Thread: 72elk

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Originally Posted by States

I thought I was following your recommendations but I must have gotten off base somewhere.

Eau contraire my friend, it was me who dropped the ball. I went back and read the entire thread a little while ago and found the point where my brain froze up. It was in post #63 on page 5 where I put the OK on those H618CP030 pistons. As soon as I had the part number, I went to the Summit site to see what the compression height was. Satisfied that it was 1.560" and failing to take notice that the crown was ( -3.5 cc's), I blessed them. I must have been in a senior moment or a semi-coma to put the OK on those pistons. They would work OK on 72 or 76 cc heads, but will not work with 64cc heads on pump gas.

I feel like an idiot for misleading you, but rest assured that it was not intentional.

Please refer back to post #50 on page 4. That should be the flavor of the build. I recommend a zero deck in that post, but if you cannot afford to cut the block decks at this time, then use a Fel-Pro 1094 steel shim head gasket on the virgin block, after being assured by your machinist that the block decks and cylinder heads are flat enough to retain a steel shim gasket. There is a limit to the waviness on the block and heads that a steel shim gasket will tolerate. Assuming a stock piston deck height of 0.025" (piston crown to top of cylinder with piston at top dead center) and a gasket thickness of ~0.015", squish/quench should be finalized at 0.040", allowing maximum detonation protection on pump gas.

The reasons for cutting the block decks to zero are twofold. One, it corrects any mis-machining at the factory and Two, it preps the block for aluminum heads at a later date. Aluminum heads, when used on an iron block, suffer from differing expansion rates than the block. This leads to slipping and sliding around and the grinding off of the softer aluminum material (called fretting). A thicker composition gasket will absorb this movement and protect the aluminum head from fretting.

Now, to explain further, when you use a thicker composition gasket, which is normally 0.039" to 0.041" compressed thickness, you are looking for a zero (0.000") deck height between the block and the piston crown so that the squish/quench is in the 0.035" to 0.045" range for maximum detonation protection when using pump gas. The piston deck height is at zero and the gasket thickness is 0.035" to 0.045". A Fel-Pro 1003, at 0.041" compressed thickness is one of the gaskets recommended by several aluminum cylinder head manufacturers to be used with a zero deck.

Now you will understand that with a stock piston deck height of 0.025", you cannot use a thick composition gasket on the motor, because adding the stock piston deck height to the compressed thickness of the head gasket (0.025" plus 0.041" = 0.066") will create a squish/quench that is much too wide to be effective at preventing detonation. Remember, we want a squish/quench somewhere between 0.035" and 0.045". So, if we are not going to cut the block decks and will be willing to run steel shim gaskets for use with iron heads, we must remember that we cannot leave the block decks stock and later on run aluminum heads with the required thicker composition gasket, because the squish/quench will be all wrong.

This is why I urge anyone building a small block Chevy to use a 1.560" minimum piston, cut the block decks to zero and use a 0.035" to 0.045" compressed thickness gasket. Even if you run iron heads for the rest of the time you own the motor, there will come a time to sell it and it will sell much easier if the block is decked for aluminum heads and composition gaskets.

Thanks for the explanation. Can you give me a recommendation on either a specific piston of the specs on what I should be looking for to achieve the compression ration I'm looking for.

It's all on post #50.
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Almost have all the parts in hand. Got the KB pistions, new high flow water pump, HEI ignition and wires..and many more. One item I am having trouble finding is Valve Covers for vortec heads with scorpion roller rockers. It seems like every where I check I get a maybe or maybe not. Any suggestions?

Originally Posted by techinspector1

Eau contraire my friend, it was me who dropped the ball. I went back and read the entire thread a little while ago and found the point where my brain froze up. It was in post #63 on page 5 where I put the OK on those H618CP030 pistons. As soon as I had the part number, I went to the Summit site to see what the compression height was. Satisfied that it was 1.560" and failing to take notice that the crown was ( -3.5 cc's), I blessed them. I must have been in a senior moment or a semi-coma to put the OK on those pistons. They would work OK on 72 or 76 cc heads, but will not work with 64cc heads on pump gas.

I feel like an idiot for misleading you, but rest assured that it was not intentional.

.

Sir: I salute you.
You're a good man.
It takes balls to publicly admit you were in the wrong, and apologise as humbly as you did.

You've certainly got my respect.
I can only reiterate: you're a good man.
And I salute you for it.

New issue. Have all parts in hand and took block to machine shop. Apparently there is a groove in one of the cylinders that is going to require it to be bored .040 over. KB does not make the piston that was selected in .040 over. I need a recommendation of a comprable piston in the same size. Any suggestions?

How much does the shop want to put a sleeve in that cylinder? Where is the groove located?

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My mechanic found identical KB pistons thru one of his vendors. He will start boring once he gets the pistons so he can verify exact size of each. Techinspector1 gave me the blueprint for this build and told me that I would be able to use my stock torque converter however I was thinking that since I've gone this far I was wondering what would be a good choice if I was to go ahead and replace mine. Keep in mind I can't break the bank on this last part.

What are the pros and cons of a lock up torque converter vs a standard one.

A lock up receives an electric signal which "locks" it up, and it stops slipping. If you install a 700R4 (for example) then it needs a signal to lock up or it always slips, which hurts fuel economy and heats the fluid.

Edit;: oops that was more of a tutorial than a pro con explanation. Simply put, if the trans requires a lock up, then that's what you need to go with.

Originally Posted by States

What are the pros and cons of a lock up torque converter vs a standard one.

What trans are you wanting to run? It can cost a huge amount of money to put a lock up set up in say a Th350 or Th400. 700r4s, 200r4s, 4l60e, and 4l80e all have lock up converters. There were some lock up 350s in the early 80s as well.

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Engine assembled, just need to remove the old one and install this one. Pictures in gallery

Ok so I went ahead and bought a Hugh's torque converter rated at 2500rpm for a Chevy BIG block which, according to to documentation should be somewhere between 2000 and 2200 go my 350.
Now a dumb question. I'm ready to pull the old 350 out, can I do that while leaving the tranny in place or do I need to take both out at the same time. The tranny is a TH350.

Originally Posted by States

Now a dumb question. I'm ready to pull the old 350 out, can I do that while leaving the tranny in place or do I need to take both out at the same time. The tranny is a TH350.

You can for sure pull the engine, leaving the tranny in place, but in my experience it's going to be a lot harder to get the new engine & old tranny aligned and done right that way. It's LOTS easier to pull the engine & tranny, connect the new engine & tranny on the shop floor, and re-install the engine & tranny as a unit. Others may disagree.

I used to stick the engine and trans together on my old 72 Camaro and then put them in as 1 piece. That was with the BBC. I did it easily on the 71 with the 5.3/Super T10 too.