Engine Damage Pics

[SteG40]

It hit nearly 8k for second or so, anyway engineering place has had a look today and both inlet and exhaust valves are bent they also reckon something has got in there. I'm guessing you can't by single exhaust valves for a big valve head so I'll have to get a set from jabbasport I think.

[hayesey]

jabbasport might sell them individually, you'll have to phone them I guess.  I'm sure they used to list them individually on their old site before the recent refresh.

[PeteG40]

depends what the big valves are from and who I suppose.

[hayesey]

jabbasport usually make the 31mm ones.  That's what is in my head too.

[Tommo]

Valves shouldnt bend from over revving it, unless with all the revs and no load on your engine the piston has hit the valve. The valves should be well up to those revs. A lot of engines rev to well over 10k without particularly special valves. Plus over revving tends to cause valves to drop rather than bend.

Check the rods for length and the big end bolts for stretch.

Detonation usually occurs in long hard 4th gear up hill pulls etc rather than a quick launch. Especially in a polo where launching it puts relatively little stress on the engine due to a lack of traction.

[hayesey]

with hydraulic tappets and standard valve springs on these heads you are risking valve float much above 7k rpm. 

Although I'd guess if something has got in there then it was big enough to get stuck between piston and valve and bend them.

[Tommo]

True, im not sure what effect excessively bouncing valves tends to have. I dont think they would bend though?

Im not sure how anything would get in there thats big enough to do that, I have heard of spark plugs disintegrating but im guessing that hasnt happened. Cam belt not jumped a tooth? I suppose there would probably be damage on other cylinders.

I have never had much to do with OHC hydraulic tappets/lifters, do they ever pump up and cause interference?

I would pull the piston/rod out for sure and check the ring lands/rings and the big end bearing/bolts. Then measure the deck height when its back together and compare with the other cylinders.

[Robin]

Ste are you 100% sure the spark plug is still in one piece?

If a ring has dead and come into the cylinder then i would expect to see some scuffing around the bores of the cylinders.

something has gone through that intake system so its just a matter of trying to find what has come loose!

[Justin14100]

Jabba only does the bigger exhaust valve, isnt your- inlet valve bigger--? inlet is the one on the left right? or on BVH's do they only make a bigger exhaust valve?

[Tommo]

Could a part have broken in the charger and made its way in there?

[SteG40]

Bingo look whats missing


how do you get in there to put a new bolt in?

[garye40]

pop rivot it

[Tommo]

What are those 4 bolts in the butterfly for?

If the butterfly bolts to the shaft then you can probably just unscrew it and take it out to fit the bolt, if it slides through the middle of the shaft then you probably cant. If you get what im saying.

[Dan]

That explains it !

[Robin]

ah ha! knew it wasn't det damage!