that fits best
it might be the metric size most equal to that but I don't have any metric bits
I keep refering to "triangular" holes in the gasket - I should be saying round holes in the gasket where the triangular ones in the bolck & head are - positioned between the cylinders
take a look at the head gasket pic and compare it to your motor's block & head - you'll see what I mean instantly - it only has the cross drill locations punched out
and , the holes are angled from the block deck surface , towards the point between the cylinders
if standing in front of the block looking at the deck the holes go down and forwards - at something that looks like a 45* angle - but I have no way to measure the angle so don't quote that as fact
Yes, I understand about the triangles and holes in the gaskets.
As far as the cross drilling goes, I understand also the description of the holes going down and forward at approximately a 45* angle. Thanks! I wish I had a cross drilled block to just measure the angle both off center (forward)as well as the inclination (down)of the hole.
As far as the actual drilling, you need to drill straight down to start the hole for the bit to bite into the block without moving. Drill SLOW speed. Once the hole is started slowly assume the 45 degree angle. As you do so, the bit will cut the shallowest part of the hole on the opposite direction the bit is going? IE the SIDE of the bit will cut the shallowest part.
Another way to explain, is don't start the hole at the shallowest point of the hole. Start it a little toward what will be the deepest part of the hole.
To be extra safe use a center punch to mark the starting point to prevent the drill from drifting on the gasket surface. I have done this with no problems but I am 70 years old and have had practice.
Here's what I found at Allpar:
"Starting in 1989, all 2.2 and 2.5 liter engines, including the Maserati-built 2.2 used in the Chrysler TC by Maserati and the longitudinal engine in the Dakota, used the same engine block. This saved money and gave base engines a stronger block; so starting in 1989 the engines had stronger main bearing supports and caps, thick cylinder walls, balance shafts (on the 2.5 and late turbo 2.2), and cross drilling between the cylinders."
As for doing this yourself or, having a machine shop do it,
I don't have ANY idea.
Personally, I would only accept advise from someone in that very field,
who has the experience to offer an educated opinion.
Once you find out(And I KNOW you will Steve),
let me know, because I've got a NON-Common block here now.
I cross drilled the common block in my current car. It was very easy, just take your time. 45 degree angle is right. I only cut 3 holes and compared them to the holes in an 89 common block for reference. I started with an old headgasket to get the alignment right and the bits worked just fine, again it takes a little bit of time to make sure they go evenly between the bores. I would have to pull out my old 89 t2 block to see exactly the size of the holes.
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