Cam

[John L]

Hi all. I have found myself with 2 modified cams. One was given to me be Mark Elder which came from his pigsty 7. The second was reproduced by the austineers. The receipt says 'high inlets'. The exhaust lobes look standard. 

My question is which is best suited for a fast road/race engine. John

SI try the links don't seem to be working from photobucket for me

[Ian Williams]

You will need to provide more information to get help John, I suggest clocking the cams and providing opening and closing timings BTDC and ABDC together with the maximum lifts, we may then be able to offer some advice. We will also need a better idea of rest of your proposed engine's specification and intended use.

[Speedex750]

Hi all. I have found myself with 2 modified cams. One was given to me be Mark Elder which came from his pigsty 7. The second was reproduced by the austineers. The receipt says 'high inlets'. The exhaust lobes look standard. 

My question is which is best suited for a fast road/race engine. John

SI try the links don't seem to be working from photobucket for me

Hi John,
As Ian says we probably need a little more information about your engine and intentions plus more on the cams themselves. That said, from what you describe, the second cam with only a little (?) more inlet lift and standard exhaust is probably milder than any of PigSty's grinds?

A quick way to determine the lift of these short duration cams is to mic' across the maximum dimension on the nose of the cam and then repeat at ninety degrees to that. Take one from the other and ignoring tappet clearance - that's the cam lift. Did they come with followers as there's another decision to make there.

Dave

[John L]

Thanks for the replies. I will take those measurements tonight and I will try to upload pics too.
I intend to use a 1 1/2" splash crank with new rods and shells.
I have large inlets and double valve springs. Lightened flywheel t.v.
The only modified followers I have are flat which I used with a standard cam in my last engine. I intend to order a set from pigsty when I decide which cam suits me best. Also need to chat to them about a suitable oil pump and jets.

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I have only just noticed that the pigsty cam does not have the off centre lobe for the fuel pump and it looks like it never had??

[Robert Leigh]

Thanks for the replies. I will take those measurements tonight and I will try to upload pics too.
I intend to use a 1 1/2" splash crank with new rods and shells.
I have large inlets and double valve springs. Lightened flywheel t.v.
The only modified followers I have are flat which I used with a standard cam in my last engine. I intend to order a set from pigsty when I decide which cam suits me best. Also need to chat to them about a suitable oil pump and jets.

---

I have only just noticed that the pigsty cam does not have the off centre lobe for the fuel pump and it looks like it never had??

The eccentric lobe only came in when a mechanical pump was introduced, late 1932. Yours must be an earlier one.

Robert Leigh

[John L]

I sat down this morning and measured the lobes on both cams. Some of the inlets differ slightly on the same cam. Is this normal?
I measured as Dave suggested:
Austineers; exhaust 3/4"×1" lift 1/4"
Inlet 5/8"×15/16" lift 5/16

Pigsty exhaust 11/16"×15/16" lift 1/4"
Inlet 9/16"×7/8" lift 5/16"
Maybe I am not measuring correctly but as you can see they have the same lift. Can anyone explain? John

[Ian Williams]

I sat down this morning and measured the lobes on both cams. Some of the inlets differ slightly on the same cam. Is this normal?
I measured as Dave suggested:
Austineers; exhaust 3/4"×1"   lift 1/4"
                    Inlet       5/8"×15/16" lift 5/16

Pigsty exhaust 11/16"×15/16" lift 1/4"
           Inlet        9/16"×7/8"       lift 5/16"
Maybe I am not measuring correctly but as you can see they have the same lift. Can anyone explain? John

Lift is only part of the equation John, you need to establish when the valves will open and close as this will dictate the character of the cam.

[John L]

I am afraid I think that is beyond me! No-one over here that I can travel to either. I have emailed the austineers a few days ago but no reply yet. I might email pigsty now with photos of theirs altho I believe they are hard to get hold of.

[Austin in the Shed]

I'd agree with Ian,the only way to check a modified cam is to set it up in an engine, (Timing disk and drop clock on the valves).even then how it is likely to perform is another matter.I have a box full of them ,some have been fitted and quickly taken out again ( Done by well known regrinders).Most have too much duration to give any power low down,and one brand new one  £330 absolutely useless.
I personally prefer a good standard cam with reprofiled followers the best compromise for power and torque for a road engine.There is also an advantage of being able to up the compression ratio a bit.

[John L]

My last engine had a standard cam with flat followers. It went well. I just thought I could get a little more out of my next engine