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Posted: Sun Aug 23, 2009 10:49 am
by spartanv8
Hi Kevin
I do have 10.5/1. Sorry but why is it helpful? Am only asking 'cos i don't have a clue!
Thanks
Fil
Posted: Sun Aug 23, 2009 11:04 am
by katanaman
10.5 could be a bit high on standard fuel these days. When your engine was made 4 star was common which a higher octane rating. If you don't have any problems at the moment though I would leave it as is. The higher the compression you can get away with the better your engine will perform.
Posted: Sun Aug 23, 2009 12:26 pm
by dnb
More than 10.5 works fine on my TVR on standard unleaded, so you should be OK if you're prepared to sacrifice a (very) little top end horsepower for better mid range.
Posted: Sun Aug 23, 2009 3:14 pm
by sidecar
dnb wrote:More than 10.5 works fine on my TVR on standard unleaded, so you should be OK if you're prepared to sacrifice a (very) little top end horsepower for better mid range.
Is 10.5:1 what TVR claim or have you actually measured it?
Posted: Sun Aug 23, 2009 3:19 pm
by poo slinger
my heads are 3.9 rr heads.
Posted: Sun Aug 23, 2009 4:04 pm
by dnb
TVR claimed 10:1 for my engine. I rebuilt the engine to have a little more compression - estimated to be 10.8:1 since I didn't have time to do accurate measurements.
Posted: Sun Aug 23, 2009 6:00 pm
by spartanv8
Hi
If I get some SD1 or 3.9 heads and they don't have the rockers, pedestals or push rods, can I use the ones off my P6 heads?
Thanks
Fil
Posted: Sun Aug 23, 2009 7:04 pm
by sidecar
spartanv8 wrote:Hi
If I get some SD1 or 3.9 heads and they don't have the rockers, pedestals or push rods, can I use the ones off my P6 heads?
Thanks
Fil
If they are in good nick you can use them!
(i.e. they will fit)
Posted: Sun Aug 23, 2009 7:50 pm
by spartanv8
Thank you Sidecar, guess I will know when I take my old ones off.
Fil
Posted: Sun Aug 23, 2009 9:16 pm
by topcatcustom
Dont forget if you fit intermediate heads as it sounds like you will with composites, there is a high chance you will need to have you rocker shaft pedestals or pillars skimmed to retain the correct preload on the lifters. If you retain the tin gaskets then you should be fine, but of course dont forget to check anyway.
TC
Posted: Sun Aug 23, 2009 9:42 pm
by spartanv8
Hi TC
Any idea of how much I will need to have them skimmed or do I put the heads on and measure the preload? Then see if they need skimming?
Fil
TC
Posted: Sun Aug 23, 2009 10:09 pm
by topcatcustom
In theory it should be the extra thickness of the composite gasket over the tin one, so about .6mm. But you really need to put the heads on properly first and measure the preload, or lack of it!
Posted: Mon Aug 24, 2009 5:13 am
by sidecar
I had the heads skimmed where the bosses actually bolt down onto the heads as according to Des Hammill this is better than skimming the pedestals. Remember that the rocker ratio will have an effect in some way. My heads were machined in order to improve the valve train geometry. I simply used adjustable pushrods to sort out the pre-load!
(Even they had to be shortened by 4mm but then again my motor had 70 thou taken off the gasket faces of each head!)
You might find that in terms of cost adjustables are not that much more expensive then getting the machining done.
I personally would not use "tins"
There was a thread running a while ago about them, many people had problems with them. In the end Rover must have realised this too as they went to 'comps' even though it ment more expense for them as they had to machine the heads more.
Then again some people reckon that they are OK!
Posted: Mon Aug 24, 2009 5:29 pm
by spartanv8
Hi
Thank you again for all you help, I hadn't realised there was so much to consider!
I only do about 1500 miles a year and and rarely rev above 4000 and that would be overtaking! I have a spare set of tin gaskets that came with the car and think I will use them, it sounds a lot easier! I think they will be ok on the Spartan, she doesn't get a lot of use and I don't abuse her, just love the sound of the V8!
I have no doubt I will be back on asking for advice on setting the pre load in October, I only tax her April to September. Just hope the tin gaskets work out ok!
Fil
Posted: Mon Aug 24, 2009 6:11 pm
by sidecar
spartanv8 wrote:Hi
Thank you again for all you help, I hadn't realised there was so much to consider!
I only do about 1500 miles a year and and rarely rev above 4000 and that would be overtaking! I have a spare set of tin gaskets that came with the car and think I will use them, it sounds a lot easier! I think they will be ok on the Spartan, she doesn't get a lot of use and I don't abuse her, just love the sound of the V8!
I have no doubt I will be back on asking for advice on setting the pre load in October, I only tax her April to September. Just hope the tin gaskets work out ok!
Fil
What will help with tins is NOT fitting the outer head bolts, the ones near the spark plug holes.
Good luck with the rebuild