1st drop & top end observations & questions - Page 22

GaryR · GaryR's Garage

What is "Ultra Gray", a Threebond product? I use Threebond 1194, very thinly applied, on paper gaskets to very good effect but I also use a flat file to check mating surfaces as Kevin has shown. It's amazing how bad they can be!

r-mm · 12-10-2013, 09:29 AM

Permatex Ultra Gray: Gasket Makers : Permatex® Ultra Grey® Rigid High-Torque RTV Silicone Gasket Maker

whiz05403 · whiz05403's Garage

So is the moral of the story mean we have to surface our cam plates, cam housing, and chain housings?

GaryR · GaryR's Garage

Quote:

Originally Posted by whiz05403

So is the moral of the story mean we have to surface our cam plates, cam housing, and chain housings?

And rocker covers, and anything else you want maximum mating surface on!

KTL · 12-10-2013, 09:56 AM

I would use the 574 sealant or the RTV, your choice. I like 574 better just because it hardens and less of it is likely to end up someplace you don't want it. It also is supposedly solvent (dissolves) in oil but I don't really see that happening in other locations around the engine.

Whereas RTV can withstand a nuclear blast w/out breaking down & it's amazing into what places that stuff can find its way. Both are a PITA to clean up and I only use 'em when absolutely necessary. Whichever you choose I agree 1000% that the amount applied is sparingly thin. Can't emphasize that enough considering future removal is not as easy as it used to be. Modern gasket/sealant solvents ain't as effective as they used to be.

Seems like surfacing the end of the cam housings and the thrust plates is good insurance. Obviously the cam housings are easy to do prior to assembly since you typically have to clean them up quite a bit anyway. Being an anal retentive clean freak, i've found the cam housings the most tedious part to clean, as well as usually being one of the filthiest, of all engine parts.

I've found the rocker covers and respective sealing surfaces on the cam housings usually are not a huge issue. Can get away with scraping those with a vertical razor blade (blade edge held perpendicular to the surface, not parallel) most of the time. It's the magnesium rocker covers that really need to be machined. Those things get all twisted up over time.

I wouldn't increase the torque spec on the thrust plate. Once it's flat, standard torque should apply. Plus if my theory of time distortion is correct, I suspect addn'l torque would increase that distortion?

r-mm · 12-10-2013, 05:34 PM

I opened things up and unfortunately did not find a smoking gun. Maybe you all can help me.

Checked the bolts - all were torqued to 88 in-lb (7.4 ft-lbs) per Wayne's book.

Working in tight quarters I foolishly forgot about the woodruff key and thought the o-ring was fighting my removal of the thrust plate. To get some purchase on it I used a little hooked wire tool to do some pulling before I realized the woodruff was there. I mention this because I'm pretty sure I caused the misalignment seen @ 9 o'clock on dissasembly. Don't see how it would have folded up like that on assembly. Besides that I can't see how the alignment of the gasket could be too much better. Question - if oil makes it past the thinnest part of the paper gasket, to the bolt, is all lost, as the oil can migrate out of the bolt, or should the remainder of the gasket catch it? I believe one of the bolts had more oil on it than the rest, but its hard to tell.

The 'meat' around the 5 o'clock threaded hole looks like its a different shape than the other two, but it looks like the factory intended this. Can anyone confirm?

Again I'm not seeing anything unusual here. Kevin can you or anyone explain to me how the camshaft axial play is controled? Is it possible that the camshaft is riding too far rear and therefore absorbing the thrust of the thrust plate and preventing the paper gasket from being clamped as tightly as it should? This assembly is an odd one to me - the steel camshaft bears directly on the alloy thrust plate? I realize its oiled but can't quite get my head around this.

One thing that caught my eye is that it looks like the opening in the chain housing is not centered on the cam carrier bearing surface, so the thrust plate will not bear on apex of the paper gasket in this area. So far as I know the heads were not cut at all, just barely skimmed flat.

The thrust plate felt reasonably flat on a piece of glass. I have a new one on order regardless. What is the correct way to flatten or check flatness of the cam carrier mating surface?

Finally, I know its not good policy to slather sealant around like peanut butter, and I realize it find its way anywhere, but for some insurance is there anything wrong with using a slightly heavier coating on this paper gasket?

r-mm · 12-10-2013, 07:05 PM

Okay after thinking this through and reading lots of past threads I think its likely that the little folded ear on the gasket at 9 o'clock did happen upon install on account of the slightly eccentricity I noted above, but the tear right next to the threaded hole was the result of disassembly.

When I give this another shot should I trim down the gasket a tiny bit to prevent it from folding like that? Or maybe just "stick" it in place first with some RTV, sliding it behind the chain cover where it is "hidden" from the thrust plate?

Jcslocum · 12-10-2013, 07:26 PM

That gasket looks like a leaker at 9 o'clock.

I would use a thin coating of 3bond to hold it and make a better seal.

KTL · 12-11-2013, 06:40 AM

Positioning of the gasket looks good. It's slightly off-center but still well within the flat area for sealing. The oil soaking around the gasket makes me think the gasket wasn't fully pressed against the cam housing, or the flatness issue we've been discussing.

Flatness of the thrust plate we've already covered- can be easily rectified by surfacing or buy a new plate. So what do we do about seating the gasket? Upon reassembly I would snug the thrust plate down nice & tight (don't gorilla tighten it) and then back off the bolts slightly, then retorque to the specified amount. That, along with use of some good sealant like RTV or 574, should ensure the gasket gets fully pressed against the cam housing and take care of the problem.

Quote:

Question - if oil makes it past the thinnest part of the paper gasket, to the bolt, is all lost, as the oil can migrate out of the bolt, or should the remainder of the gasket catch it?

No all is not lost. If oil gets past the inner area of the gasket and reaches the bolt, sure it can run up & down the bolt threads. But that oil goes into the cam housing, where the holes are "blind," or into the chain housing as the oil passes under the head of the bolt on the thrust plate. Either way it's not leaving the engine as long as that portion of the gasket beyond the bolt hole is sealing.

Don't be tempted to get excessively heavy with the sealant. Still use a thin coating. Because when it squishes, it's going to push a bunch of the sealant out. In this instance you could use a ton of sealant and it really wouldn't matter. It's not going to find its way into the cam housing, nor into the chain housing by a large amount. It's just going to get oozed out to the exterior of the engine, between the back of the chain housing and the cam housing. Sure some excess would get in the middle on the cam itself but it'd just get spun around. Not going to find its way into the oil system until it's finely ground up by the spinning cam and then spit out the center hole of the thrust plate where it runs into the chain housing and then down into the engine case.

I would not hesitate to trim the gasket where that suspect ear occurred. Or just put the gasket on the cam housing first. The sealant will be tacky enough to hold it in place as you carefully seat the thrust plate uniformly by turning in the bolts. I would turn them in an alternating pattern a 1/2 turn at a time to avoid shifting the gasket once the thrust plate begins to contact the gasket

E Sully · E Sully's Garage

That little triangle paper gasket folded just a touch on mine, same area as yours, causing the same leak you had. I carefully replaced it using a very light touch of 574 and it was fine afterwards.

GaryR · GaryR's Garage

Quote:

Originally Posted by E Sully

That little triangle paper gasket folded just a touch on mine, same area as yours, causing the same leak you had. I carefully replaced it using a very light touch of 574 and it was fine afterwards.

Exacto knife that corner, paper thin coat of 574, button her up and go drive the darn thing... well, once the roads are dry again!

r-mm · 12-12-2013, 06:46 AM

Guys- I just received a new chain housing to block gasket from PP. It is paper thin. The one that came with my Wrightwood Racing kit is very thick - the thickest of any gasket in the entire cylinder head set if I recall. For sure this is contributing to the slight misalignment I'm seeing. Should I swap in the PP paper gasket, which is almost certainly inferior as a gasket, or just live with the slight misalignment, slip the new cam seal paper gasket in place carefully, past the misaligned 9 oclock ear, and "glue" it to the cam carrier with RTV or 574 before torquing down the new thrust plate...?

KTL · 12-12-2013, 07:11 AM

That thin gasket is fine. The mating surfaces of the chain housing and engine case are a bit messy so it's good to clean those up with the vertical razor blade trick and then coat your new gasket with the sealant (thinly applied!) of your choice.

As an example of how this area is fairly sensitive to alignment, my racecar engine has apparently been built and rebuilt a number of times. So the heads have been cut a few times (they're now below min thickness & next time i'll have to find some good used heads to start over), somebody decided to surface the former cam housings once, and it's common practice to surface the chain housings the same amount the heads have been surfaced.

All that being said, when I assemble my left bank (1-2-3) I cannot use a thick gasket on the chain housing because the alignment is WAY off. Plus the chain tensioner is quite extended (will be using a custom larger sprocket on the tensioner arm). I just use some Curil T to seal it up. Works just fine since its splash oiling. Even if it was pressurized oiling, you could still use Curil T because it's a good non-hardening flange sealant.

E Sully · E Sully's Garage

I used the thin paper one from Pelican.

Smoove1010 · Smoove1010's Garage

Count me among the thin paper gasket users. I put a thin coat of Curil T on both sides, no leaks to date. I did use the thicker cylinder base gasket to compensate for the cuts made on the cylinders and heads, so I was very close on the centering of the cam to the chain housing.

I hope this does it for you, looking forward to seeing your results the second time around. Looks like this weekend is a good one for working in the garage, not so much for driving around though...

r-mm · 12-15-2013, 03:24 PM

It is cold outside. Even with propane heat, it is cold inside my garage too.

However I was able to get my the cam gasket reinstalled, this time with a thin coat of Permatex Ultra Gray RTV on both sides. It worked well as "glue" to hold the gasket in place, but to be honest the amount of force needed to send the thrust plate home (even with lubricated o-ring) is such that its hard to be positive there was no torque applied to the gasket. I did my best to stick my head all around the motor to check for clocking and found none. I'm now quite certain that it was not clocking but the folding of the ear at 9 oclock that cause my leak last time, so hopefully I got it done right this time.

A bright spot... by marking the orientation of the cam to sprocket and gear I was able to re-set the timing spot on, first try. That much felt good.

Tomorrow I'll close her up and possible get her reinstalled. Not exactly in a rush however, based on the weather and "max performance summer" tires she's wearing.

r-mm · 12-18-2013, 07:14 PM

Well the cold has broken for a day so I seized the moment and got her almost re-installed. Those of you who use the tall jackstands and ATV jack or similar method (aka those who don't have a lift) - how do you deal with the fact that the car is not parallel to the ground where the motor is? I find this is only an issue when trying to start the 4 bolts, but it is a pain.

KTL · 12-18-2013, 07:33 PM

I just shove the engine all the way up into the car. Meaning, even though the engine/trans is sorta level & balancing on the jack, once you get it up into the car the trans is usually the first part to make contact with the mount points. Then as you continue to jack upward the whole assembly will pivot from the trans end.

As the engine end moves into position, you can wrestle with it a little bit to line up the semi-flexy cross bar & get those two main support bolts started a few turns by hand. Then go back to the trans end & fiddle with getting that end lined up. With the engine end partly fixed in place via the barely started engine mount bolts, you can take advantage of those bolts holding up the engine end & lower the jack a little bit to give you some ability to align the trans mounts.

r-mm · 12-18-2013, 07:35 PM

Inneresting. So you start the engine bolts first. I've been going off Bentely which says start the trans bolts first, but what you're saying makes sense.

Smoove1010 · Smoove1010's Garage

Quote:

Originally Posted by KTL

I just shove the engine all the way up into the car. Meaning, even though the engine/trans is sorta level & balancing on the jack, once you get it up into the car the trans is usually the first part to make contact with the mount points. Then as you continue to jack upward the whole assembly will pivot from the trans end.

This is how I did mine, but the difference in my approach was that after rolling the engine into position I lowered the car over the engine leaving just enough room for me to crawl underneath. This way I only had to jack up and balance the engine for a very short distance, minimizing the risk of unintentional droppage, and rendering the car more parallel to the floor. I threaded the trans mount bolts first, but probably only because those lined up for me first.

Once I snugged up the four bolts, I jacked the car back up a few more inches to allow for freer movement underneath.