Lee the last few paragraphs talk about cooling-
http://reviews.ebay.com/Big-Block-Chevy-quot-Generations-quot-A-primer_W0QQugidZ10000000001563647
http://reviews.ebay.com/Big-Block-Chevy-quot-Generations-quot-A-primer_W0QQugidZ10000000001563647
Mark IV BBC Cooling Passages in Block/Head Question
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I have a Mark IV block from a 79 Chevy Truck. I have Mark IV heads from a 68-69 passenger car. I'm trying determine if my new Felpro 1037 Gasket will work properly for this application.
Please reference the attached photos.
My concern is this gasket does not have the coolant passages at the end. Look at the head and block. You will see (2) large coolant passages at each end. The Felpro 1037 gasket does not have the large passage, only the smaller one. This gasket says it is for Mark IV or Mark V, and says it is for performance/marine applications. Will this gasket work for my application? In the past I've used Felpro 1017-1 and 8180PT2 head gaskets.
Also, can anyone explain the path or water flow (series or parallel) through the block and into the head please. Thanks.
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Please reference the attached photos.
My concern is this gasket does not have the coolant passages at the end. Look at the head and block. You will see (2) large coolant passages at each end. The Felpro 1037 gasket does not have the large passage, only the smaller one. This gasket says it is for Mark IV or Mark V, and says it is for performance/marine applications. Will this gasket work for my application? In the past I've used Felpro 1017-1 and 8180PT2 head gaskets.
Also, can anyone explain the path or water flow (series or parallel) through the block and into the head please. Thanks.
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Tom: I agree with what you are saying. Those 4 extra holes are parallel flow cooling passages, but they are pretty small. If I went with "parallel" flow cooling, I'd probably use that gasket and drill out the larger holes (1/2") in the block that match up with the gasket holes. That being said, I have decided to get a different gasket anyway. The gasket I'm going to get has those same smaller holes you mentioned, "and" the larger cooling passage at the ends also. That way the block/head can flow series/parallel and I'll feel better about it. The head on the other side has it that way also if I recall.What Brett said. read and understand the ebay guide athttp://reviews.ebay.com/Big-Block-Chevy-quot-Generations-quot-A-primer_W0QQugidZ10000000001563647![]()
This was written by a very knowledgeable guy here on this site many years ago. Still holds true today.
FWIW, from the pics it appears to me you can use that gasket, your block looks to have the extra 4 coolant holes along the bottom side of the deck. They're in the gasket and the head too. If your block didn't have those holes (right next to the head bolt at the bottom center of each cylinder) you couldn't run that gasket.
I went through hell with one of these deals back in the early 80's, this alternate coolant routing was not well known then. The block didn't have the extra holes and the car overheated constantly. I pulled it and tore it down 3 times before it was fixed. the only reason it ever got fixed was an engineer from the GM proving grounds was in the shop and pointed it out.
What Brett said. read and understand the ebay guide athttp://reviews.ebay.com/Big-Block-Chevy-quot-Generations-quot-A-primer_W0QQugidZ10000000001563647![]()
This was written by a very knowledgeable guy here on this site many years ago. Still holds true today.
FWIW, from the pics it appears to me you can use that gasket, your block looks to have the extra 4 coolant holes along the bottom side of the deck. They're in the gasket and the head too. If your block didn't have those holes (right next to the head bolt at the bottom center of each cylinder) you couldn't run that gasket.
I went through hell with one of these deals back in the early 80's, this alternate coolant routing was not well known then. The block didn't have the extra holes and the car overheated constantly. I pulled it and tore it down 3 times before it was fixed. the only reason it ever got fixed was an engineer from the GM proving grounds was in the shop and pointed it out.
I think we need to request the guy who is author of that article come on to this post and give us an opinion, or better yet a pictorial primer on Mark IV blocks.
The reason I say that is, I believe that the original poster's block is a true Mk IV factory "series" cooling pattern, similar to my block in my Chevelle. All blocks had the little holes next to the head bolts at the bottom (I think they are more like steam holes than anything else). It is not cooled in parralel completely until ALL three BIG holes between the cylinders on the bottom are drilled out.
I used a 1037 gasket in this very same application and my engine ran hotter than a firecracker----all the time. I have since switched out to 8180 PT2 with no big holes between cylinders but both open holes in back and has since run as it was supposed to back in 1970. I didn't have the heart to modify my original block by drilling it.......thats just me
Again, it would be neat for an old timer to come on here with pictures and school us neophytes
I agree with what you're saying. Those smaller holes next to the bolt holes do not seem to me to be adequate for cooling. Perhaps you are correct as you say they may be for "steam", or other. This is why this whole issue is confusing for me. I don't know what those smaller holes are for, and I don't know what the original design engineering by GM had in mind when they designed the Mark IV block and heads, with regards to series/parallel flow, and matching head gaskets.I think we need to request the guy who is author of that article come on to this post and give us an opinion, or better yet a pictorial primer on Mark IV blocks.
The reason I say that is, I believe that the original poster's block is a true Mk IV factory "series" cooling pattern, similar to my block in my Chevelle. All blocks had the little holes next to the head bolts at the bottom (I think they are more like steam holes than anything else). It is not cooled in parralel completely until ALL three BIG holes between the cylinders on the bottom are drilled out.
I used a 1037 gasket in this very same application and my engine ran hotter than a firecracker----all the time. I have since switched out to 8180 PT2 with no big holes between cylinders but both open holes in back and has since run as it was supposed to back in 1970. I didn't have the heart to modify my original block by drilling it.......thats just me
Again, it would be neat for an old timer to come on here with pictures and school us neophytes
The article referenced to earlier helps a lot, but it does not answer all the questions.
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I dug up some photos that may help. The holes in question are on the LOWER side of the deck surface, BETWEEN cylinders.
First: A Mark IV series-flow deck surface; painted white for visibility. There is only one coolant hole between cylinders; it's between #5 and #7. Note that hole's shape and position--Kinda "D" shaped with the flat side to the bottom; and very low on the deck surface.
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With a series-flow head gasket laid on top of the deck. Two coolant holes at the end of the deck on the right side are open. NO coolant holes between the cylinders are open (not even the existing one between 5 'n' 7); the gasket has no holes there for coolant to pass through.
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Lastly, that same series-flow deck with a parallel-flow gasket on top. Note that the gasket has the three coolant-flow holes between the cylinders; just below the head bolt holes. Two of those holes show a full "circle" of the white-painted deck surface; one of them is partially over the existing hole already in the deck so some white shows but is not a full "circle". You would DRILL the two holes the same size as the holes in the gasket; and OBLONG the existing hole to match the hole in the gasket. Three (not four) holes per deck are either added or modified to match the gasket.
My apologies for the photo being so dark where the rearmost coolant passages are in the deck and gasket; that gasket has ONLY the smaller hole at the rear and would cover (block) the larger opening. This is NOT a problem because you've added the additional area of the drilled/oblonged holes.
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First: A Mark IV series-flow deck surface; painted white for visibility. There is only one coolant hole between cylinders; it's between #5 and #7. Note that hole's shape and position--Kinda "D" shaped with the flat side to the bottom; and very low on the deck surface.
With a series-flow head gasket laid on top of the deck. Two coolant holes at the end of the deck on the right side are open. NO coolant holes between the cylinders are open (not even the existing one between 5 'n' 7); the gasket has no holes there for coolant to pass through.
Lastly, that same series-flow deck with a parallel-flow gasket on top. Note that the gasket has the three coolant-flow holes between the cylinders; just below the head bolt holes. Two of those holes show a full "circle" of the white-painted deck surface; one of them is partially over the existing hole already in the deck so some white shows but is not a full "circle". You would DRILL the two holes the same size as the holes in the gasket; and OBLONG the existing hole to match the hole in the gasket. Three (not four) holes per deck are either added or modified to match the gasket.
My apologies for the photo being so dark where the rearmost coolant passages are in the deck and gasket; that gasket has ONLY the smaller hole at the rear and would cover (block) the larger opening. This is NOT a problem because you've added the additional area of the drilled/oblonged holes.
thanks Schurkey - that helps a lot. I think I'm understanding this stuff pretty good now. I've got a Mark IV "block" for sure. The parallel cooling holes by the cylinders are NOT drilled out. I can modify the block by drilling the parallel cooling passages to make it a "parallel" flow setup. Instead, I will change my gasket and get a "series" flow gasket like the Felpro 8180PT2 or 1017-1. Someday if I have to rebuild the entire motor, I may drill out both sides of the block and get parallel flow gaskets instead of series. Seems like it would be better cooling and more consistent temperatures through the cylinder head if parallel.I dug up some photos that may help. The holes in question are on the LOWER side of the deck surface, BETWEEN cylinders.
First: A Mark IV series-flow deck surface; painted white for visibility. There is only one coolant hole between cylinders; it's between #5 and #7. Note that hole's shape and position--Kinda "D" shaped with the flat side to the bottom; and very low on the deck surface.
![]()
With a series-flow head gasket laid on top of the deck. Two coolant holes at the end of the deck on the right side are open. NO coolant holes between the cylinders are open (not even the existing one between 5 'n' 7); the gasket has no holes there for coolant to pass through.
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Lastly, that same series-flow deck with a parallel-flow gasket on top. Note that the gasket has the three coolant-flow holes between the cylinders; just below the head bolt holes. Two of those holes show a full "circle" of the white-painted deck surface; one of them is partially over the existing hole already in the deck so some white shows but is not a full "circle". You would DRILL the two holes the same size as the holes in the gasket; and OBLONG the existing hole to match the hole in the gasket. Three (not four) holes per deck are either added or modified to match the gasket.
My apologies for the photo being so dark where the rearmost coolant passages are in the deck and gasket; that gasket has ONLY the smaller hole at the rear and would cover (block) the larger opening. This is NOT a problem because you've added the additional area of the drilled/oblonged holes.
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thanks alot to all you other guys that contributed as well.
Lee
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