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041 GO3 heads have wrong seats cut?
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midtravelmidengine
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PostPosted: Thu Dec 14, 2017 5:57 pm    Post subject: 041 GO3 heads have wrong seats cut? Reply with quote

Just pulled apart a pair of 041 GO3 casting heads and the seats are roughly cut to 38.5mm with a 40mm stainless valve installed. Did these just run through the factory on a friday or are these how all those castings were machined?


this is a pic of the contact of the valve face...


Image may have been reduced in size. Click image to view fullscreen.

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youngnstudly wrote:
I just wasn't sure if I should recommend the 1/3 race cam, the 1/2 race cam, or the 5/8 race cam instead...guess it depends on how much of the race he wants to lead???
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modok
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PostPosted: Thu Dec 14, 2017 6:10 pm    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

I'd guess they had 39mm valves originally, and somebody put 40mm valve on there.
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stevetim
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PostPosted: Thu Dec 14, 2017 6:17 pm    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

Those heads come from the factory with 38mm intakes and 33mm exhaust. I've complained about this for years. Also check out the ID of the seats, they are about .100 thousands smaller than a 40x35.5 standard combo.
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Dan Ruddock
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PostPosted: Thu Dec 14, 2017 6:35 pm    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

Another example of, if you want it done right do it yourself. Dan
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mark tucker
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PostPosted: Thu Dec 14, 2017 7:16 pm    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

that pic ant bad... the berger man 2386 I reworked had the 40's seating in the smaller seats on the swirl polished area of the valves.... you cant fix stupid. but they did try to open the seats up on a seat&guide machine and left a hell of a jagged mess in the pocket&seat, just didnt open it up quite enough...looked like to me it was 33mm valve seats.......you cant fix stupid.and it had a 160 hp dyno sheet too.
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fivelugshortaxle
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PostPosted: Thu Dec 14, 2017 8:51 pm    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

My old big valve 041's were the same way....big valve small seat. Had it fixed soon as I bought them.
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AlteWagen
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PostPosted: Fri Dec 15, 2017 1:26 am    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

stevetim wrote:
Those heads come from the factory with 38mm intakes and 33mm exhaust.


Is this like a factory L4 head? With the small seats do they work any better than stock? I thought the GO3 was based on the 041 casting with the bigger port, maybe less heat with the bigger exhaust valve? I do like the 12mm plug compared to the VW 041 short 14mm that always cracked.

Are these GO3 even available anymore? I havent seen them retail for years.
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Ebel
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PostPosted: Fri Dec 15, 2017 5:30 am    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

I have a new old set of those heads. Mine came with stainless 39x35 valves I think. If I have time later I'll pull the valves in one and measure the seats. I just cc'd the chambers a few weeks ago. And wanted to check the port volume anyway. Ports are bigger then stock a 040.
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Alstrup
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PostPosted: Fri Dec 15, 2017 1:59 pm    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

GO3īs came with 39/35 mm valves. Many people replaces the clumsy 39 mm intake with an SS 40 mm. hence the OPīs situation. I have never seen GO3īs with other valve sizes. That may have been some custom ordered heads for a specific part of the World.

The valve seats in these are normally cut very crude, and these heads can definitely benefit from a good seat and valve job. Again, normally, if you replace the stock 39 mm valve with a 40 mm you can usually place the seating area in the middle of the 45 degree surface and then get a good undercut anlong with a decent 30 degree inlet cut. A stock set of heads does not flow more at max with this, but the flow at low lift increases tremendeously, like 5-6 cfm below 0,250" and decreasing back to normal max flow from there. (Approx 130 cfm @ 0,550")
The lower intake port is generally not that bad. Itīs the upper port that needs help. Even small improvements can soon help them to 150 cfm. I have made one set where I sort of got carried away partly becausre they were for a good friend of mine, so I went into really detailing them and bottomed out at 175cfm @ 0,600" with a really nice flow distribution. That engine has an incredible throttle response. Havent been on the rolls yet. I gues it will be spring until we get it done.

Enough rant. Bottom line is that the heads themselves are not bad at all for medium tune engines, and can be massaged to nice power levels with a little carefull thinking.

T
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midtravelmidengine
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PostPosted: Mon Dec 18, 2017 10:03 am    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

Alstrup wrote:
GO3īs came with 39/35 mm valves. Many people replaces the clumsy 39 mm intake with an SS 40 mm. hence the OPīs situation. I have never seen GO3īs with other valve sizes. That may have been some custom ordered heads for a specific part of the World.

The valve seats in these are normally cut very crude, and these heads can definitely benefit from a good seat and valve job. Again, normally, if you replace the stock 39 mm valve with a 40 mm you can usually place the seating area in the middle of the 45 degree surface and then get a good undercut anlong with a decent 30 degree inlet cut. A stock set of heads does not flow more at max with this, but the flow at low lift increases tremendeously, like 5-6 cfm below 0,250" and decreasing back to normal max flow from there. (Approx 130 cfm @ 0,550")
The lower intake port is generally not that bad. Itīs the upper port that needs help. Even small improvements can soon help them to 150 cfm. I have made one set where I sort of got carried away partly becausre they were for a good friend of mine, so I went into really detailing them and bottomed out at 175cfm @ 0,600" with a really nice flow distribution. That engine has an incredible throttle response. Havent been on the rolls yet. I gues it will be spring until we get it done.

Enough rant. Bottom line is that the heads themselves are not bad at all for medium tune engines, and can be massaged to nice power levels with a little carefull thinking.

T


Thanks, ya my brother bought his baja bug as is. something got into the engine and took out #3 recently so i have the engine apart. Turns out to be a fairly standard 1915 with counter-weighted crank, w110 cam, these heads, around 8.5 compression with a single center mount 40mm weber.

Decent for what it is but im always looking to maximize the parts that we have. Upping compression, i unshrouded the intake side of the chamber, fixing the VJ, might go back to the 39 intake since the end castings are already likely the restriction already.
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modok wrote:
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youngnstudly wrote:
I just wasn't sure if I should recommend the 1/3 race cam, the 1/2 race cam, or the 5/8 race cam instead...guess it depends on how much of the race he wants to lead???
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nsracing
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PostPosted: Fri Dec 22, 2017 1:52 am    Post subject: Re: 041 GO3 heads have wrong seats cut? Reply with quote

somebody went big-valve and forgot the seats? Laughing
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