My rebuild thread! 3.9 disco v8

[Mr Noisy]

I thought big end knock was normally when revving up/under load?

If they're new shells dude that one looks shagged, can see pitting there?

Bad lubrication on startup?

 

[bencorkill]

Done 120miles up M1 today sat at 70mph all the way apart from 5 or so miles of traffic and i averaged 18mpg with M/T tyres! I'm happy as with that as last time i came up i averaged just over 11!

 

[Mr Noisy]

SORTED IT!!!! engine is was fine! Its the bloody cat rattling must have got damaged or had something dropped down it haha!

Oh, just read this! Must have missed a page!

Well that was lucky, but it doesn't explain that rough looking bearing shell??

 

[bencorkill]

Oh, just read this! Must have missed a page!

Well that was lucky, but it doesn't explain that rough looking bearing shell??

Must have been abit of crap on it when i put it in, as has been said its just a graze but the main body of the shell is okay, so im not going to worry about it to be honest, engines running a million times better than before !

 

[jamesmartin]

them bearings are poor ,crank could have done with a polish , gudgeon pins are semi floating and great care needs to be taken removing and fitting pin if not to distort piston and make it tight

 

[fett]

ben,glad its sorted and james gave us the correct answer re little ends. Mark let us know if you sort yours

 

[discomark10]

ben,glad its sorted and james gave us the correct answer re little ends. Mark let us know if you sort yours

Well im at billing atm, I've ordered a new idle valve so when im back im going to remove the cats to see if its that... hope so!

 

[bencorkill]

Well im at billing atm, I've ordered a new idle valve so when im back im going to remove the cats to see if its that... hope so!

Get some one to sit in and rev engine to make it rattle then go round with a metal bar and put against ear and place where u think noise could be from and you will hear it

 

[bencorkill]

Had abit of a worry today, thought i would check still going on LPG but when i switched over wouldn't run over 1500rpm :/. Then went and put some in the tank and its was completely empty ha! runs okay on LPG no where near as good as petrol but haven't done timing yet.

Did a run up M1 other day and i averaged 18mpg both ways sitting at 70mph and last time i did the journey before rebuild i got 11mpg!!!

 

[discomark10]

bit of difference then! means you have good strong spark how much advance do you intend to use on lpg, and what do you have it set to now?

 

[bencorkill]

To be honest with you haven't actually looked at what its on yet ha! its just running, runs okay at idle on LPG but over 2000rpm loose all its guts. Think i will set to around 8-12BTDC have a drive at 8 have a drive at 12 and see what works best on both as will be driven 90+% of time on LPG petrol just a reserver and start up .

 

[discomark10]

have you got a timing light?

 

[fett]

I meant to ask you rebuild guys, did you use composite headgaskets? I got mine in from real steel and I thought they had sent me 94mm bore engine ones by mistake because they measure about 93mm inside the fire rings but they checked the part numbers and said that the bigger bore engine ones would be 95mm inside the fire rings.

mines a 89mm bore engine same as the 3.5 so I would have though the fire ring would have been about 90mm before squashing it under torque. Does the fire ring not have to sit on top of the liner?

 

[bencorkill]

have you got a timing light?

Think they have one at work, if not will have to buy one about £40 from halfords

 

[discomark10]

I meant to ask you rebuild guys, did you use composite headgaskets? I got mine in from real steel and I thought they had sent me 94mm bore engine ones by mistake because they measure about 93mm inside the fire rings but they checked the part numbers and said that the bigger bore engine ones would be 95mm inside the fire rings.

mines a 89mm bore engine same as the 3.5 so I would have though the fire ring would have been about 90mm before squashing it under torque. Does the fire ring not have to sit on top of the liner?

No I used tin as my compression is low to start with, may skim it if I have troubles and fit comp, cant really help, do you not still have an old comp from stripping it?

 

[Mr Noisy]

Composite is ideal but needs a healthy skim of course

 

[rangy35]

I was under the impression there is composite head gaskets specially for the 3.5 or is Bearmach just fuc&@? with me? Check their latest catalog.

 

[discomark10]

I was under the impression there is composite head gaskets specially for the 3.5 or is Bearmach just fuc&@? with me? Check their latest catalog.

not sure, but it will need a head skim or you'l lose comp ratio

 

[fett]

lol ok thanks guys. yes I have compared old one and it is smaller but also squashed.

It is a 3.5 gasket apparently according to part numbers from real steel

By coincidence my heads have been skimmed bit also as running a 4.4 block and 3.5 pistons I would have had 9.5:1 with orginal p76 heads but now running late 10 bolt rv8 heads its gonna be crazy high for a dizzy car- like 11:1

Anyway, does the fire ring of the gasket have to sit on the liner or is it not supposed to?

 

[discomark10]

who knew