Couple of Newbie Q's. Oil pressure and diff ratio'

[Kev_BE]

Hi,

Wasn't sure where to post this, so as i'm a newbie i thought why not here.

I have searched the forum for answers but need a bit more info.

When my 1600 CVH 5 speed is idling its running about 1-2 bar oil pressure and when driving its about 3-4 bar. Is this OK.

I feel that it is but having a guage has made me a bit paranoid. If there wasn't a guage i would be blisfully ignorant.

Also. At 70mph i'm at 3500rpm and would ideally like to be runing a bit lower rpm as i have a couple of long trips planned.

I dont know my diff ratio at the moment but i would idealy have two diffs, one for most of the time and a longer ratio for touring. Do you think this is wise\possible?

Basically, is there a diff that would give me a lower rpm cruising speed of 70mph?

Hope i've made sense.

Thanks in anticipation.

Kev.

[ChrisF]

Kev your oil pressure is perfectly normal    

As for the revs at speed, it dosen't sound too bad to me...if you look at the diff it might still have a plate on it with the ratio.

[markcoopers]

Kev,

While we all assume that guages are very accurate, this quite possible only extends to noticing changes. Ie 3-4bar might not be, but if it drops to say 2 bar when driving, then i would get worried. Not that 2 bar is an issue, but the drop will be.

As chris says there is likely to be a small ally plate/tag connected to one of the diff housing bolts, this should tell you the ratio. To be honest 3500 at 70mph is good, and there are not too many std diff ratios around for the sierra diffs. Aftermarket is different, but most people want lower ratios so that sprinting is improved at teh expense of top speed.

Swapping diffs for cruising/blatting sounds logical, but in truth i question how often you would swap these, it is likely to be 3-4hours on your own to do properly all in

[Kev_BE]

Kev your oil pressure is perfectly normal    

As for the revs at speed, it dosen't sound too bad to me...if you look at the diff it might still have a plate on it with the ratio.

Thanks for that, its put my mind to rest a bit. I'll check the diff this weekend to see if there is a plate.

Cheers.

[Kev_BE]

Kev,

While we all assume that guages are very accurate, this quite possible only extends to noticing changes. Ie 3-4bar might not be, but if it drops to say 2 bar when driving, then i would get worried. Not that 2 bar is an issue, but the drop will be.

As chris says there is likely to be a small ally plate/tag connected to one of the diff housing bolts, this should tell you the ratio. To be honest 3500 at 70mph is good, and there are not too many std diff ratios around for the sierra diffs. Aftermarket is different, but most people want lower ratios so that sprinting is improved at teh expense of top speed.

Swapping diffs for cruising/blatting sounds logical, but in truth i question how often you would swap these, it is likely to be 3-4hours on your own to do properly all in

Thanks for the reply, i see your point about noticing a change in pressure. I'll keep an eye on the guage to get some reference points and work from there.

I asked a couple of people at the N.Wilts/Glos meet last night and they said the same as you and Chris. The revs seems fine.

Fair enough if thats how they are, its all a learning curve for me right now.

On the swapping of the diff thing, i thought it may be a suggestion as thats what we used to do in our Landrovers. We would change ratio's depending on what tyres we had on or what type of event it was. I was hopeing it may be an easy change like on a Defender. About an hour tops.

Its something i would like to explore a bit more. I'll do some thinking and see how it goes.

Lastly, Its really great to get these replies as a newcomer to a forum and club. Thanks very much.

Kev.

[Jenko]

Hi,

Wasn't sure where to post this, so as i'm a newbie i thought why not here.

I have searched the forum for answers but need a bit more info.

When my 1600 CVH 5 speed is idling its running about 1-2 bar oil pressure and when driving its about 3-4 bar. Is this OK.

I feel that it is but having a guage has made me a bit paranoid. If there wasn't a guage i would be blisfully ignorant.

Also. At 70mph i'm at 3500rpm and would ideally like to be runing a bit lower rpm as i have a couple of long trips planned.

I dont know my diff ratio at the moment but i would idealy have two diffs, one for most of the time and a longer ratio for touring. Do you think this is wise\possible?

Basically, is there a diff that would give me a lower rpm cruising speed of 70mph?

Hope i've made sense.

Thanks in anticipation.

Kev.

Hi Kev,

The most important thing to consider with the CVH is changing the oil. The design of the CVH head is actually quite clever, but it has a few issues to note...1st off, the cam shaft lubrication is non existent if the oil starts to sludge up, this coupled with the high spring rates required for the valves means you can wear through a cam in a few mins....Make sure you change the oil regularly (part synth 10W40) - I do mine three times / year, 2 bar at  idle 4 bar  at average load is fine......

Every now and then, whip the rocker cover off and check the cam lube holes / lifters / rocker arms are all nice and clean..........

As for the diff, I suspect you would have a 3.9diff.....My advice is stick with it....I changed from a 3.9 to a 3.6LSD recently, and yes you do find it a bit better on the motorway, but I preferred the 3.9 in general. Swapping them is not viable for a quick change, they are a pain to change....

Good luck....I see you have some sensible goddies on the car (mega jolt, kent fast road cam) :-)

Paul.

[Kev_BE]

Hi Kev,

The most important thing to consider with the CVH is changing the oil. The design of the CVH head is actually quite clever, but it has a few issues to note...1st off, the cam shaft lubrication is non existent if the oil starts to sludge up, this coupled with the high spring rates required for the valves means you can wear through a cam in a few mins....Make sure you change the oil regularly (part synth 10W40) - I do mine three times / year, 2 bar at  idle 4 bar  at average load is fine......

Every now and then, whip the rocker cover off and check the cam lube holes / lifters / rocker arms are all nice and clean..........

As for the diff, I suspect you would have a 3.9diff.....My advice is stick with it....I changed from a 3.9 to a 3.6LSD recently, and yes you do find it a bit better on the motorway, but I preferred the 3.9 in general. Swapping them is not viable for a quick change, they are a pain to change....

Good luck....I see you have some sensible goddies on the car (mega jolt, kent fast road cam) :-)

Paul.

OK Thanks, I'm doing the oil this Sunday, so i will take the time to take the cover off and have a look.Appreciate the info.

I know i should probably spend more time driving the car before i make too many descisions about ratio's etc and so far all have said stick with what you have. So i'll put that project to the back for a while.

Yep, i like the fact its had a few things done to it but not over the top.

Cheers.

[Jenko]

I found going from a distributor to Megajolt made a massive difference.....

Do you know what map it's using (did you get the software with the car).....It would be interesting to see what advance it's running, I have a very good map for CVH engines if you want it.

Paul.

[Kev_BE]

I dont know what map its using to be honest, i didn't get the software but i'll try and get it this weekend and have a look.

Thank you for the offer of the map, i'll prob take you up on that.

Going further with my two ratio theory. How about a map for touring and a map for the twisty bits?

[Pistol Pete]

Kev

An easier way to increase your overall gearing would be (if possible) fit slighter higher profile tyres. This would also give you the benefit of slightly higher ground clearance for touring.

Compared with diff, benefits would only be small, but maybe worth considering if replacing tyres only.

Pete