what about dump valves off the headers? im thinking about doing that and on the dump side just have a turn down.

what diameter pipe should i go with for the lowwww mean rumble
3"-3 1/2"?

 

I wouldn't go 3 1/2" by any means, not a 350. That will kill some torque. Even 3" is kind of big for a street 350, 2 1/2" would be plenty for true-daul exhaust.
My truck has a 350 with 2 1/4" open pipes and it still has PLENTY of rumble.

 

ok slight change in plans.

the engine for the engine swap will have vortec heads.

i was told regular and vortec head bolt paterns are different

 

I believe they are the same.... anything old-style up to Vortecs should be the same, excluding the LT1 heads. Anyone else want to confirm that? I'm pretty sure they are the same bolt pattern.

 

Vortec exhaust manifold patterns are the same, it's the intake that's different.

 

cool.
ty

 

I have a 305 and I was curious about the headers. I am looking on putting the L31 heads on my car, in time. But for now I want to put on some headers and I was curious to know if I could buy a set of headers that would bolt up to the stock 305 heads, and then also bolt up to the L31 vortec 350 heads? I wanna try to buy efficiently if I could. So if there was anyone that would lend a hand here, that would be very helpful. Sorry if this is a repeat question from somewhere else, im new.

 

Been looking at the same thing.

Same bolt pattern works for both, so they'll work fine for both.

My dilema was with whether to stick with the single cat my 305 came with, or try to convert to dual cat when I get the headers and y-pipe.

Of course its an easier decision if you live in a state without smog police....

 

Well thats good to know. I didnt want to spend the money on something that couldnt be swapped to the L31 heads. And that question is easy in the great state of michigan.. heh.

 

if you still want to run true duals, good luck. the stock 3 inch on my car would scuff any speed bump more than 4 inches tall. now if you run true duals, dont expect more than 2 inches clearence on the driver side, and forget about a suspension drop unless you run rims bigger than 17". the floor pan is simply unforgiving. if you look close, the passenger side floor sits up 2-3 inches higher to accomodate the cat and give ground clearence. now if you still want dual side exhaust, i have seen it run into a single, then split again after the trans to run to both sides, with the pipe running under the driveshaft. the was still clearence issues, but not as bad as true duals. now if youre still hung up on running true duals, try to get oval pipe or find a way to flatten it out to get some clearence. and you said it was a 305, so dont got anything bigger than 2 1/4" unless you have a cam and heads already installed, then you can run 2.5". anything larger will kill hp and torque because of the loss in velocity, therefore a loss in scavenging. a stock 350 can run 2.5" duals, and 3 inch if it has heads and a cam