The V8 Owners Forum -

Took a couple of valves out today to check them, and also removed other head, plus further dismantling prior to removal to skip.
Pistons definately are not too high in block, but I still think the combustion chambers in heads are unusual - causing detonation. Funny thing is, engine turned over as normal - wouldn't expect this if comp ratio too high.

Valves Removed













As I thought - number 3 on O/S








No. 2 O/S showing start of problem



Pistons




No 2 again - just starting to break up




N/s




O/S






Ready for coming out front end removed

Outside pots damaged on one side, inside pots the other - surely some tie up with the converted Rover manifold? Was one side of the carb running really lean or something?

Is the carb intact? Nothing missing from it is there that could've bee sucked in?

I've little experiance with detonation myself but i have an understanding of it and i cannot picture it causing that much damage!

That should've taken a long time to do that much damage with loads of warning which makes me think that something surely must've been sucked in.

Is there any debris in the exhaust? Any signs of piston rings breaking up?

IanT wrote:Outside pots damaged on one side, inside pots the other - surely some tie up with the converted Rover manifold? Was one side of the carb running really lean or something?

I am tending to lean in that direction myself. Again the worst damaged chamber is starting to be carbon free so its either burning off with too lean or detonation is knocking it off could be a mix of both. Have you used this manifold before or did you just use it when you swapped the heads? Got any pics of a damaged plug?

Car was running perfectly with it's original heads. Carb is a recent Edelbrock, and ran well. Manifold has been on the car since I got it with no problems. If something had got into combustion chamber, then valves etc would be pockmarked which they aren't.
I still think that the combustion chambers in these heads is markedly different from the P6 and the SD1 that I have. I must admit, I never really paid much attention to this - just bunged them on. I did have them for 2 years prior to fitting, and just took them out their wrappers and bolted them down - won't make that mistake again.

Pete

Well it's scrap anyway, hardluck mate, i got a spare P6 under the bench, ur welcome to it, john

I think I've located the problem. My engineer mate came up tonight and went over the engine with a fine toothcomb and discovered the following embedded in cylinder 3 O/S. It is steel, but I don't know what It's been, and how come 3 cylinders have been affected - same pattern in each. I removed carb from inlet, but nothing that i can see has dropped off it - a mystery.

John, Thanks for offer - I have an SD1 motor I'm going to rebuild I think.

Pete


pics

Well good you got to the bottom of the problem, kind of! Raises more questions. Must be very frustrated to see such a small object cause so much damage. But how did it travel between chambers. Why were the valves not damaged, just coincidence. I think you can see some kind of pebble dashing at the top of the combusion chambers. Check for missing bolts.


[quote="plastic orange"]I think I've located the problem. My engineer mate came up tonight and went over the engine with a fine toothcomb and discovered the following embedded in cylinder 3 O/S. It is steel, but I don't know what It's been, and how come 3 cylinders have been affected - same pattern in each. I removed carb from inlet, but nothing that i can see has dropped off it - a mystery.

John, Thanks for offer - I have an SD1 motor I'm going to rebuild I think.

Pete

Is it a cylinder head dowel?

Royston,

I'll check, but how could it get into 3 cylinders? I've been wracking my brains trying to work out what it could be. I don't really want to take my carb to bits to see if anythings missing - it's almost new (low miles)

Pete

Adjustment screw or brush/nut from the carb or filter that's been inhaled?

Things that shouldn't be there(TM) travel in funny fashions when engine damage occurs - remember an article about dyno'ing a V8 and debris from one piston got inhaled by the two on the other side and so on....just ends up working its way around the valves! [/code]

plastic orange wrote:Royston,

how could it get into 3 cylinders?

The design of the RV8 inlet manifold is that the two outer on one side and the two inner on the other side are connected together in one chamber. Any debris in one cylinder can be ejected through the inlet valve, bounce along , or be drawn into any of the other three cylinders.
I've seen this on engines that have smashed a piston. Pieces of it end up in the other 3 cylinders.
Most likely the piece of steel was stuck behind a valve in the Vitesse head when you fitted it.

Jim