piston choices for 5.7 vortec heads? are these acceptable?

RicardoMarine said:

Since you have ordered a rotating assembly, I assume that you have determined the cylinder head combustion chamber volume.
Just curious...... what were they... and what S C/R are you shooting for????

Also.... FYI.... your cylinder heads 10239906 are equipped with the smaller valves...... 1.94 intake and 1.50 exh.



Rick

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I am aware of the valve size, and it should be fine for the specific purpose/build of the engine..

I personally did not do the C/R calculations, but the guy at SCAT did.... with the 64cc heads, the pistons should give 9.5:1.... according to the JEGS numbers, with a 64cc head, they should give 9.7.
I dont know enough about it to even pretend that I do... I would assume the head volume, Piston dish volume, the stroke, AND the quench gap has to be figured in...

centerline said:

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I dont know enough about it to even pretend that I do... I would assume the head volume, Piston dish volume, the stroke, AND the quench gap has to be figured in...

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The bore and stroke are knowns.
The piston dish volume is determined by the cylinder head chamber volume and the S C/R that you desire.

The Quench dimension (aka squish band) is determined by the piston deck height (you will learn this during assembly) and by the necessary Compressed head gasket thickness. You will be purchasing your head gaskets based on this calculation.

on 3-31, post #23 centerline wrote

centerline said:

I have the block and heads in the shop being prepped for the build... it should be ready towards the end of next week.

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I am curious to know how it's going and which components you ended up selecting.


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Rick,
I have just gotten the block and heads back from the machine shop thursday of last week... when I dropped it off there I told them I was in no big hurry and they obviously misunderstood what I meant.. so after prompting them a couple times its finally all prepped and ready for test fitting.

I chose a SCAT forged rotating assembly with the KB135-.030 pistons, as shown previously in the thread. the rods are 5.7" H-beam stroker rods, so they minimize the machine work on the block.

the cam is a special grind from Crower, and its a marine grind to minimize any chance water ingestion (which has to do with overlap and lift) and it is a .410 lift roller cam...

so far, from what I can tell, the CR will be at 9.7, so I may need to get headgasket spacers to lower it a couple tenths. I will have to give someone else the number of everything concernd and see what they come up with for a compression ratio.

with the components I have, using the vortec block, I should have a 100-120hp gain over the old standard 5.7 that im running now...

I have everything ready, but havent had the time to start test fitting everything together.

I went with the SCAT kit because they were the only ones that knew what quench/squish was without having to explain it to them.... and they have a good reputation in the performance industry.

I am keeping a good record of all parts and specs, so that if this turns out as expected, i can post what I did so that others will have an idea of components and cost... of which I dont have that luxury in my research.

but so far I will say that with spending $350 on a vortec takeout motor, and then magnafluxing and pressure testing, boring the block, rebuilt the heads and ALL new components through out (except exhaust manifolds and carb) im into it for $3600 at this point... and that should be about it for parts.

if anyone wants numbers on the cam, I will gladly share them....

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centerline said:

Rick,
I have just gotten the block and heads back from the machine shop thursday of last week... when I dropped it off there I told them I was in no big hurry and they obviously misunderstood what I meant.. so after prompting them a couple times its finally all prepped and ready for test fitting.
I'll bet that you are excited to get it put together!

I chose a SCAT forged rotating assembly with the KB135-.030 pistons, as shown previously in the thread. the rods are 5.7" H-beam stroker rods, so they minimize the machine work on the block.
Good!
I do have a question.
Summit shows the KB135 piston with a quench surface that mirrors a "D" shaped cylinder head quench surface, whereas Speedway shows the KB135 piston with a quench surface that better mirrors the Vortec cylinder head quench surface.
Since you have the Vortec cylinder heads, I'm curious as to which profile you went with?

the cam is a special grind from Crower, and its a marine grind to minimize any chance water ingestion (which has to do with overlap and lift) and it is a .410 lift roller cam...

so far, from what I can tell, the CR will be at 9.7, so I may need to get headgasket spacers to lower it a couple tenths. I will have to give someone else the number of everything concernd and see what they come up with for a compression ratio.
With a good tight Quench dimension, you will not need to fear 9.7:1 C/R.
If you were to go with a larger compressed head gasket thickness, you may loose the Q/E.
Keep the Quench tight....... .043" or so would be great.

with the components I have, using the vortec block, I should have a 100-120hp gain over the old standard 5.7 that im running now...
FYI.... Other than the cylinder block being machined for the roller cam follower "keepers", the block is no different. It's the Vortec cylinder heads (along with the correct piston profile) that will make the difference!

I have everything ready, but havent had the time to start test fitting everything together.

I went with the SCAT kit because they were the only ones that knew what quench/squish was without having to explain it to them.... and they have a good reputation in the performance industry.

I am keeping a good record of all parts and specs, so that if this turns out as expected, i can post what I did so that others will have an idea of components and cost... of which I dont have that luxury in my research.

but so far I will say that with spending $350 on a vortec takeout motor, and then magnafluxing and pressure testing, boring the block, rebuilt the heads and ALL new components through out (except exhaust manifolds and carb) im into it for $3600 at this point... and that should be about it for parts.

You cannot buy a 6.3L (built as you are doing it) for even close to that!
The GM 6.2L version (377 cu in, with those stupid silly GM F/D pistons) will run you about $5,200.
http://www.michiganmotorz.com/377ci-stroker-base-marine-engine-2000-current-replacement-p-545.html

I'd say that you did OK!

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I am still wanting to know:

Summit shows the KB135 piston with a quench surface that mirrors a "D" shaped cylinder head quench surface, whereas Speedway shows the KB135 piston with a quench surface that better mirrors the Vortec cylinder head quench surface.
Since you have the Vortec cylinder heads, I'm curious as to which profile you went with?



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been on vacation
the pistons I bought mirror the vortec heads... after I ordered them, I seen the D dish style with the same part number somewhere else and was concerned that I might get the wrong ones... but I didn't.

the UEM catalog for KB and Claimer pistons show the "vortec" style piston and the "D" dish style pistons with the same part number, but for different applications. plus some interesting and useful information about pistons in general.. https://www.uempistons.com/catalogs/automotive_catalog.pdf

im not sure when I will get around to fitting it all together but im hoping not to lose any of my boating season swapping engines, so unless something catastrophic happens to the 5.7 im running now, im not going to rush anything. All good things take time!

As per my earlier comment regarding;

the CR will be at 9.7, so I may need to get headgasket spacers to lower it a couple tenths.

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Adding a spacer (or increasing the compressed thickness) would cause you to lose your effective Quench Dimension. With a good quench dimension, the 9.7:1 S C/R should not be an issue.

Your piston deck height dimension, subtracted from your desired quench dimension, will give you your compressed head gasket thickness. Order the head gaskets accordingly.

If you were to loosen it up, the 9.7:1 or even less, may become an issue!

The whole idea behind a SBC Marine Engine quench effect is to reduce the likelihood of Marine Load Detonation.
Keep it tight and the 9.7:1 should be ok!



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RicardoMarine said:

Good for you!

Since you have ordered a rotating assembly, I assume that you have determined the cylinder head combustion chamber volume.
Just curious...... what were they... and what S C/R are you shooting for????

Also.... FYI.... your cylinder heads 10239906 are equipped with the smaller valves...... 1.94 intake and 1.50 exh.



Rick

Click to expand...

I think I have replied to an older post here due to some glitch, but i cant delete it...

Im not familier with the "S" compression ratio.... I did confirm the heads were 64cc and they do have the smaller valves.

according to all the reading that ive done and talking with performance engine builders, the heads with the larger valves are useful for higher rev'ing street engines, but would do nothing for me on this engine, as it is a low turning, low compression build, and the smaller valves in the vortec heads will let the engine have all it can use in this application.
and,for this particular head number there were some manufactured with induction hardened exh valve seats, and some with hardened valve seat inserts. the one I have happen to have the OEM hardened inserts.

I have been told the final compression ratio is partly determined by the grind/duration of the cam, which is why I would like someone who KNOWS, to calculate the C/R for me....
the SCAT tech said the pistons with these heads would give 9.7:1, but im not sure if that is taking into consideration the head gasket thickness or just the calculated volume WITHOUT the "variable" of the head gasket thickness...

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centerline said:

I think I have replied to an older post here due to some glitch, but i cant delete it...

Im not familier with the "S" compression ratio....
S = Static..... as in Static Compression Ratio.

I did confirm the heads were 64cc and they do have the smaller valves.

according to all the reading that ive done and talking with performance engine builders, the heads with the larger valves are useful for higher rev'ing street engines, but would do nothing for me on this engine, as it is a low turning, low compression build, and the smaller valves in the vortec heads will let the engine have all it can use in this application.
and,for this particular head number there were some manufactured with induction hardened exh valve seats, and some with hardened valve seat inserts. the one I have happen to have the OEM hardened inserts.

I have been told the final compression ratio is partly determined by the grind/duration of the cam,
Yes, and that would be the Dynamic C/R.

which is why I would like someone who KNOWS, to calculate the C/R for me....
I think that I posted several links to On-Line S C/R Calculators. If not, they are easy to find.
In addition to bore and stroke, these will offer fields for piston dish volume, piston deck height, combustion chamber volume, compressed head gasket thickness, etc.
I'm sure that your machinist used his favorite site, or computer program, for these calculations.


the SCAT tech said the pistons with these heads would give 9.7:1, but im not sure if that is taking into consideration the head gasket thickness or just the calculated volume WITHOUT the "variable" of the head gasket thickness...
There is no way for him to have known for certain without this info from you.
This is the problem with today's alleged Marine Engine builders....... they do not take the time for these extra but important steps!

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I got the rotating assembly fit in and it all works great together.... but after taking measurments I find that I need to have the block decked, as the piston to deck clearance is about .012 to .018... and not even from end to end, which is normal on a stock engine, but if one is spending thousands on a balanced engine, a couple hundred more to get it right is worth it.... also, I fitted everything without the rings installed on the pistons, as I knew It had to come apart to have the crank balanced with the harmonic dampener and flywheel....

one question that I have to ask is, does anyone know if a marine flywheel is any different than an automotive clutch type flywheel? so MUCH BS found on the internet from those that THINK they know stuff, but dont, that its hard to tell.....
I only find 2 different people say there is NO difference other than price, and they have used them, and some others say a truck/clutch flywheel wont work.... most say they dont know, but would recommend getting a marine flywheel..... but at a price of $75 for a flywheel vs $275 for one that may be identical other than the label, im not forking out dollars without finding out for sure... thanks

one question that I have to ask is, does anyone know if a marine flywheel is any different than an automotive clutch type flywheel?

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Ayuh,.... They're 1 in the same,.....

Marine motor couplers bolt to the same holes as a clutch pressure plate,.....

I've been hoping to see a new post from you. Sounds like you're on your way to the assembly part of the project!

centerline said:

I got the rotating assembly fit in and it all works great together.... but after taking measurments I find that I need to have the block decked, as the piston to deck clearance is about .012 to .018... and not even from end to end, which is normal on a stock engine, but if one is spending thousands on a balanced engine, a couple hundred more to get it right is worth it....
As you said in post #1, you are not building a 400 HP Marine Engine.
Even though I tend to be a perfectionist in an imperfect world, I think that you will be OK with those numbers.

Using the tighter .012" deck height, I would do the math and determine the compressed head gasket thickness as to create a good Quench Effect!


also, I fitted everything without the rings installed on the pistons, as I knew It had to come apart to have the crank balanced with the harmonic dampener and flywheel....
I would have done the same.

one question that I have to ask is, does anyone know if a marine flywheel is any different than an automotive clutch type flywheel?
As Bill said....... the Marine Engine flywheel IS an automotive standard transmission flywheel.

The standard transmission pressure plate bolt pattern is used for the Marine Borg Warner style drive coupler mounting.
The crankshaft flange bolt pattern is used for rubber hub style drive coupler mounting (this is what you will have).

Here is what you might also want to know:
There are two sizes/diameters for the SBC engine...... the 153 tooth ring gear flywheel and the 168 tooth ring gear flywheel.
Each requires a certain starter motor (staggered bolt pattern -vs- straight across bolt pattern).

Also, the early crankshaft flange (2 pc rear main seal style) uses the larger flange bolt pattern.
The later crankshaft flange (1 pc rear main seal style) uses the smaller flange bolt pattern.
These will not interchange.

Three of these flywheels are very easy to find.
However, the later 153 tooth ring gear unit (1 pc rear main seal style) can be found in a late Camero car standard transmission application. Unfortunately we will pay a bit more for this flywheel.

If you purchase a used flywheel, be sure to look closely at the friction face for signs of friction over-heating that may have caused heat checking.
While you do not need a pristine friction face..... you will not want to see any signs of potential heat stress.

Also look closely at the ring gear teeth. If questionable, the ring gear can be replaced. They are not expensive!

Make sure that when you (or a shop) replaces the ring gear, that it is not heated "red hot" or "glowing hot" during the installation.
If it is heated red hot, or worse yet heated un-evenly in spots.........., it may cause annealing of the teeth, causing premature failure.
A good well seasoned machinist will spin the flywheel on a turn table while heating it evenly. Key word "evenly"!
It only requires enough heat for expansion to ensure a good shrink-to-fit.


so MUCH BS found on the internet from those that THINK they know stuff, but dont, that its hard to tell.....
I only find 2 different people say there is NO difference other than price, and they have used them, and some others say a truck/clutch flywheel wont work.... most say they dont know, but would recommend getting a marine flywheel..... but at a price of $75 for a flywheel vs $275 for one that may be identical other than the label, im not forking out dollars without finding out for sure... thanks
I can only hope that we here on MarineEngines dot com have not been a part of that experience.

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RicardoMarine said:

I've been hoping to see a new post from you. Sounds like you're on your way to the assembly part of the project!

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I can get a head gasket in almost any thickness needed from Cometic, so if the deck numbers are within reason, I can save $220 by not having the block decked.

the engine I currently have in the boat is an '87, so I believe it should have the 1pc rear main... so the current drive coupler should fit the '98 flywheel/crank bolt pattern.

as for automotive/marine flywheels, Im glad to hear they are in fact the same.... I have a 168 tooth flywheel we just removed from one of our service trucks a couple weeks ago (its a '99)... there is no checking in the surface it, but because the service truck is a "tool" that generates us money, I replaced the flywheel with new when we did the clutch so as to minimize any chance of problems in the next 70,000 miles....

the ring gear is good so it should be usable for the project...

and for the record... the BS on the internet is NOT from this site. there are a lot of small block chevy and performance sites that are loaded with self proclaimed experts arguing about the differences between the gen 1 engines and the gen II engines.... and yet very few even realize the vortec engine they are referring to in their arguments/discussions as a "gen II" is actually and properly the L-31, gen 1E engine, which was only available as a production engine from 1996 to 2002... and a very slightly modified version called the "Gen1+" is still available as a crate engine only.... for marine and special or replacement applications.

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centerline said:

I can get a head gasket in almost any thickness needed from Cometic, so if the deck numbers are within reason, I can save $220 by not having the block decked.
Just to be clear...... if this was a high performance auto build, I would suggest doing that.
However, your marine engine build will/should be OK.

the engine I currently have in the boat is an '87, so I believe it should have the 1pc rear main... so the current drive coupler should fit the '98 flywheel/crank bolt pattern.
If the '87 is the 1 pc rear main seal, it should work!

When I referred to the flywheel's clutch pressure plate bolt pattern, that would be for the Borg Warner style drive coupler..... not a rubber hubbed coupler!

as for automotive/marine flywheels, Im glad to hear they are in fact the same.... I have a 168 tooth flywheel we just removed from one of our service trucks a couple weeks ago (its a '99)... there is no checking in the surface it, but because the service truck is a "tool" that generates us money, I replaced the flywheel with new when we did the clutch so as to minimize any chance of problems in the next 70,000 miles....

the ring gear is good so it should be usable for the project...

and for the record... the BS on the internet is NOT from this site. there are a lot of small block chevy and performance sites that are loaded with self proclaimed experts arguing about the differences between the gen 1 engines and the gen II engines.... and yet very few even realize the vortec engine they are referring to in their arguments/discussions as a "gen II" is actually and properly the L-31, gen 1E engine, which was only available as a production engine from 1996 to 2002... and a very slightly modified version called the "Gen1+" is still available as a crate engine only.... for marine and special or replacement applications.
You will find that a lot of automotive info can be useful for a Marine build...... but when it comes to piston profile, S C/R, camshaft profile, ignition advance, etc, we can get ourselves into trouble.

Good luck and keep us up to date!

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RicardoMarine said:

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so far, I have the rotating assembly in and have indexed the cam to insure it is on spec and timed correctly, and all is good.... with the numbers I have, using a headgasket with a .026 squish, I should end up with a .043 quench and a 9.57:1 C/R.

what type of head gaskets would you recommend?

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centerline said:

so far, I have the rotating assembly in and have indexed the cam to insure it is on spec and timed correctly, and all is good.... with the numbers I have, using a headgasket with a .026 squish, I should end up with a .043 quench and a 9.57:1 C/R.

OK..... squish is an alternate term for "quench". In other words..... squish is occasionally used to describe quench! My preference is "quench"!

So after that explanation....... your .026" dimension represents the "compressed" head gasket thickness.
Your .043" would be your quench or squish dimension.
Working backwards...... if you subtract .026" from .043", that leaves .017", of which represents the piston deck height.

A .043" quench dimension sounds good for a 3.750" stroke SBC. If possible I would not exceed that!


what type of head gaskets would you recommend?
If Raw Water Cooled, you will need to use a Marine head gasket with a compressed thickness of .026"
If fitted with a Closed Cooling System, you can use a High Performance Automotive head gasket with a compressed thickness of .026".

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