ANYBODY SHAVED THEIR TB42 ENG HEAD TO INCREASE COMPRESSION?

[MEX]

If so:

1. How much can you take off before interferance between valve & piston?

2. What sort of compression gains did you get?

3. Was it worth the effort?

Cheers MEX

[Jimbo]

I was interested in this too.

[jessie928]

40 thou is good

I have about 50 thou of one ATM, works sweeeeet as on LPG.

just make sure to readjust the valve clearances.

Jes

[Fozdick]

Try this

http://www.outerlimits4x4.com/PHP_Modul ... highlight=

Shaun.

[toymad80]

I had 60 thou off mine,running on straight lpg using a vn commodore trottle body,big improvement from idle to redline.running 33' now thinkin about 35's

[Jimbo]

How much bigger is the commodore throttle body?

How much work was involved in that mod?

cheers

[toymad80]

Its around 65-70mm from memory, I made the adaptor plate from manifold to throttle body,the gas feeder fits onto trottle body then the air intake fits onto gas feeder.I used an after market air filter housing,then adaptored it to snorkel.Can email if you want to see pictures(Its nothing flash)

[Sexy Fingers]

The thing you have to remember is, if your car runs on lpg shaving the head 40 to 60 thou is going to give you good results, it it runs on petrol only, it's probably not a good idea as you'll have to run premium unleaded to minimise pinging, and even so, may not fix the problem. The other thing you need to consider is you can only shave a head so far. If the head warps or cracks as they've been known to do, and has already been shaved to the max, it's time to throw the head away and buy another one.

[ats4x4dotcom]

rather than working on a measurement, you should be aiming for a comression ratio, if using good premium fuel, up to 10-1 is possible, and, depending on the cam, if it bleeds some off, maybe 10.5 to 11-1 could be used.

I went 9.5 to 1 on mine many years ago, [before 98 octane] using a 240 grind cam, which we installed 4 deg advanced, and fiddled the valve clearances, to play with idle, power, lobe centres, and we ran around 23 deg static advance in the timing, with 48 deg max, but to run lots of timing, and to help prevent detonation, radius all corners in the combustion area, remove all dags, lumps, catch points that may glow causing detonation, and make sure your cooling system is working 110%, and ensure you artent burning oil, because oil lowers octane, slows burn, creates heat, and can cause detonation.

[Jimbo]

ats4x4dotcom, did this work well for you?


Jimmy