34 replies to this topic

[carbon]

Dave - that's a well thought out spec for your motor. CR of 10:1 with premium fuel sounds right, I am running a 1293 with almost exact same spec and this is also on about 10:1 using Shell 99 octane with Castrol Valvemaster.

 

The only two suggestions I would make about this spec are first you should find that the 'blue' clutch cover will be sufficient if you are running a standard material clutch plate (but if using sintered metal you will likely need orange). The other is with the twin HS2s these can be made to flow a lot better by carrying out the 'vizarding' mods to the carb bodies and throttle shafts, but will also need substantially different needles fitted as a result. If you're using the standard twin HS2 tin filter box there is also quite a lot you can do to improve flow on the alloy elbows.

[ACDodd]

For maximum pull between 2 and 5Krpm, fit the 1.3 rockers.

AC

[dgear1984]

For maximum pull between 2 and 5Krpm, fit the 1.3 rockers.

AC

 

Yep, copy that, Im going to return the 1.5's and fit the 1.3's once I have the head back and have sorted the rocker posts out.

 

Im happy to leave the carbs/airbox as is it is at the moment, they are something I can play with at a later date once the engine has been running. I really am concentrating on getting the actual gearbox/block/head sorted, as once that goes in hopefully it will never come out as I am a little up against it with a special time scale.

 

Just need to double check the deck height and give that to Rob for when he does the head. Looks like 10:1 is the way to go also

 

Thanks Dave

 

Edited by dgear1984, 31 December 2013 - 05:39 PM.

[minilee94]

You won't even notice the loss at bottom end with 1.5.1

[Cooperman]

And you won't notice any gain at the top end either .

You will, however, notice the dent in your bank statement for the expensive 1.5:1 rockers!

[minilee94]

1.3.1 are same price or near enough

And I'm in the same situation with rockers and I'm not looking for a gain I just want the car to run lol

[minimadles]

Just fit the std forged rockers these will be fine

[dgear1984]

Stripped down my old s rockers today. They have s steel posts

 

The posts seem to have some very strange grind marks in places mainly on the top. Not sure why it would have been done. Was going to see if I can get the missing material welded back on and flatten appropriately, mainly for cosmetic, I know you won't see it but it doesn't look right. I will speak to a professional welder on friday.

 

I don't think the rockers where in the right places (order) but I don't have my head to really check so have just labled them as they where. 

 

post 1 - no oil hole

post 2 - grind marks on the front. 6.1mm oil hole which has broken through. Is this going to be a problem? If it is I can repair it, got a couple of ideas

post 3 - locking hole and 3.1mm oil hole. The front also has some grind marks

post 4 - 5.3mm oil hole.

 

 

 

[dgear1984]

got details of the full spec now, built the bottom, top end to go....

 

cooper s 1275s thin flange block +60

21253 pistons

521 rods

480 crank mains +10/bigs std

new damper with cooper s pulley

ACL steel backed bearings and thrusts

fully balanced

12g940 1805 head flowed and ported by Rob Walker

35.7 and 31mm unleaded valves with 3 angle hard seats and bronze guides

piper billet cross drilled bp270

light weight steel duplex gears

GLP138 oil pump

lightweight flywheel

270 back plate

orange cover

new 1.3 forged rockers

rocker spacers/shims

1128 gearbox with 1040 ratios and x pin diff with 3.44 and hardys

Twin HS2 on aeg347 manifold (will be putting some H4 on at some point)

Maniflow LCB (lm004s11r)

Maniflow stainless 1 3/4 twin box

 

 

 

just need to find some steel 1.3 posts

 

 

 

 

Would I be correct in thinking with this setup the twin hs2's an AF needle / RED spring would be a good starting point to run it in on before going to the rollers with some h4's?

 

Edited by dgear1984, 05 January 2014 - 06:53 PM.

[carbon]

I'm running similar(ish) spec with twin HS2s using QA needles. These are pretty close to the AFs (QAs slightly leaner just off idle and slightly richer at very top).

 

The AFs should work fine.

[jaydee]

AF's are a bit too rich at bottom and too lean at tops, much better the QA carbon suggested.

I'd try a pair of AH2 or even M needles for the run-in process, but carb inlets play a big role on needle choice

IE, I run 6's (rich option) or E3's (lean option) with a 270 type cam and twin HS2s and mine is a small bore but with trumpets and sock filters

[dgear1984]

AF's are a bit too rich at bottom and too lean at tops, much better the QA carbon suggested.

I'd try a pair of AH2 or even M needles for the run-in process, but carb inlets play a big role on needle choice

IE, I run 6's (rich option) or E3's (lean option) with a 270 type cam and twin HS2s and mine is a small bore but with trumpets and sock filters

 

The carbs are unmodified with unmodified elbows and full oval standard cooper s air box with uncut tube. It has K&N filters in it, although thats no performance gain to the standard filters, just means I can clean them out rather than buy new when I service.

 

Thanks

[dgear1984]

AF's are a bit too rich at bottom and too lean at tops, much better the QA carbon suggested.

I'd try a pair of AH2 or even M needles for the run-in process, but carb inlets play a big role on needle choice

IE, I run 6's (rich option) or E3's (lean option) with a 270 type cam and twin HS2s and mine is a small bore but with trumpets and sock filters

 

Why would I need to use different needles for running in? Surely the "correct" needles should provide the right air/fuel ratio at what ever load and revs you are using be that normal running or running in? 

[jaydee]

You'll find out the volumetric efficency wont be the exactly same in the two situations meaning you need different settings.

And the most important thing, during run in you need a lean mixture and to never let it idle at tickover, because this will prevent the piston rings from sealing and will just wear out the honing, and in the worst case you'll end up with an engine with poor compression.

I have to add the most critical part is the first 50-100 miles.

Edited by jaydee, 22 January 2014 - 10:47 PM.

[dgear1984]

Hello,

 

Starting to rebuild my 1275 mk1 cooper s block.

 

The block is 60+ and I will be fitting a 12g940 1805 head which will have been ported, cc'ed, unleaded seats and valves etc.

 

I have a brand new Piper 270 camshaft which was recommended to me by the engine builder/machinist.

 

Should I fit my standard 1.3 forged cooper s rockers or the 1.5 forged rockers I have with that cam. I am aware of checking the springs do not get coil bound etc..

 

Thanks Dave

 

Right, ok slight technical hold up.

 

I had planned to use the minispares 1.3 rockers, they are not really suitable for this rebuild now..... long story

 

The old genuine rockers I have, have damaged pads so also no good.

 

The options I have are 1.5 forged minispares rockers, NOS bmc rockers (if I can find some) or 1.3 roller rockers (would prefer not to for originality)

 

Peoples opinions?