I can see why the 20mm spacer is needed , looking at the photo I wonder if you gave the spacer a slight angle so that its 19mm at the bottom end and 16mm at the top end would work, I was just thinking about clearance for an air filter , that slight angle might make it a bit easier , I will have to get two spacers made to test that , I might ask the guys at Hoppers Heads tomorrow
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I made the spacer 20mm long to add port volume, nothing more. I had some ally 25mm plate so used that.
It would fit fine with a stock spacer, if I owned one.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I just had a look at the Avonbar website and the only spacer listed for a HS6 is 5mm !!!! , looks like I am going see the guys at Hoppers Heads
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I like the look of it..just missing the plug as you can see in Doc's pic is blocked & the plate and spacer. Do, do a test fit...with studs in for the manifold and put some grease on it...bolt it up and the take it off and you will see if its off center or not or needs to be opened up or not

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Stop Licking the Dog...I Don't Care Who Started It

My Minispares intake is shaped differently - big bore for 1380 (with Minispares big bore LCB). Spacer is absolutely required to actuate the HIF at all and even then careful machining of the spacer was needed to fit assembly to head with clearance for floatbowl. And then careful filing was needed to allow throttle cable clearance on the manifold.

Both intake and LCB went out for ceramic coating...after careful fitment on the bench to get flange/port matches. Even though both were from Minispares they would not even bolt up together without addressing interference and intake flange shape/thickness.





Intake has ceramic coating on exterior only. LCB inside and out. Latter reduces under bonnet temps by +100F.

QUESTIONS - Could quadrant be different? Activation by throttle cable different?

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Select a gear, bring up the revs and release the clutch...off you go!

Hunter2 I will agree my throttle cable is different to yours as in yours is so close to the manifold. I'll try and get a pic Wednesday for you
Also interested in the hole on the piston housing where you also have a unpolished ring 1/2" from the the base

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Stop Licking the Dog...I Don't Care Who Started It