i still lay out two holes.then i have used long body pointed set screws for threaded transfer . laying out the hole and finding center some times work s better then just a transfer punch what bears on this is how thick the pattern is
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I use the 3/8" flanges that Speedway and many other companies sell with their header kits.... Never had to do more then elongate a hole or two. Building headers is labor intensive enough without wasting a bunch of time building flanges!!!! I'm with Jerry, maybe if I needed 500 sets, but for only a 1 time deal???? On any unique engines or unusual tube requirement, I just get the appropriate header gasket and take it out to my pal Brian at Laser Cut.... Times gotta be worth something, or at least better spent on the rest of the car???
Of course you could do 8 individual ports--I always cut them anyway
Louey--the transfer screws are sort of like set screws with a hardened point that points out and is installed with the tool holder--they come 5 or 6 to a size inside the holder, I will try to find an example
Check McMaster
part number 3385a19
yep and all the big tube stuff can be slip fit so the flanges sometimes needs to be cut .when i made the flanges up i could cut them only were i needed keep getting things mixed up. if for a slip fit tube. if a 2.1/4 or 2.3/8 tube and all needed to be slip fit the i cut up the flange more .i try not to make any headers with to may slip fits and welded header collectors tig weld a L and R on them and welded the tabs on the collector on only one way things get mixed up after there all apart. learn that the hard way after a guy beat the hell out of a set i did a long time ago chevy ll with a bbc in it with 2 1/8 he called me after beating the $hit out of them to make them fit after i bent tabs back they fit:HMMM:
from the center of a bolt hole on the right side of the port hole to the center of the bolt hole on the left side of the port hole is 2.0000'' center to center the you subtract the width of the port hole which is 1.3200'' they are round to the nearest 4th decimal place so the precision = .01 or ten thousants so 2.0000'' -1.3200'' = 0.68" divided by 2 because there are 2 spaces one on each side of the port hole from the edge or the port hole to the center of the bolt hole both sides so 0.68"/2=0.34" so from the edge of the port hole to the center of the bolt hole is 0.34" both sides
C'mon, the horizontal spacing is obviously centered and thus easily calculated;). His question is the vertical spacing of the holes relative to the center of the port. That dimension is obviously not centered, and there is no way to calculate the amount of offset from the information given. You can scale it, but he's asking for factory dimensions, as I understand his question.
It's all really moot - as has been pointed out there are already a ton of bare flanges on the market by people buying materials in bulk, and doing one that reinvents the accuracy is not going to be the multi-million dollar marketing idea never done before, but may be a dandy highschool tech center project. :3dSMILE:
OK----put 2 bplts--3/8 with sesctoion of untreaded shank into the two bolt holes---take a starret ruler ( 1/2 wide) put across the two bolt shanks, measure to top of port----measure to bottom of port---play with the constant values in this game ----3/8, .375, 1/2, .500, .1875, .6875, .875----a little addition, a little subtration, a little of this, that, etc----if you can't fiqure out the diminsions--------
Yep, you can scale it either graphically or by Jerry's method, but the point is the kid is asking for a Ford drawing that shows that dimension, thinking that if the dimension shown on some design drawing is used the world is in balance. Not saying it cannot be figured out, just that it cannot be calculated. Look back at post #23 of this thread and you and I are on the same page, Jerry. He did not like it then, either :LOL::CRY::LOL:
And the whole thing of making your own header flanges is to end up with a hole size that will exactly take a tube size--ie--the distance around the port hole in the flange equals the od circumferce of the tube for the header----like 2 x Pi ==6.28----adjust the location of the port so as to reduct reversion, etc
Sorry fellas, i'v been busy with other car stuff, (blown head gaskets in a 3.8l (88) thunderbird + getting parts for trans) and havnt had time to do much header work.
But here is the wood milled flange i made for a prototype. Its not the best picture because its just off my phone, and i was at a weird angle so the ports LOOK like they dont line up evenly, but i asure you that there is an even amount of port on all sides inside the flange.
i also changed the orginal design alittle. I got rid of the chamfer around the edges, and then i also changed the bottom out side corners to not interfere with the cyl head bolt, as it is in the picture. I'l hopfuly get a final product here soon and post pictures
you may have to make room for the lower row of head bolts / studs .that is why i made alot of my flanges
you need to raise the plate so the overlap is at the top instead of bottom to stop reversion
(and for bolt /plug clearance?
Ya i know, i changed the design for the head bolts in the way.
plugs fit in fine. i gota get a better picture up here soon.
what overlap are you talking about?
The school is closed for thanksgiving break so i'l have to start the metal work next monday.
the portion of the port at the bottom of the hole---works better if that overlap is at the top so it stops reversion factor of exhaust pulse back feeding into head/cylinder especially on valve over lap where you would contaminate the intake charge with exhaust
i dont understand what your saying. overlap? you mean cover up the bottom of the port? why would i wanna do that?
The most flow is out the top part of the port----reversion effect takes place letting the exhaust flow backwards into the port and then cylinder-----The header should be bigger than the port size----like the distance around the hole should equal the circumferance of the header tube. offset the flange upwards so that there is a dam to stop the reversion flow at the TOP where the flow would be more---reversion on valve overlap will dilute the mixture in the cylinder and even contaminate the mixture in the intake, possibly even to the point of igniting it occasionally(backfire)