GMC 270 Big Valve Conversion.mp4

[042zagor]

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[brendanraymond]

Hi John

Just a quick question about cutting speeds.

Why did you reduce the speed so much if you are using carbide inserts on your tools? I thought the edge shatters if you do that... is this trying to control chatter or heat build up or gripping the seat when cutting width increases or is there a different reason I'm missing.

Thanks for reading.

[fiatnutz]

@brendanraymond - To controll chatter because I'm not taking big cuts.

[brendanraymond]

@fiatnutz Thanks for the reply!

I was on the right track :p

Did you recieve my email in regards to the subaru porting video? I'm looking forward to that

Thanks again

Brendan

[KAKIOYZIS]

great job!!!!!!how do you test where the valve "meets" the seat???(sory for my english)!!

[piddydog]

Have you ever made a mistake and machined the intake thinking it was the exhaust seats?

[StevoM5]

From 2:21-3:51 that hole to the left of the combustion chamber that you're working on. Is there a crack running down that hole? It's probably just a drainage hole so it's not that big of a deal. Just Curious.

[pismo10]

No lube while cutting?

[seasonedtoker]

john, you make your own cutting bits? just curious :)

[pantherxx010]

can this be done to all head for valve job mod?

[Brunodu68]

nice job ! pretty scarry !

[AxSxKxONE]

i never even knew about this , there isnt one video of yours i havnt learned something, is this possible on an eg33 "subaru svx engine"

[bmays002]

The new GMC 4.2 I6 motors can be real monsters too. I remember they were running 600hp when they won baja.

[magnahelic1]

hello John, is it a good idea to remove some of the shrouding on the side of the inlet valve to even the flow, ive seen this on other heads that have big valve conversions?

maybe the costomer will do some poring and blending work. thanks for the vid

[fiatnutz]

@magnahelic1 - That's one of the reasons I cut down the 1.94" valve to 1.80".

[socamoto]

are those home made tools or off the shelf?

Really nice job!

[fiatnutz]

@socamoto - Some of them were made by me.

[fiatnutz]

@prodriver1 - To be continued...

[Slonya23]

Hi, why do you slow down the spindle towards the end ?

[fiatnutz]

@Slonya23 - To keep the cutter from chattering on the seat.

[mezapu]

Is that a crack in the coolant passage hole in the bottom left at 2:20? Or just a casting ridge?

[fiatnutz]

@mezapu - No cracks in the head...

[radum4]

@mezapu - It looks like a crack to me, too.

[Chevypower265]

@mezapu I saw that too, it looks like a deep crack to me.

[Ls3guy]

a drag car weird

[theGHETTOMAN1]

That machine is wicked! *thumbs up* I'm curious, can you cut those in old heads that have hard seats pressed in them?..if so, what happens if the seat spins while cutting it, can ya just pop in a new hard seat and recut it?

[fiatnutz]

@theGHETTOMAN1 - This can be done to almost any head. It the seat is loose, then is must be replaced. Seats should have about .005" press-fit.