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Changing heads

djp

New member
i was wondering if anyone can

i was wondering if anyone can help me with this i have a 1993 4.3lx 4 barrel mercruiser. i bought a 1993 4.3lx 4 barrel replacement motor (used) thinking i could use the heads from the motor i already had but even though the yrs and models are the same the engine numbers show different heads can i still use my heads ?
 
"You need to look at how the i

"You need to look at how the intake manifold bolts on, 2 types, bolts that screw in straight down (vortec) and ones that bolt on an angle, I beleive you have a vortec or straight bolt design.
If you use your intake from the old motor you can use your heads.

How many hours approx are on the old heads ? you may want to do a valve job on them.

Where do you see that they show different heads ? what are you looking at ?"
 
i looked up the heads on all t

i looked up the heads on all the parts websites using the two different engine numbers my old heads were about 550.00 and the heads that go to the engine i bought are about 350.00 the distributor part numbers are also different which one should i use? thanks for the response.
 
"What are the numbers you are

"What are the numbers you are using ? Dist part number could be different due to ignition system changes.

What are your old head numbers and new numbers, please include block #, and engine serial # if you have it.

there are 2 basic 4.3L v6 engines, internal balanced and non-balanced engine.

still the heads only matter depending on the manifold you want to use.

please provide some numbers."
 
this is what i know my engine

this is what i know my engine number is 0f015878 and the engine that i bought is 0d851905 but is missing the heads and carb outside of that i have all the parts with both engines im just not sure what parts i should use from which one
 
"[b]"i have all the parts

""i have all the parts with both engines im just not sure what parts i should use from which one"

Ayuh,...

just use the Heads, Intake,+Carb from the take out motor,...
It'll work Just Fine..."
 
Is there a problem with your o

Is there a problem with your old distributor ? is there a visible difference?
 
no and no its just the motors

no and no its just the motors call for two different ones im just not sure if there is a reason for that
 
"I just checked at another sit

"I just checked at another site and both part numbers for the Distributor assy. are the same.
sn# 0d851905 - 805185A37 DISTRIBUTOR ASSEMBLY
sn# 0f015878 - 805185A37 DISTRIBUTOR ASSEMBLY

And it looks like 2 diffrent heads,
sn# 0d851905 uses a 938-9427 = Sierra 18-4490
sn# 0f015878 uses a 938-824147 = Sierra 18-4491 (which is a vortec head)

So your engine being sn# 0f015878, I'd use the Vortec heads and the rest of your parts, providing good condition. :) Again depending on the age of the heads and wear you should think about a valve job while off, this will make sure you have MAX compression. To test to see if you really need to, prop the head up with the combustion chamber facing up and level, pour some light liquid ( not water ) like gas or kerosene into each valve area to cover the valves, wait an hour and see if any leak down the ports, this will tell you that air can also get by and you should do a valve job. Hope this helps. Safe Boating."
 
most of the time if a manufact

most of the time if a manufacturer changes one thing on a motor design they apply for the patent for that motor and they are required to have a new set of numbers
 
"Have to offer a counter view

"Have to offer a counter view on the link between a patent and part numbers. I’ve worked for a couple of OEM’s (original equipment manufacturer) and also file for patents.
There is no link between a patent and part number, patents are for inventions or “claims”. A patent is specific in describing the invention and how it works or how it is applied. A patent can never be tied to a specific part as you want the patent to be broad in scope but still enforceable in the eyes of the law, thus protecting your invention from copy cats.

The reason an OEM has a part number is simply control of the business, what gets built, sold and how it is maintained and guaranteed. A part number represents a something that is physically fabricated or assembled and it is defined by a set of engineering documents, i.e. paper drawings, electronic data, production specifications, inspection methods and maintenance procedures. All of this information must be maintained and controlled; NO matter if it is in production or not, the cost and maintenance of this business overhead is FOREVER! (Until it is no longer offered)

Take the cylinder head for example and not the item that has the valve train and other bits, just the head, a chunk of metal. It will have a unique part number and more specifically a unique dash number. i.e. xxxxxxx-xx, first part is the part number and second part is the dash number. Every company does it their way, it might be xxxxxxxAxx, doesn’t matter.

Just the head will have a part number and “dash”, thus the rough casting will be a (-4), then it gets forged (squeezed in a press for strength) or heat treated (same purpose) it can now be a (-3), now it is machined to a specific configuration to mount to engine “A” with a two barrel carb manifold with a unique hole pattern, now (-1). It may get machined to a different hole pattern for engine “B”, a 4 barrel carb manifold and a new number (-2). You may take an extra .020” off the deck for an different high performance gasket….new number.

Now when you put a valve guide into the head, another new number because now it is an assembly, add the valve train, new number. What drives change while a part is in active production, a million different things: new hole pattern but same casting, change in metal alloy, different hole for different valve guide, new finish, and on and on. Also if it is an assembly and a part of that assembly changes it can change the part numbers all the way up the chain to the final product.

Part numbers generally change as a rule of thumb if the change alters: fit, form, function, strength, performance, durability and/or maintenance procedure. And this is why serial numbers are important; that serial number of an engine has a specific BOM (bill of material) so you know what part is in that engine or boat.

And of course there is a whole string of tools both electronic and physical with each individual part number and assembly part number. And then there are assemblies but both are a whole new story."
 
holy cow i got dizzy just read

holy cow i got dizzy just reading that. thanks brian and steve for taking the time to look into this for me there seems to be alot of people who like to help other people out on this forum. let me do a recap of what i have learned. using my replacement motor i need to use my old motor vortec heads along with the intake.distributor.and anything else that i can reuse from my original motor. so i guess my only last question(for now) is will the camshaft in my repacement motor be ok to use?
 
hey mark !! that was an explan

hey mark !! that was an explanation i enjoyed and now understand! what did you build while in manufacturing?how about getting someone in your circle to tool up and build stainless exhaust manifold and riser sets for mercruiser stuff for under 1000 dollars a set !! i am tired of 2 to 3 seasons with the cast iron in florida brackish !
 
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