Hi all,
This is my first post here, great forum - even though most of what I read goes straight over the top of my head!
I have a '87 Land Rover 90 V8, which I'm in the process of replacing the head gaskets on.
My engine was originally fitted with tin gaskets and I'm thinking about using composite gaskets as a lot of people say they are better. But as I understand they are slightly thicker therefore they increase the CR and tappet preload.
The increase in CR I'm not worried about, performance is the last thing on my mind right now! But as I have read, to correct the preload ideally you need to have the heads skimmed.
Is this completely neccessary? Or are there ways around it? Because of the possibility of the extra cost I'm tempted to just use the tin gaskets - are they really that bad even if you don't fully torque the 4 outer bolts?
Any info on this matter much appreciated.
Composite Gasket Questions
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CastleMGBV8
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Hi,
Keep it simple, just replace with the tins, the tins are 18thou thick and the composites are 42 or 46 thou thick, and reduce the compression ratio by approx .5/1 you don't say what engine size you have.
As you rightly say if you swap to composites you should have the heads machined by 25-30thou to maintain compression and lifter preload and dont fully torque the outer row of head bolts.
Kevin
Keep it simple, just replace with the tins, the tins are 18thou thick and the composites are 42 or 46 thou thick, and reduce the compression ratio by approx .5/1 you don't say what engine size you have.
As you rightly say if you swap to composites you should have the heads machined by 25-30thou to maintain compression and lifter preload and dont fully torque the outer row of head bolts.
Kevin
It amazes me that people are taken in by that sh*te. Mind you, there's a whole cosmetics and 'alternative medicine' industry as well.......Dirty Bus wrote:Thanks Chris.
Interesting site by the way, found the 'food for tossers' bit partically funny
Chris.
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Series IIA 4.6 V8
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Series IIA 4.6 V8
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R/R L405 4.4 SDV8
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jefferybond
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Re: Composite Gasket Questions
In my (limited) experience, the tin head gaskets are just fine, especially if you don't tighten up the 4 outer bolts (or leave them out completely as I did).Dirty Bus wrote:Because of the possibility of the extra cost I'm tempted to just use the tin gaskets - are they really that bad even if you don't fully torque the 4 outer bolts?
Any info on this matter much appreciated.
However, I did have trouble with the tin *valley* gasket leaking, and i'd recommend using the composite valley gasket instead.
Jeff
I was under the impression that composite valley gaskets should only be used when fitting composite gaskets beneath 14 bolt heads.
If fitting tin head gaskets under 14 bolt heads, then a tin valley gasket should be used.
Using a composite valley gasket when using tin head gaskets beneath 14 bolt heads could lead to problems when torquing the inlet manifold bolts into the heads, owing to the composite gasket being thicker and the change in relative postion of the inlet manifold with the heads.
This is just my understanding.
Ron.
If fitting tin head gaskets under 14 bolt heads, then a tin valley gasket should be used.
Using a composite valley gasket when using tin head gaskets beneath 14 bolt heads could lead to problems when torquing the inlet manifold bolts into the heads, owing to the composite gasket being thicker and the change in relative postion of the inlet manifold with the heads.
This is just my understanding.
Ron.
4.6 Rover 3500 P6B
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CastleMGBV8
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Spend you money elsewhere before you throw out the SU's which will flow enough to support well over 200BHP.Dirty Bus wrote:Cheers Kevin, I think that's what I'll do.
It's a 3.5 running SU carbs... I'd like something a little tastier once the rest of the vehicle is up to scratch - a long way off!!!
Most people swap to a 4 barrell either for clearance reasons or for power levels in excess of 220BHP
Headwork should always be the first priority, as the standard heads are very restrictive, again you dont have to go too mad and some simple stage 1 mods can yield an extra 30+ BHP with the standard SD1 and on valve sizes.
Kevin.
Well, got the parts just waiting to finish preparing the heads - time is pretty limited right now.
Quick question, I'm about to lap the valves as they are pitted - can you go too crazy and go too far with the grinding? If so how do you know how far you can go?
Cheers.
Quick question, I'm about to lap the valves as they are pitted - can you go too crazy and go too far with the grinding? If so how do you know how far you can go?
The Landie has so much that needs doing to the body, it'll be a while before I look at getting some more horses, but thanks for the advice.CastleMGBV8 wrote:
Spend you money elsewhere before you throw out the SU's which will flow enough to support well over 200BHP.
Most people swap to a 4 barrell either for clearance reasons or for power levels in excess of 220BHP
Headwork should always be the first priority, as the standard heads are very restrictive, again you dont have to go too mad and some simple stage 1 mods can yield an extra 30+ BHP with the standard SD1 and on valve sizes.
Kevin.
Cheers.
Yes, I really am that stupid!
yes you can go too far with hand lapping. You will start to see a groove being cut in the valve, at that point give up and get the valve re-cut or replace it. If you have to go that far you probably need the get the seat cut as well. Also remember while your doing this your sinking the valve further into the head which you might have to contend with later in the preload. Basically anymore than say a minute with a lapping stick and your wasting your time.
