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Compression test results


tundrajax

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Back engine 

6 30psi

5 30 psi

4 120 psi

3 120 psi

2 120 psi 

1 120 psi

Front of engine

 

I'm guessing I need a head gasket?? Unless there is something else I'm missing. I saw no smoke, no antifreeze in oil or vis versus pr antifreeze lose. 

 

Best place to get a headgasket is there anything else I need for the job?

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When was the last time the valves seats were checked? Did you try a wet compression test to confirm? Rear generally runs the hottest. Furthest away from the water pump. Least cooling available. Last time valves were properly set?

 

Oldmopar.com has NOS head gaskets.

Edited by keithb7
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2 minutes ago, keithb7 said:

When was the last time the valves seats were checked? Did you try a wet compression test to confirm? Rear generally runs the hottest. Furthest away from the water pump. Least cooling available. Last time valves were properly set?

 

Oldmopar.com has NOS head gaskets.

To be honest I'm not sure when the valve where last checked. I will check the valves and seats as well. I did not do a wet test just a dry test. When I do a wet test and the number jumps means?

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If the numbers go up it may be the rings. Last time I did a wet test I got one of those baby medicine syringes to put the oil in with since the valve train is over the plug holes. Shove a piece of plastic tubing onto the end of it and feed it in  so that all the oil makes it into the bore where you want it.

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Valvetrain is very intersting to me. Clearances can and do effect so much. Those teeny clearances will set the ampunt of time that the valves stay closed, in their seats. When valves are in their seats they transfer heat to the block into the coolant. Those exhaust valves get very hot and need to to be cooled.  Yes that micro-second that they are closed allows them to cool. 

 

As a valve wears, it pounds into the seat. It digs in and settles deeper into the seat in the head (or block in this case). As it sinks deeper over time, valve clearances at the tappets get tighter and tighter. As clearances get tighter, the valve is forced off its cooling seat sooner, and settles back down into the seat later. Due to riding the cam lobe ramps. Now the total time that it can cool becomes shorter and shorter. The valves can’t cool enough and eventually you get... A cooked valve. Baked red hot so the metal can start to break down. Then you have pieces of valve missing. So no seal. Which equals no compression. 

 

In additon to this wonderful phenomen, as the valves wear deeper into their seats, the contact surface becomes thinner and thinner. The cut angle of the valve, in relation to the seat gets out of whack. The valve sealing properties become compromised. No seal = low compression. 

 

The conditions that the valves must work in are intense. Hi temps. Combustion pressure. Aweful toxic gasses that leave residue and corrosion. Best practice is to stay on top of your valve maintenance. Proper clearance is important. 

 

Its no small feat that man was able to engineer and design this basic valvetrain system that we still use today. Well,  well over 100 years old. Best of luck with whatever you find. Let us know!

Edited by keithb7
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This is the engine that suddenly lost power and started running rough on your way to a show? A blown head gasket makes sense based on your previously reported symptoms and the compression test results. Head gaskets should be available almost anywhere. You just need to verify if you need one for internal or external coolant bypass. Or just get the newer one with internal bypass and it should work for either application. Also, when you get the head removed inspect it carefully for flatness. It may need to be milled to make it flat again. Wouldn’t hurt to check the block too. 

When reinstaling, be sure to use thread sealant on your head bolts to eliminate coolant leaks. Then retorque the head after the first few heat cycles. 

 

Merle

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5 hours ago, Merle Coggins said:

This is the engine that suddenly lost power and started running rough on your way to a show? A blown head gasket makes sense based on your previously reported symptoms and the compression test results. Head gaskets should be available almost anywhere. You just need to verify if you need one for internal or external coolant bypass. Or just get the newer one with internal bypass and it should work for either application. Also, when you get the head removed inspect it carefully for flatness. It may need to be milled to make it flat again. Wouldn’t hurt to check the block too. 

When reinstaling, be sure to use thread sealant on your head bolts to eliminate coolant leaks. Then retorque the head after the first few heat cycles. 

 

Merle

Would this one work?

Screenshot_20180918-025007_Samsung Internet.jpg

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3 hours ago, Merle Coggins said:

Interesting that they included valve cover gaskets and manifold gaskets in a “Head Gasket Set” for a flat head engine, but it probably doesn’t hurt to have them. 

They probably assume that a head removal would also entail valve work.  Not a bad assumption, in most cases.  Probably should be called a valve grind set though.

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