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1.5 High lift rockers
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Author:  Rupert [ Thu Jan 06, 2005 9:22 am ]
Post subject:  1.5 High lift rockers
1.5 Hi Lift Rockers for Mini

Take a set of rockers from a 2K, 3K, 4K (and poss 5K) Toyota engine and also Mini rocker shaft, bushes and pedestals.
Machine the Toyota rockers to take the mini bushes to fit on the mini shaft
Turn the mini pedestals around (this sorts out the centring for the rockers) and drill out the small pedestal stud hole to suit the head stud.
Pack the rockers with shims or whatever to sort out the spacings over the valves.
And this should give you 1.5:1 rockers.

Problems with the 2K Toyota rocker conversion is as follows:

1) their width have to be machined down to 15mm;
2) the bushes sizes are as follows, ID 14,3mm OD 16,03;
3) make sure you buy a set of rockers where the foot/part pushing on the valve tip are made up of 2xsets of 4xleft and 4xright;
4) the pedestals need to be machined or grinded down/away where it locates between the springs;
5) the newly drilled holes actually penetrates the shaft hole and therefore the shaft needs to be drilled ever so slightly to allow the pedestals to enter over the studs.

Too much hard work for me. I just bought some 1.5 rollers from Karcraft.
Author:  drmini in aust [ Thu Jan 06, 2005 6:53 pm ]
Post subject: 
I tried turning the pedestals around, but they are too flimsy at the head stud end once you drill them.
I left them the right way round, plugged the shaft holes with 9/16" steel bar (BRAZE it in) milled them flat then redrilled them <edit> 4.0mm back towards the carb.
Geometry looks sweet.

I made bronze bushes to fit the Mini shaft, and narrowed the rocker bosses on the widest side by .140". Finished width 0.625".
Rocker post widths are stock Mini.

ps. you won't MIG weld these posts- they are cast? and full of OIL. But they braze nice with bronze welding flux. :wink:

I'm running MiniSpares forged 1.5s in mine now, I'll fit these Corollas in a week or two and compare the valve lift. 8)
Author:  mini065 [ Thu Jan 06, 2005 7:44 pm ]
Post subject: 
I have a set of corolla rockers for a mini in my shed. They were taken from a 1310 engine i built a while ago. Got over 100 horsepower with hardly any headwork and Mk11 valves. (bottom end had a bit of work but not excessive) When my engine was dynoed at Graham Russells he said they were a good conversion to use on minis and that the lift was just below 1.5 but not by much.( i think he was saying around 1.48 or there abouts) Will be interesting to see the lift you get with these Drmini. :wink:
Author:  drmini in aust [ Thu Jan 06, 2005 8:00 pm ]
Post subject: 
Ozmotorsport had a set on his 1380 race Clubbie that he sold recently.

Probably less lift than my MS forged ones- KC reckons they are 1.58:1...!

These Corollas will probably go into Barney, the wife's 1293 pretend S, after I check the lift out. :wink:
Author:  Chris [ Thu Jan 06, 2005 9:33 pm ]
Post subject: 
drmini in aust wrote:
I left them the right way round, plugged the shaft holes with 9/16" steel bar (BRAZE it in) milled them flat then redrilled them 4.5mm back towards the carb.
Geometry looks sweet.


Kevin. couldn't you use loctite to glue the bar in. It wouldn't be going anywhere with the offset hole in it anyway would it?
Author:  drmini in aust [ Thu Jan 06, 2005 9:54 pm ]
Post subject: 
Chris, there's more force on the rocker shaft than with stock rockers. The hole is only 9/16" (14mm+) and has been moved 4.0-4.5mm. <edit> So new hole is part in post and part in plug.
Shaft is pretty flimsy (even this thick wall one).
Needs good support & alignment from the rocker posts.

I did this one as a trial- if I get serious modding them I would mill up new posts. Probably less work too, but over Xmas I had no steel! :lol:
Author:  drmini in aust [ Sun Jan 09, 2005 6:44 am ]
Post subject: 
Forgot to add, relocated rocker shaft needs the oil hole in #1 rocker post angle redrilled to suit, and a 3/8" UNF hole tapped in another post to replace the #2 location one (which is now in wrong position). 8)
Author:  drmini in aust [ Mon Jan 10, 2005 1:07 pm ]
Post subject: 
mini065 wrote:
I have a set of corolla rockers for a mini in my shed. They were taken from a 1310 engine i built a while ago. Got over 100 horsepower with hardly any headwork and Mk11 valves. (bottom end had a bit of work but not excessive) When my engine was dynoed at Graham Russells he said they were a good conversion to use on minis and that the lift was just below 1.5 but not by much.( i think he was saying around 1.48 or there abouts) Will be interesting to see the lift you get with these Drmini. :wink:


OK I just got done measuring the Corolla rocker ratio when fitted to a Mini.
Method:
1. I set a 1275 head up on a block with #1 exhaust valve in, RE13 cam, #1 cam follower and pushrod in.
2. Measured cam lobe lift at the pushrod with a dial gauge- it was 0.290".
3. Bolted the Corolla rockers on, set rocker clearance to (-).002". Zeroed the dial gauge.
4. Turned cam over to full lift. Valve lift measured 0.423".
Calculated Corolla rocker ratio: 0.423/0.290 = 1.46

5. Repeated steps 3 & 4 with a good set of Cooper S rockers.
Valve lift measured 0.359".
Calculated Cooper S rocker ratio 0.359/0.290 = 1.24

6. Measured the same way with the MS 1.5s in my car (same RE-13 cam type)
Valve lift measured 0.450".
Calculated MS 1.5 rocker ratio .450/.290 = 1.55.

So YES, Corollas are lots better than forged S rockers. Not quite as good as my 1.5 forged ones, so I'll keep my car as is. 8)
I'll stick 'em into Barney, should `give a lift' to the Tighe/Wade 104 cam it's got. :wink:

<edit> typos..
Author:  poeee [ Mon Jan 10, 2005 2:06 pm ]
Post subject: 
Wonder if my parents would mind me borrowing the rockers off our KE55. I think they would.
Author:  simon k [ Mon Jan 10, 2005 2:46 pm ]
Post subject: 
I've located a dead corolla, just have to rob it's rockers :D
Author:  MadMin [ Mon Jan 10, 2005 6:43 pm ]
Post subject: 
So Kev, when you gonna knock up a bunch of them posts?
Author:  drmini in aust [ Mon Jan 10, 2005 6:44 pm ]
Post subject: 
MadMin wrote:
So Kev, when you gonna knock up a bunch of them posts?

PM sent. 8)
Author:  mini065 [ Mon Jan 10, 2005 8:23 pm ]
Post subject: 
Nice one Kev. Thanks for the figures. I guess i will try and fit them to 'something' in the near future as it seems a bit of a waste in the shed. :) Once the credit card has less of a bruise on it , it may be time to build something for my deluxe project.
Author:  nuclear_mini [ Mon Jan 10, 2005 9:06 pm ]
Post subject: 
guys, where bouts in sydney does anyone think i could get a set of MS 1.5 forged rockers? I would love to set them up on bricktop before the track day.....
Author:  drmini in aust [ Mon Jan 10, 2005 9:12 pm ]
Post subject: 
www.karcraft.com.au
:wink:
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