Newman cam profiles

[Dirk73]

For my sins, i bought a Newman cam from a well know online auction site last year, new but unused.

I now realise my mistake, that i should have bought direct so i could specify the profile. Newman themselves couldn't help with identifying it as they do lots of different profiles to order (although they did tell me that all their A7 profiles are designed to run on standard profile lifters which was a crucial bit of info)

It's approximately 8.1mm lift (0.318") on both inlet & exhaust. I am wondering does anyone run a similar cam? And is that amount of lift race-cam spec?

Tomorrow eve i will get the block bolted down and measure the duration at the valves. My main concern is that it might be a bit high-rpm orientated for a road car. Any comment would be much appreciated

[Speedex750]

Hi Dirk73,

I enquired with Newman in the 70's (time flies) about their range, this was after Chris Gould used a Newman profile on his record breaking Ulsteroid. They said then that they did three profiles of increasing severity; their 'road' profile, then the CG record car profile and then an 'Australian' race profile. The road profile had 0.281" lift and the later two had lifts of 0.320" so you may have one of those. The quoted timings for all three were; 15:55:55:15,  20:60:60:20 & 30:70:70:30.


See what it measures up at, and do it on a few cylinders to average the scatter in the readings and grinding. I suspect things will have moved on a lot since then and they can grind just about any timing on if there's enough material in the lobes so you may have something else. The traditional way of estimating the rev range a cam works is the inlet closing figure - the bigger the number the higher in the rev range.

Dave

[Dirk73]

Thanks for that info Dave.
My rough estimation is 285 inlet duration & 270 exhaust but i need to make up a timing disk to check it more accurately.
(and i'm forgetting that duration is commonly quoted at .050" valve lift) i will have another crack at it tomorrow to get some more precise timing figures.

[Colin Reed]

Hi Dirk,
The Figures would put the cam in the higher end for a racing cam not suitable for road use.
Also for road use The lift of 280 provided by Dave's Figures will put less load on the cam and less likely to lift the Block
Basically the overlap is to big for road use.
Just another perspective.
All the Best with your Project

Colin
NZ

[Boaty]

Hi Dirk 73
Without confusing yourself with the numbers, all you need to do is use intake centreline method. Fit cam in motor with the timing gears you are going to be using and fit keys in keyways,use standard 3/8 radius cam followers place a valve in #1 intake guide, obtain tru DTC on #1 piston you can accurately do this with the piston stop method drill a piece of flat plate to fit over head studs and  accross cylinder 1 with a nut and bolt in centre of plate that is in centre of piston this forms a physical stop.Rotate engine clockwise till piston touches stop bolt and mark your flywheel then rotate engine anticlockwise to the stop and mark flywheel again and now you have 2 marks on flywheel half the gap between the 2 and you have tru TDC. Then if you have a degree wheel that new  mark becomes your Zero, secure a dial indicator above # 1 intake valve rotate engine clockwise till you reach highest lift, then  zero indicator at highest lift have a few goes to check it is repeatable,so now you have your intake centreline at highest lift  and your crankshaft will have gone past TDC and on its way down take a look at degree wheel  in your situation you need it to say 106 degrees past TDC and it will work a treat, however the lower the number the more it is advanced and the higher the number the more it is retarded. it is absolutely critical that you achieve 106. Hope i have helped not easy to explain.


Regards Paul

[Bob Culver]

Considering the camshaft alone, 220 crank, 110 deg cam duration is a theoretical included cam angle of 180-110 deg. About 10 cam deg is lost in clearance and due the radiussed follower so the  angle is about 180-110-10. So from the included angle between cam flanks measured with a V cut in a piece of paper and protractor you can work backwards to cam duraton and double that for crank duration for a quick assessment.
(This applies only to cams with tangent flanks as the original Seven)

I take it from the appearance that the Newman cam is a new production not a regrind.

[Stuart Giles]

Maximum inlet lift on a standard A7 cam is @ 110° After TDC. Maximum exhaust lift is @ 105° BTDC so the factory cam  is fairly unusual in not being "timed down the middle" e.g. the Newman 20:60:60:20 timing quoted by Speedex in the post above would normally go in with maximum inlet lift @ 110° ATDC which would mean that maximum exhaust lift would be @ 110° BTDC. Running the factory cam slightly retarded does give better top end power but isn't likely to work well in a heavier car.

[Alan]

I agree. All the Newman cams I’ve seen rock at 110deg. Remember it’s far more important to have the valve closing late than opening early, so if you have to, err on the retarded side of this.
Another thing, with these new cams there’s precious little clearance between the cam lobes and the conrod of a 1.5in crank. You need to check this carefully. It’s not enough to check for free rotation at assembly, to avoid knocking noises at 5,000 revs the gap needs to be at least 30 thou. You might have to machine the rods slightly to achieve it.

[Terrytuned]

A new Newman 70-30 cam you have to fit the centre bearing as an assembly as the cam peaks will not go through the cam ring when it is fitted to the crankcase.  Terry.

[Boaty]

All Standard Austin seven camshafts have a 107 degree intake C/L and 107 degrees of separation.