1983 5.7L V8 Chevy rebuild

[docben]

I am now in the process of rebuilding the engine that came out of my 1985 24 foot Beachcraft Cuddy. The first bad news is all the exterior rust on the block and nearly every part. Not easy removing the driveshaft and ball gear since corrosion in the splines made a strong weld with the coupler. As seen in the photos, rust everywhere. The previous owners must have left this engine sit in water for years.Maybe fortunate it was likely "fresh" water.

So here I go with questions:

1. Do I replace the GM water pump with a "marine" one and why?
2. If valves look good and do not leak water or prussian blue between seat and valve, do I need to remove the valve springs, etc., for more inspection?
3. The engine was burning more oil than normal, the proof is the wet exhaust ports and an oily residue in the large exhaust port. I have yet to check rings. Could the valve guides contribute to oil residue?
4. Will I need a new coupling, since the old one is quite rusty?
5. The heads and block have imprints. Where do I look them up to find the vintage?
Any other suggestions on this rebuild?
Thanks!

 

[stresspoint]

your best bet would be to get the whole thing stripped then take the parts to someone that can hot tank or robo wash everything .

once you get it all cleaned up you can then assess what will need replacement and what can be reused..

bores need yo be measured and so forth to determine if re bore oversize or just a hone is required ,internal rust in the water jackets assessed , crank , camshaft recondition/ replacement , welsh plugs replacement and other requirements like oil pump etc..

i find leaving the heads to the head re conditioners to assess them and rebuild the necessary things like guides , seats and what not is the cheapest , easiest and best option.

pay attention to the sump in your case , if it has rust at all " replace it , don't skimp there as a small pit mark easily turns into a hole and you will loose your new engine.

 

[Scott Danforth]

So here I go with questions:

1. Do I replace the GM water pump with a "marine" one and why?
2. If valves look good and do not leak water or prussian blue between seat and valve, do I need to remove the valve springs, etc., for more inspection?
3. The engine was burning more oil than normal, the proof is the wet exhaust ports and an oily residue in the large exhaust port. I have yet to check rings. Could the valve guides contribute to oil residue?
4. Will I need a new coupling, since the old one is quite rusty?
5. The heads and block have imprints. Where do I look them up to find the vintage?
Any other suggestions on this rebuild?
Thanks!

1- brass impeller and stainless backing plate on marine only. an automotive one will rust out in about 6 months. if you put a heat exchanger on it and run glycol, then yes, you can use a non-marine water pump.

2 - yes. you will want to inspect the ports and do a valve job. you may also need to install guide bushings

3 - yes, so can the rings, and valve seals

4 - if you cant clean the rust, yes. I would soak in oxalic acid for a few days

5. look at casting numbers - they dont lie. however its a 1980-1984 block/motor. you cant use the better 1986 or later motors because there are no OMC stringer coupling pucks for the 1-piece RMS motor. 1985 would be the last of the 2-piece blocks with the new perimeter bolt heads.

talk to your machine shop.

 

[Redrig]

Regarding 4.

How are the splines on the Intermediate drive shaft ? Are they worn at all ?

My understanding is there was a "newer style" coupler that was made that is meant hold in grease better to protect the splines more at that connection.

They have a bottom , not open like yours.

Might be worth looking into while it's all apart .

It's on my list to do as well.

And side note. Do you know the full story of the engine ? I thought it was 70s engines that were painted that color of OMC (electric shift era) . Mid 80s were silver weren't they ?

 

[Scott Danforth]

cant make out the block casting

however the heads are the non-desirable 76cc smog motor heads

462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves

 

[docben]

cant make out the block casting

however the heads are the non-desirable 76cc smog motor heads

462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves

Casting 14010207 GM 5.7LG. what does the LG mean?
So what heads would you prefer? Why are they "non-desirable"??

 

[docben]

Regarding 4.

How are the splines on the Intermediate drive shaft ? Are they worn at all ?

My understanding is there was a "newer style" coupler that was made that is meant hold in grease better to protect the splines more at that connection.

They have a bottom , not open like yours.

Might be worth looking into while it's all apart .

It's on my list to do as well.

And side note. Do you know the full story of the engine ? I thought it was 70s engines that were painted that color of OMC (electric shift era) . Mid 80s were silver weren't they ?

Splines are good. Removing the rust they are good.
The coupler has an o-ring and a very small hole on the cap, I assume for venting.

I really wish I did know the history, but might not have bought the boat! LOL. My friend doing the same says my rust is trivial compared to his. RUST WARS...LOL.

Another good auto mechanic friend says all my parts look pretty good. Just need rings, gaskets, rod and main bearings and head bolts. Do most boat mechanics replace the head bolts?

I am trying to source the parts, not wanting any china made crap. Nor India.

How is enginetech dot com?? Good, bad or neutral?

 

[docben]

cant make out the block casting

however the heads are the non-desirable 76cc smog motor heads

462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves

On another forum was stated...

Well, there's good news and a little bad news about these heads!

The Good News; Chevy used these heads from 1976 to 1987 on 350 cid engines.
They were fitted with either 1.94" Intake/1.50" Exhaust, or 2.02" Intake/1.60" Exhaust Valves, all these heads had 76cc combustion chambers.

The Bad News; these heads are crack prone!
:roll:
So, before sink a bunch of $$$'s into them for fancy machine work and expensive parts, ect., it would be best to have them magnifluxed to check for cracks.

Are they good or bad? Depends on the heads actual condition and your plans for them.
Could be either way.
As for as making power, yep!
They'll do that, depending on condition.
Good valve size, nice combustion chamber size depending on the pistons used with them.
If there are no cracks, build'em and run'em.
If they have cracks, swap'em out for a better set of heads.

Hope this helps!

END of statement.

Mine are in good shape with no obvious cracks, BUT, should I get them magnafluxed?

 

[docben]

On another forum was stated...

Well, there's good news and a little bad news about these heads!

The Good News; Chevy used these heads from 1976 to 1987 on 350 cid engines.
They were fitted with either 1.94" Intake/1.50" Exhaust, or 2.02" Intake/1.60" Exhaust Valves, all these heads had 76cc combustion chambers.

The Bad News; these heads are crack prone!
:roll:
So, before sink a bunch of $$$'s into them for fancy machine work and expensive parts, ect., it would be best to have them magnifluxed to check for cracks.

Are they good or bad? Depends on the heads actual condition and your plans for them.
Could be either way.
As for as making power, yep!
They'll do that, depending on condition.
Good valve size, nice combustion chamber size depending on the pistons used with them.
If there are no cracks, build'em and run'em.
If they have cracks, swap'em out for a better set of heads.

Hope this helps!

END of statement.

Mine are in good shape with no obvious cracks, BUT, should I get them magnafluxed?

And another guy in same forum (Mortec) says...
"No 76cc small block head is worth time or effort or running on a engine, they are quite simply the worst head chevy ever put on a small block , terrible chamber design and spark plug location. Gas guzzlers !"

So I wonder if boaters had the same issue as the auto guys??

 

[docben]

And another guy in same forum (Mortec) says...
"No 76cc small block head is worth time or effort or running on a engine, they are quite simply the worst head chevy ever put on a small block , terrible chamber design and spark plug location. Gas guzzlers !"

So I wonder if boaters had the same issue as the auto guys??

I search the forums and get negative info on these heads! Damn. Do I take the chance and use them, OR, get something better? I sure as hell don't want to put crack-prone heads on my rebuilt engine. What would you boaters do?

 

[stresspoint]

heads would have cracked already if they were going to crack.

main thing to be aware of is their condition in regards to rust internally.

the motor pics show no signs of water intrusion to combustion areas or oil . have them crack tested "" given when rebuilding heads for a head reconditioning shop" should be .all part of the service bur it may pay to request just in case they are slackers..

chase down some double humpy fuelies if you want power , or convert to vortec set up.

i re3gards to head bolts , well its depending on the condition when it comes to older SB chevy, if bolts are rusted and clean up is just a waste of effort , replace them , if you can do a quick spin on a wire brush wheel and the look good , use them, , they are not TTY.

 

[Scott Danforth]

76cc heads can make power...... with domed pistons, etc. however with flat top pistons, you are in the 8:1 category for compression vs the 9.3-9.4 you get with the 64cc vortec heads.

all chevy SBC heads are prone to cracking if you overheat them.

get something better. just get a set of vortec heads.