Thread: Engine experts........need your help again !

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Being that when it comes to engines I don't have the expertise of a lot of you on here, I need some help. It is related to the 455 Olds in my Son Dan's rpu. I'll try to make it as brief as possible. First, here is what we have:

455 Olds
40 over flat top forged pistons
Ga heads off of a 72 442 Olds
66 442 W30 tripower intake
Comp Cam H280 cam

From almost the beginning we have been fighting oil fouling of the front two sparkplugs on the drivers side (# 1 and # 3).........it progressively got worse and we have gone through 48 sparkplugs because we keep changing them out so the car will run for a while. We thought we might have an engine that just wasn't seating yet, so he kept driving it, but oil consumption was high.

We took a compression test and it runs just about 195 across the board, and a leakdown test showed only 10% leakage in every cylinder. So it looks like the rings are seating. I called Mondello because they are Olds experts and a very nice guy named Lynn went way out of his way to help me. He said it was the fact we were using the metal pan type intake gasket and they don't seal well with that W30 intake, so we bought some Mr. Gasket composite ones from him. He said we were sucking oil out of the lifter area and into the ports. Said he sees that one a lot.

When we installed the gaskets he told me to coat them well with black rtv on both sides of the entire gasket, and to use the rubber end seals that come with the kit. We did that and after torquing I noticed the front rubber end seal had a gap under it, and I could get a feeler gauge under it. When we tried removing the intake so we could put some rtv on top of the rubber end seal, we ruined the composite gaskets.

Next day we ordered a set of FelPro gaskets from Summit because we can get those in two days compared to a week from Mondello. FelPro told me on the phone NOT to use sealer on them as it eats up the blue Print Seal portion, just put them on dry. That is what we did, and we put some rtv on top of the rubber end seals to make them seal properly.

The oil fouling and smoking, especially out of the drivers side header got progressively worse, and he used a quart of oil in about 100 miles. Today we pulled the intake because we suspected the oil was sucking from the lifter area and it turns out Lynn at Mondello was right. We can see on the gasket where oil is getting sucked into the bottom of the gasket, especially on the front two ports, but a little on the other ports too. That is our oil problem, so now we have confirmed the problem, but just need the cure.

We bought the heads for this car already done. They have ss valves and all that done to them and were surfaced. My concern is that they might have been surfaced to the point where the intake doesn't fit down into the valley correctly now. It seems like the top of the intake is putting more of an imprint on the gasket than the bottom, as if the angles don't match.

So, after that lengthy explanation, here are my questions:

1) How do we determine if the angles of the intake are the same as the heads, so that the intake will lay flat against the heads?

2) Could thicker head gaskets be used to raise the heads up to correct any surfacing that might have taken material away? (We also had the block decked, so even more matierial is gone)

3) The FelPro gaskets were very thick compared to the Mr. Gasket intake set. Could that thickness make the seating worse, or should it help?

4) Dan is afraid to have his intake milled because it is an almost irreplaceable W30 that they only made 1200 of in 1966. How do you tell if an intake is warped or needs squared up via machining?

Don had this intake on his Olds convertible years ago and he had some vacuum leak issues, but we blamed it on the 425 Olds engine having a different bank angle than the 400's or 455's. Maybe that was not why he had problems, maybe the intake is not flat and sealing properly?

Sorry for writing War and Peace to explain this problem, but it was the only way I knew to lay out everything we have done and seen so far. The problem is the oil getting sucked from under the intake, now we just need to know how to stop it.

Thanks for any suggestions you might have, and here are some pictures we took tonight after removing the intake. The ones in this post are of the drivers side and you can see how the front two are the worst, but they all have some seepage.

Don

Ok, here are pictures of the passenger side. You can see it is a little drier but there is still some oil being sucked at the bottom of the gasket.

And finally, here is the intake on the drivers side.

When I used to build engines I'd always have the blocks parallel decked and usually the cylinder heads surfaced especially if I were to use used heads. This would at times, depending on how much was removed from deck and heads, make the heads to sit a tad lower and cause a slight angle change to fit when placing intake manifold on. Caused a no go to bolt on at times and leaks from under side of manifold mating surface when manifold was bolted on. Usually we would have the machine shop fly cut the intake manifold to correct for fit. Always worked like a charm.

Don, I wrote this several years ago as a contribution to the Crankshaft Coalition wiki on another forum.

Occasionally, you may experience a vacuum leak into the intake ports from the crankcase of the motor, due to the intake manifold/cylinder head interface not being machined parallel.
For example, consider looking at the manifold from an end view, from the front or rear of the car. Unless you're using all brand new parts, you have no way of knowing if the heads, block, or manifold have been machined by the previous owner, so the interface at the manifold/head could be out of parallel. In other words, the gasket might be pinched tightly at the top of the port and sealing fine, but might be wide open to the crankcase at the bottom of the port, allowing oily vapors to be drawn into the intake manifold runner from the crankcase on the intake stroke. The manifold may also be warped a little. No amount of propane or carburetor cleaner will find such a leak due to the leak being at the bottom of the port, where the combustible agent cannot reach from the outside of the motor. The best way is to insure the elimination of such a problem while building the motor.

Be aware also, that not all cylinder blocks are cut squarely to the centerline of the main bearing bore on the block decks, so if your decks run uphill one way or the other from one end of the block to the other, you can see how the cylinder head would not be square to the centerline of the main bearing bore, and could create a condition where the intake manifold would not sit squarely against the heads. This is a very good reason to cut the block decks square to the main bearing bore before you ever start building the rest of the motor. The other reason to cut the block decks is to set your piston deck height the same from one end of the block to the other. Add up your stack of parts (1/2 stroke, rod length and piston compression height). Example on 350 Chevy: 1/2 of the 3.480" stroke is 1.740", rod length is 5.703", piston compression height is 1.560". Added together, the stack in this case is 9.003, so if you wished to run zero deck with a 0.040" gasket, you would cut the block deck height to 9.003".

Here's one way to set up the intake manifold/cylinder head interface to prevent vacuum leaks from the crankcase to the head ports:
Begin with the heads properly torqued to the block for the final time, and ready to go. Measure the thickness of your new intake manifold gaskets. Get flat washers or shims that will measure that thickness. With the manifold off and the mating surface on the cylinder heads degreased, put a dab of RTV on the washers/shims and stick them on each corner bolt hole on the cylinder heads. Let the RTV set up. Stuff paper towels into the ports to keep debris out. Make up 16 BB-sized balls ofmodeling clay. (Use oil-based modeling clay from a craft store, not Play-Doh. Play-Doh will not stay where you squeeze it to like oil-based clay will). De-grease the intake manifold at the ports. Place the balls of clay on the top and bottom of each port of the manifold, squishing them down well so they stay in place. You want them to be thicker than the shims/washers that are RTV'd to the heads. With your fingers, coat a little oil on the heads where the clay will meet the heads to keep it from sticking to the heads. Now carefully place the manifold into place on the heads, and use bolts on the four corners to just snug the manifold down until you feel a little resistance turning the bolts by hand. Remove the manifold carefully. Cut half the clay away at each position with a pocket knife. Measure the thickness of the remaining clay at all 16 positions with the depth function end of your 6" dial caliper. You'll know pretty quickly if the manifold/head interface is square. Record the measurements on the manifold with a permanent marker. The widest measurement will be the standard to which you will want your machinist to cut the other positions on the manifold to make it square with the heads, thus sealing up the motor.

Pay particular attention to interference at the bottom of the manifold at the china walls, front and rear. If you cut the manifold, you'll be dropping it down a little into the valley, so pay attention. If the manifold has been cut before, without also cutting the ends of the manifold where it mates with the china walls or the intake face of the heads has been cut, the manifold will sit a little lower. Then, if you use the black rubber end seals, they may hold the manifold up a little too much for it to seal to the head ports, resulting in an internal vacuum leak. Also, with the manifold down a little in relation to the head ports, the ports may not line up exactly. On a street motor, don't be overly concerned about it because, physics dictates that the majority of the flow is right down the middle of the port and the surfaces of the port wall will be relatively slow moving. However, if you want to be perfect on your build, you can port match to the gasket. Run your cutter down the ports a pretty good ways to prevent the port from looking like an Anaconda that swallowed a pig in side view. If you end up with that, as the mixture passes that point, it will slow down and could possibly drop some fuel out of suspension, resulting in puddling and a rich/lean/rich/lean scenario. Also, using two gaskets on each side may line things up better without any need to grind on the ports.

looks like a decent imprint on the gasket---how are the valve stem seals on the 1 and 3 intakes??? and guide clearances????
I wouldn't put the heads back on without checking the guides and seals

Thanks sbcguy and Richard, those are very good suggestions. I am also going to dry fit the bare intake onto the heads to see if I can see any difference in the angles. That clay idea makes a lot of sense, Richard. Great writeup.

Jerry. We did suspect the valve seals so we replaced the intake valve seals on those two cylinders a week or so ago. The seals that came off were in good conditon and it made no difference in the fouling. I also question if valve guides could dump the amount of oil we are getting into the cylinders. Literally, if we put fresh plugs in they are black and oily within 3 miles. After about 20 miles the engine starts popping and missing as they are too fouled to fire.

When we pulled the intake tonight the smoking gun was staring us right in the face. The gaskets are oily half way up and are only about 100 miles old. That is a major leak.

As a side question, what sealant do you guys like for intake gaskets? I have been using Permatex Black RTV, but on some sites people say it isn't the best but to use the Grey RTV instead.

Thanks for all the ideas so far, guys. I really appreciate them.

Don

take a long board with 80 git sick it paper on it for doing auto body work go long the intake gasket face of intake get it clean of oil first when clean your going to see a low spot there on the intake .you can check it with a machine shop strait edge as well . i would bet at one time in its life some one used a round rollock 3m wheel on the intake trying to clean it and screwed it up .but to have it that low you should run your hand over it and it should damn near break your wrist.... .i seen guys use them wheels all the time they will not make any thing flat. take your bottom gaskets off leave intake gaskets on set intake back on look to see if gap is even along the china wall of the block. i can tell you not much of this stuff is ever true or dead flat .i seen many blocks that were out of square .start milling them thinking how the hell did this ever hold a gasket ? but that is why they use gaskets in the first place . the print out looks good other then a weak spot on the one side sucking oil ??. like jerry said to could be alot of oil laying in the intake port as well bad valve seal no seal .worn guide or bad new guide.check that to .i am not there to see it.. but its looking to me that the intake is not sealing in that one spot .think of in take like a stopper in a bottle (cork) the bigger the opening the wider the cork . the intake being the cork . if it hits the bottom of the intake to block china walls there is only two way to fix this one if ports show still ok port match up you can trim bottom of intake so it can go down and the gasket sides of intake will seal .or if ports alginment to head to intake are way off thicker intake gaskets to help put intake port back up were it needs to be. i have allways did a dry run with out gaskets let intake sit down and shim it up with old gasket made up shims .or tape a small spot on a new gaskets so they will not move and check the fit .if you think the angle is way off you can side the intake to one side and check with feeler gauge you want the intake side of the heads clean with no gaskets . not having deck pins in the block to hold heads were they need to be can throw things off to

I think you are right about the manifold surface not being totally flat, Pat. I put a metal level over it yesterday and had Dan put a feeler gauge in various spots along it's length. Surprisingly, it was pretty flat except the feeler gauge (.002) would slip in in other spots than where I thought the low spot would be. I thought it would be low up on number 1 and 3 port, but it was low back in the middle, near number 5-7.

I will try the sandpaper/board deal tonight and will pick up a long board sheet of sandpaper today.

What sealant do you like? I've never had an intake machined, can local shops generally do it correctly?

Don

If the machine shop can surface the deck of the block they can fly cut an intake manifold. The same cutter macnhine is used for both.

it has to be more then .002 to make it leak . i can not say if you have a good machine shop there ? i only cut to a clean up but i have cut down many intakes to shorter deck engines .most of the time on set up there going to mill the intake off old intake angles thats ok . less heads of been rolled .i all ways used permatex aviation No2 on the dry part of the intake i do not care to draw down the intake dry . i use RTV only on intake rails and around water ports only.... not RTV and rubber gaskets .it one or the other and never use the rail gaskets

What kind /type of valve seals do you have and what valve stem to guide clearance????

Are you guys running those headers open or do they route down under to mufflers????You mentioned popping???

Other places oil can get thru----overporting by push rod holes, rocker arm holddown bolts that penetrate intake runners---

Its a little more complicated than just using the same machine

Yep it is. The same cutter is or can be used though. It's been awhile but I guess it would be called a surface and or profile grinder.

Yep, awhile ago--like last week--and today is the first of this week----I question whether its the manifold or something/somewhere else---like maybe even a breather thats plumbed into the intake above 1/3