1992 Buick Roadmaster sedan Vortec head/Cam swap questions - Third Generation F-Body Message Boards

buickboat · 02-27-2009, 10:11 PM

Been searching and reading a lot about the conversion to vortec heads on the TBI 350 and I think I want to go through with it, so two questions for now.

1) I know you need to get a different intake to use with the vortec heads, so do I need EGR? I have to pass emissions, but they do not check anything under the hood, just stick the sniffer in the tailpipe. Would I be able to pass the sniffer without EGR?

2) Been reading that the heads need to be milled down (and a thin head gasket used) for the 305 (L03) to keep compression at the desired level. Would this also be true for the 350 (L05) if I used heads off a vortec 350?

3) What cam would you recommend for a heavy car such as the Roadmaster, it weighed in at 4600lbs with me and a half tank of gas. I need to keep some low end power to get this car goin.

Thanks in advance.

birdtojag · 02-27-2009, 10:53 PM

If you have emissions, the egr is needed to reduce NOx. If you are using the vortec heads on a 350, you don't need to do anything in terms of milling. As for the cam, a good LT1 cam or LT4 Hot cam would do nicely. Remember to change your valve springs with the cam to be able to handle the lift.

smokingtoaster · 02-28-2009, 01:59 PM

Use 305 Vortec heads on a 305.

buickboat · 02-28-2009, 07:28 PM

Quote:

Originally Posted by birdtojag

If you have emissions, the egr is needed to reduce NOx. If you are using the vortec heads on a 350, you don't need to do anything in terms of milling. As for the cam, a good LT1 cam or LT4 Hot cam would do nicely. Remember to change your valve springs with the cam to be able to handle the lift.

I thought max lift for vortec heads was around .470 iirc. With different springs (and machining the valve guides down) I will be able to run the LT4 hotcam? I believe I saw lift for that was around .492?

Now for the EGR, the reason I was asking about going without it is I found the following on the Impala SS Forum

Quote:

Originally Posted by MrBuick (Magnum)

With a bigger cam like that, you don't need the EGR valve, because the increased valve overlap, "Self EGR's". Or so thats what I thought.

Quote:

Originally Posted by Lance

Did you know that the stock LT4 engine did not come with an EGR?
There's a GM block off plate kit for the EGR delete.
The EGR is necessary with the stock B-Body cam but the EGR is not necessary with a bigger cam and proper tune.
Removing the EGR on a stock engine = bad.
Removing the EGR on a heads/cam engine = good.

buickboat · 02-28-2009, 07:28 PM

Quote:

Originally Posted by smokingtoaster

Use 305 Vortec heads on a 305.

This will be going on a 350 (L05).

birdtojag · 02-28-2009, 09:44 PM

May need to put one on as a mock-up to get past emission inspections. If your other Forum has people that have done this with an LT4 cam, then follow their advise. If not, you might need to use the EGR valve with the way it was intended. As for the springs, you would want to match them for the lift.

buickboat · 03-01-2009, 12:55 AM

Quote:

Originally Posted by birdtojag

May need to put one on as a mock-up to get past emission inspections. If your other Forum has people that have done this with an LT4 cam, then follow their advise. If not, you might need to use the EGR valve with the way it was intended. As for the springs, you would want to match them for the lift.

No visual inspection here, so that won't be a problem. People on the other forum have done the LT4 hot cam in the LT1 but TBI performance over there is really dead, so anyone with TBI questions is referred to thirdgen.org. Just figured I would ask the guys in the know. Thanks for the help so far!