Head work (not job)...

[Stuey]

Avoided the obvious joke...

I'm doing the 12's head work in the next few weeks and want some hints please guys. Specifically, any preferences for water pumps and head gaskets would be welcome. Incidentally, I put a cheapy GMB water pump on it 7-8 years ago and it's been fine since. As I bought it some German/Austrian dude said, "Chee-Emm-Bee; day are CRRAPP! Do NOT put demm on your CAR or you vill be SORRY.."... I haven't been as it's still fine. But I'll replace it when I do the head.

Stuey

 

[JohnW]

Stuey:
Avoided the obvious joke...

I'm doing the 12's head work in the next few weeks and want some hints please guys. Specifically, any preferences for water pumps and head gaskets would be welcome. Incidentally, I put a cheapy GMB water pump on it 7-8 years ago and it's been fine since. As I bought it some German/Austrian dude said, "Chee-Emm-Bee; day are CRRAPP! Do NOT put demm on your CAR or you vill be SORRY.."... I haven't been as it's still fine. But I'll replace it when I do the head.

Stuey

Stuey,

I'm not being facetious but I suspect the main thing is to run the fan belt as loose as possible without it actually slipping! I've never heard of any seriously dud water pumps being available but that could be my igonorance. We replaced a Virage pump a few years back with whatever Caravelle supplied. My R8 - 20 years or so since the last one. I have had a Quinton-Hazell one in a box for the R8 for at least 12 years!

I presume you are having the seats done - I'd be interested to hear where you get the job done and how satisfied you are afterwards. The R8 and R12 will both need this one day.

Cheers

 

[Stuey]

Yeah John, I do tend to run my belts as loose as possible, mainly to preserve the alternator bearings. The German guy was in the process of having a go at the parts vendor (Italspares) about a problem, and I suspect it was a failed GMB pump. As for the head work, I'm getting new guides, hardened exhaust valve seats, and hopefully a three angle cut if they don't think this is too extraordinary! I'll then just open out the throat of the port a bit myself, and that's all. I'm a bit concerned about the seats as I've heard that replacements, if not done correctly, can come loose.

Another question; does anyone here recommend any sealant around the oil galleries at the back of the head, between the gasket and block/head? Or should it be left dry?

Cheers

Stuey

 

[JohnW]

Stuey:
Yeah John, I do tend to run my belts as loose as possible, mainly to preserve the alternator bearings. The German guy was in the process of having a go at the parts vendor (Italspares) about a problem, and I suspect it was a failed GMB pump. As for the head work, I'm getting new guides, hardened exhaust valve seats, and hopefully a three angle cut if they don't think this is too extraordinary! I'll then just open out the throat of the port a bit myself, and that's all. I'm a bit concerned about the seats as I've heard that replacements, if not done correctly, can come loose.

Another question; does anyone here recommend any sealant around the oil galleries at the back of the head, between the gasket and block/head? Or should it be left dry?

Cheers

Stuey

 

[JohnW]

Stuey:
Yeah John, I do tend to run my belts as loose as possible, mainly to preserve the alternator bearings. The German guy was in the process of having a go at the parts vendor (Italspares) about a problem, and I suspect it was a failed GMB pump. As for the head work, I'm getting new guides, hardened exhaust valve seats, and hopefully a three angle cut if they don't think this is too extraordinary! I'll then just open out the throat of the port a bit myself, and that's all. I'm a bit concerned about the seats as I've heard that replacements, if not done correctly, can come loose.

Another question; does anyone here recommend any sealant around the oil galleries at the back of the head, between the gasket and block/head? Or should it be left dry?

Cheers

Stuey

Oops. Try again!

I've always fitted them dry myself. Never had a problem. Keep it all very clean.

I guess one of the expensive (e.g. Hylomar) sealants in modest quantitites just around the oil hole wouldn't hurt.

Keep it clean and torque meticulously.

I look forward to the results.

Cheers

JohnW

 

[Stuey]

I used Hylomar last time I did it.

 

[Aln]

The inlet ports can be opened out inside leaving the size at the gasket face standard, being careful to avoid the cylinder head bolt holes. Very generally ports should be .84 the size of the valve on the inlet, and 1.2 to 1.25 size the valve on the exhaust. The valves can also have a second cut applied to get rid of the ridge near the seat. You can then of course use the gasket to match the ports to the manifolds, and a slightly larger cam would not hurt, but where do you stop.

 

[Stuey]

I've successfully modded a couple of heads in my time, but in this case I'm going to go easy. I've decided to just clean up the intake ports and match them to the manifold without going deliberately any bigger on the main part of the port. I really like the torque characteristics of the Sierra as it is, and reckon it could easily be spoiled by altering the gas speed through the inlets. I'm using engineers blue to help match the manifold/ports, rather than using the gasket. I've noticed that the exhaust ports are definitely small for the valve size. Again, though, I'm only going to alter obvious problems in opening out the throat of the port just under the seat. It's actually a bit narrower than the inner diameter of the seat insert. Again I'm concerned with lowering gas speed (and resultant efficiency in scavenging) that I might cause by changing the port diameter. The car is most definitely a daily driver and I like it the way it is, however, I can't leave the head with obvious flaws...

Cheers

Stuey