Hawk Headers question

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amulheirn
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Hawk Headers question

Post by amulheirn »

Hi all,

Roger very kindly sold me a second-hand pair of Hawk headers that he had spare a couple of years ago. I've just made the schoolboy error of painting them with VHT Flameproof without first checking that the bolts fit. Most do, but about three do not - the pipe curves in front of the bolt hole too much so you can't get the allen key in (I'm using cap-headed bolts because hex-head ones are too big and foul the pipe much more).

In Jon Towers' build, they heated the problem area up and dented it slightly to fit:
http://jontowers.co.uk/cobra289/wp-cont ... ented2.jpg
dented2.jpg
I'm prepared to do this, but denting it is a pain because of all the pipework in the way - it is difficult to get a thin chisel in to the right area. It would have to be quite a long chisel so that the end where the hammer goes clears the other pipes sufficiently to be whacked encouraged.

I have several questions:

1. Given that the flange is quite thick, can I get away with leaving a couple of bolts out? I would be leaving one out on one bank, and two on the other. They are not in adjacent holes.

2. Where do you get the type of bolts that we see in the picture above? I wonder if their heads are smaller than the cap-head allen bolts I have currently.

3. Would I be better with a stud and nut type arrangement?

Any input gratefully received!

Andrew
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peterc
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Re: Hawk Headers question

Post by peterc »

Andrew.
Definitely don’t leave any bolts out. I would consider studs as a way forward so long as you can get sufficient clearance to slide the header on. You will probably need to tighten up the nut one or two flats at a time as the manifold slides further onto the stud.
I doubt you will find any fixing with smaller dia heads than a socket cap screw. Depending on the radius of the pipe a lower profile head might be a possibility e.g. Button head but they will be nearer the dia of a washer. Give me the bolt size and I can give you the dimensions as I have the relevant charts.
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Re: Hawk Headers question

Post by Karl »

Andrew, US parts suppliers have the correct bolts.(ARP or similar). Yes, the bolt heads are smaller. I purchased my headers in the US and they came with these bolts, otherwise it would not have been possible to fit!
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Migge
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Re: Hawk Headers question

Post by Migge »

But you need that special wrench that fit and you have to double check if there is enough space for it.
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amulheirn
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Re: Hawk Headers question

Post by amulheirn »

Thanks everyone. These are 3/8 UNC socket caps I'm using. I do have the 12-point sockets to do the ones like Jon used up, but I guess getting the tool in there is the issue like you say Migge.

Are your headers on a Hawk Karl? If so, how were you able to be sure the downpipe would be in the right place to go between the starter motor and the engine mount?

Andrew
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Re: Hawk Headers question

Post by Karl »

Well, just some careful measuring and a few e-mails to and from San Francisco! Sanderson is the name. I recmmended them to Roger also for his last Hawk and he also had no issues.
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Re: Hawk Headers question

Post by andrewjw »

One thing you can do, like I have, is cut a short length of hex key which will fit in the socket and protrude just far enough to fit a spanner or other wrench. Then put it somewhere you will find it again!

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amulheirn
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Re: Hawk Headers question

Post by amulheirn »

andrewjw wrote: Tue Nov 07, 2017 4:04 pm One thing you can do, like I have, is cut a short length of hex key which will fit in the socket and protrude just far enough to fit a spanner or other wrench. Then put it somewhere you will find it again!

Andrew
Now that's a great idea - thanks. I already cut down an allen key's short leg, but may have thrown the small offcut away already. :(
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peterc
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Re: Hawk Headers question

Post by peterc »

I would think that AndrewJ’s idea would probably work best.
Just for info a soc cap head for 3/8” UNC is 9/16” dia x 3/8” high versus a button head at 0.656” dia x 0.199” high with a curve from the O/D up to 7/32” flat top.
Allen key size is also reduced from 5/16” down to 7/32” for the button head.
I know mine is a Rover but I suspect the bolting issue is similar. You will probably need to feed the bolts through the flanges whilst the manifold is still 12 mm or so from the head.
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clive
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Re: Hawk Headers question

Post by clive »

Real Steel can supply the header bolts. BY100 - 1202 (Bottom of last page)

http://www.realsteel.co.uk/section2b.pdf
Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
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