73-87 5.3 exhaust manifold question

[68c10owner]

Tried a search but couldnt find what I was looking for. I have a 79 C10 and planning a 5.3 swap from a 03-up truck. These years dont have the EGR so Im wondering if there are any frame clearance issues. I live in California and to be a legal swap I have to use the manifolds from the donor truck. Just trying to do my homework.

[kipps]

Everything I've seen says that the frame can be notched a little to clear the factory manifolds. I'm sure it depends on the engine mounts, and the resulting engine position.

That said, I'd just swap with 2006 trailblazer or 2010 camaro manifolds. As long as they are still equipped with the heat shields, they look very close to stock. The only way someone will know they were changed, would be by checking part numbers. I seriously doubt that happens.

[68c10owner]

Originally Posted by kipps

Everything I've seen says that the frame can be notched a little to clear the factory manifolds. I'm sure it depends on the engine mounts, and the resulting engine position.

That said, I'd just swap with 2006 trailblazer or 2010 camaro manifolds. As long as they are still equipped with the heat shields, they look very close to stock. The only way someone will know they were changed, would be by checking part numbers. I seriously doubt that happens.

Well here in California I will have to go through a referee station to make it a legal engine swap and they just might check everything. Never done it before. I know about notching the frame but I thought it was for early manifolds with EGR. Not a big deal to notch the frame but would rather not if I dont have to

[Gregski]

Originally Posted by 68c10owner

Well here in California I will have to go through a referee station to make it a legal engine swap and they just might check everything. Never done it before.

You will need the EVAP system which means stock fuel tank, stock fuel lines, stock Evaporative Emissions lines. You will need stock exhaust, which includes the CATs and rear O2 Sensors. I think you will need more than the stock PCM since it doesn't control Fuel Level etc. By the time you are done swapping components you might as well mount your 79 on top of a 2003 chassis, lol.

Originally Posted by 68c10owner

I know about notching the frame but I thought it was for early manifolds with EGR. Not a big deal to notch the frame but would rather not if I dont have to

It has nothing to do with the EGR as that port is in front of the manifold and the interference is in the rear at the three bolt flange. Both EGR and non EGR are the same castings pretty much otherwise. If you had a 1975 or older truck, these Hooker 2.5" exhaust manifolds work great:

[54Caddy]

Get headers that are C.A.R.B legal for the donor vehicle. Should work when you get it state refed

[Gregski]

Originally Posted by 54Caddy

Get headers that are C.A.R.B legal for the donor vehicle. Should work when you get it state refed

False

[Gregski]

Not to be a bearer of bad news, but I am in Nor Cal and you will not pass SMOG. Also on my '74 the driver side stock manifold cleared fine, on the passenger side the triangle flange hits the frame. I do NOT recommend notching the frame.

You need to drop $10K on a GM E-rod engine to pass SMOG in California if you own a 1976 or newer truck.

https://www.gmperformancemotor.com/category/ERODE.html

also check out this video, this guy tried to do what you are about to

MG #59 - How hard is it to pass smog with an LS swap?

hope this helps, not being rude, just keeping it real, maybe saving you some headache

[kipps]

Yeah, I'm REALLY glad I don't live in California.

Another possible but probably ill-advised route -- build the modern engine to look as "stock" as possible. There's cast manifolds designed to put a carburetor on top of a LS engine. I've seen folks bolting a drive-by-wire throttle body and MAF sensor on top of those manifolds, and covering the whole thing with a round air cleaner. I also saw one build that clustered all eight ignition coils into a plausible "distributor", that at first glance, looked like the real deal. He had it mounted in the back of the valley pan, just like the old smallblocks. There's adapters to mount smallblock valve covers onto the LS heads. If really carefully done, the engine would be virtually indistinguishable from a stock small block. Add a dash of grease and grime, and the inspectors are likely to just whiff the exhaust, and send it on.

Again, I don't advise this, because I don't know California at all. But I would love to see the result. I've dreamed of an LSx engine that fools 90% of the car buffs into thinking that it's stock.

[68c10owner]

I know it can be done because we have members here who have done it. And I see other trucks with them swapped as well and none are using the Erod. Im planning to talk to the referee before I do the swap. Im going to buy a complete running truck for the swap so I`ll have everything from the original truck to transfer over as needed.

[Gregski]

Originally Posted by 68c10owner

I know it can be done because we have members here who have done it. And I see other trucks with them swapped as well and none are using the Erod. Im planning to talk to the referee before I do the swap. Im going to buy a complete running truck for the swap so I`ll have everything from the original truck to transfer over as needed.

Anthony, the key being 1975 or older, so find out what year their trucks are, and as always please keep us posted on how this goes. Also I'm your neighboor probly 15 minutes away so don't be a stranger, PM me.

[68c10owner]

Originally Posted by Gregski

Anthony, the key being 1975 or older, so find out what year their trucks are, and as always please keep us posted on how this goes. Also I'm your neighboor probly 15 minutes away so don't be a stranger, PM me.

One guy posted about his son's 90 k5 that just passed and everything they had to do and another guy I actually knew from here with a 1979 like mine out of Orangevale. Unfortunately he passed away a few years ago so I cant pick his brain. It can be done, and done legally. Yes there are more challenges on the 1976-up but I feel like having the complete running truck to pull part sc from will make it easier

[Gregski]

Originally Posted by 68c10owner

One guy posted about his son's 90 k5 that just passed and everything they had to do

Anthony, would you mind posting the link to his thread please

[68c10owner]

Originally Posted by Gregski

Anthony, would you mind posting the link to his thread please

http://67-72chevytrucks.com/vboard/s...d.php?t=784927

[prodjay10]

Can you grind down that flange a bit? I did with mine exact same spot but they were tbss manifolds and I don’t think it needed much finessing.

[prodjay10]

Wouldn’t a swapped vehicle be more efficient and also less of a carbon footprint for these older trucks? Why would there be so many debilitating restrictions on a swap?

[Gregski]

Originally Posted by prodjay10

Wouldn’t a swapped vehicle be more efficient and also less of a carbon footprint for these older trucks? Why would there be so many debilitating restrictions on a swap?

Car companies need to sell cars. One could argue that my '54 is better for the environment than the 6 10 year old trucks that came since (think environmental impacts of manufacturing them, air pollution of making more steel and plastic, shipping the parts across the oceans, and then disposing of the old 5 trucks to always stay current / modern)