|
header size for small block
I have a 354 cubic inch 5.0 / 302 motor in my Cobra. I'm doing research on header size "again". I used an auto math web site to calculate my header size. It says I need 1 3/8" for 354 ci at 6500 rpm. But I was reading a article on master motor builders and the Ford small blocks (347 - 360 ci) used 1 3/4" or 1 7/8" headers. I have 1 5/8" headers and I'm going to replace my Lone Star side pipes with a pair of Classic Cobrapack mufflers. But now I'm confused about the header size.
Does anyone have a link to a header calculator site or know what size headers I need with a 354 ci motor at 6000 - 6500 rpm? I'm always looking for something to change:) Dwight |
If a calculator is estimating 1-3/8" header pipes, then you need to find another calculator....:LOL:
For a 351 sized engine, I would go with a 1-5/8"-1-3/4" size header....and I would probably lean more towards the smaller size. However, if you ever have plans to stroke the engine, it may be worth your while to go big now. |
that engine is already stroked
I always try to use a tube size at least 1/8 larger than the exhaust valve size--many times. this then taking into consideration the tubing thickness, will generally give an ID header size equal to OD valve size----- Also I use a sparkplug with a piece of tubing welded over it to similate socket and extension for clearance around plugs. try to keep the tube straight for a few inches before turning.The header flange should overlap the port at the top for antireversion purposes |
Didn't catch the engine description....I saw the 354 and thought it was a slightly overbored 351.
There's nothing efficient about a Cobra header/sidepipe setup, so there's no use in sweating the details. The trend I usually see, however, is that people tend to go too large on header sizes and carb sizes. |
Stroker 302's are fine with 1 3/4" pipes. Keeps velocity up with excellent flow. The sidepipes are where the loss is.
|
Back when I worked for Dynomax, our smallest header primary sizes were 1-5/8", with some big block headers at 1-3/4".
|
mufflers
I wanted to improve my old sidepipes so I bought a pair of Classic CobraPack 3" mufflers with packing. When I cut the old muffler off, I found they were 2 1/2" packed. I may not gain a lot from the new mufflers, but I'm going to install them.
Dwight |
| All times are GMT -7. The time now is 11:13 AM. |
Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2026, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: