First Race of 2024 - CSCC Donington , March 23rd

[JohnD]

First race of the season will be Donington, Saturday March 23rd.   I'm entered in the Swinging '60s Race 2, practice at 1055, Race at 1540, the gods willing.  The meeting has an enormous entry list, over 400 cars in all classes, 42 in just my race alone!   Apart from me there are two other Triumphs, TR6/250s with Graham Wilson and Roy Chamberlain, with Steve Adams in his Spitfire in Race 1.

The weather forecast looks good, cold but dry, light winds.   I have a three spare tickets, please PM me if you would like one.

John

Edited March 14, 2024 by JohnD

[Escadrille Ecosse]

Good luck John. May the gods smile upon you and the Vitesse

[michaeljf]

Hello John, Likewise from me. We have had our second run and so far things are going OK, mostly. Regards, Michael.

[Steve 13-60]

Hi John, Donnington is 20 mins away for us, so wifey & me will be there next Saturday to wave you to victory! Won't be able to get there til middayish tho. ..need to get the campervan out of storage first.

[JohnD]

Thanks to all!    See you in the paddock, Steve!

John

[JohnD]

For anyone interested who can't be here, the event is being "Live Stramed" on YouTube!    Go there, find Classic Sports Car Club and the Donington Derby.

Enjoy!  Hope I do!

John

[mpbarrett]

Just found it on YouTube, saw you on the first lap and the commentator has just said you have retired  Hope its nothing serious....

mike

[mpbarrett]

[JohnD]

Thank you mp, but his was another weekend I'd rather forget.   

Qualy went OK, not my best time but 15 secs more than my best, not unreasonable as it was a wet, cold track.   But the race went badly.   Someone, not me and well ahead on the grid, went off at the first corner (!!) And ROLLED their car.  Race slowed by Safety Car for a lap, then Red Flagged.  We stop for ten minutes, while people are rescued and debris cleared.  Meanwhile during Safety lap,my engine loses power, develops a 'knock', not big end, and starts to over heat.   I retire after two laps in fifteen minutes!  There are words for this which I won't use!  Proper investigation tomorrow - its gin time now!  

John

[Steve 13-60]

To be fair tho John, it was bloody cold so can't blame the old girl not wanting to play

[Steve 13-60]

[mpbarrett]

John,

that's a real shame.... the conditions didn't look good.

Hope there is not too much engine damage... She really doesn't want to play.

Mike

[JohnD]

Found it!  Not difficult, although the solution may be not so easy.   The 'knock' was the sound of a loose push rod or rocker hitting the rocker cover.  Two of them have gone walkabout:

 

That's more than enough to explain noise and power loss.    Are the push rods bending under strain?   I have a high lift cam shaft and 1:1.6 rockers for max lift, and I'm using  standard rods - is that foolish?    Are the "uprated" or tubular rods advertised any good?

John 

[Nick Jones]

Were the adjusters still tight?  If not.... there's your problem.  If they are still tight then check the pushrods are straight (roll on flat surface).  If the rods are straight, I doubt they could have deflected enough to come out be showing as straight, so consider whether a valve could be hanging partially open when hot as that can unseat pushrods.  As the affected valves are adjacent, could be only one is sticking and the wandering pushrod unhorsed the other.

[RedRooster]

I'd check the cam lifters on those as well John. 

 

[JohnD]

 

Thanks, Nick, and RR.

The one in the middle of the frame is as bent as .. well, a Tory PPE supplier.   I think it means valve gear off and examine, check for seized valves.  The last will mean head off, unless bopping each valve with a soft hammer will do, and checking the followers will need that anyway.   Hey, ho, that's racing.

[Nick Jones]

Is the bent one inlet or exhaust? Is this head a fresh build or one that’s previously been fine?

[PeteStupps]

Sorry to read this John, I settled down to watch the race on Youtube earlier today. Lots of offs and DNF's, and was unhappy to hear the commentator say you pulled into the pits early. 

Fingers crossed the cause is found easily, and is not too taxing to put right.

Edited March 24, 2024 by PeteStupps
Poorly worded!

[JohnD]

Bent is inlet, No.2 cylinder, the one that has come right off is Exhaust same bore.

I drove it off the track, and then into the garage like that!

John

[Escadrille Ecosse]

Sorry to hear that John.

A high lift cam and 1.6 rockers can be a bit much depending on the cam and rocker/valve head geometry. 

When I changed cam in the Spitfire from a Kent to the TLD one with significantly greater lobe lift I found that the roller path on the valve head was 'marginal' with the 1.6 ratio rockers. Fitting standard ratio roller rockers was necessary. 

[Hamish]

John that is so frustrating. 
i hope you find a simple reason for this and not a whole set up issue like too much of a rocker ratio /spring binding/ stuck valves. 
 

it seemed nasty weather and full grid lead to some (un?) foreseen consequences- using the car in front brakes to slow  was unfortunate but an oil trail into the same corner can’t help.

You are safe and able to spanner the problem. That’s us a consolation - but one I don’t see immediately when pointed out to me !

you’ll sort it John I have every confidence. 

[JohnD]

Here are the usual suspects in an ID parade.   The guilty party is not difficult to pick out.

No.3 was still engaged in its rocker!  As suggested, it must have knocked its fellow out, and the  effect of that by bouncing around is clear. on its shaft and on the inside of the rocker cover!.  No.4 is straight to the rolling test as are all the others, but I'm not using this set again!

All the cam followers are moving normally, and the rockers themselves are not damaged.    The valve springs do not not bind at full compression.  I'm inclined to source a set of new tubular rods, fit those and carry on.    Colin suggests that with high lift, the path of the rocker end on the valve stem may not be ideal.     I think I know what that means but I've never done it!     Engineers blue on the stem end, turn the engine over ad observe where they have touched, looking for that to be central?    Then adjust if necessary by shimming the rocker plinths.

Would the push rod length also adjust this?   These rods are 206mm long, end to end (not considering the ball or cup on either end), which I think is correct for the thicker 2.5L engine. My cylinder head has been skimmed - can't recall how much as it's so long ago, but I was aiming at a CR of 10.5:1, and at 87mm thick it is 3.8mm thinner .  I note that Neil Revington offers a range of rods lengths in this situation, ranging over 11.5mm! And even some that may be cut to length!    I'll be grateful for some advice on this rich choice!

John

 

Edited March 26, 2024 by JohnD

[RedRooster]

Cut one in half, thread it and use a sleeve nut to enable you to adjust the length to suit your engine, then order a new set to suit. 

RR

[JohnD]

Thank you, RR!   Could do that.   But "adjust length to suit engine"?   You mean  to achieve the correct rocker/valve geometry?

[RedRooster]

Yes, exactly that.