2838 type 4 buildup

User Name · Post by **User Name** » Sat Aug 29, 2009 11:14 am

WOW that's a lot ofwork you have put in there
this last picture of the combustion chambers to the previous one, you have taken more metal out, was that going to give you too high a compresion ratio
the picture showing the valve seats, are you making the valves aswell
very interesting stuff, very looking forward to seeing it running

Getbackontrack · Post by **Getbackontrack** » Sat Aug 29, 2009 11:23 am

Hey Username, dont quite understand what you meen about the chambers? Please elaborate.. Unless you have overlooked that the second picture is upside down.

I bought the valves, im only makin the seats myself.

Regards, Jakob

User Name · Post by **User Name** » Sat Aug 29, 2009 12:32 pm

it's probably just do to the pictures being at different angles, it's just that the comustion chambers look different sizes

Getbackontrack · Post by **Getbackontrack** » Sat Aug 29, 2009 6:12 pm

Hey username, yes its the picture that is taken "Upside down"

When I get the new seats in I will have to find out what the "new" chambers volume is, then cut/grind them to the volume I need.

Regards, Jakob

Post by **Type 4 Unleashed** » Sat Aug 29, 2009 9:17 pm

User Name wrote:it's probably just do to the pictures being at different angles, it's just that the combustion chambers look different sizes

Jakob

You do know, you need to install all the seats at the same ? And that means you've also made a tool to install the exh seats ?

Getbackontrack · Post by **Getbackontrack** » Sun Aug 30, 2009 2:08 am

Why would I need to install ALL the seats at the same time Richard?

The way I see it. When you have two holes so close to each other, there is a big chance of deforming the roundness of one of the holes when you punch in a seat with a lot of force in the other hole? Besides there is not much material left between the new seats (when both is bored to the oversize) so there will also be a chance that this area will crack when you punch them in.

And yes, I know I need another tool for the exhaust seats.

Regards, Jakob

Post by **Type 4 Unleashed** » Sun Aug 30, 2009 9:14 am

Getbackontrack wrote:Why would I need to install ALL the seats at the same time Richard?

The way I see it. When you have two holes so close to each other, there is a big chance of deforming the roundness of one of the holes when you punch in a seat with a lot of force in the other hole? Besides there is not much material left between the new seats (when both is bored to the oversize) so there will also be a chance that this area will crack when you punch them in.

And yes, I know I need another tool for the exhaust seats.

Regards, Jakob

Why would I need to install ALL the seats at the same time Richard?

The way I see it. When you have two holes so close to each other, there is a big chance of deforming the roundness of one of the holes when you punch in a seat with a lot of force in the other hole? Besides there is not much material left between the new seats (when both is bored to the oversize) so there will also be a chance that this area will crack when you punch them in.

Because, you only want to heat the heads up once when you install the seats. You don't want to have to let them cool after just installing the Int seats then reheat the heads again later to install the Exh seats, the Int's are the critical install, and could very well be an issue if they are reheated again to install the Exh. You have to remember the Int's are the seats that fall out, and thats due to the constant heating and cooling of the seats, the chamber combustion heats the head and the seats, and the cool Int charge cools the seat each and every cycle, and heating the heads to the temps needed to install the seats are far more than they would see in normal engine temps.

The two materials are different, the seats will expand at a different rate than the heads will when you re-heat to install the Exh and could very well distort then ?.

And yes, I know I need another tool for the exhaust seats.

And yes I know you know you need another tool for the Exh sears, and I know you hadn't made one yet to install the seats, cause you were probably gonna wait till after you installed the Int's, and this was an assumption since you hadn't posted a pic of the Exh tool and you hadn't cut the head for the Exh seat...

I have watched this process a few times, and it is a very fast paced procedure, Bam Bam, the Int's are installed, then Bam Bam the Exh are done, the head is then set aside to cool naturally, then the next head is done.

These are suggestions, take them or leave them, but maybe they will save you some grief in the end...

Getbackontrack · Post by **Getbackontrack** » Sun Aug 30, 2009 9:46 am

Guess you have a point there Richard. I had been thinkin about the "sideeffect" of reheating the head a second time for the exhaust seat. But My plan was only to heat the head to about 100 degrees celcius. And the heads will see that temp all the time, so couldnt see the problem in doing it twice.. What tempreture would you think would be needed to do the job?

Unkl Ian · Post by **Unkl Ian** » Sun Aug 30, 2009 6:34 pm

You can calculate the necessary temperature difference, knowing
the Coefficient of Expansion, and amount of interference.

Warm the head, cool the seats, to get the difference in temp.

Unkl Ian · Post by **Unkl Ian** » Sun Aug 30, 2009 6:34 pm

Coefficient of Expansion should be on matweb.com

Getbackontrack · Post by **Getbackontrack** » Thu Sep 03, 2009 10:43 am

So, got the two exhaust holes cut up for the new valves aswell, I have now installed them all in the head. I also made two dummy valves to put in the chambers while I grind them.

Regards, Jakob

Getbackontrack · Post by **Getbackontrack** » Thu Sep 03, 2009 10:43 am

Getbackontrack · Post by **Getbackontrack** » Thu Sep 03, 2009 10:44 am