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High Engine Compression


Galvagni
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I ran a compression check on a newly acquired 63 R1 and got consistent readings in the 215 to 225 psi, manual indicates that normal is 185. Can you have to much of a good thing? The woman I purchased it from owned it since 1985 and says that the engine has not been apart. Before her is anyone guess. Possibly at some point the heads and block were shaved? The only negative I can come up with is a high buildup of carbon. Any thoughts? The car has about 65,000 miles and ran well for the short test drive.

Second question: Since I'm pulling the engine but not tearing it down (hopefully), what items should I address/replace. I do plan to remove the oil pan and valve covers to take a look around. The frost plugs are bad so they will be replaced. Any other "must does" that are wise investments with this engine? Timing gear, oil pump? I appreciate your input.

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Yes, way too much; with compression that high, it will ping like a poltergeist on a hot day. About 195 PSI cranking is all today's pump gas will tolerate.

The probabilities are:

1. As you discussed, someone may have milled the heads and or the block and used the thin steel shim head gasket.

2. They may have substituted a stock Studebaker cam for the R1 cam. The shorter duration closes the intake earlier and raises dynamic compression.

So yes, make sure you have the R1 cam or even go to the longer duration R1+/ST5 regrind. Use the thicker composition head gaskets. If it's just a warm weather driver, use the intake gaskets which block the heat riser. Fabricate a cold air intake air filter. I used one from a '70s-80s Cad.

jack vines

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Also, if the car was not driven very much before it was parked and maybe only started and run for short times, there could be too much carbon built up in the combustion chambers, which could increase the compression. If everything else checks out, just put it together and run it on the highway and run it hard to burn out the excess carbon... or if you pull the heads, you could confirm everything and clean out the carbon deposits manually.

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If you have access to a boroscope, it might be of help examining inside the combustion chambers to see if there's carbon buildup. You could also get a can of Seafoam and slowly pour it into the large vacuum hose that connects to the brake booster. While the engine is running let the Seafoam get sucked into that hose...it will clean out the intake passages and combustion chambers as well as smoke up the neighborhood. After doing that try checking compression and see if that made a difference. You'll probably need a new set of spark plugs after the Seafoam treatment as well.

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I ran a compression check on a newly acquired 63 R1 and got consistent readings in the 215 to 225 psi, manual indicates that normal is 185. Can you have to much of a good thing? The woman I purchased it from owned it since 1985 and says that the engine has not been apart. Before her is anyone guess. Possibly at some point the heads and block were shaved? The only negative I can come up with is a high buildup of carbon. Any thoughts? The car has about 65,000 miles and ran well for the short test drive.

Second question: Since I'm pulling the engine but not tearing it down (hopefully), what items should I address/replace. I do plan to remove the oil pan and valve covers to take a look around. The frost plugs are bad so they will be replaced. Any other "must does" that are wise investments with this engine? Timing gear, oil pump? I appreciate your input.

Cleaning the water passages in the block can not be over emphasized. Dirty job with a big reward if done correctly. Replace the freeze plugs with brass plugs.While the engine is out of the car, pull the timing gear cover and replace the felt seal with a lipped seal. A search on this forum will more than likely get you to the correct information on which seal, and the installation of the seal.Once the oil pan is off, I'd consider replacing the rear main seal. Search the fourm for the correct information on how to do it and properly install the oil pan. Pull the water pump and confirm that the water pump impeller has the correct clearance to the water pump manifold. Again search this forum for the specs. Although I have not done this modification ( it's on my To Do List ), according to Jon Myer, drilling the thermostat by-pass hole to 3/4" is very beneficial.

Hope this helps

John

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Some great ideas and suggestions. Thanks. I do agree that cleaning the water jacket is a must-do. What a mess in there. Since I'll be pulling the frost plugs anyway, now is the time. I was thinking of rodding out the passages and flushing as best I can. Would a product like CLR be helpful?

It sounds like I might be wise to pull the heads and see if carbon is a issue as well as check the thickness of the head gasket and replace the valve seals. Also it would give me the opportunity to see if hardened valve seats were ever installed,

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Some great ideas and suggestions. Thanks. I do agree that cleaning the water jacket is a must-do. What a mess in there. Since I'll be pulling the frost plugs anyway, now is the time. I was thinking of rodding out the passages and flushing as best I can. Would a product like CLR be helpful?

It sounds like I might be wise to pull the heads and see if carbon is a issue as well as check the thickness of the head gasket and replace the valve seals. Also it would give me the opportunity to see if hardened valve seats were ever installed,

I don't think CLR is going to make a big difference. Home made tools to get in the passages and scrape the crud out will get you the best results. When I did mine I bent up a lot of cheap screw drivers, plus I bent up some metal rods to reach in the passages. If you have access to a pressure washer.........I'd use it. Don't ignor the cooling passages in the heads. They get gunked up as well. I found casting wires in my heads

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  • 5 years later...

Old post, I know. Here is my opinion: I hope folks are not following the advice to utilize thick i.e. ~.038"-.042"  multi-layer head gaskets here- a common mistake.  These heads provide significant quench which quickly becomes ineffective as piston to head clearance increases, and is likely mostly gone if the multi-layer gasket is used in a stock-decked 289 block at performance-oriented compression ratios. Thus detonation is much more likely to occur. The way to eliminate detonation (besides cool air, proper AFR, correct timing etc) is to MAXIMIZE QUENCH. My R1 motor uses hypereutectic (John Erb) pistons in a block decked to achieve .030" quench using, of course, the steel shim gasket, (the closest I felt I could safely go with a 6k redline; other cylinders vary due to the crank tolerances up to ~.010") with heads significantly milled to recover cylinder pressure (the pistons are dished and I was this able to achieve enough valve-piston clearance over the range of cam timings I wanted to try). The cranking pressure measures 195 psi, with some variation due to crankshaft tolerances mentioned. No detonation with 93 pump gas. I can achieve ~200 psi by increasing the intake valve clearances from .018" to .023" (a JE long-furation "special" cam that we were curious about which I advanced by 7 deg,) but decided I didn't like the added noise. Still no detonation....Note that the reduced thermal losses in these pistons should, according to John, add ~.5 compression point during operation to my computed (based upon actual volume measurements) of ~10.3:1. A last note about compression testing: Expect variations due to valve timing and varying piston height from these cranks. A leak-down test will determine the truth regarding, well, leaks... The motor runs quite well in my hot rod: 13.02@103.5 with 3:50 gears, street tires, 87deg ambient and a computed altitude of ~1900-ft..

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