Hey all,

I'm considering a set of Keith Dodd / Mini Spares 1.5:1 rockers for a 1098+.040" + 731 cam + 295 head + 2xHS4's. This has double valve springs, but I'm not sure what weight.. are there any issues fitting the high-lift rockers to this head?

I'm specifically concerned about valve spring binding, I remember seeing mention of this in one of Vizard's books but can't find it now. Also, since the higher lift effectively magnifies the spring pressure, would there be any danger (other than the increased friction) in leaving these as they are, or would I be wise to figure out what they are just in case?

Anyone who's done it, I'd be interested in your advice.. and I'm keen to know what real-world improvements can be had doing this to this sort of motor.

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Simon

The adventures of an owner builder in the Tallarook Ranges

I run those 1.5 forged rockers on my 1360. They work great with Minispares C-AEA526 springs (180lb) which have 1 less coil to allow more lift. I have 0.493" valve lift, and RE282 cam.

With a 731 cam you may have too much lift for your stock springs, which if singles are too light for any performance cam even with stock rockers.
But....
Personally I think the 1.5 rockers are overkill on a 1098, you will lose torque and midrange. You might gain a couple of HP tops, at max rpm around 6500-7000.

Chong ran my 1.5:1 Toyota Corolla ones on his 1098 with a Kent 266? cam, he says it went better when he took them off. they are now on his 1330.
I'd ask Graham Russell before you buy them...

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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.

Yepp - concur with Kev - stick to what you have on the small bores or do as I did, remove the 1.5 rockers and replace them with 1.3 rollers - big difference and coupled with the RE-13 makes a great overall difference. Plus the peace of mind of not breaking the valve spring caps(yes one of mine broke...lol)

Hooroo

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Rob Forsyth
Miniot!!

How much did you pay for your 1.3 roller rockers? and where could i get some from?

You would have to go to the mother country for them(minispares)I am afraid or minisport in Adelaide may have them. They cost me $300 but I got them off a fellow here in Canberra(never fitted and excess to his needs) but I think the landed price was around the $750 mark so they are quite pricey(bloody Customs!!!)

Hooroo

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Rob Forsyth
Miniot!!

I know a certain person who just bought a set of 1.3 roller's for 330ish landed, brand new from mini spares....

Cheers
Aaron

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Nooooooooo, the owner says they were actually from Minisport UK. Minispares' 1.3s are NLA at the moment.

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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.

Thread hi-jack as I want to do something similar:

So do 1.3:1 Roller Rockers make a difference over the standard rockers? (considering they are supposed to be 1.3:1 but usually aren't unless you have early cooper s ones). I am also interested in doing something like this to my engine (998).

Just wanting to know whether it would make a difference.

The engine is a 998 + .020", Twin HS2's, ported 295, double valve springs and probably a cam (something like a 266 etc) later on down the track. Would it be worth getting some new roller rockers that actually are 1.3:1? I like the idea of the "WANK" factor (as Hanra would put it).

Will 1.3:1 roller rockers fit under a standard rocker cover?

Thanks, Nick

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"In two years time your car will be like a lady's clothes, out of date, my car will still be in fashion when I am dead" - Sir Alec speaking to Pininfarina

Slightly off-topic, but, given we're talking importing things from the UK, I though they shouldn't charge you import duty or GST on anything coming into the country that's worth less than A$1000..? So, if you've got an invoice on the front of the parcel that says it's worth less than A$1000 (or equivalent amount in pounds sterling - I'd hazard somewhere between 380 and 410 sterling most days (I still can't find that symbol)), you should be right..? Just make sure that you only get one box delivered - if you have two boxes going to the same person at the same address from the same company, customs will cotton on and slug you the duty. Which is still only 5% import duty (on the value of the item) and 10% GST (on the value of the item + freight costs). Please correct me if I'm wrong!
So, to my mind, if the 1.3:1 rockers are worth less than say 350 quid, you should be set - no charges.
The moral of the story? If you're importing brakes, or anything else worth more than A$1000, get them to send half of the kit to someone else who you can trust! With separate invoices on each box. Or, find someone on Norfolk or Lord Howe Island to do it for you!

Alt key + 156 = £

A bloke I work with got a very $$$ mountain bike frame sent to him from the USA. The company he bought it off wrote "warranty replacement parts" on the box and it sailed through Customs with no charges.

It also happened at the time Customs was screwing the pooch with their new software and all those boats were parked off the ports.

One of those things got him off anyway...

OK, the theorist in me is confused. How is it that higher lift reduces torque? I figured that the greater lift would improve volumetric efficiency, which should improve things all over the rev range, not just at the upper reaches. Naturally, more gas flow at high revs will liberate more power, but what is it that reduces torque? Reduced turbulence at low gas velocity?

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Simon

The adventures of an owner builder in the Tallarook Ranges

With too high valve lift on a smallbore you reduce the gas velocity at the valves, causing it to take longer to get on cam, and reducing low and midrange torque.
It's not just the lift that's increased, but the rate of acceleration off the valve seat.
The same is true in a bigbore but on a more modest scale. The general rule there is if it's a road motor that will only go to 5500-6000, use stock rockers- but if it's gonna get a big rev, use the 1.5s.

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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.

Awesome, thanks Doc.. ever informative

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Simon

The adventures of an owner builder in the Tallarook Ranges

It would be worth fitting 1.3 roller tip rockers to a 1098 but they are expensive.
Another option but NLA now, is fit a set of offset bushes to your rockers, drill out the rocker post stud holes 1/16" bigger, and push them back when you bolt em down.
Offset bushes will increase the ratio of stock rockers to beyond 1.3.
Although unavailable from Minispares, you could get offset bushes made from LG2 bronze by a machine shop. Ask TheMiniMan nicely...

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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.