I have a fresh 340 engine. The pistons ( all 8 ) have some oil on top of them. Spark plugs are the same. All eight cylinders are firing. There is oil at the ends of the intake runners where they meet the intake gaskets. There is also oil residue on top of all the intake valves. The block was square decked and the intake was milled to match. I did a degree check on the block and heads, also the intake and they both come up at 48*. I did a leakdown test, several times, with a couple different type gauge setups to be sure I was doing it correctly. All cylinders are in the 3% to 4% leakdown with 90 psi of air pressure. The engine was stone cold during the leakdown test. The Edelbrock intake gaskets seem to be sealing on the intake side ( gaskets seem to be stuck to intake all the way across ), but I can't tell if they were sealing on the head side. I can see that there is oil soaked into the gaskets all the way around the ports. I will add pictures shortly.
Need some help !!!!!!!!!!!!!!!!!!!!!!!!!
- Thread starter duster360
- Start date
-
nm9stheham
Well-Known Member
What heads? What end seals were used?
BTW, angle checks need to have a very good precision to be good; just 1/4 degree off corresponds to a .010" sloping gap across a 2" flange.
BTW, angle checks need to have a very good precision to be good; just 1/4 degree off corresponds to a .010" sloping gap across a 2" flange.
Bill Conley
Active Member
Was the intake retorqued after initial warm up? (after the engine was warmed, then cooled down)
Edelbrock heads. I used blue rtv for the china walls. The dowel pins have been removed from the china walls and there is plenty of gap between the intake and china walls.
Did not retorque them. It only has about an hour of run time. The bolts were still tight when removed.
Sounds like it didn't seal well, at least that's my hope for you.
Was there any pooling of oil on top of the intake?
Was there any pooling of oil on top of the intake?
pishta
I know I'm right....
if the intake gaskets can come off, maybe you can mic them top and bottom. My money is on the bottom not sealing.
Tried that but they are kinda soft. It is hard to get a good reading.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,824
- Reaction score
- 13,127
There are 5 ways for that oil to get there;
1) through the carb
2) between the carb and the ports
3) the ports
4) the guides
5) it is coming back up from the chambers
1) the oil is in the gasoline,or it is the PCV system operating in reverse,at WOT, through a connector pipe, like the factory runs;the proof being an oil-soaked air-filter
2) is the PCV system operating in forward mode,pulling excessive oil from the valve cover. An alternate source might be a faulty brake-booster, but that would then be brake-fluid.
3) is the gaskets.Or more often,machining errors. The angles can be bang on, but if the two flanges are trapezoidal; narrower on one end,you got trouble.
4) well, it could be through or around them, and a late closing intake could blow it back up the port.
5) most likely rings. But for this level of oil to be coming from faulty oil-rings, there would also be plume of oil-smoke out the pipes, and the low LD results,kinda negate this.So I wouldn't be worrying about oil-rings just yet.
1 and 2 are easy checks.4 is hardly likely. and 5 is extremely unlikely.
So that leaves 3 as the most likely
1) through the carb
2) between the carb and the ports
3) the ports
4) the guides
5) it is coming back up from the chambers
1) the oil is in the gasoline,or it is the PCV system operating in reverse,at WOT, through a connector pipe, like the factory runs;the proof being an oil-soaked air-filter
2) is the PCV system operating in forward mode,pulling excessive oil from the valve cover. An alternate source might be a faulty brake-booster, but that would then be brake-fluid.
3) is the gaskets.Or more often,machining errors. The angles can be bang on, but if the two flanges are trapezoidal; narrower on one end,you got trouble.
4) well, it could be through or around them, and a late closing intake could blow it back up the port.
5) most likely rings. But for this level of oil to be coming from faulty oil-rings, there would also be plume of oil-smoke out the pipes, and the low LD results,kinda negate this.So I wouldn't be worrying about oil-rings just yet.
1 and 2 are easy checks.4 is hardly likely. and 5 is extremely unlikely.
So that leaves 3 as the most likely
1.Air filter is clean. No WOT runs yet.
2. It does have a PCV system.
3. I will study on the intake tomorrow and do some more measuring. Trying to get all the info I can this weekend so when I call my machinist Monday I will be well prepared.
Gasket is oil saturated.
1) check angle of head and intake face
2) remove gaskets, place intake on engine, slide it all the way over to one head. Measure open air gap on other side with calipers or feeler gauges. Take that number, add .060 and divide by 2. That is the minimum thickness gasket to use.
1) check angle of head and intake face
2) remove gaskets, place intake on engine, slide it all the way over to one head. Measure open air gap on other side with calipers or feeler gauges. Take that number, add .060 and divide by 2. That is the minimum thickness gasket to use.
ChrisPerry
Well-Known Member
Those are the gaskets with the raised sealing ring around the ports, correct?
If so Edelbrock says to use gaskacinch on the head and corresponding side of the gasket, basically glueing the gasket to the head. (I prefer to use a non hardening Permatex Aviation sealant)
Then on the intake side to put a thin layer of silicone around the coolant ports. (Again I prefer the Aviation sealant)
Then the 1/4" bead of silicone along the china wall with NO GASKETS.
I usually lightly snug the bolts, let it setup over night, then torque it down fully the next day.
I've yet to have an intake leak yet following this method.
If so Edelbrock says to use gaskacinch on the head and corresponding side of the gasket, basically glueing the gasket to the head. (I prefer to use a non hardening Permatex Aviation sealant)
Then on the intake side to put a thin layer of silicone around the coolant ports. (Again I prefer the Aviation sealant)
Then the 1/4" bead of silicone along the china wall with NO GASKETS.
I usually lightly snug the bolts, let it setup over night, then torque it down fully the next day.
I've yet to have an intake leak yet following this method.
moper
Well-Known Member
It seems to me there's more than just the intake gaskets. You need some sort of PCV system. Do you at least have breathers? The run time - was it driven or the cam broken in in the car and you run it once in a while with no mileage? Do you have any pictures of the wall finish od the bores?
It does have a PCV system and a breather. The engine was broken in and has been driven on about a 2 mile round trip. No pics of the bore finish.
nm9stheham
Well-Known Member
While I would not list rings as the #1 likely cause, I'd not depend on any compression or leakdown tests to be totally accurate with any significant amount of oil in the cylinders.
BTW, what guide seals were used? The ones that came on the Edelbrocks? They are pretty snug. Are these parts (heads, seals, intake) all new? (Pix all look new..)
If you had another set of gaskets, I'd put them in place with the intake and use feeler gauges at all 4 corners, top and bottom, to check that the gaps are all even, plus do a close visual inspection at all 4 corners. I would not expect to reliably close up more than a few thousandths gap difference top to bottom.
BTW, what guide seals were used? The ones that came on the Edelbrocks? They are pretty snug. Are these parts (heads, seals, intake) all new? (Pix all look new..)
If you had another set of gaskets, I'd put them in place with the intake and use feeler gauges at all 4 corners, top and bottom, to check that the gaps are all even, plus do a close visual inspection at all 4 corners. I would not expect to reliably close up more than a few thousandths gap difference top to bottom.
-
