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[rsfruitbat]

Does anyone know what the duration is on the std cams?
Did a search on the internet and I found mention of a figure of 274 degrees by a guy in greece in an astra who had a mate with a 33 who wanted to race him. Not too sure of this figure. Seems like a lot.

reason I need to know is I am going to get some more cams for the rally car. 300 degrees is too much and I know the std cams were an improvement so want to go a bit more than std.

Spoke to cat cams and the one they suggested, if 274 is correct is about the same as std with a bit more lift.

HHHHHEEEEEELLLP

rsfruitbat
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Alfa 33 rallycar series 1
1399cc 16V
red / white / blue

[richard33]

Not sure I can help on this one Ade, other than suggest that the Greek guy is wrong! The Piper Fast Road cams (reprofiled) have a duration of 260deg and I don't reckon Piper reduce the duration when reprofiling!
Ref:AR17BP270H FAST ROAD 1500-6500 8 BHP 260 deg 260 deg .380"9.65mm.380"9.65mm 109 deg 109 deg .040"1.00mm.040"1.00mmHYDRAULIC £336 Repro

The 1031012 Cat Cams on my racer are described as "rally and cross" with a duration of 278 / 271° (with 0.1mm clearance). Thinking about it - a dangerous activity - maybe the 'clearance' factor could be causing some confusion here. Running hydraulic lifters, I wonder what the actual running clearance actually is - I would hope next to zero, but who knows? I think you run a mechanical set-up, so at least you can know what you have got.

On the subject of hydraulic lifters, when setting the verniers, I have also been wondering about the certainty of the tappets being fully "oil charged". If not, the setting are likely to be wrong - what do you reckon?

[rsfruitbat]

Richard you are a ray of sunlight in a dark and endless tunnel.
Your thoughts are similar to mine.
I am now running hydraulic tappets as I went to std cams.
I think the only answer to your question is to recheck the cam timing after the engine has been run.
If you time the cams to max lift then there should be no difference. I did this by marking the flywheel with the correct degrees.
If you use lift at TDC then it could change. I know that most engine builders use a nominal clearance figure for hydraulic tappets.
The ones that catcams recommended are the ones that you have fitted. Changed your mind about selling them?

It would still be nice to know for sure though. I spoke to brunswick and he wasnt sure if it was correct as you have to take into account the fact that the lobes are offset. I can see worst case is I have to sit with a DTI over xmas and measure the damn things myself.
Might give AHM a ring later. He is a catcam agent now.
Spoke to Kent who werent very interested wanted cams and a head for measurement. Piper wanted cams and havent phoned back when they said they would. Newman Cams have been good but arent particularly cheap, approx £1200 for bespoke cams

rsfruitbat
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Alfa 33 rallycar series 1
1399cc 16V
red / white / blue

[richard33]

Ade,
Not sure why checking at max lift would eradicate any hydraulic issues. i.e. if the tappet isn’t fully primed, it isn’t fully primed – so will still give a false reading won’t it?
Checking after the engine has run sounds OK, but of course it’s impossible to check lift with the engine in the car, and with it out you have no idea whether the tappets are still fully pumped up! Dave Young recommended fitting a solid tappet/shim to set the verniers - quite a fiddle, but probably the only sure fire way of knowing what you have actually set The Brunswick comment raises a valid point. I have not tried timing standard cams but with the differing profiles and the offsets, it raises many questions. As you probably know, the performance cams generally have identical lobes and no offset, so I didn’t have this problem. Adie Hawkins is probably the best person to advise on this tricky procedure.
I think my “halfway house” hydraulic method will be to check the max lift on all the lobes on each camshaft to establish which have the most, and then assume that that valve is fully open and the tappet is full of oil, then dependant upon which cylinder it is operating work out the correct crank position.
By the way, looking at some of the professionally recommended procedures, some of them have you finding either TDC or max lift by turning the engine backwards! This is clearly really bad practice. I did a few trials to see what sort of errors resulted from the obvious belt tensioning/loosening effects. It was in the order of +or – 15mm of lift at TDC!

Right now, sorry but the Cat Cams cams in the black 33 are staying put, as I have postponed the winter CR increase project. That car will now be kept a back-up. I recently sold the red 33 and bought an ex-Kumho E30 BMW 325i to run in the same TTRS class D. Having an 8v engine, the capacity is discounted by 20% so can run it in the up to 2litre class. Also, it’s RWD so I’ll probably find it more fun.

[rsfruitbat]

Hi Richard
If your tappet isnt full of oil it wont transfer lift to the valve until any resistance is overcome. There are 2 methods for timing in cams as I understand it. If you time the cam with the engine at TDC and unprimed lifters the cam will have been rotated more than is necessary to get the correct amount of lift at TDC.
The second way is to time the cam to max lift at so many degrees before or after TDC. This way it shouldnt matter whether the tappet is primed or not because max lift for the cam is max lift. It may not be the correct amount of lift but the top of the lobe is only in one place.
One other trick I have heard of is to prime the tappets by cooking them in a tray of oil. Theory is the oil gets nice and hot and thin and can run into the oil ports, air is heated up and forced out, As it cools down any air thats left will contract and suck the oil in any way.
As I think I told you before my car runs just over 11:1CR and on a Gunsons compression gauge registers about 220 after cranking for 10 secs.

I have spoken to Adie but not sure how things are going to progress as my engine and sport is quite a bit different from mainstream 33 motorsport

rsfruitbat
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Alfa 33 rallycar series 1
1399cc 16V
red / white / blue

[Admin]

Hi

Is there something on it in the workshop manuals?

I know I have seen figures somewhere (as I have also seen the figures for the 145/6 16V which has different cams on the exhaust side I think), but can't remember where.

All the best

Keith
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[ZeNiTh-PbArM]

Hi,

I seem to recollect that cams for the 16V provide a slight difference between the lobes for the same cylinder, in such a way that both intake valves do not open at the exact same moment but one after the other.
If this is indeed the case it might make sense to be sure you're timing the cams on the right lobe.

regards,
zp

[rsfruitbat]

I have got the figures now from AHM, thankyou Adie.
With aftermarket cams they tend to make both lobes the same so this avoids the problem with which lobe to time it in on.
the std cam do open at different times I have heard it was something to do reducing emissions.

rsfruitbat
_________________
Alfa 33 rallycar series 1
1399cc 16V
red / white / blue