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midtravelmidengine Samba Member
Joined: August 06, 2009 Posts: 861 Location: Riverside, Ca
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Posted: Thu Dec 14, 2017 5:57 pm Post subject: 041 GO3 heads have wrong seats cut? |
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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...
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modok wrote: |
And I know you don't know because if you did you would know the reason for my knowing you didn't. |
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 Samba Member
Joined: October 30, 2009 Posts: 26743 Location: Colorado Springs
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Posted: Thu Dec 14, 2017 6:10 pm Post subject: Re: 041 GO3 heads have wrong seats cut? |
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I'd guess they had 39mm valves originally, and somebody put 40mm valve on there. |
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stevetim Samba Member
Joined: September 11, 2005 Posts: 45 Location: Riverside
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Posted: Thu Dec 14, 2017 6:17 pm Post subject: Re: 041 GO3 heads have wrong seats cut? |
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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 Samba Member
Joined: October 25, 2012 Posts: 3574 Location: Sarasota, in my adopted state of Florida
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Posted: Thu Dec 14, 2017 6:35 pm Post subject: Re: 041 GO3 heads have wrong seats cut? |
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Another example of, if you want it done right do it yourself. Dan |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Thu Dec 14, 2017 7:16 pm Post subject: Re: 041 GO3 heads have wrong seats cut? |
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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 Samba Member
Joined: May 13, 2011 Posts: 4254 Location: Aumsville, Oregon
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Posted: Thu Dec 14, 2017 8:51 pm Post subject: Re: 041 GO3 heads have wrong seats cut? |
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My old big valve 041's were the same way....big valve small seat. Had it fixed soon as I bought them. _________________ Good things come to those who wait.
2332 with lots of goodies....
Rotating assembly balanced by Brothers VW
4340 84mm crank
AA 94mm p&c' s
Total seal 2nd ring, rest are Grants
5.5 h beams
Magnum straight cuts
Steve Long XR310 on a 106
CB 1.4 rockers
CB Magnaspark 2 distributor
NGK D7ea plugs
A1 lowdown 1 3/4 with single muffler
Dellorto 48's with 40 venturies
Kennedy Stage 2 with Daiken disc |
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AlteWagen Troll
Joined: February 23, 2007 Posts: 8498 Location: PNW
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Posted: Fri Dec 15, 2017 1:26 am Post subject: Re: 041 GO3 heads have wrong seats cut? |
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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. _________________ Grapes of Wrath $200 Engine Rebuild
Official Dual Carb Thread
Cylinder Head Quick Reference Sheet |
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Ebel Samba Member
Joined: June 07, 2015 Posts: 564 Location: New york
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Posted: Fri Dec 15, 2017 5:30 am Post subject: Re: 041 GO3 heads have wrong seats cut? |
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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 Samba Member
Joined: July 12, 2007 Posts: 7182 Location: Videbaek Denmark
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Posted: Fri Dec 15, 2017 1:59 pm Post subject: Re: 041 GO3 heads have wrong seats cut? |
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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 Samba Member
Joined: August 06, 2009 Posts: 861 Location: Riverside, Ca
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Posted: Mon Dec 18, 2017 10:03 am Post subject: Re: 041 GO3 heads have wrong seats cut? |
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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. _________________
modok wrote: |
And I know you don't know because if you did you would know the reason for my knowing you didn't. |
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 Samba Member
Joined: November 16, 2003 Posts: 9437 Location: NOVA
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Posted: Fri Dec 22, 2017 1:52 am Post subject: Re: 041 GO3 heads have wrong seats cut? |
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somebody went big-valve and forgot the seats? |
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