ukadamwest · Oct 26, 2015

wammers said:
It would give a perkier engine for sure.

indeed at a higher rev.

As always there are trade-offs. a low compression engine would give more torque at the lower rev range (and as i understand a lower, smoother tickover) however as the rev range increases then a higher compression would give more 'oompf'.

Lower compression engines can accomodate variations in fuel quality, however, let be honest here.. fuel refining and distribution has changed somewhat over the past 40 years, so the possibility of using lower quality fuel in the home counties.. well the UK is unlikely to affect the running capabilities. I can understand the lower compression fuel argument if you are manuacturing vehicles to be sold from Shropshire to South Africa and the outback of Altringham and the outback of Australia 40 years ago. but fuel really isnt an issue.

What the dilemma is, i suppose is the tuning of higher compression in a carb set up whean all said and done and how the difference would affect the final build..

comments on a postcard to the usual address...

wammers · Oct 26, 2015

ukadamwest said:
indeed at a higher rev.

As always there are trade-offs. a low compression engine would give more torque at the lower rev range (and as i understand a lower, smoother tickover) however as the rev range increases then a higher compression would give more 'oompf'.

Lower compression engines can accomodate variations in fuel quality, however, let be honest here.. fuel refining and distribution has changed somewhat over the past 40 years, so the possibility of using lower quality fuel in the home counties.. well the UK is unlikely to affect the running capabilities. I can understand the lower compression fuel argument if you are manuacturing vehicles to be sold from Shropshire to South Africa and the outback of Altringham and the outback of Australia 40 years ago. but fuel really isnt an issue.

What the dilemma is, i suppose is the tuning of higher compression in a carb set up whean all said and done and how the difference would affect the final build..

comments on a postcard to the usual address...

Main thing you will need to change for higher compression is static timing. And maybe the dizzy to give more advance at higher RPM. Carbs will need setting up no matter what pistons you use. HC pistons will give more power and torque at all engines RPMs. Can't remember if the HC engines had a different cam. James may know.

ukadamwest · Oct 26, 2015

The camshaft is the same for both HC and LC.

my head is saying go HC my gut LC..

Essentially there's chuff all difference in price between the two..it's within £20 variation

jamesmartin · Oct 26, 2015

ukadamwest said:
The camshaft is the same for both HC and LC.

my head is saying go HC my gut LC..

ive allways found l/c felt like a 4cyl and h/c like a v8, you probably would benefit changing dizzy ,but they seemed to run fine without

Jam1 · Oct 26, 2015

Thing is, it's a V8 why strangle it if you're going to have one and all the down sides that come with it why not enjoy it! Who the feck buys a V8 because it's the sensible option if that's the case you may as well stick a potato up the exhaust pipe! yeah it'll run like **** but it may give you better mpg and low down torque

ukadamwest · Oct 26, 2015

i never knew a tuber in the exhaust increased mpg.. who would've known

ukadamwest · Oct 26, 2015

jamesmartin said:
ive allways found l/c felt like a 4cyl and h/c like a v8, you probably would benefit changing dizzy ,but they seemed to run fine without

so the consensus is.. dont take the V8 out and put a diesel in then

ukadamwest · Oct 26, 2015

wammers said:
Main thing you will need to change for higher compression is static timing. And maybe the dizzy to give more advance at higher RPM. Carbs will need setting up no matter what pistons you use. HC pistons will give more power and torque at all engines RPMs. Can't remember if the HC engines had a different cam. James may know.

but static timing is only going to be a couple degrees out, nothing too problematic in setting up the engine. and then timing will be from a strobe anyway ?

Jam1 · Oct 26, 2015

"so the consensus is.. dont take the V8 out and put a diesel in then"

Hang on have I missed something? don't remember that even being the question

jamesmartin · Oct 26, 2015

ukadamwest said:
so the consensus is.. dont take the V8 out and put a diesel in then

ive done quite a few of those conversions a good few years back when it was a common practice ,but theres little comparison

Saint.V8 · Oct 26, 2015

given what you originally intended for this old timer, I'd go for the 9.35:1 set.....

Grrrrrr · Oct 26, 2015

Saint.V8 said:
given what you originally intended for this old timer, I'd go for the 9.35:1 set.....

Would HC stress the engine more? Presumably there's a reason the top of the pistons are dished in the LC? Shock waves? Heat distribution? Prevention of pre-ignition?

ukadamwest · Oct 26, 2015

Saint.V8 said:
given what you originally intended for this old timer, I'd go for the 9.35:1 set.....

saint.. you're not *that* old..

.. oh you mean the RR !

Saint.V8 · Oct 26, 2015

ukadamwest said:
saint.. you're not *that* old..

.. oh you mean the RR !

Cheeky begger.....still younger than you

ukadamwest · Oct 26, 2015

mate.. the sodding Suffix A is younger than me (just)

ukadamwest · Oct 26, 2015

Grrrrrr said:
Would HC stress the engine more? Presumably there's a reason the top of the pistons are dished in the LC? Shock waves? Heat distribution? Prevention of pre-ignition?

I think the lower compression piston was to accommodate the varying qualities of fuel. the V8 has seen service in literally all corners of the world in a Land Rover product, so with the fuel quality varying in often hard to reach places the lower compression made it available to run on lower octane fuel. Of course here in Europe, lower octane fuel rating use is no longer an issue my head has been saying go for the HC pistons, the gut was saying to for LC in case any later problems emerge due to the change.

HC it is then.. by consensus

wammers.. any final comment on that before i pull the trigger ?

jamesmartin · Oct 26, 2015

Grrrrrr said:
Would HC stress the engine more? Presumably there's a reason the top of the pistons are dished in the LC? Shock waves? Heat distribution? Prevention of pre-ignition?

h/c pistons are dished the same just not as deeply

dove · Oct 26, 2015

better going for the 10.5-1 Pistons from the rover p5-p6

wammers · Oct 26, 2015

ukadamwest said:
but static timing is only going to be a couple degrees out, nothing too problematic in setting up the engine. and then timing will be from a strobe anyway ?

Yes but you need a dizzy that gives enough advance.

ukadamwest · Oct 27, 2015

wammers said:
Yes but you need a dizzy that gives enough advance.

It's only going to be a couple of degrees difference surely. . ?

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