safe compression ratio sbc

timguy said:

Yup, makes little difference, but I would insulate the supply line on a long run. Compression is King....what you have on your avatar is proof, eh?
Just MY opinion, but 8 to 1 compression is for farm tractors.

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Returntrip said:

Thanks for the response on cooling gentleman, I was planning initially on using a crank driven pump.
Another good call.
The Johnson F5B-9 is an excellent choice for the Half System. If you do a Full System, you can go with the F6B-9.
Both mount in the same way.

FYI.... when both F5B-9 ports aim to Port side, the lower port becomes the suction side, and the upper port becomes the supply.
If you were to aim the F5B-9 ports to Starboard, the upper port will be suction, and the bottom port will be supply.

Keep in mind..... if you are running a Merc A drive, the A drive seawater pump must remain active for upper unit cooling.

I am planning on making a fully closed cooling system.

I have brand new bowtie Vortec heads but have never even seen a carb. Vortec intake manifold, i have no idea of flow pattern or if there are any wter outlet port to work with?
FYI.... with your Closed Cooling system, you can use one of the Edelbrock Automotive SBC Vortec intakes if you want to.
These will have the port for cabin heater and/or water heater coolant supply in the correct location.

SBC edelbrock vortec intake manifold - Google Search

can i use the crnk driven pump in conjunction with stern drive pump?
You'll have a choice.
1..... T the A drive seawater supply into your thru-hull pick up for the Crankshaft seawater pump supply.
2..... divert the A drive seawater pump supply over-board after it passes through the upper unit.


Also my forged crank is about ready for balancing (1 pc. rear, Mercruiser 377) Should I get double roller T-gear set so I can give the shop lower gear?
Did you mean "sprocket", or are going with gears?

Is double actually necessary?
If going with a roller cam assembly, the friction is quite a bit less, therefor putting less force against the timing chain and sprockets.
Your call on that.


Can i use a Vortec sbc flywheel I have from another 5.7 engine i have for the Mercruiser 377 crank balance?
The 377 (std 4.000" bore) and 383 (4.030" bore) rotating assembly is based on the SBC 400 cu in engine.
The flywheel is unique to this crankshaft, as is the harmonic balancer.


One more question Too Rick... Do you still love Lucy???
I've always loved Lucy!


By the way the original Flywheel that was on that crank, had a GM casting #93433010 which i believe ive seen for sale on e-bay listed as 5.7 flywheel & should I try & bring back to life the front damper (salt water sinking) Will they need that one or maybe guide to wher i could buy if needed for crank balance.

The 3.750" throw crankshaft needs the correct flywheel and harmonic balancer.
The 5.7L flywheel and/or balancer will not work.

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Returntrip said:

Thanks for that input timguy, Im going to pick up crank tomorrow, had it magnafluxed and mains got cut .010. Ill definitely stay in touch about balancing parts.

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Returntrip said:

Wow, your knowledge is a great help Rick.
Thank you.... glad to help!

I would have never known about upper cooling on the A drive. Although I was planning on installing a "T" before the pump.
I have a good heat exchanger and a Sherwood crank driven pump I took of a bb chevy before it got scrapped.

The Sherwood P-105 and the Johnson F5B-9 and F6B-9 are interchangeable. Same mounting bolt pattern.
The Sherwood impeller is keyed to the shaft.....

...... whereas the Johnson impellers are splined to the shaft.


Instead of fabricting all my own brackets for my own system I think ill buy one.

Im not familiar with the Johnson FB systems you mentioned, Ill hve to google that and check it out & see who sells them.
See above. Either are good seawater pumps.

I did see some systems on line @ Mr. Cool & Performanceproducts?


I bought the Bowtie Vortecs so i can go either way on Intakes I have 2 Mercruiser Quad intakes one with choke stove and anothe 5.7 with aluminum intake, roller engine but non, vortec head with 6 per side itake bolts. Obviously I want the closest match to the bowtie vortec runners.
Yes, good call!

If you think the sbc Edelbrock is a good choice I might just go with that. What do you think of Brezinski Intake?
I'm seeing cast iron only. I like the idea of the weight savings w/ the aluminum.

My mistake on calling the sprocket a gear.
No biggy..... that is a very common error. I just wasn't sure which way you were going.

Im extremely confused, I have the original flywheel that came off the mercruiser stroker crank. It definately has a standard GM casting number that fits 5.0 5.7 sbc 1 piece rear main seal cranks, WHAT GIVES???
I can't answer that one. I would see if you can contact a Merc Factory Rep and ask the question.
Or..... ask your machine shop person who will be doing the balancing for you.
The flywheel will either balance out with the crankshaft, or will not balance out with the crankshaft. He will know immediately.

The crank has a laser inscribed mercruiser number that comes up as 377c.i.
That would be correct.
The standard 4.00" bore block with a the 3.450" stroke crankshaft works out to be 377 cu in.
When you see an engine listed as a 377 stroker, it is a new engine from GM, not a re-man.

forged $1,342.00 crankshaft that is no longer available anywhere. The journals all mic.d out at standard sbc measurements. 5.7 rods where attached to crank. Is it possible G.M. made this crank specifically for Merc?
Very possibly!

Could it be internally balanced?
That is possible. This would be a good question for a Merc Rep.
Also, see the thread that I link us to below. Post #61 touches on balancing.

Also rod journals are hollowed out , I assume for lighter weight or oiling>very confused, but loving it! The more knowledge I gain the better! Cant figure out crank, why the 5.7 flywheel?????

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RicardoMarine said:

.............

You no doubt know this....... the OEM 400 crankshaft's main journals are 2.650" in diameter, and will need to be turned down to 2.450" diameter in order to fit into the 5.7L cylinder block. Rod journal size is the same between the 350 and 400 cranks.
Now with that said...... your Merc 377 crankshaft may already be at 2.450" before you removed .005" (.005" off = .010" under).






If interested, here's another thread (started back in September of 2019) regarding a 6.3L build.

Once again, you'll see a few Nay-Sayers right out of the gate, so be prepared to wade through several disruptions.

http://www.marineengine.com/boat-forum/showthread.php?460276-383-Inboard(V-Drive)build

Just for fun, look at the image in post #29 where I explain LPCP and how LPCP is affected by the piston profile and ignition TA.

If I recall, we also discussed rod length and where that puts the wrist pin and what it does to the piston skirt length, etc.

In post #59 we discuss harmonic balancers.

You might find post #65 interesting.





To sum up.... many of the Nay-Sayers in that thread completely lost sight of Bracker's intentions.

Stick your guns Returntrip.... if you want to build a Q/E 6.3L stroker, pay no attention to the Nay-Sayers.

.

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Returntrip said:

.......... I is a special forged merc. crank. Hans, the machinist said there is added weight to the crank and then he looked at my old rusty flywheel and said it has no weights, its neutral.
That's good news then.

The crankshaft is a rre mercruiser internally balanced forge crank.
what is rre ....... typo..... rare????

There was also a much heavier fillet radii on both mains & rod journals than I see on other sbc cranks. Upon a little more digging about bearings< I believe I need "H" series bearings which are chamfered more and slightly narrower??? Clevite ok? we use them in diesels.
I would suggest asking your machine shop person for a recommendation.

This is from SpeedWayMotors dot com:

Info

Clevite's H-Series was developed primarily for use in NASCAR type racing, but they are suitable for all types of competition engines. These sets are specifically for 1969-Up 302-305-327-350 S/B Chevy.

• Use H-series bearings with crankshafts that have oversize fillets and where engines run in the medium to high RPM range.
• H-Series bearings should be used if contact patterns obtained with P-series parts are too narrow. Contact pattern should ideally cover 2/3 to 3/4 of the bearing surface.
• If you aren't sure which type of performance bearing to start with, the H-Series will be your best choice.

I want decent forged rods & pistons ("I" beam rod, LCQ piston) Can you guys recommend rods that upper part of journal that is tapered to help with cam clearance and I realize I'll have to do some clearance work around the bottoms of cyl. bores and also casting around block near oil pan. I am having the machinist bore the hole in fuel pump mounting boss for a mechanical pump, Is that okay?
If they have the proper jig or fixture for boring the push rod hole, yes.
Make sure that your camshaft offers the fuel pump lobe.... I believe that most will.

Or do you guys all run electric pumps?
The electric fuel pumps work well.
However, with the electric fuel pump, you will also need to install the wiring and the LOPS (low oil pressure switch).
The LOPS must be able to cut the power to the fuel pump in the absence of engine oil pressure.
USCG rule.
Along with this system, you will want to create a "start-by-pass" circuit that will energize the fuel pump prior to engine oil pressure coming up.
If you go with the electric, I can help you with a wiring diagram.


Thanks on the pump pic. Rick, that maybe the same pump i have, I haven't seen it in year, Its been in storage. Came off bbc, Im not sure I might have to do some machine work on mounting flange if bolt pattern is different from bbc to sbc damper.
Actually, the Crankshaft Pump's mounting flange attaches to the crankshaft pulley, and uses the three bolt holes in the harmonic balancer spokes.
The pulley will have two (2) stamped/raised dowels that will correspond to the pump's flange for alignment.
The flange will actually bolt on in one of three indexings.... but only one indexing will be correct.
(it will make sense to once you start installing it)



I agree Rick on the weight and other benefits of Alum. intake. I just couldnt bring myself to go with Alum. heads, even with full closed cooling...
FYI... aluminum cylinder heads (along with a nice tight quench dimension) will allow you to increase your S C/R some.
This is due to the more efficient cylinder head "heat dissipation". Not necessary.... I'm just tossing that out there.

Torque loads, Salt water, ya know, I guess Im old school.
With your Closed Cooling System, the heads and intake manifold will never see salt water.


........ Im also confused about timing chain sets, I know double roller will obviously be deeper, requiring deeper T-chin cover.
Let the cylinder block determine which timing chain cover it requires.
If going with a roller cam and roller cam followers, the cover must work with that set up.
Again, these would be good questions for your machine shop person.

Will that leave me sufficient room between water pump?
All of your belt driven accessories, and their alignment, will be based on the short body coolant circulating pump (i.e., water pump).
Make sure that the pump clears the timing chain cover.

SBC Coolant Circulating pump.... ( called a water pump in a misnomer fashion )

and how about snout depth on the damper for pulley alignment?

I was going to ask earlier if you knew if the 400 harmonic balancer must be used with the Merc 377 crankshaft.
I mentioned that earlier........ that's a good question for your machine shop person.

I was going to use all the original bolt on hardware, like p.s. pump, alt. etc. all "V" belt drive from boats original 5.7 non Vortec. I do still have the serpentine set up from original MPI stroker but everything is rusted pretty bad from sinking. I also have to consider the room for the closed cooling system possibly between the the two styles of pulley systems, although you can probably get for both. I guess Ill take my time until I hear how the block turned out. Ill just order the .010 mains and do my oil passage porting work and block clearancing. Im jumping ahead of the gun as usual,

I obviously cant order rods and pistons because I dont know what deck hieght will be yet,
You will need these parts before determining that!

..... Are you going with the 5.7" rods? Keep in mind that the longer rods move the wrist pin further into the piston, creating shorter skirts.
Hot Rod guys like the shorter skirts... but I think that the longer skirts work best in the Marine version. There are other dynamics that come into play also.

..... Are you going with the LCQ style pistons? A good choice with the Vortec cylinder head quench surface.

..... Do you know what Vortec cylinder head combustion chamber volume is? They differ slightly.


I may even deck off a little material on the new heads, then check comb. chamber c.c..
Don't touch the heads just yet!
Do the math on the cylinder block first ... i.e., deck height, desired quench dimension, compressed head gasket thickness, etc.

I dont want to have the pistons sit too far down in the jugs.
Exactly!
If the piston deck dimension is excessive, in order to obtain a good quench dimension the compressed head gasket thickness would need to be very thin!
Piston deck dimension + compressed head gasket thickness = quench dimension.
Your shop will know exactly what to do.

Please see my images in the thread that I linked you to earlier.

NOTE: the HP Auto guys shoot for a larger quench dimension. For your Marine build, you will want to be a bit tighter!

Can you guys recommend a good place to do my parts purchasing that might have people that would work with me through that process?
I'd suggest reading articles by people like Jeff Smith and the others mentioned in post #26.
Some of these guys represent companies who manufacture and sell these parts.
Keith Black, for example.
Dennis Moore has a wealth of knowledge to share, and he is an authority on the SBC Marine engine.
Granted, most of these men represent HP Auto. However, a great deal of the info can be applied to the Marine SBC engine.


One last thing.... Ignition System!
You will eventually need to decide upon an ignition system.
With your Q/E build, your system can now throw a tad bit more TA at the engine.
More on that later!




Keep up the good work and your good research.
You'll get there!

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Returntrip said:

Hello, Typo,yes he said rare on crankshaft, he said "made exceptionally well", happy to hear that!
Thanks, I read that article on the "H" series bearing. I was thinking about that electrical design on the fuel pump factors regarding low oil press. shut off & start. I will be running mechanical, but maybe back up with an electric system, using an industrial Murphy switch with a good marine grade 4 way ignition switch.
In my opinion, it's rare to see anything other than a off/ignition on/start key style switch being used in a Marine application.
Any accessories are best if powered outside of the key switch circuit.


Your info is invaluable to me thanks.
You are welcome.

The short body pump info for accessory drive, great! Ill have to figure out protrusion meas. on double roller covers, I believe the short body pumps are 5 5/8 in. from machined face of block. And definitely yes on the 5.7 rods, longer skirts, decent piston angularity and good comb. chamber dwell time. After reading yours & others posts, I am absolutely convinced on the mirroring & LCQ effect with piston choice, especially with the Vortec heads, Thank you.
Yep!

My Bowtie heads supposedly have 66cc chambers, I was just going to take off the rough decking finish from GM. I will take your advise & wait. I will cc the heads myself to see what they are, prior. I was thinking about steel composite head gaskets, somebody mentioned those to possibly use? Im not sure. I do know about compressed thickness calculations, just not sure about what materiel.I also have seen head gasket bore sizes differentiate on cylinder bore size, again, not sure on that one either!

Im looking for a .038 quench when all is said and done.
FYI.... .038" quench dimension is used for the 5.7L Marine build with the 3.480" stroke.
You will want to increase that some for the 6.3L Marine build with the 3.750" stroke.


Ive been trying to get stuff to read from Dennis Moore, They want over $700 for his book?
I'm not surprised. I own a signed copy.... I guess I should sell it. LOL

Where can i find stuff he has written, without spending my forged piston rod money>>>>
Ya wanna buy a copy????


On the ignition thing, I will be totally lost!!! Ignition I'm used to, comes from high compression cylinder pressure & highly pressurized injected fuel, Lost, Lost, Lost.
I hope you guys dont get sick of me & I wish to contribute something whortwhile at some point. Thanks, much so far! Johhny V.

Please read the other thread that I linked us to.
Look at the illustration whereby I explain LPCP, and then read my explanation as to how ignition lead affects LPCP.

You'll want to also know that with the GM build (full dished pistons) ignition advance is held back to offset the likelihood of Marine Load Ignition Induced Detonation.
When this is held back, so is the LPCP. A lazy LPCP makes for less torque and horse power.

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kghost said:

You are attempting to build an engine that will far exceed the demand or need, in my opinion.

You could purchase a brand new crate Marine stroker small long block for 4-5 thousand dollars or a re-manufactured for less and get exactly what you need from it.

All this special detail is great when building a high performance engine but you do not have that need nor will it make any real world difference in your boat. 300+/- horse power is the same no matter what the internals are.

If you are doing this for the fun of it then fine, but all this detail is completely unnecessary for a engine that will not see past 4500 rpm. There is no real benefit.

If you were on a mission to build a high power short in length speed boat with a bullet proofed stroker then following your suggested internal build plan may bare fruit but for a simple salt water boat to be used at low to moderate speeds......Way over kill

Also after all this special effort if you have a hiccup and the motor inhales salt water and you push a piston thru the cylinder wall or bend a rod.........It will all be for not!

Remember this, The 90's Vortec GM Truck engines routinely last for 200,000 miles plus, as built by GM and do not use any of PCKR's reccomendations

This is a Mercruiser marine repair help site, NOT a small block chevy high performance engine build web site.

The majority of this post does not belong here and has gone completely off topic (as usual with PCKR when he tries to impress)

You should think about starting a completely new topic in this section.

http://www.marineengine.com/boat-fo...-Gas-Inboard-Mfgs-IO-and-Sterndrive-Questions.....

and title it - (How to build a small block Chevy by da man PCKR)

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Jack said:

You are attempting to build an engine that will far exceed the demand or need, in my opinion.
Yes, in your opinion.
It is MY opinion that Johnny will do better with a Q/E build.

You could purchase a brand new crate Marine stroker small long block for 4-5 thousand dollars or a re-manufactured for less and get exactly what you need from it.
Absolutely not true.
Johnny is wanting to do a Q/E build. How can he get that with the GM build?

All this special detail is great when building a high performance engine but you do not have that need nor will it make any real world difference in your boat. 300+/- horse power is the same no matter what the internals are.
You have missed a very important aspect of this. The Q/E build is not necessarily a High Performance build. It is a build that greatly benefits the SBC Marine Engine. This has been mentioned here and in many other threads regarding the Q/E build.

If you are doing this for the fun of it then fine, but all this detail is completely unnecessary for a engine that will not see past 4500 rpm. There is no real benefit.
Again, that is not true.


If you were on a mission to build a high power short in length speed boat with a bullet proofed stroker then following your suggested internal build plan may bare fruit but for a simple salt water boat to be used at low to moderate speeds......Way over kill
Again, in YOUR opinion, and an opinion that has no base experience behind it.

Also after all this special effort if you have a hiccup and the motor inhales salt water and you push a piston thru the cylinder wall or bend a rod.........It will all be for not!
If Johnny's C/R is the same or very similar, why on earth would a Q/E built SBC pose any greater risk of a bent rod, than that of the GM build?
I am anxiously awaiting your answer on that one!

Remember this, The 90's Vortec GM Truck engines routinely last for 200,000 miles plus, as built by GM and do not use any of PCKR's reccomendations
Johnny, Jack's reference to PCKR = Post Count King Rick.
There is no need to be threatened by post counts, yet he mentions this routinely.
I'd like to see Jack pay more attention to content, and less attention to post counts.

This is a Mercruiser marine repair help site, NOT a small block chevy high performance engine build web site.
Again, the Q/E build is not necessarily a High Performance build. Please understand that!
It involves a very simple change to the piston profile... so simple, that any Merc mechanic would be capable of doing it.


The majority of this post does not belong here and has gone completely off topic (as usual with PCKR when he tries to impress)
Again, in YOUR opinion!

You should think about starting a completely new topic in this section.
http://www.marineengine.com/boat-for...rive-Questions.....
Actually, that wouldn't be a bad idea. Jack rarely visits that forum section.

and title it - (How to build a small block Chevy by da man PCKR)
Again, there is no need to be threatened by post counts. Post counts only represent one's number of forum contributions.

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Dieter said:

best post in this thread. Started with what is a workable compression ratio
Yes, that was Johnny's fair and honest question.
However, is also begs the question; "what type of combustion chamber will be used?"
You cannot successfully build an engine without knowing this!

it’s not opposing views or nay sayers.
There certainly have been opposing views and Nay-Sayers.
You guys that Nay-Say the Q/E build have most likely never done one, so how on earth can you say that it is not the better way to go?
Please explain that one!

There are several ways to skin the cat.
That may be true.
What you may not be understanding, is that the furrier dealer (the guy who buys the furs) will tell you that some cat skinners will bring him a better pelt.


Sure a proper quench build is ‘more better’,
So you do agree then.... yes/no????

yes ... But that also doesn’t mean an off the shelf GM base engine will not work as it does in a S load of boats around the world every day.
No agreement there.
There are umpteen thousands and umpteen thousands of GM builds out there, and they are working just fine.

Kgohst correctly and properly lays out the options.
I highly doubt that he has ever built a Q/E combustion chamber into a SBC. If he had, he just might understand the value of it.


OP is a mechanic and can decide what he wants to spend and what he wants the boat to do.
Precisely.
Read Johnny's posts more closely and thoroughly, and you'll see that he is interested in doing a Q/E build.

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Returntrip said:

Thanks about the switch wiring. What would you recommend on stroker Quench? .040? or greater?
As said earlier, the .038" quench dimension is used on the 5.7L SBC. This is a suggestion by Dennis Moore.
When the stroke is increased by .270", the quench dimension will be increased some.
I have always targeted .042" to .045".
The Hot Rod guys will shoot for approximately .060" for the 6.3L build due to the higher RPM that these are operated at.

And yes on the book, I would absolutely buy a copy of that book.
I would be willing to loan mine out for a reasonable deposit. I'll shoot you a PM if interested.

I'm currently reading a couple books, one about blueprinting and another about sbc chevy builds, written by David Vizard. They are almost too intense.
Any idea on a KB part # for the suggested "D' shaped LCQ pistons 4.030.
With your Vortec cylinder heads, you won't be using a D-Dished piston. You'll do better with a LCQ style piston.
Keep in mind (no matter which piston profile you go with) that the piston must be correct for the 3.750" stroke and the 5.7" connecting rods.

Dont see them in my Summit catalog. Scat pro comp 'I" beam rods look quite affordable wit the correct KB pitons.

To the Nay-Sayers, I am trying to repair, rebuild & modify a MERCRUISER power plant! It just happens to be, the heart of the plant is produced & manufactured by GENERAL MOTORS..... made for Chevrolet.
Yes, and this is not necessarily an exclusive Mercruiser related build.
The minute that Mercruiser is mentioned in a Q/E style build, several of these guys get their underwear in a knot.
These guys are typically parts changers and are not able to think-outside-of-the-box.

Had Wilbur and Orville limited themselves to In-the-box-thinking, they would have NEVER flown.


Im interested in this build, I have some down time due to weather and some money. I would rather go swimming with a Rolex instead of a Timex....
Well said.
Your proposed Q/E build is the Rolex..... and the standard run-of-mill GM build is the Timex!

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kghost said:

You are attempting to build an engine that will far exceed the demand or need, in my opinion.

You could purchase a brand new crate Marine stroker small long block for 4-5 thousand dollars or a re-manufactured for less and get exactly what you need from it.

All this special detail is great when building a high performance engine but you do not have that need nor will it make any real world difference in your boat. 300+/- horse power is the same no matter what the internals are.

If you are doing this for the fun of it then fine, but all this detail is completely unnecessary for a engine that will not see past 4500 rpm. There is no real benefit.

If you were on a mission to build a high power short in length speed boat with a bullet proofed stroker then following your suggested internal build plan may bare fruit but for a simple salt water boat to be used at low to moderate speeds......Way over kill

Also after all this special effort if you have a hiccup and the motor inhales salt water and you push a piston thru the cylinder wall or bend a rod.........It will all be for not!

Remember this, The 90's Vortec GM Truck engines routinely last for 200,000 miles plus, as built by GM and do not use any of PCKR's reccomendations

This is a Mercruiser marine repair help site, NOT a small block chevy high performance engine build web site.

The majority of this post does not belong here and has gone completely off topic (as usual with PCKR when he tries to impress)

You should think about starting a completely new topic in this section.

http://www.marineengine.com/boat-fo...-Gas-Inboard-Mfgs-IO-and-Sterndrive-Questions.....

and title it - (How to build a small block Chevy by da man PCKR)

Click to expand...

RicardoMarine said:

I'm seeing some almost unbelievable and definitely uninformed responses in this thread.

Johnny, hang in there. You will get through this, in spite of all of the disruptions and Nay-Saying.


And more importantly, let's all put our differences beside, and wish each other a Merry Christmas and Happy Holiday season.


.

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Docksidemarineservices said:

"if you have a hiccup and the motor inhales salt water and you push a piston thru the cylinder wall or bend a rod.........It will all be for not!"

In other words, unless your engine is running 100% all the time, you don't loose ignition while running 3500rpm and live in a perfect world any water ingestion is going to kink a connecting rod with a QE build.

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