GUYZER90 Posted December 29, 2011 Share Posted December 29, 2011 Hi I have to replace the headgaskets on my 1985 Classic V8 with carbs , at pressent it has the original tin head gaskets fitted now should i be replacing them with tin or should i go for the composite type? If i use the composite type should i be changing the bolts aswell , maybe i should be changing them even if i use the tin type again? Any thoughts will be gratefully appreciated. Happy new year to you all. Regards Guy. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 29, 2011 Share Posted December 29, 2011 Best IMHO are ELRING and Compositite I would not fit tin to anything. Aviod cheap copo ones ! Nige Quote Link to comment Share on other sites More sharing options...
GUYZER90 Posted December 29, 2011 Author Share Posted December 29, 2011 Best IMHO are ELRING and Compositite I would not fit tin to anything. Aviod cheap copo ones ! Nige As in Britpart and alike you mean..!! Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 29, 2011 Share Posted December 29, 2011 Esp Britpart - they will be prob tapered thickness wise or have 9 inlets Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted December 29, 2011 Share Posted December 29, 2011 In general i've always been told composite as its a little more forgiving, however when i did mine people with experience said go for tin, so I did, been ok for about a year I asssume your going to skim the heads too? Quote Link to comment Share on other sites More sharing options...
GUYZER90 Posted December 29, 2011 Author Share Posted December 29, 2011 In general i've always been told composite as its a little more forgiving, however when i did mine people with experience said go for tin, so I did, been ok for about a year I asssume your going to skim the heads too? Yes for sure , false economy otherwise i would of thought. Cheers Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 29, 2011 Share Posted December 29, 2011 Why ? peeps skim heads for no reason - forget the comp ratio difference is pub arguement levels Only skim them if they absolutely need it ? Nige Quote Link to comment Share on other sites More sharing options...
p76rangie Posted December 30, 2011 Share Posted December 30, 2011 Switching from tin to composite will drop your compression ratio by around 15%. So it makes a high compression motor a low compression type and it makes a low compression motor useless. Quote Link to comment Share on other sites More sharing options...
Team Idris Posted December 30, 2011 Share Posted December 30, 2011 I've gone for composite and an ARP stud kit. Bolting into an ally casting felt wrong Hopefully it will be a lot better than factory now? I got my heads skimed and the valves lapped at the same time, as the gaskets were showing blow marks. I'm also working on the theory that my fuel sits around in the tank a lot, so low compression is no bad thing. Its currently beer coloured. It's been a full rebuild, so I did the mains studded as well. I hear rumour that a tin valley gasket shifts more engine heat? And this was a fix on the LDV V8's. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 30, 2011 Share Posted December 30, 2011 Some tech info from memory : Tin gaskets compressed thickness 0.45mm /18 thou + Composite compressed thickness 1.0mm / 40 thou. Frankly, if you're running a standard engine you won't notice any difference, even more if its done loads of miles and not in the 1st flush of youth, peeps argue but you wouldn't be able to tell if the gaskets were switched without your knowing and you drove it - you wouldn't see any difference in the real world Nige Quote Link to comment Share on other sites More sharing options...
p76rangie Posted December 30, 2011 Share Posted December 30, 2011 Some tech info from memory : Tin gaskets compressed thickness 0.45mm /18 thou + Composite compressed thickness 1.0mm / 40 thou. Frankly, if you're running a standard engine you won't notice any difference, even more if its done loads of miles and not in the 1st flush of youth, peeps argue but you wouldn't be able to tell if the gaskets were switched without your knowing and you drove it - you wouldn't see any difference in the real world Nige Been down that path and on a low compression motor you really do notice it. The difference between tin and composite is actually 30 thou. Due to the shape of the combustion chamber, Land Rover shaved the heads by 40 thou when they fitted composite gaskets. I do not think that you will find anyone that will say that 40 thou shave of the heads is not going to change your compression ratio noticeably. Quote Link to comment Share on other sites More sharing options...
loopylulu Posted December 30, 2011 Share Posted December 30, 2011 Landrover recommend tin for the A engines, and composite for the B engines. They also say not to change types. Have just done mine, with the correct tin type. As for the bolts, they're not the stretch type, so you can reuse them. pete Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 30, 2011 Share Posted December 30, 2011 ARPStud kit is s defo must have IMHO Quote Link to comment Share on other sites More sharing options...
Team Idris Posted December 30, 2011 Share Posted December 30, 2011 I felt ARP studs were worth the cash. New higher torque settings are specified, but I was told the old settings are fine. We believe the actual clamping force is much higher as the ARP studs run a fine thread, whereas the OE bolts are course. Using the new torques the clamping force could be double? And the outer studs are only tightened to a tocken value, so the heads arn't pulled over to one side. I see later engines don't even have this row of external bolts. I have no idea where A & B engines come in. But I'm not a fan of steel head gaskets, even though the one on the S1 has worked fine for many a year. I think any gasket should be softer than the mating faces. But from an engineering viewpoint I would expect it to work better with the higher clamping force of studs. No head gasket lasts forever. Or to look at it the other way around; It'd be a good engine if it didn't like head gaskets, move the mains, eat cams and had a decent oil pump. So I've gone studs on the mains and heads, fitted a piper cam and gone dry sump. Maybe now it will behave. Nah Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 30, 2011 Share Posted December 30, 2011 Doubt it Loads more to fail on Buicks cast off junk that leyland spotted in a corner - Bought from them then popped it though BLs R&R Dept to BLs bodgerooshed Nige Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted January 2, 2012 Share Posted January 2, 2012 I have a manual somewhere that tells you the tolerance if you don't want to get the heads skimmed Quote Link to comment Share on other sites More sharing options...
g&t Posted January 3, 2012 Share Posted January 3, 2012 Some tech info from memory : Tin gaskets compressed thickness 0.45mm /18 thou + Composite compressed thickness 1.0mm / 40 thou. Frankly, if you're running a standard engine you won't notice any difference, even more if its done loads of miles and not in the 1st flush of youth, peeps argue but you wouldn't be able to tell if the gaskets were switched without your knowing and you drove it - you wouldn't see any difference in the real world Nige Agree entirely, used compo's on my old '89 3.5efi (heads checked by engineers, skimming not required) & noticed no 'real world' diffference. Also it could be argued that a slight drop in CR is no bad thing if you are running standard 95 octane as, according to the handbook, these engines were designed for 97. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 3, 2012 Share Posted January 3, 2012 I run composites with old (un-skimmed 3.9) heads on my 4.6, it doesn't really seem lacking if you've got a low-comp 3.5 on carbs you may as well give up anyway. IMHO composite gaskets are much nicer, and there's surely a reason most gaskets are composite these days. Quote Link to comment Share on other sites More sharing options...
p76rangie Posted January 3, 2012 Share Posted January 3, 2012 I run composites with old (un-skimmed 3.9) heads If they are 10 bolt heads they are suppose to have composite gaskets. During the 3.9 production is when they changed over from tin to composite. The earlier 3.9 heads were still 14 bolt heads, but the later 10 bolt heads had been shaved by 40 thou. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 3, 2012 Share Posted January 3, 2012 They're 14-bolt heads, they came off my old 3.9 which had tin gaskets. Quote Link to comment Share on other sites More sharing options...
p76rangie Posted January 4, 2012 Share Posted January 4, 2012 I will attempt to explain this for you. A 10% change in compression ratios on a rover V8 will change the torque by around 5%. Higher the compression ratio the more power the motor will produce and the better the fuel economy will be. Lower the compression ratio makes both these worse. Rover V8's came out in a 9.35 and 8.13 compression ratio version. Motors do not like much below 8.0 unless you are planning to super or turbo charge it. The compression ratio is calculated by dividing the swept volume of the cylinder, plus the volume of the combustion area into the combustion area. The combustion area varies with the various rover V8s and the compression ratios. But they are around 50CC. The change in heads to cater for the composite gasket was 8cc or 16% of the combustion area. Basic maths will tell you that if you change the combustion area by 16%, the compression ratio will change by a slightly less percentage, say 15%. So if you run a composite gasket on a motor with a 9.35 ratio that should have a tin gasket you will drop the compression ratio to around 8.0. The motor can still operate at this compression ratio even though your power, torque, and fuel economy will reduce. But if you do the same thing to a 8.13 motor your compression ratio will drop to around 6.9 and it runs like a dog. Therefore I will come back to my original statement, that is, if you swap gaskets on a high compression motor you will get away with it. You may or may not notice the change in power (depending on the reason you had the heads off in the first place). Do it on a low compression motor and you will certainly notice it. I had a low compression 4.6 that had tin gasket heads on it but had composite gaskets. I was far from impressed with the power. The only change I made was to change the heads over to the correct ones (only difference is that they are 40 thou shaved) and the difference in power was VERY noticeable. Quote Link to comment Share on other sites More sharing options...
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