340 build

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You will need to choose the right head gasket when you go back together........How thick was the one you pulled off????
Any ways you need a Minimum of .040 between the piston and the head. You have one piston that is .020 out of the hole, so 40 + 20= a head gasket that is .060 or more.
 
maybe the bore would mic better if it had a torque plate installed before micing(sp?). Or maybe it would be worse. I dunno, but I'm sure it would be more accurate.
 
Cudafever said:
You will need to choose the right head gasket when you go back together........How thick was the one you pulled off????
Any ways you need a Minimum of .040 between the piston and the head. You have one piston that is .020 out of the hole, so 40 + 20= a head gasket that is .060 or more.
Click to expand...
Ill find out for sure what head gasket was on it tomm when Im back at the shop

Quote: The ones with the shallow machined areas around the main chambers are intended for 340 pistons like yours................

Was their a thread about this somewhere? Id like to know more, it sounds like these are the wrong heads then but it also sounds like they can be made to work with the correct head gasket.

I think like I mentioned that the valves hit the top of the pistons at some point, made VERY minor indentations, I can get a picture of this hopefully tomm.
 
I will be real interested to find out what thickness the head gasket is. Maybe it was the piston to valve clearance that caused the cam to fail.
Was the lobe that failed on # 7 or 8?...... them are the tallest pistons.......
I'm not as much interested in brand as in thickness of head gasket.
The eddys came in two flavors one ment for the higher compression eng and one ment for the low compression 340/360 eng.
So yes, them are the wrong heads, BUT the proper head gasket will fix the problem.
The 340 head had a small ring, the same size as the bore to let a pop up piston have plenty of clearance.
 
KnuckleDuster said:
The 8553PT are what you show in your picture.
Click to expand...
Im curious how can you tell by the picture, is it the color or is there a shape?
Cudafever said:
I will be real interested to find out what thickness the head gasket is. Maybe it was the piston to valve clearance that caused the cam to fail.
Was the lobe that failed on # 7 or 8?...... them are the tallest pistons.......
I'm not as much interested in brand as in thickness of head gasket.
The eddys came in two flavors one ment for the higher compression eng and one ment for the low compression 340/360 eng.
So yes, them are the wrong heads, BUT the proper head gasket will fix the problem.
The 340 head had a small ring, the same size as the bore to let a pop up piston have plenty of clearance.
Click to expand...
Ill measure the head gasket tomm, of course it wont be dead nuts cause even though they have been compressed Im sure there is some bounceback.

Ill either get better pictures of the bad lobe/lobes and or try and figure out what and where things went wrong.
Let me ask how am I gonna get a specific C.R if Ive got to put such a thick head gasket just to stop the valves from bouncing off the pistons? Am I gonna have much choice or control or is it gonna be what it is assuming I can get one thick enough.
Can I have a chamber cut into the head to allow for the tall pop-ups?

Maybe I need to get a shorter piston?
 
It will be way cheaper to have a custom thick head gasket made then to have both of your heads machined!!!!
Remember that even thow them piston are above the deck. Once you figure in them big valve reliefs in the piston, you may be closer to flush then you think. As far as cc above deck.
it was something like 6 or 7 cc below deck once you figured in the piston valve reliefs.

With 70cc heads my compression came out to 9.4
63cc head +.060 head gasket(12cc) 7 cc below deck, I come up with 9.70:1 compression.
You will have to cc you piston to know if your valve relieves are the same size as mine were, but i bet it close.
 
question: the pics of the piston tops, show eyebrows for valve clearance, but the eyebrows appear to have a dent or something about mideyebrow where the eyebrow meets the top of the piston(inboard) side. The dent, or whatever it is, seems to vary from piston to piston. So what''s going on there?
Also, what size valves are we dealing with in these heads? Have you tried to clay the top of the pistone to gauge what kind of minimum clearances(piston to head, & piston to valve) you have?
 
rustycowll69 said:
question: the pics of the piston tops, show eyebrows for valve clearance, but the eyebrows appear to have a dent or something about mideyebrow where the eyebrow meets the top of the piston(inboard) side. The dent, or whatever it is, seems to vary from piston to piston. So what''s going on there?
Also, what size valves are we dealing with in these heads? Have you tried to clay the top of the pistons to gauge what kind of minimum clearances(piston to head, & piston to valve) you have?
Click to expand...

That is where I am assuming the valves have contacted the pistons that I had mentioned earlier, Im assuming the heads have the 2.02 intakes and not sure on the exhaust.

No I havent done anything with clay, dont have any experience with that yet.
 
Cudafever said:
It will be way cheaper to have a custom thick head gasket made then to have both of your heads machined!!!!
Remember that even thow them piston are above the deck. Once you figure in them big valve reliefs in the piston, you may be closer to flush then you think. As far as cc above deck.
it was something like 6 or 7 cc below deck once you figured in the piston valve reliefs.

With 70cc heads my compression came out to 9.4
63cc head +.060 head gasket(12cc) 7 cc below deck, I come up with 9.70:1 compression.
You will have to cc you piston to know if your valve relieves are the same size as mine were, but i bet it close.
Click to expand...
I would think some of the info such as valve relief size would be avail. from manufacturer. Im gonna google CC the piston anyway though
 
My valve pocket were deep enough but that 90* self on the pistons valve pocket, was what made the clearance to tight. Die grinder with a cut off wheel, to the 90 degree shelf, had boat load of clearance after words. My clearance was too tight on the exh valve (MP .474/280 Hyd cam)
 
1930 said:
I will do my best to measure all 4 corners
Click to expand...

dont get to excited about the deck height being all over the place went you measure it with the pistons in it...
Unless the crank has had it stroke indexed and equalized...and the rods have had their center to center blueprinted ....they would all be different even if the deck is square...
 
I think I sky made a cutter that looked like a valve, but with a cutter head built into it. you bolt the head on the block with a couple of bolts, and the cutter in place, and then you chuck the cutter-valve valve stem in a drill and spot face each piston head properly. It's not super hitech, but it's pretty quick and easy, and there is little guesswork, and the piston cuts should be pretty consistent.
 
With the TRW L2316F pistons ...you can run quite a bit of camshaft without getting a Valve to Piston problem...and besides it is not the gross lift of the cam...the valve to piston clearance problems shows up in the cam overlap period...at max lift the piston is way down in the bore.

more then likely with the 474 hydraulic cam and single valve spring ..the valves got floated and that is what caused the eyebrows...
 
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My buddys 383 we welded on some brake lathe bits to the edge of the intake and exh valve(junk one of course) and when to town.
70aarcuda is 100 percent correct. it is the overlap that the valves are the closest to the piston. NOt tdc
 
true enough. The problem comes at 0 to 15degrees after TDC for the intake valve on the intake stroke, and 0 to 15degrees before TDC on the exhaust stroke. I've never done it, but if you Google "flycutting pistons" on the Corvette forum, some guy explains it pretty well, with pics and drawings. I guess I was full of cap about using a power drill, he says you'll take too much off with a power tool. He recommended doing it by hand with a tap handle.
 
we used a drill but, we were trying to put valve relieves into a flat top piston that didn't have any. A die grinder is way faster to true up tho piston valve pocket. But when there is not relieves in the piston, you don't know where to start without a valve pocket cutter.
 
1930 said:
Im curious how can you tell by the picture, is it the color or is there a shape?
Ill measure the head gasket tomm, of course it wont be dead nuts cause even though they have been compressed Im sure there is some bounceback.

Ill either get better pictures of the bad lobe/lobes and or try and figure out what and where things went wrong.
Let me ask how am I gonna get a specific C.R if Ive got to put such a thick head gasket just to stop the valves from bouncing off the pistons? Am I gonna have much choice or control or is it gonna be what it is assuming I can get one thick enough.
Can I have a chamber cut into the head to allow for the tall pop-ups?

Maybe I need to get a shorter piston?
Click to expand...


The number is on them in your picture. Center tang sticking up between cylinders.

028.jpg
 
OK so before I make a mistake should I be dropping the crank/removing the pistons today or is there something else I should be doing first. I dont want to keep going forward and then backwards again.

It sounds like I need to follow a very specific order of doing things here now instead of bouncing all over the place because of some issues.

Im not trying to build and engine here that is gonna be raced so Im not sure how far I need to bring this thing however I do agree there is only one way to do something and that is the correct way.

Hopefully this is not the point where I lose anyone interest but I got to say, some of the things you guys are mentioning are way beyond anything Ive ever fooled with or have knowledge of and so Im getting worried I am in over my head.

What I would like in the end here is a super fast revving ( this is important to me ) great sounding engine ( as in compression and cam ) that I can put in one of my trucks, take to shows and be the envy of everyone at the show.

I dont expect it to go fast necessarily ( its in a 6 thousand pound truck with truck gearing ) but of course I dont want an absolute slug either.

I understand that with final gearing the truck is prob. gonna be on the slug side for sure, certainly not like what you guys are typically into AKA ..........Hopefully this is not the point where I lose anyone interest............

So with that said Id sure be interested to learn more about claying, indexing, blueprinting and all the other stuff mentioned but I have to be realistic as well in that I have to also make a living working on everybody elses cars in my shop and so time is very limited.

I wish I had more time to learn all the things Id like to know.:(
 
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Im heading to the shop now and will gather all the info asked hopefully. Ill report back and thanks to everyone that has posted so far with the information you have posted.

Its all very interesting
 
These pict, are taken from drivers side of block, I tried marking the cam on the two worst lobes, may be hard to see, the lobe marked with red is almost non existent, the one in front of it marked in white is in pretty rough shape as well.

The first cylinder in the front and the 3rd cyl back are marked minor damage.

Definitely a set pattern where contact was made on all of the pistons, I dont know enough to say what thats all about.

Picture 397.jpg


Picture 396.jpg


Picture 398.jpg


Picture 399.jpg


Picture 400.jpg
 
These are taken from pass side, there were no minor imprints, they all pretty much match the closeup I show here on the 6 cyl

Picture 401.jpg


Picture 402.jpg


Picture 403.jpg
 
What stops the cam from moving back and forth, I noticed that just sitting in there the way it is there could be alot of rearward movement.
 
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