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Re: Cheap Junk 1971 Build

Posted: Wed Jan 10, 2018 11:24 am
by raygreenwood
Piledriver wrote:
Mon Jan 08, 2018 10:25 pm
Something doesn't sound right.
The rockers don't vary that much.

The pushrod can end up out of the pocket in the lifter its meant to ride in, and seem a bit long.
(depends on lifter design)

If you are using used stock pushrods for some strange reason their length is going to be all over the place.
This is because they suck (technical term)

Solid spacers and hd rocker studs are always recommended, with the side play set at .003-.004.
They are sand to fit.
The stock spacer setup is really kinda junky.

The hd studs and spacer kits are cheap and will make for a quieter, lower hassle engine, esp in combination with good swivel feet. They are more work than cost, much like getting the geometry right.
Some of the rockers do vary. Jake mentioned years back....that he found a variance in rocker ratio on type 4....some were like 1.23-1.25-ish and others closer to 1.3.....just going off memory so not sure. He noted that he set up a jig with a rocker shaft and pushrod button to check lifters for ratio.

I started doing that with my bucket of lifters.....found 2-3 that were different. This may be what he is running into. Ray

Re: Cheap Junk 1971 Build

Posted: Wed Jan 10, 2018 1:59 pm
by Clatter
The exhausts don't lift as much as the intakes, either.

Another reason to consider a dual-pattern cam..

Re: Cheap Junk 1971 Build

Posted: Thu Jan 11, 2018 7:38 am
by oprn
I don't really know if the rockers have different ratios, what is happening is I can't back the adjusting screws out far enough to get a gap. Those two rockers may have a thicker casting on the adjusting screw end or perhaps the rocker shaft hole is bored at a slightly different height. I put a straight edge across the valve stems and they look pretty even.

I haven't tried putting the valve covers on yet but suspect there could be some clearance issues there to deal with too.

Re: Cheap Junk 1971 Build

Posted: Sat Jan 13, 2018 4:09 pm
by oprn
No valve cover clearance problems!

Now I am thinking about CHT sensor installation and looking at your picture Clatter. It looks to me like it is just a ring crimp connector with thermocouple wire twisted together and crimpt in place. This means that the ring is not the sensor but just transfers the heat to the two twisted wires which is the sensing point. Have I got that right?

If I do then it is a very simple thing to make these sensors.
http://images.thesamba.com/vw/gallery/pix/1283676.jpg

Re: Cheap Junk 1971 Build

Posted: Sat Jan 13, 2018 9:11 pm
by Piledriver
The wires must be in "intimate contact" (aka twisted together) in the crimp, but the crimp connector itself is not part of the bimetal TC other than as a noise source. It would also be perfectly legitimate to wrap some kapton tape around the twisted wires and jbweld the whole shebang rather than crimping, this will eliminate the electrical noise source on the TC.

Re: Cheap Junk 1971 Build

Posted: Sun Jan 14, 2018 4:08 am
by wreck
I got screw on thermocouples from Omega and wedged them to the side of the head beside the plug boss with tooth picks then built up Devcon/JB weld over it . once the first coat cured I pulled away the tooth picks and built up a more where it needed it , then tie wired the leads to the head and ran the leads forward and out through a small clearance hole in the front lower tin .

I didn't want to grind down the plug boss or drill into the head , many people have and have not had an issue but my heads have had a lot of time and money spent on them and didn't want to risk it . The only thing the I'm not happy with is I'm sure I ordered stranded wire after reading advise from here and I received solid (which will break after a while ).

Re: Cheap Junk 1971 Build

Posted: Sun Jan 14, 2018 9:29 am
by oprn
Yes my thermocouple wire is solid too but I have yards of it left over from burner upgrades at work so replacing it if it breaks is just the labor involved. I would like to get some proper type K connectors though to use by the firewall for convenience. I see Omega has stick on and glue on thermocouples starting at $35 up to $80 each + exchange on the dollar + shipping + duty and tax... I think a little ingenuity like yours wreck, will get it done more reasonably.

I am thinking of drilling and tapping the plug boss, right where Clatter ground it out, for a small screw and anchor the thermocouple there. I have a couple of options for indicators/controllers to use (again, left overs from burners) but they need to be taken out of their bulky cabinets and remounted neatly in the dash. Both are just 2 channel though, it would be nice to monitor all 4 cylinders.

With that in mind, which 2 cylinders would you choose? Stock Bus cooling system.

Re: Cheap Junk 1971 Build

Posted: Mon Jan 29, 2018 11:36 pm
by oprn
Here is the solution I came up with for fastening the thermocouples. Made 2 aluminum plates to fit right beside the plug, drilled and tapped the head, put a little groove on the head surface to keep the thermocouple in place and screwed it down. Now I need to anchor the wire to the cooling fins to keep them from cracking off from vibration.
shrunk 1.jpg
shrunk 2.jpg

Re: Cheap Junk 1971 Build

Posted: Tue Jan 30, 2018 5:01 am
by Gnasha
How much, if anything would this alter the reading. I'm aware the length of wire is calibrated to the reading on the gauge on some designs.

Re: Cheap Junk 1971 Build

Posted: Tue Jan 30, 2018 7:50 am
by oprn
Wire lengths that we use to go from the engine to the dash are not great enough to have any significant bearing on accuracy. More of a concern is that the wire material be the same as the thermocouple type in use. This avoids the "cold junction" everyone talks about that generates counter signals to the signal you want from the thermocouple. Companies that sell the cheaper gauges assume you will use regular copper wire extensions and create this situation so try to build in a compensation factor to account for that. It works - kind of - as the error changes when the ambient temperature changes.

Re: Cheap Junk 1971 Build

Posted: Tue Jan 30, 2018 8:17 am
by Gnasha
oprn wrote:
Tue Jan 30, 2018 7:50 am
Wire lengths that we use to go from the engine to the dash are not great enough to have any significant bearing on accuracy. More of a concern is that the wire material be the same as the thermocouple type in use. This avoids the "cold junction" everyone talks about that generates counter signals to the signal you want from the thermocouple. Companies that sell the cheaper gauges assume you will use regular copper wire extensions and create this situation so try to build in a compensation factor to account for that. It works - kind of - as the error changes when the ambient temperature changes.

thanks for that.

Re: Cheap Junk 1971 Build

Posted: Tue Jan 30, 2018 11:42 am
by Ol'fogasaurus
Be careful around that braided wire. The frayed end of the shield is ready to do damage to itself and any other wiring near it.

(FYI) One of the reasons I do not recommend braided hose or braided wire covers for wires as if there is any continual motion the strands can get fatigued (aka "worried") and start to fail/break then become something that can cause damage to other standard wire wires.

http://www.hydraulicspneumatics.com/hos ... se-failure

Re: Cheap Junk 1971 Build

Posted: Tue Jan 30, 2018 8:27 pm
by oprn
Thanks, I am hoping to retain some of the braided shield to protect the wire where it is next to the engine. I have not decided yet how is best to finish the frayed end.

Re: Cheap Junk 1971 Build

Posted: Sat Mar 31, 2018 4:08 pm
by oprn
Back on the engine. I was hoping to drop the old 1600 this weekend and trial fit this new one but I don't have proper heat in my shop. It was -21 this morning with a -34 wind chill!

So... there are plenty of little thinks to finish up, got the dipstick done and the temp probe that I will be putting in the dipstick hole is wired up and ready. Next is mounting the fuel regulator and setting up a spot to take off oil pressure for the gauge in the dash. I still have the choke linkage to figure out too.

Re: Cheap Junk 1971 Build

Posted: Sat Mar 31, 2018 4:19 pm
by oprn
This is the probe.