Valve timing

[robbo]

Hi all just want to make sure I have got my head round this. I will be re fitting the heads tomorrow as well as all the timing gear. My plan is this. First I will be finding TDC on no2 cylinder front L/H bank with a dial gauge. I will then check the timing marks all line up if not I will adjust the quadrant. Then I will fit the heads with no cams fitted and torque down in three stages. Then re fit the cams with the marks lined up with the front bearing caps. Then fit the chains etc making sure that the rotor arm is pointing at no2 plug lead. Not to sure about the inlet manifold I think it's going to trial and error. I think that by doing things this way the valve timing should be right. What you guys think.
Rob.

[stag8manod]

Hi Rob, Suggestion, Nip the inlet manifold up before tightening the heads to ensure the heads pull up to the manifold faces. Have you Heli-coiled the manifold threads in the heads?
Cheers Ian A

[Richard G]

Hi Rob, Suggestion, Nip the inlet manifold up before tightening the heads to ensure the heads pull up to the manifold faces. Have you Heli-coiled the manifold threads in the heads?
Cheers Ian A

Good tip. I did my inlet manifold after heads ,difficult job to line up, and should have checked/cleaned threads in heads before fitting. I had a coolant leak so removed and refitted with sealant around water ports particularly.

RG

[Staggard]

If the heads are off why do you need a dial gauge you can see the piston is on TDC. Why fit the cams after? shim up the cams and fit the heads all in one go, that's why BL designed them that way and why we all have trouble getting them off.

[flying farmer]

You can't time the cams accurately until the heads have been torqued down. The compression of the new gaskets is quite significant.

As Staggard says, just fit the heads with the cams.

Fitting of the inlet manifold can be an issue. If the heads have been skimmed significantly there is the possibility that the excess width of the inlet manifold will transfer a lot of leverage to the heads, and may not let them clamp down evenly.

Fitting the manifold after the heads requires a lot of fettling, but with the aid of a coarse file you can make sure the manifold sits between the heads with no gaskets, and gaps are even all the way round making the gaskets chance of keeping the water in much better.

Neil

[robbo]

Thanks for the replies guys. The reason for the dial gauge is to check the the timing marks are true I thought this would be a good opportunity to do this. The heads are all together and have been shimmed up so I will fit as they are. I helicoiled the head where needed. I think I will fit the heads first then worry about the inlet afterwards. Like Neil said I can always attack it with a big file. Doing it this way at least I know the heads will be pulled down nice an even. I will be tackling this today so will let you know how I get on later.
Cheers Rob.

[V Mad]

Maybe I am wrong here, but I didnt think that fitting the inlet manifold after torqueing both heads was a sensible option, the heads need to be brought parallel to the manifold or there could be large gaps.

You dont have to tighten all the manifold bolts, just enough to pull the heads into alignment.

[DJT]

+1

Do head fastenings up finger tight. Fit manifold to pull heads parallel, then check for manifold gasket thickness.

[pagan]

What would happen if the inlet manifold was not true?

[Paul Roberts]

This subject seems to be as controversial as the other, unmentionable (retro-fit cooling system), one.

Vee engines which have a single (common) inlet manifold are a bugger when it comes to fitting the top-end correctly.

In the case of the Stag engine it is made even more challenging by the design incorporating slanted head studs (they are trying to move the head across the block as well as clamping it down.)

My opinion; it's imperative the heads are tight and flat to the block; otherwise the head gaskets WILL fail.

It's not possible to tighten the heads down flat if the inlet manifold is fastened before fitting them. The only way this could be achieved is for the inlet manifold (a rigid casting) to be made of a flexible material.

It's not.



For every millimetre the heads move down (toward the block) they move inward (toward each other) by the same amount. If the inlet manifold is attached and fastened tight - this prevents the necessary (down and in) movement.

Even if re-torquing the heads; the inlet manifold should be removed and refitted anew.

Dead simple practical demonstration; make the vee sign with one hand; place three fingers (flat) of the opposite hand into the top of the vee and press down. Voila; the vee opens as the fingers descend.

I shall, now, repair to my hammock and await the storm.... .

[pagan]

This subject seems to be as controversial as the other, unmentionable (retro-fit cooling system), one.

Vee engines which have a single (common) inlet manifold are a bugger when it comes to fitting the top-end correctly.

In the case of the Stag engine it is made even more challenging by the design incorporating slanted head studs (they are trying to move the head across the block as well as clamping it down.)

My opinion; it's imperative the heads are tight and flat to the block; otherwise the head gaskets WILL fail.

It's not possible to tighten the heads down flat if the inlet manifold is fastened before fitting them. The only way this could be achieved is for the inlet manifold (a rigid casting) to be made of a flexible material.

It's not.



For every millimetre the heads move down (toward the block) they move inward (toward each other) by the same amount. If the inlet manifold is attached and fastened tight - this prevents the necessary (down and in) movement.

Even if re-torquing the heads; the inlet manifold should be removed and refitted anew.

Dead simple practical demonstration; make the vee sign with one hand; place three fingers (flat) of the opposite hand into the top of the vee and press down. Voila; the vee opens as the fingers descend.

I shall, now, repair to my hammock and await the storm.... .

Not to mention inlet manifold/gasket variations and quality.

[DJT]

Must have been lucky on the several occasions I've done it successfully then....

[Staggard]

What would happen if the inlet manifold was not true?

It would be an out and out liar

[robbo]

Well heads are on and so is the inlet manifold. It all went rather well apart from I missed one of the manifold bolt holes when helicoling so had to do that one with the heads in place. Heads are torqued up to 55ftlb and the manifold is nipped up nice and tight. I used wellseal on the gaskets and ceramic grease on the studs and bolts. I won't know if it's water tight until I fill up the cooling system fingers crossed on that one. Timing chains next.image.jpg
Rob.

[Guest]

Looking nice and shiney! Good luck with the fill up and first start up.

Jason