Off with its heads

[evilfij]

I am taking the rangies heads off tomorrow.

Any advice? After the fawking disco debacle (3 times all big $$$$) I have decided to DIY the rangie.

While I am at it I thought I would see if I should do anything else to maybe make the lil old 3.5 put out some more oomph.

I was thinking about going to the composite gaskets but I don't want to lose compression and the gasket set I got came with metal.

And I will of course check the heads/block with a strait edge unlike the professionals.

if the heads are off I guess I will have them skimmed and go to composite gaskets anyone know the formula to determine compression after a skim?

How about doing rings and main bearings while I am at it or maybe the cam?

So who has torn into their rover V8?

Ron

[Diesel Jim]

you could invest in some gas flowed heads to improve performance, but they're not cheap, unless you know someone with a prifile grinder and a few spare hours?

tip: when you re-install the heads, smear a little grease on the inlet manifold gasket (the big flat one that goes in the 'valley' 'tween the heads) as when you bolt the inlet manifold up tight (or the plenum chamber if it's EFI) it can rip the gasket if there is no lub in there.

also, does skimming the head actually change the compression ratio? at TDC there will be less volume in the combustion chamber for the air to be in, so there will be a little more 'pressure' there,but the only way to change the complete compression ratio is to alter the profile of the crank, so that it pushes the piston up a different amount (or allows it to come down further at BDC to get more air in.)

Jamie

[Old Scout]

Jamie were did you learn about engines? I think you need to go back and study up.


Evilfij go here:
http://www.kb-silvolite.com/calc.phtml


With all things the same Look at what pop up style pistions can do for compression ratio:
Total head CC
58cc -14.1
62cc - 13.3
64cc - 12.9
76cc - 10.9



Same pistion/same stroke just a different head volume.

*************************************************
Low pop up
Total head CC
58cc -12.5
62cc - 11.8
64cc - 11.5
76cc - 9.9

[Old Scout]

The R&R is very simple, but the lifter pre load looks to be a PITA.
lifter pre load


I would port the heads yourself. I ported my Scout heads myself and it took ~1hr per port,but the alum will be much quicker.
Here is a 98 4.0 head:


The IH scout engines have the same problem with gaskets. I needed to have 0.022 milled off to make up the difference between the old steel shim head gasket and the new composite style.

[Old Scout]

A ton of good info on these:
http://www.robisonservice.com/servic...n_fouling1.pdf

http://www.robisonservice.com/servic...n_fouling2.pdf

Download em and print them , they will help a ton

[Diesel Jim]

Jamie were did you learn about engines? I think you need to go back and study up.

D'OH!! i think i had drunk too many last night! of course getting the head skimmed/changing the gasket will make a diference to the comp. ratio. so too will different profile pistons.

(and to think i'm a trained up mech!! tsk! )

Jamie

[evilfij]

Thanks old scout.

One gasket looked like it had a little blow by. The other problem is that it looks like I have a leaky injector as there was a ton of fuel in the oil. Teh second problem is what worries me.

The engine looks ok overall. Some build up but nothing terminal. will know more when the heads come back (crack etc.)

Ron