Piston in the Hole WAY to Much?!?

[Hickfied]

I just stripped this 357 down, and found this!

Is that not in the hole way too much? I can't find my feeler gauges... But the engine ran fine for 9.5k mikes, with a stock type head gasket.

I just bought some .039 ROL head gaskets... And I do not want to ping!

 

[onefstsnake]

they arent going to come completely to the top of the deck... I know stock 5.0's dont. and if you think its sitting low then that would mean the compression is lower and wont ping as easily.

 

[86bluecobra]

that doesn't seem to low to me. I would be worried about all that carbon. Looks like you are running 2 rich. What kinda timing are you running and what fuel are you using?

 

[89white50]

they arent going to come completely to the top of the deck... I know stock 5.0's dont. and if you think its sitting low then that would mean the compression is lower and wont ping as easily.

WRONG...its not the compression that makes it ping....its when the timing is way off, or there is something causing a spike in pressure. And, the more your piston is in the hole, the MORE likely of ping because it's not at zero deck height. The corners of the cylinder bore cause pressure spikes creating detonation. This is why when you build a motor, you want to be at zero deck, and to lower compression we have step dish pistons.

If this is a mild-power engine, i wouldn't worry about if it was running fine. How much in the hole is it?

 

[Modular2v]

looks fine to me. And there is going to be a certain amount of carbon

 

[86bluecobra]

looks fine to me. And there is going to be a certain amount of carbon

maybe i'm just used to looking at my engine. My pistons are very clean. I bet it is the nitrous that keeps em looking that way.

 

[Modular2v]

maybe i'm just used to looking at my engine. My pistons are very clean. I bet it is the nitrous that keeps em looking that way.

mine were very clean too......must be the sauce

 

[Hickfied]

I bought the engine off my ex g/f's dad. He ran a 750 carb on a stock 69 357 w/ a mild cam. I guess he was always running way to rich lol. I was hoping to be spraying atleast a 200shot with 4340 internals. I am gonna hve to find my feeler gauges... Because I just bought a .039 head gasket... That leaves me with .011 to be in the hole... Eh... Not looking good for me.

 

[302RollinHard]

My 357 is .020" in the hole, which is within spec. optimal, no, but will it really hurt things? I don't really think so. Look at it this way....lets you have just a touch more piston to valve clearance....

 

[Hickfied]

I just don't want to fubar my quench when i'm spraying a 200 shot.

 

[89white50]

oh god nitrous and that much quench? lol To be honest .011 is not THAT bad for NA, but i have no idea with a 200 shot! as rick91gt
i didnt even see you were using nitrous, that thing will ping like a SOB when you get on it.

 

[thumper460]

STOP guessing.. go and borrow a mic and check it out!! you will NEVER know your compression with out knowing the Deck!! 200 shot will rock!! .010 and .015 used to be pretty common!! .020 is also do able!! but MIC the suckers!! and then you'll know!! and it is always good to mic BOTH sides of the engine!! we have seen blocks as much as .030 differance between the sides!! Just a thought!!

Just me...........................

Thumper

 

[Hickfied]

Yea, I was planning on micing it once I get it cleaned up, and the stores open back up

I have to tear this thing down to be decked... Imma just go 408

 

[86bluecobra]

well building a 408 would be nice.

 

[tmoss]

they arent going to come completely to the top of the deck... I know stock 5.0's dont.

my stock short block had zero deck through negative .009" deck (out of the hole).............

 

[thumper460]

The way to deck the block is with the four pistons in the 4 holes they belong in.. then mic the deck of each piston... then remove the amout of deck so each piston is equal in the bores and the deck is also equal!! Having the block "Squared " is another way, and will get real close.. the best way for any engine is with the 4 cornors in the block!! Then you "Have .005 in or -009 out..

Just me...............................

Thumper

 

[mstngjoe]

My shop uses a BHJ Block-Tru to ensure the decks are perfectly flat front to back and square with the crankshaft centerline.

And relative to what TMoss said about his piston being out of the hole....I just pulled down a bone stock '89 5.0 that had the pistons .006 above the deck. Unfortunately, I didn't measure the head gasket before I tossed it.