how to size a 4-2-1 header for my SBC



Re: how to size a 4-2-1 header for my SBC

Postby grumpyvette » January 26th, 2014, 8:04 pm

WELL?
ANY FURTHER COBRA build progress?
PICTURES?
recent mods?
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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new gaskets by Harley Davidson :o)

Postby Carlos » April 19th, 2015, 1:41 pm

Latest update.

After having run my headers, it turned out I came to close to the footbox/floor. Very good during winter :mrgreen:
So I got had to make two 4 hole flanges as a spacer between the top and bottom part of the headers, to lower them a bit.
Flanges and gasket custom made (laser cut)

Unfortunately the gaskets didn't work out very well at the end...although flanges are perfectly plain.
Due to the fact that the bolts are not putting enough pressure to the edges of the flanges, the gaskets are worn out after a few hundred miles.
Blown off at the edges, as the pictures show.

Discussing this with my buddy who is a genius in workin on all years of Harleys, he came up with a new idea...
Why not using the gaskets they use for the HD motorcycles?
Fortunately the dimensions were perfect.
The flanges had to be modified to offer a proper seat for the gaskets, which needed a bit of milling work.

I will take the Cobra for the first trip in two weeks from now, hope this works better now.

Carlos
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If you can make black marks on a straight from the time you turn out of a corner UNTIL the braking point of the next turn, then you have enough HORSEPOWER
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Re: how to size a 4-2-1 header for my SBC

Postby grumpyvette » April 19th, 2015, 4:35 pm

WOW! thanks for posting those clear pictures AND for relaying the idea for the gasket inserts!
hows the car running now and can you post more pictures of that cobra??
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: how to size a 4-2-1 header for my SBC

Postby philly » April 19th, 2015, 9:19 pm

thanks for the awesome pictures... did you ever get the car tuned up properly?
-phil

There's never enough money to build it right, but there's always enough to build it twice!
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Re: how to size a 4-2-1 header for my SBC

Postby Carlos » April 23rd, 2015, 3:09 pm

...well, I am still lacking the final tune up. Since 4 years now as I just recognized when reading my own post.
Unfortunately the last year (again) was a year with too much business, so I put a few miles on the Cobra only.
I hope I can see the dyno soon. You can be shure I will post the figures / curves as soon as I have them.
First priority is to get on the road this weekend and hear the sound :mrgreen:
Carlos
If you can make black marks on a straight from the time you turn out of a corner UNTIL the braking point of the next turn, then you have enough HORSEPOWER
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Re: how to size a 4-2-1 header for my SBC

Postby grumpyvette » April 23rd, 2015, 3:45 pm

lots more pictures of your cobra, your cobras engine, and posting several detailed updates on the tune up , and the changes and results of those changes, will be very much appreciated
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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