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PostPosted: Wed Apr 06, 2016 10:14 am 
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So it seems that common opinion is that the rev 2 head requires modifying to accept high lift cams and in fact HKS etc typically provide a low lift & high lift variant to avoid the modification in the Rev 2 head.

My understanding was that the head requires the existing cam lobe cutouts in the head enlarged to provide additional clearance (I may be wrong - this is from memory)
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From this pic you can clearly see the standard head grooves for above & below the bucket to provide clearance for the standard cam lobes.

My questions is: - Has anyone actually done this or had to do this? I have a rev 3 HKS 256 "High Lift" inlet cam (9.5mm lift) and they seem to drop straight in with no clearance issues. (what is sufficinet clearance? I'd estimate using my calibrated eyeball guage more than 1mm) Is there any other mods required that I have missed or got wrong?

(I will go shim under bucket or 1ZZ solid lifter to avoid shims flicking out)

The idea is to use the HKS Inlet cam and something like a rev 3 3sgte inlet cam on exhaust (240 deg duration and 8.7mm lift) or Rev 2 3SGE inlet on exhaust at 244 deg duration and 8.5mm lift to avoid running too much exhuast duration (overlap) and keep good spool up and on a Fraser McKellar mildly ported Rev 2 head I have.

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PostPosted: Wed Apr 06, 2016 11:13 pm 
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I hadn't heard about lobes fouling on head. I seem to remember a problem relating to valve lift and needing the spring seats machining down but I wouldn't be certain about this. All you can do is try it and do the measurements.

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PostPosted: Wed Apr 06, 2016 11:28 pm 
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It is a bit new to me TBH.

Would using a spring that becomes coil bound at a reduced length have a similar effect as machining the spring seats down?

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PostPosted: Wed Apr 06, 2016 11:33 pm 
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A bit of digging and it has been suggested that there is 2 variants of Gen 2 Head! Someone has suggested the later type head with 9-stud manifold accpetance has better clearance but doesn't say where! The Fraser McKellar head is 9 stud as are the other 2 spare heads I have on the bench. Arsey currently has a 7-stud head so may be different at present.

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PostPosted: Thu Apr 07, 2016 11:02 pm 
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The usual trick is to go for double valve springs so they can be made out of thinner wire but still provide more closing force overall.

If you machined the spring seats down, you would need different springs anyway as you'd lose closing force.

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PostPosted: Fri Apr 08, 2016 8:43 pm 
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I've personally not heard of any issues.

I have my original Rev 2 engine with (iirc) a 7-stud head which is being rebuilt (WIP) using the following components (amongst other things):
• HKS 2.2L Stroker Kit
• ACL Race Bearings – Rod #4B8366H; Main #5M8361H; Thrust #2T1689
• HKS Metal Head Gasket 1.6mm Thick x 87.5mm Bore
• HKS Camshafts (Intake, 264/9.12mm; Exhaust, 264/9.12mm)
• HKS Uprated Valve Spring Set (HKS 3SGTE 90-95, #2201-RT014)
• Ferrea Valves (+1mm INT, +1mm EXH)
• Ferrea Valve Clamps and Locks
• JUN Strengthened Bronze Valve Guides
• Toyota 1J-ZZE Shimless Bucket Conversion

If you want the number of my engine builder (Chris) to discuss, give me a shout.

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PostPosted: Sat Apr 09, 2016 10:33 am 
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Interesting. So you have stuck with the Rev 2 designed "low lift" hks came as the Rev 3 264 came are 10mm lift intake and 9.7mm exhaust.

The Rev 2 hks 272 however provide 9.4mm lift as opposed to my rev3 256 cam at 9.5mm so not much difference in lift. Maybe I will just get away with it!

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PostPosted: Sat Apr 09, 2016 8:34 pm 
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It would be worth knowing whether the valves are still the restrictive poart at this lift.
Back in my ford days, maximum flow was achieved before maximum lift so increasing lift was pointless. I followed the route reccomended by my local tuner and went for duration rather than lift, and kept the low end torque by keeping port size standard and just removing the lumps round the valve stems. This setup worked very well.

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PostPosted: Sun Apr 10, 2016 11:53 am 
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I wonder if a vacuum cleamer would flow sufficient cfm to create a cheap flowbench. It would be useless for actual cfm measurements but map vs valve lift might be interesting


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PostPosted: Sun Apr 10, 2016 9:49 pm 
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Most vacuum cleaners seem to be 70-80cfm to too low.

Interesting point Chris. A very simplistic area calc indicates that 8.1mm lift provides the same area as a 33.5mm standard valve with 6mm stem. I know this isn't flow but is likely to indicate the restriction point. All I can think of is that the higher lift allows the valve to be open sufficiently for longer with a lift higher than required; so flows more volume per cycle. Toyota have used lifts upto 9.5mm on the 3SGE with 33.5mm inlet valves so I thought there some merit in it.

Shame you can't have square camshafts :-) I guess F1 style hydraulic valves solve this!

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PostPosted: Mon Apr 11, 2016 10:39 am 
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Hmm,
I may have to think about this a bit more. My industrial vacuum is roughly twice the flow at 140cfm. I have one of these http://www.conrad-electronic.co.uk/ce/e ... 0wodmQoC7g for pressure and velocity measurements (not much cop for small ports to measure flow though due to pitot tube obstruction.) IMHO a balometer would be better but I don't have one of those

Balometer - http://www.tsi.com/Alnor-ABT-Balometer- ... ds-ABT703/

It would however be good to get some data on flow inconsistency of inlet manifold, TVIS restriction & Impact , valve lift, port flow (Std & mild port) and intercooler pipes & core. Seeing as I have 3 heads on the bench along with inlet manifolds and a variety of cams and porting it coudl be worth reading up a bit more when time allows to make a cheap flow bench.

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PostPosted: Mon Apr 11, 2016 5:44 pm 
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I think I'd start simple with a hoover, 3 or 4 inch pipe and shed load of plasticine pretending to be a cylinder and a u tube manometer. These whizzbang gadgets are all well and good but you're reliant on the electronics goon who designed them :lol:

Maybe you can use your CEOs seemingly endless hot air supply as a more realistic source :D


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PostPosted: Mon Apr 11, 2016 5:50 pm 
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two_OH_five wrote:
Maybe you can use your CEOs seemingly endless hot air supply as a more realistic source :D


I'd be worried the alcohol content may not pass the H&S risk assessment.

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PostPosted: Mon Apr 11, 2016 5:53 pm 
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A quick google of "DIY flow bench" threw up this, prexactly what I was thinking but using a block instead of plasticine. You could possibly use a toilet pan connector to seal the bore if you went that route

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