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Supercharging (this time, it's real)


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If I may add my two cents: Although I admired your enthusiasm and all the effort you have put into the project thus far, I must also encourage you to put the parts back on the L-67. Another point for doing so is the fact that the bottom end of that motor was built for the extra power. The conn. rods for example are different, for a reason.

We're all still pulling for you. cool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gifcool.gif

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Thank you Padgett and Maui.

I agree. Pointless to keep doing something over and over when you keep getting the same result. I've done this with the gaskets, but am figuring this out.

I wonder what 2seater's experience with head gaskets has been. But you know, very possible mine was weak to start it, whether boosted or not. It probably blew due to the boost. His engine has pretty much stayed together while making 260-280 hp. What may be the fastest non-prototype Reatta is based on an LN3. What I wish to say is that I don't think my efforts are in vain.

Yet.

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Willren seems to be a knowledgeable guy that has experimented extensively with s/c engines although not exactly what you have done. The oil problem does sound like a head gasket, the leaking coolant in the throttle body wouldn't have any direct path to the oil. It would either leak externally, or possibly get sucked into the air inlet path. The PCV system is somewhat divorced and even if it pulled some of the leaking coolant it should be into the intake tract? I can't imagine you developed enough boost to have bothered the head gaskets up to this point unless a pre-existing condition existed, or it got into detonation but that should have showed up on the knock sensor? Head gasket might show up on a conventional compression test but a leakdown tester would be best. I don't see any giant advantage to the L67 heads unless they have roller pivot rockers but I suspect they do not. They would allow the integrated PCV system to be fully functional, which would be neater and cleaner regarding appearance, but of no real advantage as long as the external system is working. I do not know if the head gaskets are different, and it is possible they are. Only comparing them would tell, or check the part numbers? If so, my fingers are crossed on mine too, although I have 25k miles on my stock vin C rebuild with up to 10+ psi of boost on occasion frown.gif Curious situation.

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Thank you 2seater. Support is good.

Do you think that the head gasket leak would let coolant up into the intake manifold and throttle body? I'm thinking I've got that and the throttle body heater leak.

I suppose my PCV system, with the front valve cover being connected to the throttle body, and the rear valve cover getting vacuum from the tree, could be the source of the leak. I guess the only way to know if my head gasket is bad is to go ahead and do a leakdown test. I'm going to check on the hardware to do this tomorrow.

Your words seem positive 2seater. But note to all...I don't at all mind criticism. I'm one of those that find it "constructive." You guys know tons more than I do when it comes to this stuff.

We'll see. Thank you.

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Well, my PCV intake is in the Fernco in front of the throttle body. I really don't think my vacuum for that is enough to draw coolant upstream, through the throttle body, and into the engine via the front valve cover tongue.gif

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I do not know if the PCV system could possibly pull coolant from a leak in the throttle body. If I remember the photo of the engine in the car the air filter is fitted directly to the MAF, right? The air inlet line from the front valve cover should be into the air tract ahead of the MAF/throttle body, I don't think there is a fitting for that purpose on the body itself since it wasn't designed for an external system. I would guess the line is attached to the flange on the big side of the filter. If that is the case, I don't see how coolant could get to it. I cannot think of any path from the head gasket to the intake that would leak coolant to the intake. The cooling system is under a pressure higher than anything you will see from the blower, so if a path exists, the coolant would have the pressure advantage. The only way I could see the coolant leak at the throttle body getting to the oily side of the engine would be if the inlet to the PCV system is somehow connected to a point close to the leak and vacuum from the PCV valve from the vacuum tree on top would tend to pull it into the engine. The throttle body gasket is a pretty good design with discrete silicone ribs to crush down and seal everything pretty well. A missing bolt could cause a leak, but unless the gasket is physically damaged, it looks to be reusable, and would likely seal up fine if all the bolts are tightened evenly.

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It's not all bad. A leakdown test will give a good idea of the internal condition of the engine, not just the headgasket. Rings, valves and of course into the coolant system will all be revealed.

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Philip, don't let this temporary setback get you down. Chalk it up to a learning experience instead.

If you go ahead with a leakdown test, make sure your radiator cap is on and you have some coolant or water in the overflow tank. If you have a blown head gasket, air bubbles will come up in the overflow.

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I picked up an Actron compression test kit at Advance. I used it without the gauge. With the radiator full of water, radiator cap on and locked, and the coolant tank mostly full. I removed the spark plugs and threaded the hose into each cylinder, attached the air compressor hose (around 115 psi) and turned the harmonic balancer clockwise by wrench/hand until the valves closed and I felt the engine to be in the power stroke. Could tell when the valves were closed cuz the crankshaft was really hard to turn. I held the wrench so the cylinder would stay in the power stroke for at least 30 seconds each. I could hear a tiny bit of air movement I suppose because of blow by but I think it's negligible.

However, I did not get any water movement or air bubbles from the two ports that go to the S/C and throttle body (were otherwise filled to the top), the coolant tank, or the top of the raditor. I checked the radiator last. When the compressor wasn't on, I listened closely and couldn't hear any air bubbles anywhere in the system. Did this for each cylinder.

I really don't think my head gasket is faulty. What do you suggest next?

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Think we are back to the possibility that despite everything bolting up, there is a difference between the "L" and "C" heads that is causing the problem. Either that or the s/c manifold is damaged.

Now that everything is apart again, how difficult would it be to put the original N/A manifold back on (after flushing the engine) and try that ? Since you have the original computer, just replace the original PROM.

Never know, something may jump out at you, is just an itch I have.

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Thank you Padgett. I'm going to take off the L67 manifold tomorrow and inspect it closely. It may be damaged and leaking into the area right below it in between the two banks. Don't know what this area is technically called. Are the intake manifold to head gaskets reusable? Not being cheap but I wouldn't have to order them.

Page 1 of this thread has a photo of the L67 with the manifold off, and page 2 has a few relevent photos with the gaskets and manifolds side by side. I took a few minutes to review them and rethink things, but I can't figure out why our L67 manifold wouldn't be compatible. I'm thinking that unrelated to compatibility, the head to manifold gasket is leaking. I've got more or less important stuff to take care of tonight but will pull off the manifold tomorrow.

If all else fails, I can try the LN3 parts again and see if it runs. Problem is that I no longer have a stock '89 Reatta memcal. Closest I have is a '90 Lesabre, which ran the car fine, but instrumentation and the ECC were "out there". And that's a lot of work.

There's something wrong, somewhere. It can't be that difficult. We'll find it.

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I was under the impression that the intake from a later model, 1991 and up would not fit the earlier engine blocks. When I had asked about putting on a

later model fuel injection manifold I was told this by someone, I don't remember. Can anyone verify this for me?

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Maybeso.

Remember that Greg started with an "L" crate engine.

Have also heard that due to different PCV routing, you cannot put "L" heads on a "C" block.

Sounds like to supercharge a Reatta, it is best to start with either an complete L-67 or a turbo(supercharger).

BTW the area between the banks is called the "valley". Some engines (like Pontiac 400s) have an open manifold between the runners and a seperate "valley cover".

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From 63viking's thread, this is what 2seater said about manifold and head compatibility:

<span style="font-weight: bold">I have a '92 aluminum TPI manifold and it will fit just fine. All the bolt holes and such are in the same place. The difference is in the PCV port in the opposite corners of the manifold that would be blocked on a Vin C head although it appears a hole could be drilled in the earlier head to make that functional</span>

So, I'm thinking my gasket just failed

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Theoretically the intake gaskets with the silicone o-ring style sealing is reusable, but if there is a possible coolant leak, or you see any evidence of such into the valley, it isn't worth the money to try to reuse them. I do not know if you have run into this problem or not, but I have had a couple of problems with the valley end seals splitting, meaning the clearance is smaller than it should be. The recommended fix from other 3800 users was to apply a solid small bead of silicone instead of the end seals. I was told to let it firm up a bit but still pliable before installing the intake. It would be a long shot, but maybe insufficient clearance exists on the ends to allow the gasket at the heads to pull down properly? If that was the case the end seal should be split in two. The deck height of the two engines is supposed to be the same, so the spacing between the heads should be also, but subtle differences could exist and be tough to spot. The intake gaskets are big and thick and should allow for a fair amount of manufacturing tolerance. The coolant ports in the intake aren't eroded are they? This is a fairly common occurance, and usually some does exist. The gasket does a good job of sealing but only if the erosion hasn't progressed outside the seal area. This could leak coolant into the valley and thence the oil.

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Philip, that is good news if you didn't get any bubbles up thru the cooling system during the leakdown tests. The little amount of air you heard escaping was probably that which was working its way past the piston ring end gaps.

Of course there is still a very small possibility that you might have a cracked cylinder. It wasn't clear exactly how you did your tests but if you did them with the piston at bottom dead center, that should check the whole cylinder bore for leaks.

At this point, like another person said earlier, it is far more likely you have a gasket or intake manifold failure that is letting coolant into the oil and induction stream. I would remove the lower intake and inspect all sealing surfaces carefully. DO NOT try to reuse the intake gaskets; it's not worth the risk. Also, if you use RTV on the end seals, apply the RTV, install the lower intake, start the bolts but do not tighten them down for about 30-60min. After that time has passed, torque the intake to specs. You don't want the RTV to fully cure before tightening down the intake because the RTV could prevent the proper gasket crush to take place. Also, allow the RTV to cure overnight before starting the engine.

Let us know what you find once you get the intake off.

-ryan

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All here in NWI are pulling for you in your quest to SC your Reatta.

Try not to view whats going on with the car as problems. What's really going on is that the car is <span style="font-style: italic"> <span style="font-weight: bold">talking</span> </span> to you. It's telling you what it needs. You just have to learn the language.

Good luck.

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Got the manifold off...

The manifold, mating surfaces, and gaskets have no visible flaws. I looked pretty closely but it looks normal to me. I did find a bit of coolant in the valley, indicating to me that the head-to-manifold gaskets were at fault. There is a little bit of spillage when actually taking the manifold off but not enough to have as much as I found in there. Below the ports, the gaskets were wet, and with a wipe of a finger, more coolant than oil.

So, there was coolant in the valley. With the round PCV ports dead-ending at the heads, are they under pressure? Could it have disrupted the nearby coolant port?

sc19.jpg

I'll see about some new gaskets

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I did go back out and re-inspect. No cracks or flaws. I also measured the front ports to back ports in the valley of both the LN3 and L67, and they're the same. Being both GM 60 degree V engines, the angle is the same. I obtained the funding for the gaskets so I can order tomorrow cool.gif

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The unused PCV port should not bother the coolant port, they are sealed independantly. I do not know exactly how the passengers side port ends at the manifold. I would imagine it is above the lower intake so it does not see boost pressure. It could end below the actual blower if they were expecting the PCV valve itself to act as a check valve, but I have not found them to seal perfectly all of the time. In any case, the coolant pressure can be approx. double what the maximum boost pressure will be.

I measured the TPI and stock vin C manifolds every which way I could think of and they appear to be identical regarding the sealing surfaces. The machined length of the valley ends is exactly the same, the distance between opposite ends of the valley are the same, all the bolt holes are in the same location, the distance between the upper edges of the sealing flange to the heads is the same and the angle the between the port flanges and the machined edge where the valley meets is the same, almost a dead perfect 45* on both manifolds. There is no apparent reason the two manifolds will not interchange. I have found that you need to tighten the intake manifold in small steps over and over as you torque it down. These gaskets are better than most since the silicone bead squashes very easily but the main body is very solid so they don't keep flattening over time. The flange of the manifold is relatively thin so it pays to sneak up on the final torque a little at a time. I don't recommend reusing the gaskets, but I did look at the gaskets I pulled from the junkyard engine that donated the TPI manifold and if it wasn't dirty from being used, the sealing beads of silicone are all above the surface and unmarked so they would look brand new if clean. This is a 90* V6, the Chebbie 2.8 and 3.1 are 60* grin.gif

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Think in terms of torquing the lug nuts on on a wheel, you stagger your tightening across/ around the pattern. You really should consult the service manual. Certainly the one I have for the S/C I'm certain lays out the torquing sequence for the intake dome.

Think of it like a clock face, only squarer. You start at 12 o'clock and just snug the bolt, go from there to 6 o'clock, then 3 o'clock, then 9 o'clock, then 4:30, then 1:30, then 10:30, then 7:30. Back to 12 o'clock and start all over again. You'd go around this pattern 3 or 4 times with a spanner or socket wrench before you ever got near the torque wrench. As Hal says, sneak up on it.I would use a half value on the torque wrench, in this case 4 and a half Ft Lbs and step it up a pound or two ber torque pattern. Brute force should be left in the Tool Box for when you need to bust stuff loose. Overtorquing any portion of any assembly is going to result in unbalanced stress-break off bolt flanges or result in leaks. I guess I forget you're just a Pup! Torquing correctly is vital to any mechanical assembly for reliability, etc, etc. Same would apply to cylinder heads, check a FSM and you're going to find a specific torqing pattern for this type assembly. But the same pre-torque approach must be applied, getting uniformly snug pull on each and every bolt to pull the faying surfaces together and compress that gasket evenly over its' entire surface.

Need to ask now, how exactly did you tighten down both the the manifold and the blower when you installed these on your 3.8L or had them off and reinstalled.

Hope this is coming across as helpful, don't mean to be critical but this is basic mechanics, also have to realize you have to learn it somewhere. And the School of Hard Knocks is definitely the best and enduring way to learn!

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Looked in both 88 and 92 manuals and the spec is 88 in-lb (actually about 7.3 lb-ft and that seems incredibly low for an intake manifold. I would have expected more like 15-20 lb-ft. Any idea why it is so low ?

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<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> I'm pretty new to torque wrench use </div></div>

Phil, let's go back to some basics. First of all get a good torque wrench. Get the kind where you dial in the torque at the handle, not the old "beam" type. Mine is a Craftsmen, got it for $75.00 on sale. Always zero the wrench after every use. I think the guy on the Bonne board suggested new bolts because some are designed to stretch when torqued. Make sure all threaded holes are clean. Like Greg said, use a criss-cross pattern when tightening, and arrive at your final torque value in steps, using the same pattern. I have done far less stripping and breaking since I figured out that using the torque values was the only way to go. This becomes very important for sealing some gaskets.

I hope this helps. cool.gif

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Frankly I am a bit puzzled. While I am used to torqueing in stages for head and wheel nuts, both are usually over 50 lb-ft. Your tighten to "snug" then alternate. I am not at all sure how to do that for a 7.3 lb-ft spec when "snug" is around 10 lb-ft.

Obviously the last time I put a manifold on a 3800, I must have done it wrong because I tightened like a spark plug which is more like 15 lb-ft. That was five years ago and it never leaked.

BTW I do have a Craftsman beam wrench in in-lbs. It is a 3/8" drive. Just put in a vice and went to 100 in-lb with my little finger.

Something just does not sound right but checked FSM for both "L" and "C" - same-same 88 in-lb

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I did find the bolt torqueing sequence on page 6A5E-8 of the FSM.

Advance had the head to intake gaskets in stock which I picked up, but have to wait until tomorrow or Saturday for the throttle body and supercharger gaskets. I did pick up some more RTV which I will be using as you guys described instead of using the two rubber strips that run bank to bank. That what you had in mind?

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You have the right idea on the RTV instead of the gaskets on the ends. Just form a small bead, let it sit to firm up a bit before installing the manifold. Frankly I did not remember the torque value on the intake being so low. I just did a 5 liter Ford this last weekend and it was 22 ft/lb, but that was a composition gasket that squashes down over the entire surface. The silicone bead requires very little force to flatten them but I would have though the torque value would be somewhat higher since the bolts pull the manifold down at a small angle to the actual surface and I would think sliding friction would require a little more force? With a torque value that low it is critical the surface is perfectly flat since there isn't enough force to move the flange. It would seem, as Padgett points out, that overtorquing a little didn't hurt anything as long as it was done in small steps and in the right sequence. The substrate of the gasket is very firm and should prevent the flange from warping.

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Before, I used my 1/2'' drive, 10-150 lbs or so clicking Ampro clicking torque wrench. I did just kinda set it under to do the 7.3 or so ft/lbs (88 in/lbs) but I'm learning quick, and that's not going to be accurate enough. Advance and Autozone didn't have a torque wrench that goes down that low (120 in'lbs was the starting) so we went to a hole in the wall auto parts dude thats been there for 30 years or so, and he'll have one in for me tomorrow morning (20-200 or so in/lbs). I guess when it comes to this, you can't really guess at things.

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There's a good chance I may have the gaskets tomorrow and can assemble. With the throttle body and the supercharger gaskets, should I use anything at all on them? I've used that brown permatex stuff but maybe I should use them as they are. I'll be sure to do a top notch prep job cuz I'm tired of pulling things apart frown.gif. Counter dude at Advance suggests blue RTV on the gaskets, but I don't know. Will be torquing everything though, and in sequence

Do know the intake manifold gaskets should not have anything though.

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