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-   -   Vortec head conversion - EGR (http://www.hotrodders.com/forum/vortec-head-conversion-egr-155820.html)

chevy_c10 03-28-2009 07:48 PM

Vortec head conversion - EGR
 
I am going to be swapping some vortec heads onto my 76 C10 pickup in the next few months and I want to keep my EGR. I know there will be those who say just ditch the egr but I am wanting to eventually update most everything on the truck and pass emissions. We do not have a visual test, just the gas analyzer test. My question is this, how is the exhaust gas plumbed to the intake. I am aware that I will have to weld a pipe into my #5 or #7 header pipe. However, does that pipe run to the top or the bottom of the intake and if it is to the bottom of the intake, how does that work? Does there have to be a hole drilled through the heads or the block to run the pipe through? Any insight would be greatly appreciated. I have been searching on this for a few days but am coming up empty handed. By the way, the truck has been converted from carb to TBI so the intake I will get will have a place for an EGR.

F-BIRD'88 03-28-2009 08:05 PM

If you'll also be changing the camshaft out for one with more duration and overlap than stock, then you can forgo the EGR plumbing. The increased overlap of the cam results in a internal self EGR effect at low engine speeds.

chevy_c10 03-28-2009 08:34 PM

I do intend to upgrade the cam. The one that I would like to use is the comp cams 12-262-4 with 262 intake/ 270 exhaust and at .050 has 218 intake/ 224 exhaust and the lift with 1.5 rockers is .464 intake and .470 exhaust and finally the LSA is 114 degrees. Is this enough to create the self- egr effect?

F-BIRD'88 03-28-2009 08:45 PM

I would think so and I would not go larger if emissions are important to you.
I ran a similar summit 1103 cam 214-224-112-.442-.465 in my old 350 vortec motor and it was very good on exhaust emissions on the smog test, even with no cats.
It passed easily.

Cats would have reduced that even further.

chevy_c10 03-28-2009 08:52 PM

That is great news then. At least I do not have to worry about spending the money and figuring out how to plumb the gasses. I want one day to have my truck updated with modern systems for economy and power but still cut down on my emissions. Sure going to be an improvement over my "smog" engine now.

va4cqd 03-28-2009 08:53 PM

TBI will probably freak out with that cam

chevy_c10 03-28-2009 08:55 PM

va4cqd I will have a custom chip done by Brian over at tbi chips. He is the one that suggested to use that cam with the vortecs.

va4cqd 03-28-2009 08:58 PM

what emissions requirements will the truck be tested to? as a 76 or the year the TBI is from?

chevy_c10 03-28-2009 09:06 PM

It will be tested as the 76 but I am one of the few that wants to clean up the engine as much as possible.

curtis73 03-28-2009 11:43 PM

Find someone with a sniffer. Some old shops have them for carb tuning. You can really clean up a tune that way.

Additional cam can clean up the NOx that an EGR would normally create, but the increased compression associated with larger cams kinda negates that. Plus larger cam often equals increased HC emissions.

I would personally keep the EGR if you can rig one up, but truly, emissions is largely in the tune. Many of us LT1 guys have gotten away with pretty hefty power numbers and still pass OBD2 emissions in CA. A common setup many of us have done is fully ported stock heads, ported intakes, cams in the 230 duration range, headers, and compression in the 10.5-11 range and with careful tuning it still passes CA emissions testing for 96 vehicles.

I would say focus on the tune first. Down the road if you want to continue cleaning it up then you can add EGR and other smog magic :)

chevy_c10 03-29-2009 11:20 AM

Curtis, I have one question about the cam that basically serves as EGR and still keeping the EGR valve. If the cam lets in exhaust gasses, and then the egr adds in exhaust gasses, won't there be way too much? Or, will the cam just let in exhaust gasses at low speeds and not highway speeds where the EGR will kick in? Still just a slight bit cloudy on the subject. Also, what do you think the performance difference between the carb vortec intake w/out egr and the tbi vortec intake with egr would be?


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