Home Built Hot Rod (With full build videos)
08-07-2019, 02:41 PM
#244
Great job Jeff!!
I can recommend the digital degree device as well. Roger bought one by my shop and showed me the device. Its well made and is a great tool to have. Unfortunately we already have something that does the same thing. Unfortunate, because our one cost PD over $ 8000.00 many years ago. Progress I guess.
The way we do our Piston to valve clearance is required, as we typically use custom pistons, larger valves and custom camshafts. If there is any interference, its all on paper and we know at that cam position we have to remove "x" amount from the valve pocket. This is typically done on a prototype piston and all other pistons are made to clear. We have an idea of the total amount of cam timing changes we may want to test, and this is taken into account when doing this check. As Jeff said, once you do the valve seat to piston check at the different crank degrees, these numbers never change. Now you change the cam timing, (valve lifts) to whatever you wish and do some simple math to calculate your clearances. In dyno testing, we often move the cams and know the clearances before we do any mechanical changes. Sometimes you can see before you pick up a wrench that it will not work.
Your cam supplier will be able to give you the valve lifts before and after TDC at any cam position. This is the number you subtract from the seat to piston dimension. If that's not possible, there is way you can measure this on the engine. It requires some assembly though. You go through the same TDC check as Jeff showed to establish true TDC. Then you would remove the piston and rod. This would be done if it is known that you may have some interference. If its known no interference would happen, you can leave the piston in the engine. Remove the valve springs and replace with softer checking springs. Reassemble the valves into the head and install the head, cam deck and time the cam to what you want. Then as Jeff showed, place a dial indicator on the valve stem and measure the valve drop at each crank position you are checking. We typically do 20° BTDC every 5 or 10° through to 20° ATDC. This is the valve lift number. Obviously, the reason for removing the piston is, if there was any interference, again its on paper.
I can recommend the digital degree device as well. Roger bought one by my shop and showed me the device. Its well made and is a great tool to have. Unfortunately we already have something that does the same thing. Unfortunate, because our one cost PD over $ 8000.00 many years ago. Progress I guess.
The way we do our Piston to valve clearance is required, as we typically use custom pistons, larger valves and custom camshafts. If there is any interference, its all on paper and we know at that cam position we have to remove "x" amount from the valve pocket. This is typically done on a prototype piston and all other pistons are made to clear. We have an idea of the total amount of cam timing changes we may want to test, and this is taken into account when doing this check. As Jeff said, once you do the valve seat to piston check at the different crank degrees, these numbers never change. Now you change the cam timing, (valve lifts) to whatever you wish and do some simple math to calculate your clearances. In dyno testing, we often move the cams and know the clearances before we do any mechanical changes. Sometimes you can see before you pick up a wrench that it will not work.
Your cam supplier will be able to give you the valve lifts before and after TDC at any cam position. This is the number you subtract from the seat to piston dimension. If that's not possible, there is way you can measure this on the engine. It requires some assembly though. You go through the same TDC check as Jeff showed to establish true TDC. Then you would remove the piston and rod. This would be done if it is known that you may have some interference. If its known no interference would happen, you can leave the piston in the engine. Remove the valve springs and replace with softer checking springs. Reassemble the valves into the head and install the head, cam deck and time the cam to what you want. Then as Jeff showed, place a dial indicator on the valve stem and measure the valve drop at each crank position you are checking. We typically do 20° BTDC every 5 or 10° through to 20° ATDC. This is the valve lift number. Obviously, the reason for removing the piston is, if there was any interference, again its on paper.
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MFX233 (08-07-2019)
08-27-2019, 08:45 AM
#247
Instructor
Love the build series Jeff, please keep it up!
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MFX233 (08-27-2019)
08-29-2019, 09:14 AM
#249
Rennlist Member
Jeff, you're KILLING me, buddy! I've watched all 68 episodes in the first series over the last two or three days. My eyeballs are drying up in my head!
A few observations so far:
Also: I'm a sticker guy too. You should sell some in your store! Something with the stripe would be nice.
A few observations so far:
- Love the color choice, including the purple. I think the interior carpets should have been bound (edged) in purple.
- I think the rear script might be a *tad* busy. I'm not sure what I would do different, but the letters transitioning black to orange to purple to orange is a little eye-dazzling.
- I like the purple tartan, but I thought you might be going wrong with it in the interior. However, it worked out brilliantly. I am concerned about it sun-fading over time, though.
- I was wondering why you were doing the first pass on recovering the seats using your hide, rather than some cheap vinyl, but then you made the same observation yourself!
- You might want to invest in a rotary fabric cutter if you're going to be doing more seats and interiors.
- I think Mrs. Jeff is a great sport for brightening up your 911 build videos!
Also: I'm a sticker guy too. You should sell some in your store! Something with the stripe would be nice.
Last edited by Shawn Stanford; 08-29-2019 at 11:45 AM.
08-29-2019, 07:17 PM
#250
Racer
Thread Starter
Glad you are enjoying it though mate.
09-13-2019, 04:37 AM
#251
Racer
Thread Starter
In this episode I tackle the chain alignment on my old 911 engine which is trickier than it looks. I also clearance and fit my new EFI harmonic balancer.
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MFX233 (09-13-2019)
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markaria1 (09-27-2019)
10-03-2019, 08:51 AM
#255
Racer
Thread Starter
This week I get stuck in and actually make some good progress on the 911. Painting engine parts, fitting the chain tensioners and then replacing the dreaded fuel lines