Please help! Header diameter too big?
Thread Starter
Instructor
Joined: Apr 2015
Posts: 238
Likes: 96
From: South Carolina
Please help! Header diameter too big?
Hello all. Shop has just finished my 350 vortec engine.
My mechanic was about to install the header/sidepipe combo when he calls to tell me that the header tube diameter is 2 inches which he says is way too big and will kill performance. In his words "like trying to run with a bag over your face".
The header/tube combo is a maximizer set(obx) that many here have used. The actual diameter is 1.9. Hes telling me 1 5/8 is most I should use. He's also worried about the gasket sealing.
Any opinions from those running obx header/sidepipe or with performance c3s is welcome.
Thanks
link to headers
http://www.ebay.com/itm/171794324739?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
My mechanic was about to install the header/sidepipe combo when he calls to tell me that the header tube diameter is 2 inches which he says is way too big and will kill performance. In his words "like trying to run with a bag over your face".
The header/tube combo is a maximizer set(obx) that many here have used. The actual diameter is 1.9. Hes telling me 1 5/8 is most I should use. He's also worried about the gasket sealing.
Any opinions from those running obx header/sidepipe or with performance c3s is welcome.
Thanks
link to headers
http://www.ebay.com/itm/171794324739?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Last edited by TanksFull; Jun 11, 2015 at 01:30 PM.
Race Director
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
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I doubt it's 2"..maybe 1-7/8"? That is pretty big for a stock 350....but they are awful long so that will help low/mid range.
Hey....you'll be ready for that nasty 383-406 you really want later on!
JIM
Hey....you'll be ready for that nasty 383-406 you really want later on!
JIM
Pro
Joined: Oct 2009
Posts: 664
Likes: 89
From: Marysville Ohio
Lots of us have run these or Hooker side pipes with mild or even stock 350s. The closer to stock you are, will cost you some low end torque but it's not huge. I ran them on a vortec-headed 355. I still had fun.
He is right that those headers are not an ideal primary tube size for a 350 but not unusual for these cars.
Install'em and keep upgrading until you are running a big cubic inch stroker to fill up that header...
He is right that those headers are not an ideal primary tube size for a 350 but not unusual for these cars.
Install'em and keep upgrading until you are running a big cubic inch stroker to fill up that header...
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
I run the 1 7/8" headers with side pipes. The only size they come in from hooker. 350 CI engine. Ran fine stock and now modded @ 377 HP. You may need some jetting adjustments depending on which inserts you get.
Some performance may be missing, but the cool factor is all there. Get a higher stall torque converter if you want to get a better launch. Mine stalls @ 2600. That and a shift kit for the Th350 make it a lot of fun.
Some performance may be missing, but the cool factor is all there. Get a higher stall torque converter if you want to get a better launch. Mine stalls @ 2600. That and a shift kit for the Th350 make it a lot of fun.
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
IMO they'll still meet or beat the low end torque available w/ ram's horns. And certainly decimate them at mid-range and top.
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Team Owner
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From: Western NY
The listing that was posted, says the header primaries are 1.9" Overall Diameter. This translates to approximately 1.75" ID, which is the dimension you should be concerned about. A "street" header would possibly be better at 1.625", but in all reality, I wouldn't quibble over it.....
Melting Slicks
Joined: Jun 2011
Posts: 3,114
Likes: 597
Hello all. Shop has just finished my 350 vortec engine.
My mechanic was about to install the header/sidepipe combo when he calls to tell me that the header tube diameter is 2 inches which he says is way too big and will kill performance. In his words "like trying to run with a bag over your face".
The header/tube combo is a maximizer set(obx) that many here have used. The actual diameter is 1.9. Hes telling me 1 5/8 is most I should use. He's also worried about the gasket sealing.
Any opinions from those running obx header/sidepipe or with performance c3s is welcome.
Thanks
link to headers
Maximizer Header Amp Resonated Side Pipe 63 82 Corvette C2 Amp C3 Stingray SBC V8 | eBay
My mechanic was about to install the header/sidepipe combo when he calls to tell me that the header tube diameter is 2 inches which he says is way too big and will kill performance. In his words "like trying to run with a bag over your face".
The header/tube combo is a maximizer set(obx) that many here have used. The actual diameter is 1.9. Hes telling me 1 5/8 is most I should use. He's also worried about the gasket sealing.
Any opinions from those running obx header/sidepipe or with performance c3s is welcome.
Thanks
link to headers
Maximizer Header Amp Resonated Side Pipe 63 82 Corvette C2 Amp C3 Stingray SBC V8 | eBay
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
SB Corvette sidemounts have had 1.875" OD x ~45" long primaries as long as I can remember. And I made a point of posting that latter dimension. IMCO it would be a mistake to overlook that primary length is just as important in header design as diameter. It helps to think of primary diameter as locating the fulcrum, and primary length as how much weight is on each end of the lever. So, while in theory a shorter primary of only 1.625" OD may locate peak TQ nearer to your intended target, it is entirely possible that the long-tube sidemounts could put more TQ under the curve within your intended performance RPM range. And, at the end of the day whatever you put aft of the collectors could well compromise whatever is ahead of them anyway.
In any event, assuming that you're not racing for serious money or you wouldn't rely on asking the interweb, I'd relax and install the sidemounts if that's your preference. Besides, you'd think if they were all that far off for most applications that someone would have gone back to the drawing board after all these decades, no? FWIW, the BB ones are 2.125" OD, and none of the 427s I've built have lacked for TQ/HP. My $.02
In any event, assuming that you're not racing for serious money or you wouldn't rely on asking the interweb, I'd relax and install the sidemounts if that's your preference. Besides, you'd think if they were all that far off for most applications that someone would have gone back to the drawing board after all these decades, no? FWIW, the BB ones are 2.125" OD, and none of the 427s I've built have lacked for TQ/HP. My $.02
