Silver Sprint Head/camshaft failure

[Paul Roberts]

Hi guys

Haven't posted for quite some time due mostly to having little to report on the motorsport front. After a a motor rebuild with new head (new Newman cam - Tarmac Rally 290/400) and running 45DCOE Webers car was going fantastically. I will post a couple of pics from annual Albany Around the Houses and link to Albany hill climb event where we finished a respectable 15th overall. However, the Albany weekend seems to have prematurely taken its toll on the the head. After approx 400 miles of driving down, 40 miles of competition driving and the 400 miles driving home, the head is completely knackered. This was revealed by a ever increasing tappety noise on the way home and a complete loss of power over 4000rpm; previous to this (ie in competition) the car was spinning to 6500-7000 very happily. The cam is slightly chewed out and will need replacing, and the cam buckets and some of the lobes on the rocker are badly worn - number three in particular is very noticable.
My objective with his car is to have a reliable and fun competition car that is reasonably competitive. Now I am faced with more bills which wasn't the objective. Theories and advice greatly received. I am particularly interested in any information relating to what machining might have been advisable to the head to accommodate the increased lift of that particular camshaft. Prior to the problem, everything seemed perfect and the engine sounded and performed fantastically. Over to the experts ......

Thanks

Paul Roberts
Perth, Western Australia

[bodgerben]

Hi Paul - sorry to hear about your engine.

The TR290/400 should not need any special head mods - this is a relatively mild, torquey cam. I don't see how cam instalation could work fine for the drive down and then fail on the way back home.

When you have serious head issues like you describe I'd check the oil circuit. Pop the pump off and check that and the relief valve.
The oil filter/ transfer housing/ oil cooler and thermostat - are any O rings nicked. Is the filter in good condition or has it broke up?
Loose oil gallery plug on the main oil gallery - any oil leaks?
What was the oil pressure like on the way back home (although this will only say the bottom end pressure)?

If the oil feed side is OK look at the oil feed to the head and into the rockers.
Front Jackshaft bearing - is it now silly oversize bearing (or did you have a new bearing put in - has this moved)?
Rocker shaft - are the core plugs OK - any feed holes blocked?

It's early days - but when you rebuild the head put a set of Arrow oversize cam followers in. New rockers are a pain to find but some people on here may have the odd spare new one.

Cheers,
Ben

[Dolly-Nut]

I would point towards an oil supply issue.
What oil was used?

[paulsprint]

I'm also thinking head oil supply issue. Has the locating screw come out of the rocker shafted the metel cap come out of the end. If you have had bearing put in the block for the jackshaft, has this spun. The oil flow for the head is controlled by the jackshaft so any problem there will cause oil shortage at the head.

[Paul Roberts]

Appreciate your comments and input. The oil was Mobil 1 fully synthetic (always used in the past). Oil pressure was very good and continued to be so. General feeling at my workshop was that oil starvation had created the problem, but that maybe the oil was also part of the problem (ie not containing necessary additives). Will certainly look into this further. Also going to rebuild head using single valve springs and not the doubles this time. Think I am going to persevere with that Newman cam (ie, buy the same cam again) as it did seem to produce nice tractable horsepower. That said, I am open to options based on other's experience.

Any further thoughts greatly received.

Cheers

Paul Roberts
Perth, Western Australia

[Dolly-Nut]

I don't know from experience but I have heard, especially in the states that racers were having extreme head wear issues with modern oils not containing enough ZDDP. In the running-in process once higher revs were reached the cam lobes would become noticeably worn or completely fail within just a few hundred miles. Search ZDDP and cam wear on Google and you will find quite a few posts. I'm not saying that the oil will be the problem because an oil supply issue does sound likely, the oil just wouldn't have helped.
I recommend this http://www.ebay.co.uk/itm/Valvoline-VR1 ... 45ff6691dd It's a highly-refined modernised mineral oil that still contains enough anti-wear additives for our cars. I've been using it for 9k and will continue to do so.

[Paul Roberts]

Dan, that is fascinating. You know what really p155es me off though, is when you find this stuff out after it is too late to prevent something that was possibly very preventable. I have this saying ... "trap for young players". I'm not that young anymore!! Anyway, thanks for your input - it has been very valuable.

Cheers

Paul

[bodgerben]

Don't fret about Mobil 1 15/50 motorsport - I've been using it for well over 10 years in Sprints with no head issues.

[Dolly-Nut]

Are all the various cams made from the same material? Obviously regrinds are the same as standard and as far as I'm aware the standard cam is fine with modern synthetic oils, but perhaps some of the performance cams are made of a softer material that require specific oil with higher ZDDP levels?

[SPRINTPARTS]

My objective with his car is to have a reliable and fun competition car that is reasonably competitive. Now I am faced with more bills which wasn't the objective.

I know that feeling well. This is why the my Dolly has been retired from regular competition and I am now racing a more modern car, but I can assure you it also has its problems.

Your issue certainly sounds like an oil supply problem to the head. Check the jackshaft end float, if the keeper plate is worn excessively or the groove in the jackshaft is worn too much end float will restrict or stop oil flow to the head.

I will make a long story short. I have had a similar problem with a cylinder head, worn cam lobes, rocker etc. A another head was fitted but oil pressure remained low. Numerous oil pumps fitted and problem continued. Eventually oil cooler was removed and everything returned to normal.

My preferred oil is Penrite HPR15 (15w/60).

Good luck with the repairs.

Mark

[mahony]

My objective with his car is to have a reliable and fun competition car that is reasonably competitive. Now I am faced with more bills which wasn't the objective.

I know that feeling well. This is why the my Dolly has been retired from regular competition and I am now racing a more modern car, but I can assure you it also has its problems.

Your issue certainly sounds like an oil supply problem to the head. Check the jackshaft end float, if the keeper plate is worn excessively or the groove in the jackshaft is worn too much end float will restrict or stop oil flow to the head.

I will make a long story short. I have had a similar problem with a cylinder head, worn cam lobes, rocker etc. A another head was fitted but oil pressure remained low. Numerous oil pumps fitted and problem continued. Eventually oil cooler was removed and everything returned to normal.

My preferred oil is Penrite HPR15 (15w/60).

Good luck with the repairs.

Mark

Mark is that penrite hpr15 fully synthetic or semi synthetic looking on the penrite site it looks like they no longer do the semi hpr15 ( i found the semi syn here http://www.holden.co.uk/displayproduct. ... de=015.933 )

[SPRINTPARTS]

Mark is that penrite hpr15 fully synthetic or semi synthetic looking on the penrite site it looks like they no longer do the semi hpr15 ( i found the semi syn here http://www.holden.co.uk/displayproduct. ... de=015.933 )

The HPR 15 started as semi synthetic, but has now gone full synthetic. I have continued to use it with no problems.

http://www.datateck.com.au/Lube/PenriteAus/

I use the same grade of oil now in my Jaguar XJR, Audi S3, Dolomite Sprint race car and Mitsubishi Mirage Cyborg race car, buying it in 20 litre drums, but maybe I should buy in 205 litre drums.

Mark

[Dolly racer 33]

You say ou used double springs, did you set up the poundage/fitted length correctly? Are they matched to the cam? Yes it is an oil supply issue but very likely too much pressure on the cam squeezing the oil off the cam. I had this problem 15 years ago using stronger than previously used springs. I overcame it by fitting an oil spray rail injecting oil straight at the cam/finger. Problem cured. I use Motul 15/50 oil, expensive but worth it.

[Dolly racer 33]

You say ou used double springs, did you set up the poundage/fitted length correctly? Are they matched to the cam? Yes it is an oil supply issue but very likely too much pressure on the cam squeezing the oil off the cam. I had this problem 15 years ago using stronger than previously used springs. I overcame it by fitting an oil spray rail injecting oil straight at the cam/finger. Problem cured. I use Motul 15/50 oil, expensive but worth it.