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Bleeding lifters!
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Christopher Schimke Premium Member
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PostPosted: Sat Nov 29, 2008 7:27 pm    Post subject: Bleeding lifters! Reply with quote

I had to do this recently and though somebody might find it useful to see exactly what is involved.

New/rebuilt(?)/empty lifters should be bled prior to installation. If they are not bled, they can get air-locked and not self-adjust properly. You can read all about it here:

http://www.bostonengine.com/articles/hydraulicll.htm


The first step is to pry the little clip out of the top making sure that it doesn't fly across the room when it comes out. Holding a finger over the top of it prevents this.

Image may have been reduced in size. Click image to view fullscreen.

Disassemble the lifter. Removing the plunger can be a little challenging because it wants to stay inside the valve body. Using a drift punch, push it through the hole in the center of the plunger while holding the valve body upside down. This will help drain the assembly oil making removal of the plunger easier.

This is the guts of the lifter on the right, laid out in order. In the center of the photo is the valve body and from the bottom up are the plunger spring, plunger assembly (ball check valve, check valve spring, check valve retainer not shown), metering disk, pushrod socket and lock ring. If these are new lifters, you will see a small amount of a light oil in the bottom of the valve body. Dispose of this oil at this time. I don't know if it is necessary, but I clean all of the components with brake cleaner at this time.

Image may have been reduced in size. Click image to view fullscreen.

Although some of the following photos show the lifter laid on it's side, you will want to stand the valve body upright for the next operations.

With the valve body standing upright, fill it about 1/3-1/2 full with motor oil. You will see a small hole in the side of the valve body as well as in the side of the plunger. Carefully line up these two holes and drop the plunger into the valve body. These two holes must align during the following procedure so that you can insert a 3/32" drift punch into both holes in order to hold the plunger in place while the rest of the components are assembled.

Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.

At this point, the plunger will not drop far enough down into the valve body to get the rest of the components in place due to the hydraulic nature of the assembly. In order to get the plunger to sink and to purge the valve body of any air, you will need to use a drift punch, inserted in to the hole in the center of the plunger, to depress the ball check valve. This will allow air and oil to escape while the plunger drops to the desired level. In order to have some control over the alignment of the holes, I like to use a large screwdriver that wedges itself into the large opening of the plunger. This allows the plunger to be pushed down as well as rotated in the valve body so that the holes can be aligned.

Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.

Trying to align the holes can be trying. With oil running out all over, it becomes hard to see the holes line up. I have found that it helps to depress the plunger just slightly more than necessary and then lighten up on the downward pressure of the plunger so that it can rise slowly, all the while trying to fit the 3/32" drift punch into the two aligned holes. Sometimes it takes several tries to get it right. Since there is excess oil in the valve body, it is difficult for air to get sucked back in. Therefore, raising and lowering the plunger several times is just fine. Just make sure that there is enough oil in the valve body cover the hole in the top of the plunger. Once the holes are perfectly lined up, insert the drift punch and remove the screwdriver.

Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.

The drift punch holds the plunger down so that the rest of the components can be assembled. When installing the lock ring, you will need to be sure that you push the ring tight into the groove around the valve body so it does not pop out. If it pops out even partially after the drift punch is removed, the whole procedure must be done over again.

Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.
Image may have been reduced in size. Click image to view fullscreen.

You have probably noticed that there is no oil spilling all over in the pictures above. I did everything dry so that it was easier to photograph and easier to see the details.
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Last edited by Christopher Schimke on Tue Dec 02, 2008 5:41 pm; edited 1 time in total
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D Clymer
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PostPosted: Sat Nov 29, 2008 9:24 pm    Post subject: Reply with quote

Nice write up, Chris! Thanks for taking the time to put this together. We should put this in the stickies section so it's easily available.

David
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PostPosted: Sat Nov 29, 2008 9:35 pm    Post subject: Reply with quote

Yup, well done. You looking to get hired by Bentley?? Laughing

Thanks for the clear write-up.
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PostPosted: Sat Nov 29, 2008 10:06 pm    Post subject: Reply with quote

Yeah, your welcome! If something isn't clear or just doesn't makes sense to anyone, let me know and I will definitely clarify.

One thing that I should mention, it is a really good idea to do one lifter at a time. I took some all apart one time and accidentilly mixed up one of the plungers with the valve bodies. On the very last set I assembled, the plunger would not go into the valve body smoothly. It jammed about half way in and would not come out. At first I thought a piece of grit or a bur that caused it, but upon close inspection, nothing was found. I ended up measuring everything and found a small amount of variation among the plungers and valve bodies. I was able to match up the best fitting pieces and all was good again. Lesson learned!
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PostPosted: Sun Nov 30, 2008 12:28 am    Post subject: Reply with quote

This is very good information but also a little bit disturbing.

From what I have understood in BostonBog write-up, even if they are bled properly, the lifters that are under compression could fill back with air if the engine is not started within days of being rebuild????


Also, if/when I buy a rebuild engine, I guess I will now ask about the lifters...have-they been bled...not sure everyone does it.
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PostPosted: Sun Nov 30, 2008 9:45 am    Post subject: Reply with quote

Chris, you beat me to it. I was prefilling a set of new lifters the other day and took pics in preparation for a thread just like this. Nice job! your pics are a lot clearer than mine.

Couple things to add:

I use a straight blunt scribe to depress the ball-valve when I lower the plunger down in the body, and then a 90deg. bent scribe to hold the plunger down. The bent scribe's point never has any trouble finding the hole in the side of the plunger as long as I drop it in reasonably aligned with the hole in the body.

I have an extra pushrod I mount in the chuck of my small drill-press, and when I have the plunger bled in and the other parts in place, I move the lifter to the press and use the arbor to hold it all down while I refit the clip. A bungee cord wrapped around one handle of the press arbor and tied off to the workbench holds tension on the handle. I have it positioned such that the bungee slides toward the hub of the arbor handle when I lift it away, so it's a very easy one-hand operation to pull the handle down and slide the bungee out to the end of the handle. Then I can let go of it and my bent scribe.

The small disc is an oil metering disc to control the volume that passes out the socket cup and up the pushrod to lube the rockers. It doesn't matter which way it goes in, either, on that type of lifter.

Those lifters are the new no-name ones CB, and other vendors, I suppose, are supplying. They've worked well so far. They used to supply the Meyle brand, which had a shorter plunger and longer pushrod cup. The Meyle plungers are only as tall as the level of the hole is in the no-name plunger, so you don't have to align the holes; instead, you just insert a tool thru the hole in the body and catch the top rim of the plunger with it. The tradeoff is that then the metering disc and pushrod cup are separated from the plunger by the tip of the tool. You have to press them down as you quickly withdraw the tool so the plunger doesn't rise, which would prevent your getting the clip back in.

If you are prefilling but then the lifters will be installed and stored awhile in a loaded valvetrain, it's best to use a heavier oil, like a straight 30 or 40-weight, so they will be less likely to bleed down under the valves that are parked open. In operation, there is a constant bleed-off of oil from the lower cavity out along the gap between the plunger and the bore, which is replenished by oil being admitted by the ball valve when there is any slack in the valvetrain.

The rate of bleedoff is a function of the plunger-to-bore tolerance and the oil's viscosity. In regular use, lighter baseweight oils will bleed off more when parked, but refill more quickly when running. The reverse is true of heavier oils, but if parked for several days the differences are moot because the tensioned lifters will leak down anyway. So, I favor the quicker refilling. Lighter oils are also better for the engine overall as long as pressure can be maintained, which is a function of controlling temperature. Good lifter operation, then, is another benefit of having an effective oil cooler.
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PostPosted: Sun Nov 30, 2008 11:15 am    Post subject: Reply with quote

tencentlife wrote:
The rate of bleedoff is a function of the plunger-to-bore tolerance


Thanks for the detailed descriptions (and loogy). Tencent, I have a question regarding this statement above. Is this implying wear over time on the plunger and bore or just a matter of production tolerances (or both). I'm trying to decide if I want to mess around with my problem lifters. Reasons not to are that they match the cam wear and that they may just be air-locked and/or dirty. Both of them, but especially #3 exhaust, have continued to click continuously on a hot engine.

That's why I'm curious about your statement. Should I be more concerned about the wear of the bore to plunger tolerance causing a leakdown and airlock issue or should I be more concerned with a new lifter breaking-in on the cam and see if I can fix the old ones first?

Anyway, thanks for sharing your knowledge.
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PostPosted: Sun Nov 30, 2008 1:18 pm    Post subject: Reply with quote

It's both, but wear is negligible in this area because during engine operation the tolerance is always filled with slowly-flowing oil and the range of movement is very small, in total well under .010" thru complete engine heat cycling. The movement is also not rapid oscillation but slow, resulting from the bit-by-bit increase and decrease of the volume of oil trapped under the plunger. I've taken lots of wel-used lifters apart and have yet to see any evidence of scoring or wear in the body/plunger interface. My best guess is that most lifter troubles are caused by impurities and varnishes corrupting the seal of the ball valve, and/or by an inability of the engine oiling system to deliver oil to all the lifter bores at consistent flow and pressure.

The notions of lifters becoming "airbound" or expanding to the point that the lifter is holding the valve off its seat have both always seemed to me to be basically impossible. Air at its worst has a much lower viscosity than any oil, so it will be displaced out the bore tolerance, offering no practical resistance, whenever pressurised oil is supplied to the lifter. Then it's up to the ball valve to trap the oil. A lot of people are tempted to fool around with their lifters because they are conviced one of these things is occurring, absent proofs, and I have yet to see anyone actually solve a lifter problem definitively by fiddling with the preload, or running them with clearance, or any of that. The only things I've seen that have actually helped have been running a high-detergent oil thru the system to clean the lifter internals, or disassembling them to accomplish the same. Other than those two routes, or outright replacement, the best policy is clean oil and filters, running the lowest baseweight oil your engine can use while still maintaining oil pressure, and to set 'em and forget 'em.
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PostPosted: Sun Nov 30, 2008 1:30 pm    Post subject: Reply with quote

Thanks Tencent. I really appreciate you sharing your experience. For the record, I think I will do both with my lifters. First clean and bleed followed by detergent, oil, and filter.
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PostPosted: Sun Nov 30, 2008 3:30 pm    Post subject: Reply with quote

To add a note to what 10c said, lifters can over pump. I do not know if it is air or oil but it can and does happen. But for it to happen something else has to be wrong as well, specifically the valve spring tension needs to be at spec. If the spring pressure is too low the lifters may over expand. When VW went to the hydraulic lifters on the later T4 in the buses and early Vanagons they increased valve spring tension.

If you have old fatigued valve springs, or are getting recession of the valves and/or the seats you may no longer have sufficient pressure against the lifter for it to operate properly. Partial failure of the cheap keepers and retainers used on AMC heads may first manifest itself with lifters that over pump and hold the valves open.
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PostPosted: Tue Dec 02, 2008 5:43 pm    Post subject: Reply with quote

Thank you for the additional information. It's nice to have so much collective insight in one place, you know?
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PostPosted: Mon Jul 06, 2009 1:04 pm    Post subject: spring orientation Reply with quote

Nice write up.

Would you say that the large spring that holds the plunger up is symmetric? The reason I ask is that I had one of the valve assemblies pop off while putting too much pressure on the valve to sink the plunger. I was able to put it all back on and it seems snug. The spring seems to seat over the flange of the housing that holds the valve spring and disc.

Have you looked inside that valve assembly? My Febi lifters weren't like the lifters with the ball in Bentley. It was a disc/spring combo. Same effect.

When it came apart the little spring turned sideways while taking it out, so I didn't know which way it was originally in there, but could make an educated guess. I reassembled in the housing like so

-- disc
\/ small spring

(spring is the type that coils inward and could compress flat)

Thanks again.

Everything seems ok, but there on the bench, not running at 3000 RPMs
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PostPosted: Mon Jul 06, 2009 3:29 pm    Post subject: Reply with quote

Of the several types I've been into, the main spring is symmetrical. The retaining cup for the small spring and ball just pops into place and stays there on its own. Can't say Ive seen one with a disc instead of a ball yet, but I haven't seen them all, that's for sure.

If you aren't sure, take apart one of your other ones!
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PostPosted: Mon Jul 06, 2009 4:08 pm    Post subject: Reply with quote

Wildthings wrote:
To add a note to what 10c said, lifters can over pump. I do not know if it is air or oil but it can and does happen. But for it to happen something else has to be wrong as well, specifically the valve spring tension needs to be at spec. If the spring pressure is too low the lifters may over expand. When VW went to the hydraulic lifters on the later T4 in the buses and early Vanagons they increased valve spring tension.

If you have old fatigued valve springs, or are getting recession of the valves and/or the seats you may no longer have sufficient pressure against the lifter for it to operate properly. Partial failure of the cheap keepers and retainers used on AMC heads may first manifest itself with lifters that over pump and hold the valves open.


I don't know what earlier valve spring pressures were, but even with the dual springs wbx seat pressure is only 100#, not very high. I expected more when I first measured them, given the dual springs, but I think the duals are there for harmonic dampening due to the higher expected rev range than earlier AC boxers had. That's a very common reason to use dual springs anyway.

Air holding a valve open would be to me unimaginable. Seat pressure is 100#, multiplied by 1.1 means 110# pushing on the lifter. Even though that's not a very high seat pressure as these things go, with the very small bearing area within the lifter, much less than one square inch, whatever air might be inside a lifter would be compressed easily to irrelevance. When air is still inside the opposite occurs; you don't get maximum cam lift, and the lifter fails to track the lobe (which is the clattering we're so familiar with). So I don't think it's air.

As far as oil-binding, I can only imagine one scenario where the engine expands, the lifter extends as it should to take up the lash, then when the engine contracts again that lifter fails to bleed off the extra oil. That is the only occurrence I can imagine where a lifter could end up holding a valve off its seat due to being "overpumped", and it would only leak at the valve while the engine was still cool. Once the engine expanded again that lifter's size would be matched to the engine's again and the valve should seat, assuming nothing else changed in the interim.

Hydros used in other engines do have occasional mechanical binding, where the internal plunger gets physically jammed in the bore in an extended position. Given that the construction of the ones we use is pretty much identical to those others, I suppose that may be the most likely cause of a lifter holding a valve open. I would think the lifter would need to be pretty severely worn, physically, before that could happen, although with the close tolerances very small particles could cause physical jamming of the plunger.

I actually don't think they're terribly sensitive to spring pressure, either. I've run 1.25 ratio rockers on and off the same engines, which would mean pressure is 1.25/1.1 or 13% higher when seated, and the lifters don't care either way, they work well and adjust quickly to changes. I've even added shims under those springs which would have increased seated pressure at the lifter by over 20%, and still no irregularities in how a healthy set behaves. If there were seat recession and/or loosening keepers that allowed the spring to extend further than the designed height, the dimensional changes would be tiny, and the change in spring pressure I measure from a 1 or 2mm lengthening is insignificant, only a few pounds. Now, that would mean less pressure, not more. Someday I'd like to run without the inner springs to test that theory, but I can say for sure that they're at least not very sensitive to higher pressure..

There's definitely something funny that happens with them at times, though, but I have yet to nail down exactly what causes it. It's common enough that I almost always see irregularities in comp tests on engines that leak test tight. Test the same engine later and the lower-comp cylinders may even move around. Pretty strange. But in spite of these little annoyances I still prefer the quiet and maintenance-free operation that hydros provide.
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PostPosted: Mon Jul 06, 2009 11:05 pm    Post subject: Anatomy of the Febi Lifter, part two Reply with quote

Curiosity, and suggestion, got the better of me and I'm glad it did.

My assumption on spring orientation was wrong.

I took a few of the lifters apart. The valve housing pulls off quite easily with a pick.

First shot is an exploded view, like loogy's, but one step further. I took out the contents of the valve housing.

Image may have been reduced in size. Click image to view fullscreen.

You can see the spring and the disc. Notice the spring orientation.

Image may have been reduced in size. Click image to view fullscreen.

Here's a close up of the disc and the spring. I took four apart to ensure the spring orientation was consistent. Some notes.

The large spring does *seem* to have a tighter side that snuggles up to the disc/spring housing. The housing flares out where it fits on the plunger, and the spring diameter is tight so it holds it in place. It's just a pressure fitting. Whether the tightness is intentional or not I cannot say, it just seemed that one side was snugger. The spring, however, looks symmetrical to the eye.

The small plate (second from the right of the exploded view), seems to just be thrown in there randomly. The way the channels are, I doubt it matters, though I'm putting them back together with the inner most ring raised side facing up.

Rich
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PostPosted: Mon Jul 06, 2009 11:17 pm    Post subject: Reply with quote

Got a picture of the outer body of the llfter?

The plate is a metering disc to restrict oil flow up the pushrod. Doesn't matter which way it goes in.
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PostPosted: Tue Jul 07, 2009 7:15 am    Post subject: Reply with quote

tencentlife wrote:

I don't know what earlier valve spring pressures were, but even with the dual springs wbx seat pressure is only 100#, not very high. I expected more when I first measured them, given the dual springs, but I think the duals are there for harmonic dampening due to the higher expected rev range than earlier AC boxers had. That's a very common reason to use dual springs anyway.

Air holding a valve open would be to me unimaginable. Seat pressure is 100#, multiplied by 1.1 means 110# pushing on the lifter. Even though that's not a very high seat pressure as these things go, with the very small bearing area within the lifter, much less than one square inch, whatever air might be inside a lifter would be compressed easily to irrelevance. When air is still inside the opposite occurs; you don't get maximum cam lift, and the lifter fails to track the lobe (which is the clattering we're so familiar with). So I don't think it's air.



I puzzled over lifters for a long time, wondering what caused the symptoms that people describe having. I agree that air trapped in a lifter seems unlikely once the lifter has been run for hours, but something does cause problems so what is it? I also question the 2 turns is wrong explanation that so many people harp. My personal experience for a long while with hydraulics for very good. I have never had a problem on WBXer engines and friends that have had air cooled Vanagons have run hundreds of thousands of largely trouble free miles, getting far better service than the owner of a solid lifter engine would hope for. Quite a few years ago now I rebuilt the engine in my 411 and used hydraulics and have had zero problems, my machinist though was very adamant we find the correct valve springs to match with the hydraulics. He has decades of experience so I don't question his knowledge here.

I even bought (to part out) a one owner '79 Bay with 350,000 documented miles before it had finally died from head problems. To me hydraulics just seemed to have a very good track record, far far better than solids. Then when I sent my '77 Bay off to college with my kids I bought a '78 for myself. It took some minor work to get it going, points, vacuum leaks, etc. It then ran very good, until it got hot at least. Once warm the valves weren't closing, and the compression disappeared. I went through the normal check of the adjustment, I tried 2 turns, I tried 1 turn, I tried 1/2 turn. I took all the lifters out and cleaned them, no dice, they still over pumped. The only way I could get this engine to run with the valves closing all the way was to set them with some lash. It took about .004" of lash cold to still have some lash when hot and thus prevent pumping.

Not wanting to run the engine this way, I kept looking and trying to learn. One of the valves on #2 was the worst so I looked carefully there and noticed that the keepers and retainer were failing and had reduced the spring pressure on that valve. At this point I pulled the heads, fairly new AMC ones, and sent them in. Sure enough all the valve springs had too little tension. I know this is only one incidence, but I think it is representative of a larger problem with using hydraulic valves on T4 engines. If my machinist is correct in that VW spec'd stronger valves for use with hydraulics then VW must have put them there for a reason, and that reason could well have been to force out a tiny amount of extra oil each time the valve cycled.
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PostPosted: Tue Jul 07, 2009 8:06 am    Post subject: Reply with quote

Could be, I dunno. I would have to have a set of the older valve springs to measure and compare. Like I said, I haven't looked at what happens with less spring pressure, but I can definitely say they don't mind more.

Wondering if you had the right pushrods in that AC engine. Pushrod composition is key with hydros. If you had aluminum ones in there I would expect the hydros to have a tough time managing the expansion.

But it's true that something is going on, sometimes. Despite that I agree that on the whole they're less trouble than solids. I love having a boxer that I don't have to service all the time. Owning several AC's over the years, and working on hundreds of them, I don't care if I never have to lay under the back and do a valve adjustment ever again, especially just to have to do it again in 3k miles or whatever; the shine wore off that BS about 25 years ago.
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PostPosted: Tue Jul 07, 2009 9:44 am    Post subject: Reply with quote

tencentlife wrote:
Wondering if you had the right pushrods in that AC engine. Pushrod composition is key with hydros. If you had aluminum ones in there I would expect the hydros to have a tough time managing the expansion.

But it's true that something is going on, sometimes. Despite that I agree that on the whole they're less trouble than solids. I love having a boxer that I don't have to service all the time. Owning several AC's over the years, and working on hundreds of them, I don't care if I never have to lay under the back and do a valve adjustment ever again, especially just to have to do it again in 3k miles or whatever; the shine wore off that BS about 25 years ago.


As someone who really likes Bays and would like to see them kept running as long as possible, not just mine but other people's, I would like to get the valve thing figured out totally. We have so many bays sitting around here just growing moss because people can't afford the time and money to get and keep them going. My guess would be that two out of three Bays in the pacific northwest are not road worthy at any given time, and are just sitting out back sheltering the squirrels. A typical bus sits for a few years and finally the wife complains about the hulk out back so it gets sold, the new owner puts a grand or two in and then after two weeks or two months the heads let go and its back into the brush for another two years in a new location. Having hydraulics lifters that worked correctly would get and keep a lot of these buses on the road. Not having to pay someone to crawl under the bus every 3000 miles (or 7,000 or 20,000) to have them adjusted (likely incorrectly) would be a major plus with keeping them running.

Manual adjustment just doesn't work for most people, on any vehicle. I remember tearing into a big 700cid Continental engine one time that was not putting out its requisite horsepower. The valves ended up being something like .040 too loose. Its inconceivable how anyone could be that far off, but bad valve adjustments happens over and over.

No worry that the push rods weren't the correct ones. I don't think you could put an other wise stock engine together with the wrong push rods. The aluminium ones are something like 3/8" longer than the steel so they just plain would not fit.
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tencentlife
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PostPosted: Tue Jul 07, 2009 1:50 pm    Post subject: Reply with quote

Wildthings wrote:

No worry that the push rods weren't the correct ones. I don't think you could put an other wise stock engine together with the wrong push rods. The aluminium ones are something like 3/8" longer than the steel so they just plain would not fit.


Good, thanks for that intel. I used to build the Type4's a lot years ago but wouldn't touch an aircooled today, so I don't have the pushrods to compare. Good to know that they're so different in length.
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