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Shim Shim N E

I finaly "Made" time to work on the engine again between Ball games. Was down in the shop till 2330 last night and back up at 0600 this morning, so if I miss spell anything over look me.

I got the rods degunked of cosmoline, the WD40 and an old tooth brush worked great. Re-weighed the rods and they are very much within tolerance for a stock engine. Lubed up the crank, rod bearings and assembled the rods on the crank. Ok, there goes an hour, I know, I work slow. All the rods ride smooth on the crank when the crank is turned in the case, SWEET!

Now on to the P/C's, I "rig" up a way of torqueing the jugs down and take a measurement of the deck height. My number of one of my cylinders deck height is .041 of an inch. I used Aircooled.net for the calculator and with all the numbers plugged in I get a CR of 8.1:1. To get the RAMVA recommended CR of 7.4 to 7.5 I need to add .040 to my deck height. Looking on Aircooled.net, I see I have a couple options:

1.) Standard barrel shims that go between the jug and the case. Cost could be factored in at about $10 for a set.

Option #2 and I am leaning more to this one, will explain later:

2.) Copper Head Gaskets, described to be recommended for 180hp engines and will seal the combustion chamber when used and are reusable after annealing them. Cost factor $30 for a set of 4.

Now, I have read on this group that the use of anything between the head and jug in not recommended as the jug and head should form a tight seal if all things are as they should be. But I would like to hear if this copper gasket would still be frowned upon and why? Yea, it cost more, but too know that the chamber is sealed means alot and the fact that they can be reused adds to the equation in my mind.

I have only done one cylinder and will do the rest tonight too see if there is any differences and if I need to swap things around any. Just want to get a feel for which direction to go. I know I could have the piston tops shaved, but that just is not an option for me, as I think cost would be a limiting factor.

What sayeth the net wisdom?

Reply to
TerryB
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Could the collective wisdom let us know what you think about leaving

8.1:1 as the CR, for a 'carefully' rebuilt engine.

If driven carefully (owner driver - not boy racer ! ) , what would the MPG, HP be like for example ?

Rich

TerryB wrote:

Reply to
tricky

I hope you dont mind me jumping in on your thread Terry.

Rich

tricky wrote:

Reply to
tricky

Mind, MIND!!! Of course I mind! You topic jumper.....LOL

I had thought the same thing, but I know that to run the higher CR, will require top grade Petrol at the pump and with gas prices what they are here in the South, I could pay for the shims in about 4 fillups. Premium gas is at least 20 cents per gallon higher then regular (87 octane). Not sure I would want to go that route, unless there are other advantages?

Reply to
TerryB

Cost of Gas / petrol is not an issue here in the UK. Its 3 times the price you pay and no choice of premium/regular any more .

If I could see a better MPG or safe-ish HP that would be good.

I will be biulding an engine soon, and I wondered, if I found myself in your position, what actual difference it would make. And how high CR would be too risky even for carfull driving.

Rich

TerryB wrote:

Reply to
tricky

borderline for a stock cam....higher static CR's are feasible because of larger cams with more overlap.....

Reply to
Joey Tribiani

engines

Copper sealing rings are acceptable for thin-walled jugs (I've no idea what you're building). The problem is, as received most are hard as nails when they are supposed to be dead-soft when you torque-up. SOP is to anneal them.

But if you are using stock jugs you don't need sealing rings, in which case the best option is to add shims under the barrels... assuming you know the right size. (see below)

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I always check all four. (Shit happens.) I use the SMALLEST deck-height to compute CR... and round up to the next available shim-size.

-Bob Hoover

Reply to
veeduber

My personal theory on head gaskets is that you double the surface area that can leak. With no gasket there are two surfaces that seal against each other. With a gasket, there are four surfaces. You are also adding a third metal that expands and contracts at a rate different from the other two metals (which are of course different themselves.) Just some points to ponder. -BaH

Reply to
Busahaulic

Well, there seem to be more nay than yea's. Which is fine for my thoughts and dreams. This is why I asked. My mind is made up, I will go with the barrel shims at the base and leave the combustion chamber alone.

Just need to borrow some time from one of you that have lots of extra on your hands. Mine is running very scarce right now, never would thought a ball game which only lasts for 75 minutes could occupy so much of my time. LOL But it is tons of fun to watch them kids play.

Be back soon with more updates/questions/quests for encouragement.

Reply to
TerryB

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