Header size for 347 stroker?

[Gotta_gofast]

Before everyone nibbles my butthole for asking yet another "what header should I buy for a V8 swap?" question, I promise I've scanned through the pages of yesterday through yester-years and have some good info.

I have come to my senses and am looking into either a 347 stroker or a 351 to replace the mild 302 which resides in the truck, but since this thread is about displacement and header specs, I'll keep it at that. Looking into long-tube headers, I made a call to James Duff. Those headers have 1.5" primary tubes and 2.5" collectors. I have a feeling this will greatly choke a 347 (powerband 3500-6500rpm). Anyone with agree/disagree? If this is going to be a minor issue, I might live with it. But if it will be a big deal, what should I look into?

I've built headers before. My second option was to purchase various bends and some flanges and go to town. But even then, what size is optimal for this application. And what length? I would like to be in the ball-park of 26" primary tube length with 1.75" diameter into a 3" collector.

Basically, any advice is appreciated. Thanks!

[847b]

I think you are on the right track. If you are going to use factory ported heads, the standard sbf size of 1 5/8" would work well. If you are going to use a set of aftermarket heads such as Trick Flow or AFR, go with the 1 3/4". As for the length, anything in the 26-30" range should be close enough.

I built my own set of fender well exit headers for my 351W. They have 1 5/8" primaries, 36" length and 3" collectors. I'm pretty sure the smaller tube size hurts power above 6000 rpm (it makes close to 500 hp @ the crank). I used the hooker flange kit and have had good luck with it.

[Gotta_gofast]

If it isn't too much of a pain, would you post some pics of the fitment? I'd just like to get an idea. Both a 347ci stroker or a stroked 351w are equally appealing. With around 500 horses, how does your ranger respond to it? Do you have a lot of frame flex/twisting? Thanks man!

[847b]

Yeah, in the next couple of days I will try to get some pics up. My header length was a function of fit more than performance. One advantage of the smaller tube size is more clearance around the frame, heater box, etc.

Twisting/flexing? Minimal, there is some but not enough to cause any damage I have found so far. I made my own motor mounts and engine torque arm which couples the engine to the frame well. I think of it like a motorcycle where the engine actually acts a contributing member of the frame. Then in the back, the cross-member holding my 4 link is fairly stout as well stiffening up the back of the vehicle.

[Gotta_gofast]

Well thats good news. I don't think I will go the 4-link route unless I get some chassis-4 link 101. I'm familiar with ladder bars, so this might be my weapon of choice. Can't wait to see some pictures!

[847b]

Hate to post twice in a row... but hope this helps.

[Gotta_gofast]

Cool! Teegan (girlfriend) walked into the room, looked at the pictures, then asked if I was lookin at car-porn again. What can I say, its a habit.

Anyhow, I really like the set up. Did you start with a set of headers and cut them up or did you purchase a kit with mandrel bends? I was looking at a kit with various bends and the flanges.

[847b]

A guy I knew who was an addictions counselor had a philosophy "I dont care if you're addicted to something, it's what you're addicted to that I care about." I figure being addicted to small block fords is a lot better than drugs.

I bought quite a few mandrel J-bends to make the headers. In retrospect, it might be less expensive if a guy bought a couple of 8ft pieces of straight tubes and just enough J-bends to make the arcs. I wanted all new metal for my headers, but I'm sure a set of used headers could be useful to fabrication.

[Gotta_gofast]

I thought about finding some long tubes from a small passenger car with a 302 and cutting/moving the sections that interfered with the frame and the steering linkage. I can't really see too many other obstacles.

I called James Duff Enterprises and they quoted me $399 for ceramic coated full length headers. But the primary tubes are only 1 1/2" in diameter. If it costs me a couple ponies I would jump to it, but if its going to be a noticable loss of power then I'll fab my own.