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Roller Rockers, 276 Cam And The Quest For Moar Power


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#1 Spud_133

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Posted 13 August 2013 - 06:04 PM

Hi all, I've already got a rather sorted 1293 road motor which I'm pleased with the power output, the thing is I just want more, so I'm going to get a set of roller rockers, I've been told that 1.3s would be best with the 276 and this is backed up with DVs yellow bible, and on one of his graphs, the torque is higher with 1.3s than 1.5s up to 5500, and the power goes higher between the two. The problem I've found is that the 1.3s seem to be double the price of the 1.5s, and I being stupid or is there a reason. Will 1.5s be better? All advice appreciated.
Cheers, Spud

#2 racingbob

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Posted 13 August 2013 - 06:17 PM

my mates with 1.5 have taken them off

 

you sure there more expensive



#3 Spud_133

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Posted 13 August 2013 - 06:28 PM

Ok, it might be me, what ones do I need?

#4 jaydee

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Posted 13 August 2013 - 06:41 PM

I've used both sintered and 1.3 rollers with the 276, the difference was night and day.

I'd say mainly because sintered were tired and very low ratio the cams are designed with 1.3 or 1.5 ratio in mind



#5 Spud_133

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Posted 13 August 2013 - 07:01 PM

So what would you recommended out of 1.3s and 1.5s?

So what's the difference between,
http://www.minispare...|Back to search
And
http://www.minispare...|Back to search

Cheers

#6 jaydee

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Posted 13 August 2013 - 07:30 PM

1.3 all the day you can have them for a lot less, paid mines 140 inc vat and delivery



#7 A-Cell

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Posted 13 August 2013 - 07:33 PM

Std sintered rockers are 1.3 ratio so you would gain nothing by changing to 1.3 ratio roller rockers. Save your money IMO.

#8 phil hill

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Posted 13 August 2013 - 08:17 PM

Std sintered rockers are 1.3 ratio so you would gain nothing by changing to 1.3 ratio roller rockers. Save your money IMO.

Standard sintered rockers are not 1.3 ratio, not even close.  You may think they are but at best they are between 1.21 and 1.26.

 

As for 1.5 ratio rockers with a Kent 276 from my experience on a 1380 stick with the 1.3's.  Admittedly the compression ratio of the engine wasn't really where it needed to be but adding the 1.5 rockers on that profile gave only a few more hp at the top end but moved the torque up the rev range.

 

Now a 286 with 1.5 ratio rocker, that's a different story !!

 

Phil.



#9 Spud_133

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Posted 13 August 2013 - 08:43 PM

So what's the difference between the two linked above?

#10 DILLIGAF

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Posted 13 August 2013 - 09:39 PM

Just stick a 286 in it, cheaper than roller rockers and at least he designed the 286, rather than just the mid point between the 286 and 266 (the other cam in the range that was designed properly).......



#11 Spud_133

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Posted 13 August 2013 - 09:54 PM

I really don't see the point in pulling a 1500 mile old engine out when I'm happy with the cam though? Doesn't really help my debate either really

#12 DILLIGAF

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Posted 13 August 2013 - 10:03 PM

A bit of a contradiction really then, if you was really happy you wouldn't be thinking about the rockers.........



#13 Spud_133

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Posted 13 August 2013 - 10:26 PM

You say you always want to try everything before you ever condemn it, so why cannot I try the rockers with the 276?

#14 DILLIGAF

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Posted 13 August 2013 - 11:23 PM

You can try anything you want, only offering a bit of advice...........



#15 Cooperman

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Posted 14 August 2013 - 05:10 PM

Spud,
First of all decide what you want to use the car for. The decide where you want the peak power to be. If you want to rev to 6800 all the time when using the power, then go for a 286 cam and suitable induction 7 exhaust system. The 286 gives fantastic power at 6400 rpm and is strong right to the optimum change up point of about 6800 rpm. It is truly a beautiful competition cam.
However, if you don't want to be using such high revs all the time, and if you fit that cam and don't use those revs then you have the wrong cam, go for the 266 or 276. The 266 will give peak at 5700-ish, whilst the 276 peaks at 6100 rpm.
Higher lift rockers really won't make a heap of difference, but 1.3:1 roller rockers will reduce valve guide wear.
When I fitted 1.5:1 rockers on my 1293 'S' with a 286 I gained 2 bhp at over 5700 rpm up to about 7000 rpm, but although I didn't measure it I'm sure I lost torque at lower revs, like at 3000 to 4500. But then, my 'S' is a competition car, so it's no issue. I strip & rebuild it after every 6 or 7 rallies.
A hotter cam requiring more revs will need more frequent rebuilding.
For the road, if you are looking for more power, you may not want to be revving at 6000 or over whenever you want top power. In fact, on the road, better mid-range torque is what is needed.




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