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**Guest** · 01-30-2012, 06:48 AM

and a pic of the boat just for the heck of it

Attached files [img]/media/kunena/attachments/vb/651157=24407-IMAG0246.jpg[/img]

**2850Bounty** · 01-30-2012, 08:12 AM

I don't want to take anything away from these great automotive shops who build these engines, but they tend to build to automotive high performance specs, not fully understanding Marine loads.

You have F/T pistons with the 76cc chamber cylinder heads being used with a 3.750" stroke.

The Flat Top is a great choice for a 3.480" stroke (5.7L) and 76cc heads...... but with the 3.750" stroke (400 cu in), the C/R is increased quite a bit.

Then we add the Marine application to this, and Yikes!

If you run the calc's, and plug in an average deck height dimension, a decent quench dimension, toss in a few cc's for valve relief's....... this comes up to be a static C/R of approximately 10.1428:1..... not 9:1 !

That's over one full point difference between their numbers and mine.

Here's a calculator if you want to run the numbers for yourself.

You also mention timing advance of 28*.... but do not mention the RPM.

We can't make any sense out of TA numbers without an associated RPM.

Where was your TA in terms of RPM???

I can detonate just about any SBC Marine engine if I throw in too much advance and too soon... even on a well built Q/E SBC engine!

While this assembly does offer a Quench, the Marine head gasket set did not help promote this. We typically want to bring this down to approximately .038" for Marine use.

However, I'll take a poor quench any day over no quench at all.

Your damage does not appear to show much heat. It may still be damage from Detonation, but you'll need to know a few other things...... F/A ratio and TA for example, of which either can lead to detonation damage.

Did this shop know that this engine was being used in a Marine app????

How many pistons were damaged like this... just the one????

What RPM were you running at when she failed????

Which connecting rods were used.... long rods/short skirts by chance????

Long rods place the wrist pin higher and reduce the top ring landing dimension.... and typically shorten the effective skirt length.

Not a good combo for a Marine 377/383, IMO, but works well for street use.

Can you get a piston part number from them?????

Can you get a rod part number from them????

The shop is likely who you looked to for advice on how this was to be built. And I understand that.

However, what you do from there (F/A ratio and Ignition Timing) is out of their hands, and unfortunately leaving the burden of proof up to you!

IOW, assuming that this IS Detonation Damage......, did this detonate due to an incorrect build.... or did it detonate due to several other factors out of their control????

BTW, baring short skirts and ring landing dimension...., these F/T's are an excellent choice in that these are single valve reliefs. No need for a double relief piston.

This, or a similar piston with the correct deck height and gasket thickness, and a 76cc chamber would be very good in a 5.7L.

The negative thing is..... I think that they're incorrect for the longer 383 stroke and 76cc combustion chamber volume.

Tough call... I don't know what else to suggest.

Do you dare mention the shop's name????

.

**Guest** · 01-30-2012, 09:25 AM

2850Bounty wrote:

Do you dare mention the shop's name????

Boy, I'm kinda nervous now. The seven year warranty leads me to believe that I know which shop it came from and I have been debating a 383 from them before Spring to swap out my 5.7 in my 2655.

**2850Bounty** · 01-30-2012, 09:45 AM

skot0123 wrote:
Boy, I'm kinda nervous now. The seven year warranty leads me to believe that I know which shop it came from and I have been debating a 383 from them before Spring to swap out my 5.7 in my 2655.

Do not fret having one built.... but educate yourself so that the correct parts and build techniques are used..... and steer clear of certain automotive builds.

The 377/383 is an excellent engine when done correctly. It's also nothing new.... guys have been building this version for years.

The only draw back is that most builds suit the high performance auto applications and not Marine.

Many of these shops are stuck with the mind-set that the Auto Build works for Marine as well, when in fact it does not.

The differences are minimal, and they don't need to break the bank!

Anyone can do it!

BTW, MichiganMotors has indicated that they are willing to do a Quench built 377/383 for us on a custom order basis.

**Guest** · 01-30-2012, 12:08 PM

Given everything you have mentioned, I would lean toward too high of compression and maybe to lean on fuel mix.

Also what temp thermostat are you running - the lower (160) the better with 383's.

I did my first 383 build from a company out of the PNW - worst decision ever. They tried to balance internally and undercut the piston landings resulting in a grenade going off inside it. My current is custom built by local shop. The BAD PNW shop had an "S" in the name, not going to say anymore about that!

My advice (if you care

) would be to pull all the pistons, check block for scoring, replace all the pistons with good "D" dish Keith Black's, verify and / or retool the heads / block for .038 - .040 quench, lower the temp cooling, and recalc your carb to run slightly rich until you can plug read the mixture after 50 - 100 hrs or so, then adjust slightly still staying on the rich side (this is what I do on a Edelbrock 1409 carb) After the first 100 hrs I had just a small amount of "black" carbon on the plug edges - which would be slightly "rich" - excellent for a marine cruiser! Also you may need / want to verify the advance on the distributor curve to get the right "curve" for marine cruiser.

Hope this helps.

**Guest** · 01-30-2012, 04:37 PM

Thanks for the responses the engine was sold as a marine engine and they were fully aware of what its use was. I am from alaska and i my engine on a trip bit the dust just before i am flying out to OK to drive back with some horses. I think well i will just pick up a long block and throw it in the boat when i get home save me some time and shipping costs. I was suposed to pick this engine up at there shop in Portland on my way to alaska i had another stop to make there so it seemed to all work out good. I called them a few days before i would get there and they said they did not have it done and i would be a week i told them i needed it now gave them 4 weeks build time. Then the truck i was driving caught fire in WY and burned to the ground trip got redirected to MT were i had family to get my horses set with then i went and bought a used dodge pickup and finished my trip and never made to get my moter that was not done anyhow. They a few weeks go by and one moter shipped to the wrong place i get my moter from fedex. The company is CHS machine and the owner is Greg is the biggest lier i have ever seen dont know how there are still in business never buy from them ever.

The timing was set at 28 degrees at 3200 rpm seemed way safe to me

The moter let loose i would say at around 3400 rpm i just got on step

Thermostat is a 150 degree and i am a closed cooling system

The rods and pistons i am not sure of the place i got it from will not take me anymore i just get hung up on the machine shop they are at now my dad took them in i am few hundred miles from the moter right now going to give a call later in the week see if they can tell me just droped off last week. The shop i took them to is known to be a good shop should have had them build it i guess.

The carb i took to the best carb guy around here been doing it for 53 years he also knows marine carb setup well i took him the same specs i posted here and he rebuilt my carb i dont know what the burn on the plugs were did not go long enough

I could have set i up wrong i dont think i did but been wrong before at this point am done with machine shop i just want to get it back togeather. With what got is there any way of lowering the compresson ratio to get it to run on pump gas? would i be better off puting this back togeather and selling it as a street moter and starting over? as it is winter now i a have a motor in my boat that runs ok but is not new and i dont like break downs.

thanks for the help i just dont know what to do anymore oh sorry for the misspelling i have some messed up finger that dont let me type so well at the moment

Attached files [img]/media/kunena/attachments/vb/651320=24413-IMAG0227.jpg[/img]

**Guest** · 01-30-2012, 04:52 PM

Dude, your like a bad country song - I just hope your dog does not die!

I am really sorry to hear all this.

That was a fairly new truck to burn. What happened?

I am not sure what to suggest on the engine. See if you can change pistons to a "D" dish to lower your compression ratio? Are the walls scored?

Something was not built right in it.

**Guest** · 01-30-2012, 04:59 PM

rmk4x4 wrote:
Thanks for the responses the engine was sold as a marine engine and they were fully aware of what its use was. I am from alaska and i my engine on a trip bit the dust just before i am flying out to OK to drive back with some horses. I think well i will just pick up a long block and throw it in the boat when i get home save me some time and shipping costs. I was suposed to pick this engine up at there shop in Portland on my way to alaska i had another stop to make there so it seemed to all work out good. I called them a few days before i would get there and they said they did not have it done and i would be a week i told them i needed it now gave them 4 weeks build time. Then the truck i was driving caught fire in WY and burned to the ground trip got redirected to MT were i had family to get my horses set with then i went and bought a used dodge pickup and finished my trip and never made to get my moter that was not done anyhow. They a few weeks go by and one moter shipped to the wrong place i get my moter from fedex. The company is CHS machine and the owner is Greg is the biggest lier i have ever seen dont know how there are still in business never buy from them ever.

The timing was set at 28 degrees at 3200 rpm seemed way safe to me

The moter let loose i would say at around 3400 rpm i just got on step

Thermostat is a 150 degree and i am a closed cooling system

The rods and pistons i am not sure of the place i got it from will not take me anymore i just get hung up on the machine shop they are at now my dad took them in i am few hundred miles from the moter right now going to give a call later in the week see if they can tell me just droped off last week. The shop i took them to is known to be a good shop should have had them build it i guess.

The carb i took to the best carb guy around here been doing it for 53 years he also knows marine carb setup well i took him the same specs i posted here and he rebuilt my carb i dont know what the burn on the plugs were did not go long enough

I could have set i up wrong i dont think i did but been wrong before at this point am done with machine shop i just want to get it back togeather. With what got is there any way of lowering the compresson ratio to get it to run on pump gas? would i be better off puting this back togeather and selling it as a street moter and starting over? as it is winter now i a have a motor in my boat that runs ok but is not new and i dont like break downs.

thanks for the help i just dont know what to do anymore oh sorry for the misspelling i have some messed up finger that dont let me type so well at the moment

um.....why did your truck burn up???was it cuz you came down from alaska and the truck spontaniously burned up???

man..thats tough.....

hope you get everything all back together.....I would go with what jeff says about the 383...it's usually a bullet proof motor for boats....if built correctly...

:arr arr

**Guest** · 01-30-2012, 05:02 PM

i think an oil like blew on the turbo oil pressure droped and pulled over and seen the engine in flames so did a fast unpack the truck was from down south. it was taken care of with insurance but i got another dodge cummins to make the rest of the trip.

**2850Bounty** · 01-30-2012, 05:49 PM

I think that this was your red flag that should have prompted you to ask many questions of them.

I'll try to find out what the local word is on this company.

**Guest** · 01-30-2012, 06:09 PM

2850Bounty wrote:
Do not fret having one built.... but educate yourself so that the correct parts and build techniques are used..... and steer clear of certain automotive builds.

The 377/383 is an excellent engine when done correctly. It's also nothing new.... guys have been building this version for years.

The only draw back is that most builds suit the high performance auto applications and not Marine.

Many of these shops are stuck with the mind-set that the Auto Build works for Marine as well, when in fact it does not.

The differences are minimal, and they don't need to break the bank!

Anyone can do it!

BTW, MichiganMotors has indicated that they are willing to do a Quench built 377/383 for us on a custom order basis.

Rick

Out of curiosity couldn't an engine like that be tuned to live happy with 10.1 compression. I'd assume if the quench were nice and tight and the timing dialed in slowly, with the right cam, you could pretty easily avoid detonation. But that's coming from car/bike experience only.

**Guest** · 01-30-2012, 08:26 PM

2850Bounty wrote:
I think that this was your red flag that should have prompted you to ask many questions of them.

I'll try to find out what the local word is on this company.

they have a bad rating at the BBB a fast web search turns up lots of people with same issues of being lied to about things. at the time i just wanted to get an engine called them sounded nice on the phone before they got my money they were in the right place for my trip so i went with it. I wish now i would have done more research still kicking myself. Seems stange that they never wanted to even see a pic of the damage. i am out of things to do other than move on and try to make somthing out of this engine with out spending alot more on it. they also go by the name motercrate engines.

**2850Bounty** · 01-30-2012, 08:54 PM

courtjeste wrote:
Rick Out of curiosity couldn't an engine like that be tuned to live happy with 10.1 compression. I'd assume if the quench were nice and tight and the timing dialed in slowly, with the right cam, you could pretty easily avoid detonation. But that's coming from car/bike experience only.

You could probably pull this off in a small or high altitude boat...., but in a near sea level cruiser (lets say anything 25 foot and up) it becomes an almost impossible task.

High cylinder pressures being one obstacle of which can lead to high cylinder temperatures of which can lead to detonation.

Yes, the quench or squish helps greatly, but it is not the complete answer unless all else is harmoniously planned out.

Another method would be to do as Dave McCloughlin has done (aka Yachtman). Dave is using a D-dish style quench piston with aluminum heads that will help pull heat away from the combustion chamber. Even so, Dave's piston dish volume gives him a C/R suitable for a Marine build.

I am sometimes puzzled as to why these people have trouble selecting the correct components for a 377/383 Marine build. Most any piston company can provide a piston that does we want it to do.... including the quench surface and correct dish volume, wrist pin height, skirt length, etc.

Like said earlier, this is nothing new. The 6.6L SBC (400 cu in w/ 3.750" stroke) came out in the 70's. Due to the Siamese Cylinders we don't use them for Marine......., but we do use the crankshaft stroke by building the 6.2L (377/383 cu in) in the 5.7L cylinder block.

If we could use the 6.6L as is, we stil need to keep the C/R down, and we still want a Quench Effect, IMO.

The Siamese cylinders prevent this from being a good candidate for Marine..... otherwise, it would be great!

.

**2850Bounty** · 01-30-2012, 09:05 PM

rmk4x4 wrote:
they have a bad rating at the BBB a fast web search turns up lots of people with same issues of being lied to about things. at the time i just wanted to get an engine called them sounded nice on the phone before they got my money they were in the right place for my trip so i went with it. I wish now i would have done more research still kicking myself. Seems stange that they never wanted to even see a pic of the damage. i am out of things to do other than move on and try to make somthing out of this engine with out spending alot more on it. they also go by the name motercrate engines.

How 'bout this?

If the bores are not damaged, you can give them a fresh honing to break the glaze!

Then you can order the correct pistons/rings set, and install them. IOW, do what CHS should have done in the first place!

rod

This would be a piston that mirrors the cylinder head "wedge" area, and has a dish volume that brings the C/R within desired specs.

Consult with a pro at a company of your choice..... they will recommend the correct p/n for you.

Something like this piston..... (example only!)

An automotive machine shop can swap the connecting rods for you.

Replace rod bearings if need be (not all that expensive to replace them).

If you are careful, and keep everything together, you probably won't have to replace these.

Your engine is Closed System Cooled, so you do not need the Marine Head Gasket set.

Instead, use a high grade automotive head gasket that nets the correct quench dimension.

Check the deck height, and select the gasket thickness that will bring the squish/quench down to approximately .038" for Marine use.

The cylinder that showed the damage may need a valve dress-up only.

Take that head in and have those two valves looked at.

Put her back together.... set your cam followers using the static 8 stop procedure.

Fire it up and double check your Ingition Timing and remember that BASE is BASE ONLY.... so be sure to check the TA @ 3.2k rpm.

Run it under load and seat your rings...... and then start using it.

**********************

http://"http://www.marineengine.com/...d a quick read... it may help you understand why we don't want to use the full dished piston to lower the C/R.

Post #7 will link you to a few good articles re; quench, squish waves, detonation, etc.

.

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