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1.5 rockers on stock engine

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64rocksprite

64rocksprite

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Hey all..I'm ready to start finishing off the 1275 (bolt on the head basically) and install in the car.
I bought a set of 1.5 rockers/shaft/pedestals from MiniSport in the U.K. Question is, with a stock cam, no head porting and a "street" LCB is this worth installing?
Vizard indicates that it is worth 4+ HP on a 1275, citing that although duration is not affected, obviously the valve is further "open" or off the seat..and these were a way to essentially take a single step up the 'cam chart' without actually changing the cam. If this is the case, I'd like to get them on.
but I've read other articles on small bores that said 1.5 rockers can reduce torque due to loss of intake velocity. Perhaps this only holds true for the smaller bore engines.

So..My thought was to install the stock rockers/shaft to get the engine broken in, tuned etc. Then try the 1.5 rockers later and see if I can see/feel a difference.
Or should I just install while I'm at it and be done with the mechanicals..i.e. am I being to conservative?

Since the rest of the internals are stock, do I need to worry about piston/valve interference? MS mention to check that the valve springs are not overly compressed. I would think this is related to use with a non-stock cam with more lift(?) otherwise, what can you do other than open the clearance a little?

Is anyone out there running 1.5's and if so, did you notice any change in street manners and/or power?(good or bad) How much hassle were they to get them set-up right? Vizard talks about making sure they are centered..using shims.

Appreciate your thoughts..
 
Hello, I just built a 1275 , bored out to 1363, purchased a high lift kit from Swiftune in the UK. Comes with 1.5 roller rockers, valve springs, cam SW5 and oil pump. The rockers are beautiful, they seem to work ok, but I have nothing to compare them to. You will need shims under each rocker post, I made my own, forgot to buy them, otherwise the rockers will not adjust, the pushrods are to long so that is why we shim them. Shims come in many sizes, give your rocker guy a call if you need them. I had a sick 1098 before, and only 300 miles on my new engine. In a few months I think the truth will come out. I am running a stock head, waiting for my ported head, Hap is building, should have it in a couple of weeks. I had know valve clearance problems, but I am no expert,(evo 73mm pistons from minispares 10:1 comp.) not sure of your setup. Hope I helped.
Cheers Phil
 
Thanks Phil..
You have a monster of an engine! Did you need the shims to add to the stock pedestal height? The rockers from minisport came with taller pedestals..so will I still need shims?

Appreciate the feedback.

Devin
 
Hi Devin,

I am not sure if you need shims, from my research I needed them, give minisport a call. If you install your rockers you will see the problem,(if shims requird) the adjusting nuts will be full out and the push rod will still be to long. I was not aware of the shims and it slowed me down.
It was fun building my engine but I am not a expert, just wanted to save you some grief with a heads up. I really love the look of the rollers, they look fast and when I open the hood I know there just underneath my alum valve cover. IMO I would install them now, easier to adjust on the bench.
Phil
 
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