swapping to Vortec heads WITH smog

[gramps77]

For you guys more familiar with the workings of an engine, am I gonna shoot myself in the foot if I swap from old boat anchor 76cc crate engine heads to Vortec 64cc heads?
I buddy had mentioned the efficiency may cause some of my readings to go up. It passes CA smog easily now. I did the swap in a 66 Nova I had (no smog) and the car ran a lot better and gained noticeable power is my reason for wanting to swap

[MikeB]

Efficiency is a good thing when it comes to emissions, unless you live in Bizarro World like this guy.


If everything but heads and intake manifold stays the same, I'd bet the Vortecs will have cleaner exhaust.

[mattcrp1]

NOx may go up due to the higher compression.

[gramps77]

Originally Posted by mattcrp1

NOx may go up due to the higher compression.

And thats exactly what was mentioned.

Any one have some real world experience?

[bmchevy1979]

Also I don't think there is a smog legal intake for vortec heads with a carb

[gramps77]

Originally Posted by bmchevy1979

Also I don't think there is a smog legal intake for vortec heads with a carb

well dang it, thats not good.....although they looked up the Edelbrock I have on there now and showed me some CA smog code that said what I had was ok. (they initially thought it wasnt but the wording made it ok)

[MikeB]

Originally Posted by mattcrp1

NOx may go up due to the higher compression.

I've read that your statement is true for some combustion chamber types, most notably hemispheric chambers, which is why the new Hemis really aren't Hemis at all.

However, I seriously doubt if GM would have designed and implemented Vortec heads AND increased compression if the result was increased NOx vs. the old heads with D-shaped chambers.

Depending on the piston style used in the OP's old engine, as well as actual deck height (typically around 9.030"), compression with 64cc chambers may increase to only 9.0:1, which is less than 96-up Vortec 350s at 9.4:1.

On another note, doesn't California offer any kind of exemptions for older vehicles?

[mattcrp1]

Originally Posted by MikeB

I've read that your statement is true for some combustion chamber types, most notably hemispheric chambers, which is why the new Hemis really aren't Hemis at all.

However, I seriously doubt if GM would have designed and implemented Vortec heads AND increased compression if the result was increased NOx vs. the old heads with D-shaped chambers.

Depending on the piston style used in the OP's old engine, as well as actual deck height (typically around 9.030"), compression with 64cc chambers may increase to only 9.0:1, which is less than 96-up Vortec 350s at 9.4:1.

On another note, doesn't California offer any kind of exemptions for older vehicles?

If it were only 4-6cc I would more inclined to go with your train of thought, but the OP stated 76cc original heads going to 64cc heads. 12cc is quite a jump.

When I had my smog license here in the bay area I performed combustion chamber cleanings to remove carbon from trucks to get the NOx readings in spec.

I think this calls for a before and after test

I think it is also a function of the old pellet style cat converters verses the newer honey comb style and there efficiency.

[Ziegelsteinfaust]

I know on the tbi's they get the egr from the exhaust manifolds. So a possibility is there.

The real problem may lay in making it look stock enough to fool the people.

Having built, and been a part of several smog "legal" builds I would just use standard performance heads.

[MikeB]

So they actually look at the engine on a 30+ year old truck to make sure all the parts are factory stock? Just how in the heck do all the engine and car builders in CA sell anything to in-state customers? What's next, jail time for installing aftermarket parts?

It's so sad that politicians run amok have taken over such a beautiful state and the home of hot-rodding.

[beamn7]

Gramps, if it was me and knowing how our smog laws are, I wouldn't bother. Drive it and enjoy it and keep your fingers crossed that someday the law will change and allow for rolling model year exemptions....
A smog legal fit you could do is a set of World Products sportsman 2 heads and a performer manifold. That would wake it up a bit and be legal.
http://www.theengineshop.com/product...ron-heads.html
On the other hand, you could do an entire late model motor swap and then take it to a referee to get it signed off on but then you have to meet emissions level for the engine model year you install and not the vehicle model year...

Mike, yes, in CA we have to smog any vehicle newer than 1975 and it gets a visual inspection as well as a tailpipe sniff. You would think it would be 30 years or older but no, they base it off when cats first got installed on vehicles...

Oh well, I'm going to go an pretend to water my yard now...

[gramps77]

keep in mind, a CATALYTIC CONVERTER IS NOT REQUIRED for me. Its a Heavy Half Ton and makes the cut off by 50 pounds according to the door sticker Matt. Just about everytime I smog it, the guy will go back and forth to "the book" and GVWR sticker verifying its not.
The engine is the 260 hp crate 350 which is "rated" at 8.5-1 compression but Ive read its actually closer to 8.1-1.

['68 Newtricks]

Are these actual Vortec heads or just TBI heads? I'm running '92 heads on my 400 with a ProProducts intake manifold and EGR. Passes visual and sniff My comp is ~9.2:1

[gramps77]

actual Vortec, 062/906 heads are what Im looking at.

['68 Newtricks]

The aluminum heads I believe have a carb conversion manifold but no provisions for EGR. I'd love to see one in person as it might be possible to drill a couple holes, tap, and install a dummy EGR. As long as it's there, that's all that maters. It doesn't even have to work

[Tom]

Even if the emissions do go up slightly with the better heads and compression, your not running a cat yet so you can always add one to bring the readings back down. I put a vortec 350 into my old 79 and ran cats just so I wouldn't have to even worry about emissions or emissions tuning before taking the test.