Would You Use it?

[woodiewagon46]

Russ, it MIGHT be fine, but then again it MIGHT not and it will always be on your mind, especially when you are stuck in traffic and the temperature is climbing. If something does go wrong you will be asking yourself why you didn't do it right in the first place. Do it once right and get the proper gaskets. Think about all the work it will be to replace the wrong gaskets.

 

[flatheadmurre]

Head gaskets kinda evolve during time...manufacturers change the sizes of holes to maintain a better distribution of the coolant in the heads as they learn from issues.
I usually go for the latest version that match the head...and starting to modify the holes with no reason is like saying the gasket manufacturers engineers have no clue
And as long as the fire ring in the combustion chamber match up i don´t worry about the others in the coolant.

 

[JSeery]

Here's something to thinking about with those gaskets with the small round holes. A wise and respected engine builder told me this. Why would you want to restrict the water from leaving the block?

No idea who the builder is, but couldn't disagree more. Why do you think they make the holes the size they do? Read flatheadmurre post, they are designed that way for a reason! If you look at the total area of all the water passages in the head you can see the volume of fluid they can handle. Making larger holes is just like short circuiting wiring. Yes, the original center holes were larger (the large holes are there mainly to help clean out of casting core, not for cooling), but later designs in head gaskets attempted to correct the overheating issues of the rear cylinders. Take a look at the head, what good is a larger gasket to match the block going to do? Also, see the corrosion where the older style gasket was used? By reducing the size of these center holes even further in later models, it is forcing more of the flow to the rear cylinders. You don't want the majority of the flow to go from the pumps straight through the center of the block and back to the radiator.

 

[Tim Ayers]

No idea who the builder is, but couldn't disagree more. Why do you think they make the holes the size they do? Read flatheadmurre post, they are designed that way for a reason! If you look at the total area of all the water passages in the head you can see the volume of fluid they can handle. Making larger holes is just like short circuiting wiring. Yes, the original center holes were larger, but later designs in head gaskets attempted to correct the overheating issues of the rear cylinders. Take a look at the head, what good is a larger gasket to match the block going to do? Also, see the corrosion where the older style gasket was used? But reducing the size of these center holes even further, it is forcing more of the flow to the outside cylinders. You don't want the majority of the flow to go from the pumps straight through the center of the block and back to the radiator.

Yep. I see it, but also look hole small the hole is in the head gasket on the bottom center. Something to think about.

I would also not assume that the gasket companies are looking to constantly improve their stuff. There could be many reasons why they changed it

 

[Ol' Ron]

It's hard to know which is right??

 

[Bored&Stroked]

Wish I had a dyno, all the spare time in the world and a couple "extra" blocks . . . not going to happen! LOL

 

[Brian]

I seem to recall a service bulletin which describes how to enlarge those centre holes in particular heads.I think it pertains to the heads like pictured in post #23.

 

[JSeery]

Interesting, any idea which service bulletin?

 

[Russ/40]

If I recall correctly, it states to enlarge the 5/8" center hole in the head to 3/4".

B&S, that 99A in post 16 is mighty pretty, a true work of art! Those Cometic gaskets are amazing, and expensive, but with a choice of thicknesses could be very handy.

 

[Bored&Stroked]

If I recall correctly, it states to enlarge the 5/8" center hole in the head to 3/4".

B&S, that 99A in post 16 is mighty pretty, a true work of art! Those Cometic gaskets are amazing, and expensive, but with a choice of thicknesses could be very handy.

Thanks Russ - you might say there are "a few hours" of work in that engine block - starting with a NOS engine from WWII.

I decided to use the Cometic gaskets as an expensive test - wanted to see how well they did as they are probably a viable option for a decent amount of boost, such that we don't have to do CNC O-Rings in the block and heads (which really help in high levels of boost, but are not easy to implement).

I built this engine as kind of my 'experimental' platform to try a few things out (like the really long duration roller cam, coatings on pistons, valves, bearings, nitriding a Merc crank, etc).

 

[Tinker]

It's hard to know which is right??

Yep, if it seals run it. Boy we get so worried about details. absolutely restricting water flow with a gasket, forces water to other areas. But is that enough? The flow design always leaves the rear of the block unattended. Run your flatty up to temp or more than run a IR gun over the block. It'll always be hotter at the rear of the block. Just look at how water flows and why the back of the block needs more rodding out of debris. Its a river bank collecting debris.


or not... my opinion.

 

[Tim Ayers]

Yep, if it seals run it. Boy we get so worried about details. absolutely restricting water flow with a gasket, forces water to other areas. But is that enough? The flow design always leaves the rear of the block unattended. Run your flatty up to temp or more than run a IR gun over the block. It'll always be hotter at the rear of the block. Just look at how water flows and why the back of the block needs more rodding out of debris. Its a river bank collecting debris.


or not... my opinion.

Good look at it. I agree about the back of the block collecting a ton of crud. Need to make sure you pay extra attention to that area when cleaning out.

 

[FL&WVMIKE]

Regarding the use of two different gaskets on the same engine... The gasket needs something SOLID on both sides, or it will not seal. Running circles and trapezoids together will NOT seal. Plus, you're killing compression even if it would.

I'm no flathead expert. On OHV engines, the water pump drives the water through the block from front to rear... then there is an opening at the rear of the block for the water to flow up into the cylinder head, where it then flows forward and out the front of the head into the intake. From there it goes out the water neck into the top of the radiator. The only place water travels between the block and head (minus tiny steam holes), is at the rear of the engine.

ALWAYS use the correct gaskets... installed in the correct orientation. Compared to the hassle of something not working right, and all the work to change them... It's a no-brainer.

Good Luck!

 

[Russ/40]

FYI, I have decided to use the proper gaskets on my build, Felpro 7548B. Decided to remove any doubt, and the price was too good to pass up. Mike, don't get your "killing compression" comment? ?

 

[Tim Ayers]

FYI, I have decided to use the proper gaskets on my build, Felpro 7548B. Decided to remove any doubt, and the price was too good to pass up. Mike, don't get your "killing compression" comment? ?

I read it he was thinking if someone used two gaskets stacked on top of one another. I could be mistaken.

 

[FL&WVMIKE]

I read it he was thinking if someone used two gaskets stacked on top of one another. I could be mistaken.

Yes. The reduction in compression ratio would be drastic. Using two gaskets on a OHV sized combustion chamber (simple circle) adds a lot of space. Doing it on a flathead sized combustion chamber adds even more.

Glad you've made the right decision! When it comes to engines, the mantra is generally "Buy once, cry once".

Good Luck!

 

[Tim Ayers]

Yes. The reduction in compression ratio would be drastic. Using two gaskets on a OHV sized combustion chamber (simple circle) adds a lot of space. Doing it on a flathead sized combustion chamber adds even more.

Glad you've made the right decision! When it comes to engines, the mantra is generally "Buy once, cry once".

Good Luck!

Believe me, after going through an engine rebuild with one of the best in the game, I agree.

 

[Ol' Ron]

Most of my engines are bored oversize, so I have to use "Big bore" gaskets. And yes they have water hols designed to help cooling

 

[Bored&Stroked]

FYI, I have decided to use the proper gaskets on my build, Felpro 7548B. Decided to remove any doubt, and the price was too good to pass up. Mike, don't get your "killing compression" comment? ?

It will surely run just fine - and the price was right as well.

 

[rotorwrench]

Barney Navarro mentioned that he set the early (post-pump in head & pre-8BA) blocks up with a catch tray behind the water pump that had a tube attached that would run to the back of the block. The set up wouldn't prevent coolant from flowing at the front of the block but would force some to the back. His idea was to get a cooler supply of coolant to the back. His improvement wasn't striking but was a noticeable improvement in cooling.

In a normal configuration with center exit heads, the coolant that did get to the back of the block had already picked up a lot of heat so even though it was force back there by the head gasket flow, the coolant was still pretty hot back there. He didn't have to do anything with the 8BA since the coolant would flow right back there then flow all the way back forward through the heads. Having the coolant exit at the front on the 8BA made a difference so that's why Ford set it up that way. It worked very well compared to the earlier designs.