Header tube for 327-350

Alan Roehrich · 03-18-2017, 08:46 PM

I try to answer most questions, provided I have useful input.

However, if the question does not include anywhere near enough information to allow for a useful answer, I usually simply do not have time to write out a list of things needed to give a useful answer.

Coleydog · 03-18-2017, 09:38 PM

Ok... I don't think the tube length on my 340 Engine is right, I think they build too long a pipe. All I want is just a general size for the 3.25-3.5 stroke crank, since after 60 years someone should have it pretty close give or take a few inches, not trying to fine tune to the 1/4 inch. How about 66-327 Chevy 2, 69 Z-28 302, 70-1/2 Camero Z28-350, all running stock. I had off the shelf pipes on them then but can remember what size after all this time. Just a good starting point to compare. Thank you

rboyle · 03-18-2017, 10:09 PM

I use off the shelf Dynatech steps 1 5/8" primaries to a 3" collector. I'm sure there's more power to be found

ron mattson · 03-19-2017, 12:33 AM

1-5/8 to 1-3/4 14-16 inches of each
With a merge collector for a 4 to 1 set up
or 1-1/2 to 1-5/8 for a tri-y will get you
In the game.

Alan Roehrich · 03-19-2017, 12:39 AM

Stroke is only one factor. There's port lengths, volumetric efficiency, RPM, and cam timing to name a few.

The suggestion that you buy PipeMax was a good one. Pays for itself on the first set of headers.

Alan Nyhus · 03-19-2017, 09:04 AM

Quote:

Originally Posted by ron mattson

1-5/8 to 1-3/4 14-16 inches of each
With a merge collector for a 4 to 1 set up. Or 1-1/2 to 1-5/8 for a tri-y will get you
In the game.

Coleydog, Ron has given you good advice.

What body style/year are you working with? Also, what's your budget for headers? -Al

Coleydog · 03-19-2017, 10:57 AM

That is good info, right along my thinking. My plan is to make up a set in reg steel (inexpensive) make adjustable, test, then do in SS. 70 Duster 340 (with the stock intake lol) E F or G. Still finishing up the cage but trying to get all my ducks in a row now. Info so far is helpful, thank you all

GTX JOHN · 03-19-2017, 02:31 PM

If we are not doing steps we run 1 3/4 Primary 34 to 36 long and a merged
collector if budget allows....That is on both High and Low Comp. 340 Mopar
in Stock (E to G). I would generally expect a similar class 4 Brl. 350 to be
in the ball park with those numbers (Similar compression/Valve Size/HP/Wt.).

03-18-2017, 08:46 PM	#1
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,118 Likes: 1,573 Liked 1,837 Times in 417 Posts	Re: Header tube for 327-350 I try to answer most questions, provided I have useful input. However, if the question does not include anywhere near enough information to allow for a useful answer, I usually simply do not have time to write out a list of things needed to give a useful answer. __________________ Alan Roehrich 212A G/S

03-18-2017, 09:38 PM	#2
Coleydog Senior Member Join Date: Jul 2014 Posts: 572 Likes: 39 Liked 53 Times in 38 Posts	Re: Header tube for 327-350 Ok... I don't think the tube length on my 340 Engine is right, I think they build too long a pipe. All I want is just a general size for the 3.25-3.5 stroke crank, since after 60 years someone should have it pretty close give or take a few inches, not trying to fine tune to the 1/4 inch. How about 66-327 Chevy 2, 69 Z-28 302, 70-1/2 Camero Z28-350, all running stock. I had off the shelf pipes on them then but can remember what size after all this time. Just a good starting point to compare. Thank you

03-18-2017, 10:09 PM	#3
rboyle Senior Member Join Date: Jan 2015 Posts: 604 Likes: 1,454 Liked 586 Times in 162 Posts	Re: Header tube for 327-350 I use off the shelf Dynatech steps 1 5/8" primaries to a 3" collector. I'm sure there's more power to be found Last edited by rboyle; 03-18-2017 at 10:59 PM. Reason: Misread question

03-19-2017, 12:33 AM	#4
ron mattson Member Join Date: Nov 2005 Location: cloquet mn Posts: 466 Likes: 17 Liked 67 Times in 30 Posts	Re: Header tube for 327-350 1-5/8 to 1-3/4 14-16 inches of each With a merge collector for a 4 to 1 set up or 1-1/2 to 1-5/8 for a tri-y will get you In the game. __________________ Ron Mattson 5015 STK

03-19-2017, 12:39 AM	#5
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,118 Likes: 1,573 Liked 1,837 Times in 417 Posts	Re: Header tube for 327-350 Stroke is only one factor. There's port lengths, volumetric efficiency, RPM, and cam timing to name a few. The suggestion that you buy PipeMax was a good one. Pays for itself on the first set of headers. __________________ Alan Roehrich 212A G/S

03-19-2017, 10:57 AM	#7
Coleydog Senior Member Join Date: Jul 2014 Posts: 572 Likes: 39 Liked 53 Times in 38 Posts	Re: Header tube for 327-350 That is good info, right along my thinking. My plan is to make up a set in reg steel (inexpensive) make adjustable, test, then do in SS. 70 Duster 340 (with the stock intake lol) E F or G. Still finishing up the cage but trying to get all my ducks in a row now. Info so far is helpful, thank you all

03-19-2017, 02:31 PM	#8
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,733 Likes: 2,803 Liked 2,486 Times in 697 Posts	Re: Header tube for 327-350 If we are not doing steps we run 1 3/4 Primary 34 to 36 long and a merged collector if budget allows....That is on both High and Low Comp. 340 Mopar in Stock (E to G). I would generally expect a similar class 4 Brl. 350 to be in the ball park with those numbers (Similar compression/Valve Size/HP/Wt.). __________________ John Irving 741 Stock 741 Super Stock

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