I had a very good 2Ltr engine (Vulcan head) and it made almost 190 Bhp with the RL31 but it blocked the rev capacity like a hammer. The same engine made 193 Bhp with HT1e
The engine the RL31 cam came from (also Pinto but 2,1 Ltr and IDF carbs) hardly made 150 Bhp. So as you can see, the cam is not the only part to make power.
I already have a modified head which I’m going to get Graham to make sure it’s good enough for what I need, I have forged 93mm pistons, offset ground crank and GAF 001 rods ready for pinto pin size, I have an RL32 Cam in that head but not heard great things regarding that grind and after reading about ‘pete’ with RL31 I’m very impressed with the results!
I’m just so intrigued regarding ‘Lulabelle’ as it sounds very interesting
Originally Posted by onyd
Thanks Dirk, I understand it’s not just the cam it’s how it all comes together with the right bits! Especially the head, if I lose a few bhp up the top but gain 10-15 bhp lower in the rev range then that’s cool, it’s not a track car and I want to drive down to Le-Mans Classic next time it’s on, but need to keep up with the rest of our crowd with there TVR’s, Ferrari’s, Etc lol
when i was young, A much older engine tuning guy i used to hang out would say stuff like, " your not getting any more power you are just pushing it up the rev range" at the time that statement didnt make any sense to me or many others, but substitute the word power for torque and it makes sense.
and he was right, in the real world where we do most of our driving torque is what we drive on, not power, which is only torque at high revs. ever wondered why 120bhp diesel is faster than a 120bhp petrol? the answer being the diesel doesn't rev so the "power figure" is low but has much more torque.
you can improve torque to a point by adding more compression, a LITTLE more cam, better breathing etc, but unless you go with forced induction the only real way to make more torque is make the engine bigger.
choose the cam to suit where you most want the power
I love the statement that says it blocked the rev capacity like a hammer.
This is exactly how my engine behaved, it used to rev really well to 7k then just drop down dead, litterally wouldn't rev any more.
Last edited by rallyrob; 24-12-2020 at 15:29.
You haven’t seen my driving!! Lol
not enough valve spring can do that, been there done that got the tee shirt!
not enough valve spring can do that, been there done that got the tee shirt!
When you say not enough valve spring what do you mean? Been a while but I'm pretty sure it's got double valve springs.
Not sure about this either, but I don't think it's going coil bound.
Last edited by rallyrob; 24-12-2020 at 17:02.
Correct Graham, soft valve springs can stop an engine from making higher RPM like a block. But please don't start pushing you Pinto springs to the limit, Pinto's valve train does not like high numbers.
The engine I was working on was part of a sponsored engine I gave to a rally driver in Belgium. With the RL31 he reported the engine was no longer able to "over rev". In practice he had to change gear where it was too difficult, where you normally would keep the same gear and rev the engine over the point of making more power but gaining corner speed. So I had to replace the cam again. There was not a huge torque advance anyway but the engine's throttle response was slightly better.
If the engine is more like a track day setup, it will be hard to find a camshaft any better as the RL31, Newman 4.75 or Piper BP300
I will answer this question for you, we "gear heads" have our own language which we barely understand ourself. Not enough valve spring does not mean you don't have enough valve springs fitted, we use this for not enough valve pressure (totally wrong use of the word but there are a lot more things we say that does not stroke
Okay I get you Onyd.
So even though my engine has double springs it still doesn't necessarilly mean they are strong enough for the camshaft, but then as you also say they don't need to be too strong either.
Am I right in thinking I've seen this number for spring pressure before about 160lb, for a good pinto?
Last edited by rallyrob; 24-12-2020 at 17:23.
you got it, valve springs also go off, get softer with time/age
you got it, valve springs also go off, get softer with time/age
Its's sometimes not a bad thing to have a 7k engine imposed rev limit on a Pinto, especially if it's on a bottom end with std rods and pistons of high mileage.
I once used a set of CVH valve springs on a Pinto head which was recommended by an experience Race & Rally engine builder. The springs were a tad on the stiff side but they served their purpose and did the job asked. The most appealing thing at the time was, they cost approx £8.00 a set off Ford.
Like most developing Males.
installed height or on the nose? 160lb would be on the nose, that would probably be enough for fast road cams not being revved to hard, you want more like 190-200 for stuff like HT1 etc
looking at a dyno graph you can usually spot the difference between a cam which doesnt want to rev more and an engine running out of valve spring, if it just the cam wont let it rev on the power curve rapidly rolls over, if it valve spring usually the power abruptly tails off in a straight line heading down
Maybe not a bad idea someone can tell us the ratio between Kg and the English way of measuring.
For an RL31 36-40 Kg closed valve and 85-90 Kg at full lift should be more as needed. Once over 100 Kg, Pinto rockers and cam lobes start to get a hard live
Dirk, its easy, multiply your numbers by 2.2 to get Lbs so your 85-90kg full lift is 187- 198lb to me, that makes our number pretty close
http://www.turbosport.co.uk/showthre...pring+pressure
Okay, so this thread talks about installed height. I take it the poundage over the nose is at the valve end of the rocker/follower?
And it was last on a rolling road in 96 with no printout at the time,and yea, that's last century now.
And the engine's got a Holbay 4011c in it, which admittedly is an old 80's rally profile with alot of duration I believe.
Last edited by rallyrob; 24-12-2020 at 18:45.
we say on the nose as in nose of cam, but what we are really saying is installed spring pressure with valve at full lift of whatever cam is in usehttp://www.turbosport.co.uk/showthre...pring+pressure
Okay, so this thread talks about installed height. I take it the poundage over the nose is at the valve end of the rocker?
And it was last on a rolling road in 96 with no printout at the time,
And the engine's got a Holbay 4011c in it.
As I mentioned before, we use a language we hardly understand ourself
How would you measure that on a pillar drill and scales then?
Compress the spring to the lift you have on the cam, so, for example, approx lift = 10.50mm-11mm and that should give you your 190-200lb over the nose when compressing the spring by that amount?
And obviously, you have to make sure it doesn't go coil-bound in that measurement too.
Last edited by rallyrob; 25-12-2020 at 15:13.
pretty much, you start by compressing to the springs fitted length, then add the full lift amount
pretty much, you start by compressing to the springs fitted length, then add the full lift amount
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