Header size...

Snacol · #1 (**permalink**) 07-03-2002, 10:17 PM

I have SPF #648 with a 351c bored to 396..I was wanting to get larger headers on the car ...Any experience or setups that anyone know about..I would like to get at least 1.75 if possible..Thanks for the help...

niles · #2 (**permalink**) 07-03-2002, 11:00 PM

Which heads 2v or 4v?
there exhaust ports are
considerable different in cross section.
gn

Snacol · #3 (**permalink**) 07-04-2002, 07:49 AM

2v............

niles · #4 (**permalink**) 07-04-2002, 02:47 PM

I just went and measured some I have.

the 2v port size is 1.25x1.5 in and the 1 3/4 pipes looks like a good size/area match.

the 4v is a hugh 1.5x2.0 in (almost twice the area) and a 2 in pipes is what the eng uilder suggested

gn

Mike Braddock · #5 (**permalink**) 07-08-2002, 09:23 PM

Snacol,

If you plan to stick with the 2V heads, I would go with minimum 1-3/4" primaries. If the car spends a lot of time above 5k rpm, you might even consider 1-7/8" primaries with the 396 you've got, as the port velocities will be more than adequate for such a light car. However, you might also consider upgrading to a pair of 4V heads down the road to make better use of the extra displacement and really wake that cleveland up

. (If you've got the hood clearance for a decent 4V intake.) If that's the case, I'd go with 1-7/8" primaries now and call it a day. Grover has good advice as well. But note that his motor was built by Bill Parham and was designed to be a screamer. The 495 HP in his signature is a modest understatment

. Hehe...

Grover, have you gotten a chance to fire up that beast yet??

Mike

Snacol · #6 (**permalink**) 07-09-2002, 09:27 AM

Thanks for the help guys...........

niles · #7 (**permalink**) 07-09-2002, 11:27 AM

Mike:
No; I'm so slow it painful. It's awfully hot to make progress in Fl this time of year.
I'm hoping to have noise for thanksgiving

gn

coyled · #8 (**permalink**) 07-09-2002, 02:46 PM

I have a yates headed 358ci motor, over 660hp. The builder said 1 7/8 to 2 inch step headers for my combo. Any bigger and you loose low end but do not gain on the high end. So, I think the 1 3/4 will work fine. Good luck, Scott.

Mike Braddock · #9 (**permalink**) 07-09-2002, 03:09 PM

Niles,

I finally made some noise with mine about two weeks ago for the first time in--well--too long

. Sounds good even with the mild cam that's in it. Since we're limited with hood clearance to running 2V heads on this car I've obtained a pair of 2V quench chamber Aussie heads and plan to do a head and cam swap eventually. But first we're going to get used to driving the car like it is now--probably around 320 - 340 hp. Then we'll decide if we really need the extra umph. We've had it on jack stands breaking in the new tremec and can tell already this car is going to be fun to drive once it's done

. We're almost at the point where we have to pull EVERYTHING off the car and paint the frame, suspension and body. But we also have to build a set of headers and sidepipes first, so that should be happening pretty soon. Right now the car has 2" primaries, which are ridiculously large for this motor, as Scott pointed out. But the headers and sidepipes are 1 piece and the previous owner wanted the vintage look of the 2" primaries entering the collectors on the sidepipes (I assume). But these pipes are located too close to the body as well, so we're going to build our own. Probably 1-3/4" primaries into a 4 into 4 bolted flange into 2" primaries that enter the collectors. Oh what fun!

After the headers we have to do something for a softop and then the disassembly will begin. We're shooting for Thanksgiving as well, but it will probably be closer to Christmas

Mike