What is the proper rocker gap for my 1275 with 1.5 roller rockers?

thanks

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Mew

Depends on the cam...
for a stock Mini cam and 1.5s, .015-.016".

with a Kent 266-276-286 etc, or a Graham Russell RE13, .016" is right for stock rockers, but for 1.5s- .018-.020" is recommended.

I use 1.5 rockers with an RE282, I run (the GR recommended) inlets .022" exhausts .024".

<edit> rule of thumb is, (stock rocker clearance + .003").

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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.

My Cooper S has these roller rockers fitted (see pic), I assume they are 1.5's.

Without knowing what type of cam is fitted is the role of thumb mentioned the best setting.

They seem to be set at around .020 at the moment.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Yep, those look like the miniSPARES 1.5 rockers.

Kent state that for ANY of thier cams being used with 1.5's that the clearance should be 0.019"... hope that helps Doc...

GR was saying the other day, that it depends on the profile of the cam and the ramp up (how quickly it opens)

... and I'm not arguing with that, he is right...

but it is safe to say that with higher lift lobes, considering that the lobe only has (for example) 290 degrees to go from 0.000" to 0.340" (at the lobe) and then back to 0.000" agian,,, its pretty safe to say that it will have a pretty quick opening rate and extra clearance should be made.

Most manufactures of high lift rockers recomend 0.018,, but if your lobe lift is higher than say 0.260" to 260 degrees duration I don't think it would hurt giving it an extra 0.001-0.002"... it won't kill your motor giving it extra clearance,, but it will kill it if it doesn't have enough....

if there is toooo much clearance, obviously you are going to rob yourself of some of the potential lift...

EDIT--> thats better, quote fixed

Might have to go back and re-adjust. Must admit didn't even look at the book - just set what I do on the Chev V8 engine ( 0.008 inlet and 0.010 exhaust)

BTW - Standard rockers, 266 cam, double valve springs.

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Dave K.
1979 Moke Californian + 1981 'Coke' Moke

this is different from a small bore or is it the same?

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1964 smooth roof panel van
1967 Mk 1 X-Police cooper s
1970 mini k
1975 leyland

Exackery da same.

Small and big bore, it doesn't matter.

miniDave, wow, how long have they been like that for?

The reason they are wider is as I stated. You want the same lifter to lobe clearance after the rockers are changed.
Yes the rule of thumb is .003" increase, but the formula for 1.5 rockers is :
new rocker clearance = (rocker clearance spec for the cam) x 1.5/1.25

For a .016" gap (Kent cam) it comes in at .0192".
So, .003" increase is pretty damn close.

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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.

yeah sorry doc, I wasn't saying you were wrong mate, I was telling you what they say you were right anyway

PK I was actually replying to phillb, in a simplified fashion.
I am a man of few words...

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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.

Yeah, I'm still learning how to do that

Thanks to both PK and DrMini for the answers and explanation.

The other thing I was wondering is would a standard original rocker cover fit over these rockers. An alloy cover is fitted at the moment, the style that has the slope from rear to front (of the car) in the top.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

std cover fits no worries I'm a bit odd,,,, I actually like the standard covers So I have them on all my motors.

I'm the same, I like the original. I love the hot run tested sticker too.

Also I have noticed the oil filler cap of the alloy one has been rubbing on the bracing of the underside of the bonnet.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

how curious?

Yeah, I prefer the originals for a few reasons,,, they're sneaky (you don't suspect a thing ),,, they usually seal properly (alot of the current alloy ones don't and leak oil),,, I find them astheticlly appealing (they don't look like something you'd cook a sandwich on)....

But lots of people like them, they're "meant" to be quiter (less tappet noise). I say good for them... more stockers for me