Noise after a fully throttle run!

DaviesDJ · Post by **DaviesDJ** » Fri May 09, 2014 5:44 pm

Hi guys - since it's Friday and I am in the mood I rescinded to post 2 current queries I have for discussion (the other regarding nos).

On my RV8 after a full throttle run I get a rattle tappets noise that lasts for about 10-15 minutes only. I run approx 120-150 shot of gas - it's a 5.0 litre lump with (take a deep breath!) standard tvr pistons.

The cam is a real steel typhoon item - rockers are yella terras, double springs big valve (1.7 inlet) heads and standard lifters.

Compression is fine - about 180 psi per pot, I have not taken the exhausts of but tightening the bolts and joints didn't make a difference - preload set on all lifters is ok - and I re-threaded a striped spark plug thread that ok though was the problem. It runs very well, and last time I shaved a second off my PB (14.3 seconds - in my old Landy!) so I'm not that worried - but it is quite a loud metallic tappet like sound, that does go away, but at the run off after a run it is always there! It's on the even number side.

Any thoughts guys?? Thought about pistons during expansion etc - but I have generous clearance, with each individual piston 1 thou extra.

Cheers

Dave

Ian Anderson · Post by **Ian Anderson** » Fri May 09, 2014 6:46 pm

Oil heating too much and thinning too much for the lifters to. Work properly

Afte 10 mins it all starts to cool off again and thicken back up

My guess any way

Ian

mgbv8 · Post by **mgbv8** » Fri May 09, 2014 7:35 pm

What oil do you use and what is the engine temp after a run on track?
Also do you have an oil pressure gauge?

DaviesDJ · Post by **DaviesDJ** » Fri May 09, 2014 8:40 pm

I have an oil pressure gauge yes; and an oil cooler, will look more close at the pressure - oil is 15/40 4 litres with 1 litre of oil stabiliser in it. The oil cooler is often not open before a run - maybee it does not have enough time to loose the heat of a run??? The coolant temperature certainly increases during a run. Perhaps some thickening additive, or 20/50 with stabiliser???

mgbv8 · Post by **mgbv8** » Fri May 09, 2014 9:06 pm

Crank driven oil pump or dissy driven oil pump?

If dissy driven try 20/50 mineral oil with Comp cams Zinc additive.

j.johnson23 · Post by **j.johnson23** » Tue May 20, 2014 8:33 pm

I had the same problem as you.
After a hard run one day the noise refused to go away and I assumed a lifter had failed.
On taking the inlet manifold off I found ONE bent push rod.I stripped its lifter down (std)and found that the little spring inside had collapsed,this on an engine with just over a 1000 miles on it after a rebuild.Not sure which was the problem though.All the others were fine and did not collapse with oil in them
Anyway I replaced that lifter with a std replacement from a local 4x4 supplier and fitted a push rod I had lying around that was within 5 thou of the others in length.I used a 15/40 oil.
Engine still ticked after a hard acceleration run so I bought some own brand 20/50 mineral oil and a new oil filter from a local eurocarparts and no more noise!
I think the problem is with the lifters as all you can get these days seem to be Britpart or Allmakes (I suspect both are cheap knock offs).
I will use the 20/50 for a while and see how things go.

bigaldart · Post by **bigaldart** » Wed May 21, 2014 6:54 am

What rpm and what lifters, also how old are the valve springs, they don't last long at higher rpm.

Alan