4.6 head mods

kevcon · Post by **kevcon** » Tue Nov 09, 2010 1:50 am

After getting Graham at Motor Tech to do some work to my 4.6 heads.
Have in mind fitting 1.63" inlet and 1.4 exhaust valve, opening up the seats and recutting with 3 angles , blending bowls in, smoothing out the ports and matching to manifolds.
Anything else I should have done, please keep in mind that I'm on a very tight budged.

thanks
kev

ChrisJC · Post by **ChrisJC** » Tue Nov 09, 2010 7:55 am

Maybe a skim to raise CR if you're running LPG? (just don't forget to ensure the tappet preload is within spec afterwards)

Chris.

kevcon · Post by **kevcon** » Tue Nov 09, 2010 8:11 am

already sorted chris. running 4.0 pistons on 4.6 rods and crank.

thanks mate

Denis247 · Post by **Denis247** » Sun Jan 09, 2011 12:29 am

kevcon wrote:After getting Graham at Motor Tech to do some work to my 4.6 heads.
Have in mind fitting 1.63" inlet and 1.4 exhaust valve, opening up the seats and recutting with 3 angles , blending bowls in, smoothing out the ports and matching to manifolds.
Anything else I should have done, please keep in mind that I'm on a very tight budged.

thanks
kev

Don't 3-angle the exhaust seats. The loss of contact leads to overheating and burning/pitting. There is very little gain 3-angling the exhausts, certainly not enough to outweigh the disadvantages, especially on a road engine.

Darkspeed · Post by **Darkspeed** » Sun Jan 09, 2011 1:41 pm

Do not match exhaust manifolds.
Consider bulleted guides - if port work is being done then removing the guides is a must if you are to make any gain from the bigger valves - If leaving the guide and that area of the throat unworked then there is little point going to larger valves.

Andrew

mgbv8 · Post by **mgbv8** » Sun Jan 09, 2011 9:21 pm

Dont polish the inlets of the manifold to a smooth finish. Leave the port walls slightly rough. If they are too smooth you may get fuel drop out on nthe smooth polished walls. The slight rough finish keeps the boundary layer of the inlet charge quite turbulent which is good for a petrol engine.

kevcon · Post by **kevcon** » Mon Jan 10, 2011 7:21 pm

Thanks guys.
But have already refitted the heads in standard form. Saving up for a pair of Merlins (noticed that RPI have dropped their prices on these) But wont be buying from them.
Still waiting to get her run in and will be up with you Perry at the rolling road day.
Looking forward to pick your brains on the gas front.

Thanks again
kev

mgbv8 · Post by **mgbv8** » Mon Jan 10, 2011 8:58 pm

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4.6 head mods

4.6 head mods

Re: 4.6 head mods