mercruiser 4.3 thermostat housing

[ste80]

The non vortec and true vortec heads the intake and exhaust ports and combustion chambers are designed for better airflow and make more power. The easier way to tell is the intake manifold bolt pattern.vortec heads use 8 vertical head bolts instead of 12 angled into the cylinder heads. Ona 4.3 the vortec heads add about 20 hp.

the engine you show in the photos with vortec on the valve cover does not have vortec heads as shown by the intake bolt pattern. GM used the engine name vortec prior to introducing what became vortec heads in 1996.

Thanks. I know is not vortec but i was not sue
Re what was the difference because at the beginning i heard just the shaft balancer but is not true .
Tks

 

[ste80]

cool little Fiat

Thanks it took me 2 years to rebuilt it totally, now i use it just with sun and for fun

 

[ste80]

history lesson on the "vortec" name. for many years, GM (and many others) did not want to pay royalties to Sir Harry Ricardo for the better combustion chamber shape used today.

Vortec was a sales name given to the V6 about 1985 when the 4.3 was released. as Scott mentioned, the heads came in 1996

the Ricardo combustion chamber, AKA Vortec head chamber was not used until the reverse flow LT1 Gen 2 SBC when the patent ran out. then in 1996 the "vortec heads" were released for the Gen 1 SBC family.

Thanks very nice explanation very nice to see all this information . Congratulation to you and to all here in the forum very nice

 

[ste80]

Yep the Vortec heads are designed for more efficient combustion and add about 20 hp. The FIAT reminds me of the air cooled VW Beetles we all drove back in the 70s as broke college students….

This is 1968

 

[ste80]

But in your opinion. I i wanted to make my motor a vortec one cabs was it possible just using efi intake manifoold and heads?
Now from efi i also took alternator (70 amp vs 55 lx) and starter motor

 

[Lou C]

I thought of doing that with my pre Vortec, I had to replace the cylinder heads 7 years ago because of previous overheat damage. However I just wasn’t sure of all the details of the conversion (such as could I use the same pushrods & rocker arms) and so to keep it simple & avoid problems I just used the same casting number heads that it came with. Bought a set of remanufactured heads from a local machine shop for about $550 USD…& a marine gasket set (Fel Pro) and new cylinder head bolts (APR) …..worked out well….

 

[Scott Danforth]

If you want to swap the motor to vortex heads, just get vortex heads and a matching intake

 

[Lou C]

If you do be aware that the torque specs for the intake manifold are much lower that they were for the the pre Vortec (like 10-15 lbs vs 30-35 lbs for the pre Vortec) and I think the procedure for torquing the head gaskets may be different as well….

 

[Scott06]

But in your opinion. I i wanted to make my motor a vortec one cabs was it possible just using efi intake manifoold and heads?
Now from efi i also took alternator (70 amp vs 55 lx) and starter motor

as stated the difference between vortec and non vortec is the heads and intake manifold with the 8 vertical intake bolts. If you can find the heads worth the effort if you are rebuilding the engine.

the balance shaft came out maybe in 1992 and is not connected to the vortec head. lots of misinformation but you can research the various generations of Chevy/GM 4.3. in the US many of them were used in trucks and cars, parts were plentiful. outside the US maybe not so much.

 

[Lou C]

Also leaking intake gaskets were very common in the first few years of the Vortec engines & that will put water or antifreeze right into the cam valley and into the motor oil with deleterious consequences for engine wear. So if going that route make sure to use good quality gaskets and follow GM torque specs. On the pre Vortec the gaskets rarely if ever leaked.

 

[ste80]

Also leaking intake gaskets were very common in the first few years of the Vortec engines & that will put water or antifreeze right into the cam valley and into the motor oil with deleterious consequences for engine wear. So if going that route make sure to use good quality gaskets and follow GM torque specs. On the pre Vortec the gaskets rarely if ever leaked.

No no, now i'm doing all with prevortec components because i bought head 181 final so i have to go like this. I was just wander.
When you put the gasket you had only the 2 gasket for the intake i suppose and not the 2 parts that goes on the front and back part of the motor (still between intake manifold and cylinder block) where manual said to put silicon compound (black like motor seal)
But it is not clear to me if the 13 mm that they said to ovetlap where the gasket are is between gasket and head or between gasket and manifold.(Not sure if is clear my question)

 

[ste80]

If you want to swap the motor to vortex heads, just get vortex heads and a matching intake

Thanks. I won't do now but was my doubt.
Now i've got head for prevortec just bought and machined. I'm just wander if i can use the valves roket but i do not think so because they have same diameter but one code 17339 length 7.192" and one 17339 1 that should be 7.182 (but i don't know why the second is much more expensive)

Same i dont know for the the lifter that on lx is 811844 and efi is 811844 1 (they add the 1 at the end but i don't know the difference)
Do you or someone know?

 

[Lou C]

Ok for the intake gasket question the front & back ledges of the block you are going to use RTV. The way I did mine was to use just a little Permatex Aviation sealer on the water ports at the front & back of each cylinder head. This will keep the gaskets in place while you apply the RTV. Then lay a bead of RTV on the edge of the gasket where the edge of the manifold will contact it, run it up to the edge of the cylinder head. Next the trick is to lower the the manifold straight down without disturbing the gaskets. Then carefully torque down the 12 bolts to spec. I’m sure if you look there is a diagram showing exactly how to to this. I also used gasket sealer on the shank of each bolt this prevents oil from leaking up onto the manifold from the cam valley inside.
Valve driver differences and push rods/rocker arms Pre Vortec vs Vortec I can’t say that’s why I just went back with the pre Vortec heads (on mine the casting # ended in the # 68 that I remember from the originals).