Progress on the Nomad...

MGVWfan · Post by **MGVWfan** » Sat Oct 01, 2005 10:49 am

The 412 is sitting in the driveway now, the Duster is in the garage. I got the steering back together last night, yay!!! Now it's on to the heads and engine, and then the car will be driveable. Progress is a wonderful thing!

The MG is back in my driveway, with two new front tires. I discovered the spokes on the rear wheels are loose and need to be tightened. It was an interesting trip back from Dayton, the rear end felt like it was going to break loose every time I turned the wheel. Funny, the rear wheels were OK before the attempted evacuation of the MG.

BTW, my tire store found some PVC pipe tape that's thick enough to use as rim tape on the wheels, it worked great.

No pictures, unfortunately, other than what Ray sent me a few months back. I couldn't find the digi cam after the unpacking-from-Rita flail, argh!

raygreenwood · Post by **raygreenwood** » Sun Oct 02, 2005 4:12 pm

I will re-mail some pics of the guts of the new link to MGVW. I may even have some pictures of the old guts....the rotted ones. Glad you got it! It should steer nicely! What a new centerlink will also do....is pinpoint all the other locations that cause the dreaded "shimmy". Ray

MGVWfan · Post by **MGVWfan** » Sun Oct 02, 2005 7:14 pm

Yeah Ray, it should drive much better than when last it was on the road some 10 years ago! New strut inserts, new centerlink, new tie rod ends, new balljoints, new tires, lots of sweat and cusswords.

Since it's outside and away from the water heater now, I put 2 gals of fuel in the tank, jumpered the fuel supply line back at the engine compartment to the regulator (with a pressure gauge and "T"), and connected it to the return line, and powered up the fuel pump for a test. 29 psi, no leaks in 20 minutes of testing. The gauge does quiver a bit (0.5 psi) from time to time, so I may do the L-jet pump addition mod...or just see how it works.

MGVWfan · Post by **MGVWfan** » Tue Oct 04, 2005 7:23 pm

After a total of 1 hour of test run time on the fuel pump, it's quivering a bit too much now, say 2 psi. I'm thinking the original pump's just tired, and I'm going to see how adding an L-jet pump in series after it from an '80's Volvo works out. I may also troll the junkyard again and see if I can snag one of those fuel accumulators from late 80's Rabbibbits/Golfies for grins. I suspect 2 psi of rapid variation in fuel pressure would play heck with fuel delivery and therefore mixture. Oh yeah, the pump check valve is weak, it bleeds down to 20 psi rather quickly after shutdown.

raygreenwood · Post by **raygreenwood** » Mon Oct 10, 2005 7:17 pm

A peculiar thing those fuel accumulators.....they don't help much on D or L jet....in their stock form. The problem is that the spring inside.....is set for CIS pressure. The stock pressure from D or L...cannot compress the spring and diaphram...so no help.
But...and I have done this...and it works great. Carefully cut-off the back end of teh accumulator where the spring is. Get a piece of steel pipe collar....and well an extension into the end of teh spring tube...then weld teh rear cap back on. Before you weld it back together...weld a nut to the outside, drill a hole and install a bolt...welded to a washer under the spring.
Immerse the unit in water while welding so as not to cook teh diaphram. What you end up with...is a unit with reduced pressure and a spring tension adjuster screw.
Mine worked great, until I found that I did not need an accumulator after i added an extra main pump. Ray

MGVWfan · Post by **MGVWfan** » Fri Oct 21, 2005 5:53 pm

After further testing, it looks like the regulator is "farting". When I flow air through it to test it, the darn thing quacks like a duck in heat. I tried the same test with a more modern Bosch reg, and it smoothly regulated no matter what the pressure on the inlet...it just opened the orifice wider and flowed more through the reg, whereas the D-Jet reg oscillated from mostly closed to open, causing the pressure fluctuations I saw. Maybe a new reg?

BTW, tonight I got around to cc'ing the new heads, the pistons, and checked deck height. Deck height with no shims = 0.025", and with the 8.6cc dishes in the pistons and the ~45cc heads, and 0.010" base shims, the compression ratio looks something like 8:1, just below what I wanted to run with the used P&C's I've got (even though they're nice Mahle's they've got 20K on them all run with the injection in full-rich mode, so I'm wanting to be a bit more "gentle" with the CR). I guess the question is this...is 0.035" total deck height OK? That's 0.025" deck with a 0.010" base shim. I can't seem to find a spec in the service literature I have, though I've seen a figure of 0.040" as the minimum batted about on this and other sites.

I'm thinking I'll just press with the 10 thou base shim and around 8:1 CR, since in my experience, 25 thou of clearance is more than enough between the piston crown and the bottom of the head. If so, the engine will be back together tomorrow, and probably in the Nomad on Sunday!

MGVWfan · Post by **MGVWfan** » Fri Oct 21, 2005 6:10 pm

Oh, yeah, in case you're wondering where I was, it's been rough at work for the last week or so, and I've been scrambling to finish the Nomad off at the same time. The last thing on the list is engine reassembly and installation, thus the cc'ing and deck height measuring and fiddling with those obnoxious Goetze 3-piece oil rings (they are a real PAIN to get compressed, why can't they use one-piece rings with a spiral expander like TRW???).

I'm really hoping the ASTROS IN THE WORLD SERIES FOR THE FIRST TIME IN THE 44 YEAR HISTORY OF THE FRANCHISE will finally improve my luck so I can get it back on the road this week!!!

GO STROS!

vwbill · Post by **vwbill** » Fri Oct 21, 2005 9:53 pm

Hey MGVWfan, sounds like you are busy with the measurement setup! I know I have asked the clearance question and need to look it up in my notes too but I thought .025 was good. How was setting up the jugs to take the measurements? Also did you get any jugs that were different from each other? Did you have any ring gap issues? Hey look at the post by Deadhead for cc'd my engine.... I thinksomeon said .035 was good for total deck height but Ray says .040...

MGVWfan · Post by **MGVWfan** » Sat Oct 22, 2005 7:01 am

I get the impression from my measurements that these NF Kolbenringe/Goetze rings (from Bus Depot, BTW) come pre-gapped, all the compression rings were within the OE spec out of the box (though on the large side). It's impossible to tell what the gap is on those 3-piece oil control rings, so no idea on them. I've not checked deck height on all jugs yet, but so far no major variance. The heads were 1.7L opened up for 1.8L jugs, so the combustion chamber cc's do show some variance, not enough to make me want to get the Dremel grinder out (less than 0.5cc out of 45cc total). I decided to hold the jugs in with a set of washers and the normal nut on one stud, snugged down finger-tight, to keep the jug in place, and it seemed to work OK.

Yeah, that post is what got me thinking that maybe I need to use 0.010" shims under the jugs to get to 0.035" total deck height, but that's still not 0.040" as specified in the post you noted. I'm thinking 0.035" is OK.

raygreenwood · Post by **raygreenwood** » Sun Oct 23, 2005 2:20 pm

Deck height minimum on air cooled engines is .035" anything below that is risky. 8.0:1 cr...would be a bare minimum on anything other than a bus. If you are using D-jet...you will find that under compression makes it hard to tune and finiky on its fuel mixture.

Add the shim....the .035 will be fine. Stock deck height....especially with the domes....was a little iffy to get correct. This is where a lot of people mess up.

With deck height...we are looking at two issues. (1) will the piston have enough clearance to keep from striking a valve? That deck height is measure from the center of the piston generally.....or anywhere on the piston where you are likely to come within the influence of a valve head.
(2) Actual clearance when hot from the edge of the piston to the head casting itself....valves issues aside.

On the domed piston....clearance from the dome to the closest approach of the valve at full lift must be considered. In light of that.....the factory left the clearance at the EDGE of the piston...quite large. On the 1.7 with domes...generally you had a shim of .010" and a head gasket compressed to .028". That gave .038" average....but the piston edge itself had a natural .040". That gave a total deck at pistons edge....of about .079". Coincidentally....the 1.7 dome....rises some .079"...from the surrounding surface of the piston...

.

Now...thinking piston edge....on a dished or dome piston.....I do not see why they could not be a bare minimum of .025-.030 for deck...without shims and head gasket....as long as the required .035 minimum for center of dish to valve clearance was maintained. I would consult others like Jake...about .025" piston EDGE to head gap....when piston head to valve clearance is not at issue. Ray

MGVWfan · Post by **MGVWfan** » Sun Oct 23, 2005 4:26 pm

Yeah, I figured 0.035" would be OK, even for an ACVW engine from a clearance-when-hot standpoint, thanks Ray.

As for the CR, with the pistons I have (8.6cc dished Mahles) and the minimum tolerable deck height it's got, the best I'll see is something like 8.2:1, which is OK for now. I'm going to get it on the road and start looking for flat top 93mm pistons (and jugs, maybe) for a rebuild next fall. Now that I know the engine's important parameters, I can get shims made once I find the right pistons, and dial-in the CR.

I just ordered a K-D piston ring compressor to help get those slugs in the jugs...darn German rings appear to need a proper compressor to keep them fully and consistently compressed, not a wrinkle-band type like I was planning on using. My old reliable steel shim barrel-type compressor won't work either, it's too long for these Mahle pistons and doesn't keep all the rings compressed well as the piston slides out, leading to issues with the oil control ring. Glad I test-fit everything before commiting to final assembly.

BTW, I'm planning on fitting the pistons to the cylinders on the bench (leaving the wrist pin end exposed), then sliding the wrist pins on the rods with the pistons in the cylinders, then sliding the jugs home. I looked at the idea today, and think it's better than trying to keep the rings compressed with the piston on the rod, and sliding a jug on all at the same time. Seems others have done it this way, too. Any comments?

Today I got to diagnose an '89 MoPar 2.5L turbo FI funny...man, I'll be so glad to get that VW running with its simple analog FI. I hate digital FI systems. Turned out to be a coolant temp sensor, but the symptoms were very strange.

MGVWfan · Post by **MGVWfan** » Mon Nov 28, 2005 5:48 pm

Hey guys, sorry I've not posted for a while, I've been busy...

THE NOMAD IS ON THE ROAD!!!!

I got it going a few days ago. Man, what a SMOOTH air cooled powerplant, and that AT is the best I've ever driven. Firm, controlled shifts, low slip in the TC, excellent. Just got to hook up the Eber and the A/C, but it's there! Photos soon!

Thanks to all of you for your help and encouragement over the last 18 months getting it back going. You guys are the best. Thanks especially to Ray for the centerlink, and all the great advice.

ubercrap · Post by **ubercrap** » Mon Nov 28, 2005 8:17 pm

Sweet man! Very exciting!

MGVWfan · Post by **MGVWfan** » Mon Nov 28, 2005 8:28 pm

Thanks Uber

. It was a LONG strange trip indeed, from June 2004 to November 2005. A totally rebuilt AT, rings and new heads on the engine, NOS pressure sensor, replaced old brittle wires and new CHT sensor for the D-Jet, an engine compartment and engine tin sandblast and repaint, overhauled Eber and A/C compressor, rebuilt brakes, totally new front end (except the steering gearbox), new strut carts and rear shocks, cleaned and relubed CV joints and new boots, replaced rear wheel bearings and seals, completely new hoses (including the fuel filler neck hoses, those are a ROYAL PAIN to install), repaired and installed a Blaupunkt Emden radio...wow, it really was most of a restoration, eh? Only big thing left is the paint (gotta HATE those Maaco/Scheib paint jobs, they're really crap), the rest is small stuff.

ubercrap · Post by **ubercrap** » Mon Nov 28, 2005 8:50 pm

Definitely a lot of work, but I knew you would get there. Get that Eber hooked up too, you'll love it I think. The one in my recently acquired wagon seems to be working OK again for the moment. I just got back from a very toasty test drive a bit ago!