Cylinder Head Removal

[Doug_RS2]

Originally posted by Mikes2
the Evo engine cost 4.5k to fix - hope yours is cheaper

Luckily I still had oil - it was just getting low - hopefully it is just thespark plug t-certs, valve stem oil seals and something to the valves(the thing where the get re-seated by spinning them round with some paste on the mating faces- can't remember what that is called) that will need done.

Do the heads usually need a skim or are the big enough not to need that done?

Thanks for the link Mike

[Glen Chamberlain]

Originally posted by Doug_RS2
Luckily I still had oil - it was just getting low - hopefully it is just thespark plug t-certs, valve stem oil seals and something to the valves(the thing where the get re-seated by spinning them round with some paste on the mating faces- can't remember what that is called) that will need done.

Do the heads usually need a skim or are the big enough not to need that done?

Thanks for the link Mike

Valve lapping! I didn't skim mine when i took it off, its a big lump to warp! but you will want yours a perfect as poss with the HP your developing! keeping in mind that skimming will raise the compression slightly and i gather you want to reduce compression?

[Doug_RS2]

Originally posted by Glen Chamberlain
keeping in mind that skimming will raise the compression slightly and i gather you want to reduce compression?

Mmm - what do I do then? The head has been off before so might even have been skimmed before. Sienna didn' like the 2 head gaskets idea as the seal between the 2 head gaskets isn't very good. Ideas/Suggestions anyone?

[Dutch_RsBlueS2]

Make a CNC replica of the head gasket out of alluminium?

I heard some people doing this before. But i dont know the sort of AL they where using.

What kind of material is the original gasket made of?

Dont know if this helps but its worth a try


Cees

[newsh]

If you want to be really flash have a 5 angle job done on the valve seats before re lapping them. It improves filling and emptying of the cylinders.

The head should be checked for true, if it's within spec it won't need skimming. Since you havent had overheating trouble you should be ok.

Compression ratio can be lowered by removing material from the combustion chambers. I don't know of a special head gasket for the I5, but there may be one.

[Habib]

GET UR PISTON CROWN SKIMMED, ITS AN IDEAL WAY TO LOWER COMPRESSION. IVE HAD TAKEN 1.8MM OF EACH PISTON, havent done the maths to find out compression ratio but it is ideal for big boost and big hp.

[audiman]

I have no personal experience with t-certs. But i have used helicoils on allsorts of threads. Spark plugs, mainfold threads(!), I have even used them on an alloy block where a head bolt pulled when tightening it down. This held fine and has never caused a problem since doing it over 5 years ago! The other option would be to have the hole partially ally welded up and just drilled and tapped to original size with NO thread insert. Just a thought and it is possible as long as the person can weld well etc. That way the plug will seal fine in the head.

@Mark, tell your missus that if you did Dougs head then it would help pay for something in the house that she wants! No harm in a small lie! Is there?

[Doug_RS2]

That place that Mike posted, agra engineering have quoted £220+vat for the 5 time-certs, valve stem oil seals, the valve lapping and checking the trueness.

Some cash to be taken off becasue I will supply the VSOS.

Seems reasonable to me, provisionally booked for 6th Jan.

I'll see if I can find anywhere that will do it over xmas but I doubt I will.

What special tools will I need to do all this? What size is the cambelt pulley nut?

[Dr H]

I had time certs fitted to a bike engine. The exhaust studs snapped and were that hard and siezed they had to be machined out on a milling machine!

Had the t-certs put in by a bike shop and they worked fine.

[sal_s2]

When taking the head off, don't the head bolts have to be removed in a certain order aswell to prevent warping the cylinder head?

[Doug_RS2]

Originally posted by Habib
GET UR PISTON CROWN SKIMMED, ITS AN IDEAL WAY TO LOWER COMPRESSION. IVE HAD TAKEN 1.8MM OF EACH PISTON, havent done the maths to find out compression ratio but it is ideal for big boost and big hp.

I didn't want to get into taking the crank out - that will be later next year. That sounds like it will make a big difference to the compression ratio.

[desmo888]

Head bolts do not need to be removed in any special order. Just be sure the engine is cool.
Any other method besides changing the pistons to reduce compression ratio is not recommended. If a proven thick head gasket was commercially available, that might be okay. But two gaskets or a custom one is not a good idea. You are just asking for trouble.
As mentioned, the head may not need to be shaved. Some shops tend to shave every head that comes through, especially aluminum. This insures they get a good surface for resealing.
Talk with the shop and tell them you wish not to have the head shaved unless completely necessary. And then only the bare minimum needed.
If you are after big HP then sh*t or get off the pot - replace the pistons!

[Jeffer]

I know that MTM has a special thicker head gasket. But mind you! They also charge MTM prices

[Mihnea]

Originally posted by desmo888
Head bolts do not need to be removed in any special order. Just be sure the engine is cool.
Any other method besides changing the pistons to reduce compression ratio is not recommended. If a proven thick head gasket was commercially available, that might be okay. But two gaskets or a custom one is not a good idea. You are just asking for trouble.

I beg to differ Dave but I know of at least 8 people in germany running 400+ HP on ABY engines and 2 stacked head gaskets with no issues so far.

Even reputable tuners from Germany will tell you to do this when you're asking for more boost and no detonation, so go figure!


Cheers,

Mihnea

[desmo888]

My bad then.
In my experience with American V8's, this is frowned upon...


I am new to German engine rebuilding...