Retitled: Gypsie's rebuild

bus71 · Post by **bus71** » Thu Apr 30, 2009 11:22 am

I woudn't call 140-150 bad, a little high. It may mean you need premium gas on hot days to prevent pinging, it may run just fine on regular. I had a used engine that needed this- no shims at all when we tore it down. Ran great for 60,000 miles. It had 165-170 compression, too much stress.

Gypsie · Post by **Gypsie** » Thu Apr 30, 2009 11:43 am

airkooledchris wrote: Let's back up, if there's still time to do so - what did you do when you were 'fine tuning the settings' over your 200 mile drive with the LM-1?

The main adjustment on Sunday evening was to enrich the idle mix at the afm air bypass screw. It was reating 18-20 in the idle range and 13-14 at most other speede above 1500rpm (multiple steps.)

Advance checked and speced (both mech and vac).

This has been about a year of trial and error afm adj and return to orig. Both all over and dynamic adj. Currently I have returned to what it was set at when I bought it 2 years ago and it is now 4 clicks leaner on the dynamic adj.

I could go back through all the machinations I have gone through to this point but I have passed my own tipping point. I am not finding an engine pull to be beyond my comfort zone to resolve this outstanding question. I may avoid a full extraction if anyone can tell me if just pulling the heads will give me the opportunity to do all the calculatin' necessary to get my cc/deck height info or if the entire engine needs to be where I can get cylinder data? Any links to threads anyone can think of will speed searching for guidance.

If I can get by just dropping it down to an angle that gives room enough to remove heads I will do that and inspect/gather data. I am curious to see if the heads have been flycut in the past as I did not look for that last pull.

No looking back, onward...

Another area I will look at when reassembling will be spark. My last spark check geve me a yellowish spark. I will try different coils as well as give the distributor a once over. Any suggestions on distributor cleaning? I run pertronix and vac/mech advance seems to be working to spec thus far, so I'm not too worried there.

Colin you said the 90lbs comp area may be an indicator? Could this be an indicator that without the head rings there is an improper deck height?

I have time but not too much $$$ so I hope to not have to have the heads rebuilt. I am thinking that if I am this far the expense may be called for. I will look for indicators but hope that the sealing rings will be the thing.

bus71 · Post by **bus71** » Thu Apr 30, 2009 11:59 am

You can pull heads on a Vanagon with engine in. I would try some more tuning 1st. Our 80 isn't a poptop but mpg went up from 15 after using Colins AFM prcedure. I don't think these big boxes get the mpg a bay does. (no LM)

Gypsie · Post by **Gypsie** » Thu Apr 30, 2009 12:58 pm

another possibility is that when I torqued the heads after last rebuild I went straight to spec and did not do the overtight overnight and then back method. Over time the expansion factor may have created a leak at the head (which is what is creating the burp sound and oil residue that keeps building up on the heat exchangers making the heat stink.). I will know when I remove the heads. I will do tuning procedures when I reassemble. I will not be reassembling again until have confirmed whether or not I need the sealing/spacer rings. Those rings are pretty thick and would have a noted impact if they are not there when they should be.

Exhaust, heat exchangers, harness, coil, intake runners, fuel injectors, afm, fuel lines, engine elect. have all been disconnected/removed.

No more test tuning. pull heads, confirm, reassemble...

I will attempt to remove the heads with the engine in if I can get all the data I need to eliminate deck height concerns. I think I need to have the cylinders locked down and take a measurement from the lip to the top of the cylinder at tdc. This can be done in place as far as I can reckon. Or do these need to be measured with liquid? The heads need to be on a bench to measure cc's right? this is the liquid measurement portion?

I may settle with the mileage described above. Bob said he had similar mileage in his watercooled vanagon. There is alot 'o weight on them.

but (and this is what is driving this extraction)

I will always wonder if the rings are needed if I don't settle it once and for all.

bus71 · Post by **bus71** » Thu Apr 30, 2009 1:30 pm

Deck height can be done with short pieces of pipe and nuts,washers to lock cylinder down. Lay a 3/8 ext. across and use feeler gauges. CCing on bench. Need a srynge, a flat clear plexiglass plate cut chamber size. I think someone who's a better teacher should chime in now!

spiffy · Post by **spiffy** » Thu Apr 30, 2009 1:44 pm

[quote="bus71"]Deck height can be done with short pieces of pipe and nuts,washers to lock cylinder down. Lay a 3/8 ext. across and use feeler gauges. CCing on bench. Need a srynge, a flat clear plexiglass plate cut chamber size. I think someone who's a better teacher should chime in now!

[/quote

I am not the better teacher but doing what you described will get you the measurements you need. Er.... That gypsie needs.

Lemme know what you find stephan, I may doing this in the near future. FWIW AC.net has different sizes of head sealing rings if you need some.

Gypsie · Post by **Gypsie** » Thu Apr 30, 2009 1:45 pm

bus71 wrote:Deck height can be done with short pieces of pipe and nuts,washers to lock cylinder down. Lay a 3/8 ext. across and use feeler gauges.

Can I measure from under the pipe I use to clamp the cylinder with (if said pipe is gutenstraight). As I recall when I had the heads off there was quite a gap from tdc to the top of the cylinder.

Pic from last year before tlc.

I'm sure that some of that buildup is down the side of the piston above the top ring. What kind of measurement should I expect from top of piston to lip of cylinder?

bus71 wrote:CCing on bench. Need a srynge, a flat clear plexiglass plate cut chamber size. I think someone who's a better teacher should chime in now!

This is the head measurement, right? Once I have the data I presume I will be doing some calculatin' to figger deck height requirements. Can anyone direct me to these calcs? Maybe Jasan can chime in (or stop by Friday eve?...)

Bob just did this so I will pick his brain too. I was hoping he could come over Friday to wrench and do some pickin'.

Side note- We had a spontaneous jam the other night that was magical. Boy we sure do have fun playin'.

bus71 · Post by **bus71** » Thu Apr 30, 2009 2:02 pm

Not sure if we are measuring in the same place. You need to measure from center top of piston to line across center of cylinder (veritical). This is where the better teacher steps in!

vwlover77 · Post by **vwlover77** » Thu Apr 30, 2009 7:17 pm

The liquid measurement is for the head volume.

You probably have dished pistons, so you need to measure the deck height as the distance from the flat part of the piston (undished portion) to the top of the cylinder jug. You may want to take multiple readings around the circumference of the piston and average them.

Here's a link to a nice CR calculator:
http://www.aircooled.net/gnrlsite/resou ... /calcs.htm

Don't forget to add the volume of the dished area of the piston to the combustion chamber cc's that you measure in the head. I forget what that dished portion is... 5 cc???

Post by **Amskeptic** » Thu Apr 30, 2009 7:25 pm

I measured my deck height in-situe with a bunch of big washers and nuts to clamp the cylinders to the case. Razor blade the piston until you see the spirals of the manufacturing process below the carbon. Clean the pistons until they are consistently clean. A spray of GumOut will rinse the walls and piston crown, paper towels can wick the crap out from the land area. Do not screw around with extensions and whatnot, get a machinist's ruler/steel straight edge across the cylinder and test both horizontally and vertically, or diagonally one way then 90* away, and see what feeler blade slips under the straight edge without digging the piston between its edge and the dish, just a nice sticky slide. I am good with a tight deck height because I always use the head sealing rings, so my deck height was .020" last time around. I am also using the .010 spacers down at the case spigots.

Piston dish volume comes in two quantities shallow with just a light little diagonal to a small center, that it the 7.5 cc dish, then there is a more aggressive drop-off into a more defined bowl, that is the 15 cc dish.
I wish I had photographs, but I don't.
Colin

hambone · Post by **hambone** » Thu Apr 30, 2009 9:38 pm

Those heads are AMC which have notoriously bad components. Take them to Halls.
Aren't you springing for new P&Cs too? What the hell do a topend 100% right and then you won't have to second guess yourself for the next 12 years. Also make sure that distributor is advancing correctly, it may need a refurbish too but that's cheap. I know $ is limited but how many times ya wanna pull that $%@@$$% engine (I think ya kinda like it ya sick0)
Deck height is pretty easy. I'll bring the Wilson book over. Not sure about tomorrow yet I really don't want to go to that saw class but I feel guilty.
Do it right then ya don't gotta worry about it.
Papa Hambone's 10 cents, adjusted for inflation, deflation, bad economy, bad vibes, hot rattlers, pistol packin mamas, rough likker, too many hard nites and a bunch a daisies ya forgot about behind the garage and now it's too damn late.

Gypsie · Post by **Gypsie** » Fri May 01, 2009 8:51 am

These look like deep dish. ?

My spacial sense says those dishes are well over 7.5cc's

Ooooh- new P&C's. I might try to slip them through as long as I can stay at your house for a while when I get discovered...

The heads may get rebuilt though. Probably.

I will look very closely when I have things disassembled. Hoping not to have to do PCs if possible.

dhoch14 · Post by **dhoch14** » Fri May 01, 2009 9:38 am

keep pushing Gypise, it looks like you are making some progress. The right answers will come around and when they do, you can do that happy dance

tristessa · Post by **tristessa** » Fri May 01, 2009 10:03 am

New set of slugs & jugs isn't that 'spensive, under $250 shipped from cip1.com .. if they're really needed. I'd be looking at ignition for your starting issue, and heads for most of the other stuff...

Post by **Amskeptic** » Fri May 01, 2009 1:21 pm

Gypsie wrote:
These look like deep dish. ?
My spacial sense says those dishes are well over 7.5cc's

Yep. How many miles on this engine? I am looking at blow-by traces on the piston.
Colin

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Retitled: Gypsie's rebuild

Re: Injector issues