Bb ford 180 degree race headers

[Big Block]

I need some help guys.
I'm going to make a set of 180 degree race headers for a (600 h.p., 607 lbs./ft.) FE 428 CJ. and I need real facts - no guesswork.
Material is polished 304, 2" O.D. stainless steel. I believe the engine firing order is: 1,5,4,2,6,3,7,8. What is the correct cylinder location?
F/R back/right/passenger
F/L back/left/driver
and which cylinders fire at 180 degrees?
Tubing will be equal length and tuned 18 or, 16 guage. Not sure yet. Maybe you can provide some feedback on this.
Flange is 3/8" thick, and collector is 3 1/2" O.D. x 12"L
If you can help, I would be most appreciative.

Thanks,
Big Block

 

[Ranger Mike]

which is 180 deg..you have got to be kidding me!

read post on Mech Eng forum 180 Degree Header Design
Apr29-09, 08:36 PM

 

[mender]

For your firing order (1-5-4-2-6-3-7-8), the ones that are 180 degrees apart are 1-4-6-7 and 5-2-3-8; you'll have to cross the middle pipes on one side to the outers on the other. If you really want to get fancy you can also bring them into the collectors so that the pulses rotate around the collector.

You may compromise too much by wanting to build 180 degree headers; to work properly they should be equal length and the right length for the rpm range. I doubt that you'll be able to achieve that unless you can put the collectors over the bellhousing.

Stainless can be thinner.

http://www.burnsstainless.com/bundleofsnakes-2.aspx

 

[Ranger Mike]

the Ford 428 cj is a torque engine..i raced one in a stock car in 1970..it has mucho torque..so why the 180 deg headers? you are better off going with tri-y headers..also the size collector you want to use is way too large and will kill of bottom end torque...one benefit of the 180 headers is to free up the flow..typical 4 into one headers, and tri-y design have two cylinders dumping into one collector at one time..the 180 pluses so only one primary tube is emptying into the collector at anyone time so you can run smaller collectors..

 

[mender]

Mike, it sounds like they might be doing a tribute project, and they're likely spinning it to around 6500+ rpm, something a stocker didn't do very well! Making 50% more hp kinda makes it into a hp motor!

 

[Ranger Mike]

that was one brute motor...plus i had my doors blown off of my 55 Chevy when i tried to out drag race a 69 green 428 cobra jet Torino on summer night in 1969...pulled him out of the hole only because of my 50 pound flywheel and 4.56 gears..then it was all over...

 

[Big Block]

These questions are for Mender, but anyone can reply.
What gauge of 304 Stainless would you recommend for the primaries and why? 18 or 20 guage?
The 180 degree cylinders you stated were 1-4-6-7 and 5-2-3-8. How did you calculate this and which specific cylinders are the 180 degrees?
Could you please tell me the differences in sound and pitch between a smaller gauge vs. a larger gauge tubing?

Thanks,
Big Block

 

[mender]

What gauge of 304 Stainless would you recommend for the primaries and why? 18 or 20 gauge?

I'd use the 18 gauge; thicker than that just takes longer to fit the tubes. I use a belt sander to get the joints fitting tightly before welding, makes for nicer looking welds and headers when you use tig. If you're leaving the welds as is for polishing, grind your tacks flat before final welding to get a consistent bead.

The 180 degree cylinders you stated were 1-4-6-7 and 5-2-3-8. How did you calculate this and which specific cylinders are the 180 degrees?

It takes two crank rotations to run completely through the firing order. That's a total of 720 degrees. Divide the 720 degrees by eight cylinders and you get one cylinder firing every 90 degrees. Since you want to find the cylinders that are 180 degrees from each other, you look at every other cylinder in the firing order and join them together.

Your firing order is 1-5-4-2-6-3-7-8, so the bold ones get grouped into one header and the regular into the other. On Fords, the cylinders are numbered front to back, 1-2-3-4 on the right (passenger's) bank and 5-6-7-8 on the left (driver's) bank. You'll need to bring #6 & #7 over to the right side and #2 & #3 over to the left side.

As I said earlier, you're likely going to end up with a set of long primaries; depending on what you're using for heads, cam and intake, you could lose a couple dozen hp or more over a shorter set of headers.

If you don't mind me asking, what are you working on and why are you considering 180 degree headers? I build engines for various classes of racing for a living, up to and including NASCAR and Gt-1; without more info about your engine combo, I can't give you a recommendation. If you don't want others to know, send me a private message and we can continue there.

Could you please tell me the differences in sound and pitch between a smaller gauge vs. a larger gauge tubing?

There won't be a pitch difference and I sincerely doubt that anyone can tell the thickness of the metal by the sound. In other words, no differences. Unless you mean the diameter of the primaries?

While I will agree that a set of 180 degree headers has a nice sound, I would question using only that as a reason to build a set. Here's a set of 180's:
http://www.youtube.com/watch?v=CAOqx_FqueM&feature=fvwrel
And regular:
http://www.youtube.com/watch?v=WhufkCcyUbY&feature=related

I like them both!

 

[Big Block]

Mender, you've been great. Thanks. I will get to you privately. But I do have some final questions.
Would a 3" O.D. x 12"L collector be ideal without killing off bottom end torque.?
How hot is the temperature of 2" O.D. x 18 gauge 304 Stainless primary tubing? And is their major tube discolouration?
What are the pros nad cons of 180 degree headers vs. Tri -Y headers for this engine.

Thanks again,
Big Block

 

[mender]

The temp will depend on how hard the engine is pushed; same for the discolouration from the heat.

Collector size: the smaller the collector the more it favours the bottom end, same for the primaries.

180 degree headers help the top end, Tri-Y are more for mid-range. 180 degree are the most complicated, Tri-Ys are usually (but not always) the easiest.

 

[Ranger Mike]

12:1 engine running av gas , pretty hair cam, maxed out port job..400 degrees at Head/header junction..220 degrees at collector, idling..1500 rpm..do not forget to use a cross over tube to connect the collectors , especially if you have single plane intake manifold.

 

[Big Block]

..do not forget to use a cross over tube to connect the collectors , especially if you have single plane intake manifold.

Ranger Mike,
You do mean the cross-over tube in the "H" pipe after the collectors, Right?

 

[Big Block]

Collector size: the smaller the collector the more it favours the bottom end, same for the primaries.

Mender.
For the 428Cj with 2" O.D. primary tubes,
Questions: Should the collector size be: 2 1/2" O.D., 2 3/4" O.D. or, 3" O.D.?

Which type of header, the 180 degee or Tri-y, have that awesome "knarly, throaty" Ford sound that seems to "burble" at idle?

What would be the best lengths in inches (ideal length = ___"L, or a range from ___"L to ___"L) for the primary tubes for:
1) mid rpm range - from 3200 rpm and up to 5500 rpm
2) high rpm range - from 4500 - 5500 - 6500+ rpm

 

[mender]

From what you've described so far of your engine combo, 3" collectors. 2" primaries are a little excessive for that engine size, I would consider dropping that to 1 7/8".

The burbling at idle is mostly caused by the amount of overlap of the cam; a traditional 4 into 1 header with equal length tubes will sound the raspiest (the "V-8 sound") and be the cheapest, as you can likely buy one instead of having to build.

180 degree headers smooth out the sound by introducing the exhaust pulses evenly spaced into the collector. Tri-Y essentially are about half-way between a 180 degree and a 4 into 1, depending on tube lengths and routing.

The tube length will vary from about 36 inches for the low to mid range to about 32 inches for the upper range. Which one to use will depend (again!) on your engine and vehicle combo.

This article might be helpful:
http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/index.html

Don't worry, it also applies to Fords!

 

[Big Block]

Mender,You suggested 1 7/8" O.D. for the primary tubes, but you forgot to mention the O.D. size of the collectors?

 

[mender]

First line:
"From what you've described so far of your engine combo, 3" collectors."

 

[Ranger Mike]

Cross over pipe is as you stated..it ties the two collectors togeather..if you run a stock dual plane manifold, and without this cross over pipe, the engine acts like two 4 cylinder engines connected at the crank shaft. as exhaust pulses hits the 15 psi atmosphere it reverbs back toward the exhaust valve until it hits another out going pulse..this is why having the header tuned to the cam shaft and rpm range is needed. we want the ex. pulses all going the same way and as un-interrupted as possible. this is why 180 degree headers ate almost the optimum set up ( 8 into one is ultimate..but another discussion)... the cross over tube connects exhaust pulses from each cylinder bank togeather to smooth out the pulses and cancel any negatives created during long periods between each pulse.

Tri-Y headers are the way to go for street and low to mid rpm operations ..they are not optimum for wide open throttle...4 to 1 headers are for mid to hi rpm operation and will hurt low end operation.

 

[Big Block]

Mender and Ranger Mike,
Thanks for everything guys. You are the best...And your knowledge and information regarding headers has been so helpful to me. Thanks again.
Question:
Can you hook me up with the names and phone numbers of some suppliers of 304 stainless header components (like flanges, collectors, etc.). Destination point: Toronto, Canada

Regards,
Big Block

 

[Ranger Mike]

http://perfweldheaders.com/
Mark Lelchook...he is THE MAN on one off stainless steel stuff...he steered me straight on latest hedder tech..we run his stuff on the Formula Car..

 

[Big Block]

Thanks guys for everything.
This topic (and thread) is now officially closed!

Big Block