Valve guides
Turbo Mini Forums

Ive been thinking bout hbis for a while cause ive got my head off and im gas flowing it. Im thinking of removing the valve guides that protrude into the ports. It should increase airflow but im scared that it may lead to the valves bending or something.
Anyone any ideas?

Back once again like a renegade master

in short no! it wont

dont remove all of the guide boss on the exhausts tough as they are needed to help conduct the heat away from the valves

drift the old guids out and then re fitt minispares manganize bronze guids

but ...... after they have been PRESSED in they "MUST"........be hand reamed out using a 9/32 reamer

othewise your in the deep stuff!

the above is ony a decent guide and there is a lot to learn about head modding

iam still learning and iam 83...lol

Edited by BENROSS on 6th Dec, 2006.

Personally I am not equipped with fingers that have the power of mole grips, so I prefer to use a tap-wrench to drive reamers.

However each to their own.....!!!

Has anyone got any pics of how much they take out of the guide boss on a turbo head? Got to do mine soon

If you really are meaning flushing the valve guides with the roof of the port, think again. BLow would be massive, but you'd have to change the guides every 1000 miles. This is because of the rocker arm pushing the valve sideways. A short guide will have little area between guide/valve which wears it out.

Although these are inlets, this is what you want: http://home.online.no/~lyngset/artimages/8...reracetopp2.JPG

You just want to bullet nose the guide as Vegards pictures show. I certainly wouldn't advise removing the guide where it passes into the port. The length of the guide is needed to support the valve.

Phil.

WWW.TURBO-MINI.COM

So bullet nose valve guides are the way to go? Is it worth while removing the guides. Ive heard that they are a ball ache to do. nice clean head by the way:cool:. mines covered in oil and swarf in our machine shop. lol

Back once again like a renegade master

Depends if they are worn or not relly

(Athough i would say they are attualy quite easy to do and proper porting is hard/impossible with them still fitted!)

Edited by slater on 7th Dec, 2006.

use a 3/8" pin punch

and drift them out from the valve port side

how eay are they to put back in? Is it a hammer and punch job or a press job>

Back once again like a renegade master

They can be put back with a hammer and punch and CARE! but a press is a far better way if you can get access to one.

The most important thing is to ream them properly to size after they have been fitted.

well might do that when ive skimmed it. Not a turbo.....YET? so will increase comp and get turbo head when swapping over.

Back once again like a renegade master

Got some great pictures over the weekend off guides:

Standard:

Bullet nosed ones:


This means. Bullet nosed guides in a standard exhaust port is pointless. Also, in a standard inlet port it would be next to pointless as well.

Cheers for that ill sort it out when ive got time to properly port and polish the head. Weve got a press to put them in but id rather get some anger out and use a giant sledgey!

Back once again like a renegade master

I pressed my own in once.

Pressing them in, and fitting them so they are 100% true, and the valve will indeed seat properly are 2 very different things.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I would only use a press to fit the new guides. In my experiences the guides need to be reamed in most of the cases and always need re-cutting the seats after changing the guides. Unless you are extremely lucky. So, you´d better take that into cosideration as well.

do it properly and press them in dont use a sledy you rough bugger

no longer a series, but still 1.3 turbo.

You know me carl! I'd proberly sit around all day making teas at the factory and then at the end of the day get maybe 1 valve guide done. LOL

Back once again like a renegade master

Must admit..when i say I pressed a set in.....a hammer was involved lol.

Needless to say I had to get it re-done properly

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

hi.

I have removed and fitted a quite a few guides using this horribly welded piece of kit..
total cost about 15 quid including the 5 ton jack

a 2 ton is just not big enough and the extra sections need to be welded in because the thick walled box section bended quite a bit. the u- shaped bits are 1/4 thick..now it does not flex anymore

you can't change a guide without recutting seats.. but you can push the guides back a bit (which is fairly controlled using a press) for porting then push them back.. even then i recut the seat to ensure concentricity but mostly you could do without and just lap the seat in for a few seconds...if you need more than 5 seconds (I just put an slow accu drill on the valve end and switch directions) the seat is out too much

contrary to what some people say.. ANY guide needs to be reamed to size after fitting, including cast iron ones

an old wheel nut stacked on a BIG M 20 nut and a knackered exhaust valve make a pretty decent drift..

I tried hammering guides.. and managed to break a couple




putting the guides in the freezer or heating up the head a bit in the oven as well as wd40 for lubrication will help when installing guides

Edited by Sir Yun on 28th Apr, 2007.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

That is the best contraption i've seen in many months!

Edited by minimole23 on 28th Apr, 2007.

I know its an old post, but is the valve guide holes the same despite valve stem diameter???

Yes they are. I guess you're thinking of turbo exhaust guides. The head casting is the same.

That makes life simpler...thanks Vegard