1.5 Roller Rockers

[Skyedriver]

I've read differing reviews
Do these much difference to the power output on a mildy modded 1275?
Been looking at the Minispares December 15% off offer
Also see the racks are reduced, I know I should get one and do my but the impetus to argue with 41 year old unmoved tower bolts isn't exciting much. Or at all.....

[FWDRacer]

On a car with a standard cam or mild road profile these are a great edition. Loads more lift equals loads more torque.

[Skyedriver]

Thanks FWD
Cams a Minispares EVO not sure what the opening/timing is but supposedly best cam for road use. Perhaps Richy cam help here?
Only concern about extra lift is that I decked the block so there is no clearance between piston top and top of block.
Thinking it may be worth while gain in torque at the cost - if only I can bring myself to sort the steering rack out.

[Altrezia]

I have these on my car, but it still feels very slow and gutless.

Each to their own, I guess. I'm not impressed.

[DanGT]

Theu do open the valves more but the fule/carb woute have to be tuned to match.

[Cooperman]

Mine has a 286 and all the other goodies. I gained 2 bhp at 5700 rpm & above when I changed to 1.5:1 roller rockers, but I lost a bit of bottom end torque. A lot of cash for minimal improvement at high revs I thought.

[Skyedriver]

So i might be better off spending the money on tyres but thats another thread, there's an 008 that is legit for road going in the Blue Book, cannot recall which off hand but they might be better on 10" than current A539 on 12"

Anyone in the NE fancy doing a steering rack ....?

[Skyedriver]

1 for, 3 against.
I would have thought the extra lift would be like adding a peakier cam but maybe it is the timing that is all important

[FWDRacer]

Skyedriver said:

... but maybe it is the timing that is all important

Nail. Head. Hit.

Using 1.5 on already peaky long duration cams will result in exactly what Cooperman describes - Higher peak but a loss in torque due to poor cylinder filling due to the cam timing lower down.

On a short duration cam the results are markedly better - Cylinder filling isn't adequate because of the shorter cam timing, so in affect the rockers make the most of whatever valve opening period is available.

...some figures.

A+ 1.3 motor - Rob Walker modded head on MG valve sizes - standard cam and factory timing. 1.5 ratio roler tip rockers, HIF 44 on modded MG metro inlet, BDJ needle (modded), K&N inc stub stack and a Maniflow LCB and twin box RC40. Spec wise, unashamedly modest.

• 85bhp at 5500 and *64lb/ft from 2300 - 4600. It went very well on the road, even with a 3.1 final drive and standard ratio box.

• Please note these figures weren't recorder at Peter Baldwins RR.

[Altrezia]

FWDRacer said:

Please note these figures weren't recorder at Peter Baldwins RR.

(To be fair to Peter, I had my previous turbo mini measured at his place and it made 143bhp @ 11psi. I took it to Slark 12 months later and it made 140bhp..)

[ace01]

I have a reasonably tuned 1275 fitted with an Evo 001 cam and twin 1 1/4 carbs that I happened to have at the time of the engine build. On the rollers it had approx 76hp at the wheels. A little later I put a pair of 1 1/2s on and a set of MiniSpares 1.5 rockers (not the fancy roller jobs) on the rollers at set up it now had approx 90hp at the wheels and the car feels so much more responsive. Not a definitive analysis I know, but in my mind proof that 1.5 rockers can work with the right cam, in this case an Evo 001.

[Skyedriver]

ace01 said:

I have a reasonably tuned 1275 fitted with an Evo 001 cam and twin 1 1/4 carbs that I happened to have at the time of the engine build. On the rollers it had approx 76hp at the wheels. A little later I put a pair of 1 1/2s on and a set of MiniSpares 1.5 rockers (not the fancy roller jobs) on the rollers at set up it now had approx 90hp at the wheels and the car feels so much more responsive. Not a definitive analysis I know, but in my mind proof that 1.5 rockers can work with the right cam, in this case an Evo 001.

Right cam and larger carbs allowing more air although I wonder if the "more air" caused a drop off at lower revs.
Was that a Minispares Evo cam?

[guru_1071]

im also amazed at how many people just 'bolt' a set of 1.5 rockers onto the top of their engine and don't bother checking and adjusting the ratios etc - then complain that they don't do what they think they will do!

[ace01]

Skyedriver said:

Right cam and larger carbs allowing more air although I wonder if the "more air" caused a drop off at lower revs.
Was that a Minispares Evo cam?

The pick up at the lower end of the rev range is about the same. I think the engine needed the large carbs.

Yes, it was the MiniSpares cam.

[Cooperman]

That sounds about right.
I've never tried 1.5:1 rockers with a mild cam and with a decent head, carbs & manifolding, but I suspect that there is where the gain will come.
I have the 1.5:1 roller tips on my 'S' but it only gives a couple of extra bhp at the top end.
The best advantage for me is that it reduces the wear rate on the valve guides, especially at high revs.
One does hear good things about the higher ratio rockers with milder cams.