750 pipe headers

B

Basketcase

Senior member
Do the 750 SF header pipes fit small valve heads ?

I rather like the look of those for my GT.

If they do, are they pathetically short if not using an underneath collector box ?

Cheers,

Rob
 
The experts will set you straight for the manifold end. As for the connect to the muffler, it is usual to weld a stub to the header or use a clamped stub in between to the muffler when eliminating the collector on SF 1-3. I have tweaked up my headers at the last bend for more clearance as well. I corner too hard to live with the collector box, it is an item for the rivet mob but not for me.
 
Hi Rob - I've just measured the small port and large port heads - the exhaust port dimensions are the same at the outlet - so the later pipes should fit. I do have a small port head on my proddy racer 750 and don't remember having to modify this area at all - except for inserting an aluminium sleeve to reduce the length of steel ex pipe residing in the head - not a requisite for everyone. I did the patterns for "Armours" for the longer downpipes that negated the need for a crossover tube about 20 years ago - think they still supply them. - regards - Phil
 
I have some of the Armours long header pipes (purchased about a 18 months ago). Had to buy their silecers as well as the header pipes were larger diameter than my previous header pipes. The clamp to connect the silencers to the headers was a bit wimpy so I ground it off and am using some conti clamps. Overall happy with the whole system, sounds and looks great, not sure about performance losses from the lack of balance pipe.

Chris
 
Have never noticed any drop in HP whatsoever from removing balance pipe. Correct me if I'm wrong, but didn't the original SF balance pipe actually operate as a separate cross-over, where the gases never even mixed (right crossed to left and v-versa)?
And definitely extra clearance to be gained by carefully bending in the right places to tuck the headers as high as poss. A single header into the muffler definitely looks cleaner than fitting a linking pipe; good butt welding might go close. I had some bewdiful headers made by a craftsman in Perth back in the late 70s by the name of John D'Arrietta, tucked right up and raced with those with good clearance - I need to find another master like John (any suggestions Melbourne-based?). I sadly let those headers disappear when I fitted the factory SFC 2/1 30+ years ago - regretting it now (likewise so much 'unwanted' old stuff I tossed).
With a 270 twistie I'm planning on going back to a twin sys with some siamesing - the reverse cone definitely doesn't work with the twisted crank the way it did with even firing pulses and as SFC cam.
The Staintune sys on a friend's SF1 in my garage is a terrible fit - mufflers are hanging like a hyena's arse-end! Wouldn't even try and test cornering clearance. Beware the cheap auto muffler benders that deform the pipe and reduce the dia.
Interesting topic, header and port sizing. I mistakenly took too much metal out of my ex ports and ended up having them machined out and fitted a sleeve so I could start from scratch again! Bigger definitely ain't always better when discussing exhaust ports.
 
Looking at my GT headers and comparing with photos of big valve SF headers.

It appears that the GT swaged collars are about 20mm from the pipe ends, so the pipe fits further into head past the counterbore.

SF header collars appear flush with the pipe ends.

Or maybe the photos I am looking at are of 40mm pipes instead of 38mm so they have to stop flush ?

Cheers,

Rob
 
Basketcase said:
Looking at my GT headers and comparing with photos of big valve SF headers.

It appears that the GT swaged collars are about 20mm from the pipe ends, so the pipe fits further into head past the counterbore.

SF header collars appear flush with the pipe ends.

Or maybe the photos I am looking at are of 40mm pipes instead of 38mm so they have to stop flush ?

Cheers,

Rob
Click to expand...

Mounting isn't the same. Small valve head collars use half rings which abutt against a raised part of the header to ensure it's tightened to the head. That raised part is distinct and far from the end of the header.
The large valve head headers are flanged at the end, the collars tightening against the flange and so nearer the head.

Paul
 
I'm not sure but whether split rings are used or not may depend upon whether the downpipes have a balance pipe or not, only the pipes with balance stubs need split rings to fit the collars on those without balance stubs the collars can be slid on from the silencer end.
 
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