I can say that not 1 of the 60s or 70s 318,340 or 360s ever had the soft plugs in them when I took them apart. Kim
oil pressure was 25 - 30 on cold start, then dropped to 10 - 15 when warm...
After putting the plugs in, it went up to 65 cold start and 55 warm...
The oul comes through the bolt and drips down... If you use the drip tab, that directs it onto the timing chain... If you don't use the drip tab, it will drip down onto the crank and the oil slinger does it's job and slings the oil around and it gets on the timing chain...
(Ray Charles told me that...)
A 50% loss of oil pressure from that plate seems damn near impossible to me. You can leave a plug or and have that kind of pressure.
That's unreal.
IMHO, there is nothing guaranteeing that plate will always seal true to the block. It is machined flat on the back but who knows for sure. I can easily see one getting a kink, or a burr on the edge that raises it in one corner, from being dropped, poorly machined at the factory. etc. And the bolts are spread too far to make sure you get a good seal.A 50% loss of oil pressure from that plate seems damn near impossible to me. You can leave a plug or and have that kind of pressure.
That's unreal.
OP, IMHO, you are asking for potential trouble by not putting some short plugs in there. It's the same reason as above... the plate for the tensioner is not at all designed to guarantee an oil seal. One bit of warpage, a burr in the wrong place, etc., and you are losing pressure. I don't think those tensioner plates are machined flat on the back like the original plates tend to be.Thanks for all the input.
I think we will just take those pipe plugs out of there and put the timing tensioner on with the passenger side galley covering drilled out with a 1/64 hole.
The 318 always had great oil pressure and it had nothing in those galley holes.
IMHO, there is nothing guaranteeing that plate will always seal true to the block. It is machined flat on the back but who knows for sure. I can easily see one getting a kink, or a burr on the edge that raises it in one corner, from being dropped, poorly machined at the factory. etc. And the bolts are spread too far to make sure you get a good seal.
OP, IMHO, you are asking for potential trouble by not putting some short plugs in there. It's the same reason as above... the plate for the tensioner is not at all designed to guarantee an oil seal. One bit of warpage, a burr in the wrong place, etc., and you are losing pressure. I don't think those tensioner plates are machined flat on the back like the original plates tend to be.
Are the threaded plugs all the way in? If so, I'd find some shallower one, or grind those down 'til the fit under the tensioner plate. Then drill an oiling hole on one plug (in the driver's side IMHO, since any loss there is less critical to the engine) and another hole in the cover plate in front of it, or use a drilled jet like suggested.
BTW a 1/64" hole is only about .015" diameter.....maybe you meant 3/64" ?
I've got to pull the timing cover off a 340 on the stand in the shop. It's got a used 100k plus mile cam plate on it. Before I take the cam plate off I'm going to see if I can get a feeler gauge in there anywhere around the plate.
1 /16 is too big 3/64 would work anything around .040
Hi YR, You might try spinning the oil pump when you have the timing cover off. If there are no plugs behind the cam plate I bet you will see oil squirting out. I did this and that's what happened to me (flat block and plate). Is it a lot of oil? No. But it will probably make a mess with the cover off. Does it cause a big oil pressure loss? Not in my experience. I ran without plugs behind the cam plate and did not experience low oil pressure. But, during a cam change I spun up the oil pump with the cover off and noticed oil squirting out (40+ psi on the gauge). I put the plugs in before wrapping up my cam change. Just my experience.
Just my best thought of why it may make a difference to have the plugs or not. The flow area of a .040" hole is .00125 sq in. The flow area of a .005" gap across a 1" long bowed up plate area is .005 sq in... so any plate bowing or lack of flatness can add up fast in that area. And I can see guys getting burrs and grit in there, or leaving out a bolt like a top bolt to oil the chain like came on some SBM's and the plate has a pretty god gap and let's out oil. I'd bet YR is pretty meticulous on his assembly and so is likely to not have such issues.
It is just not a guaranteed oil pressure seal area. So it may be fine on one engine and a crap seal on another that has plate issues or is done in a way that can leak without realizing it. And a weaker oil pump will show pressure losses a lot more readily with any leaks whatsoever. So a lot of variables as to why it may become an issue.... or not.
YouTube channel? That would be interesting....!
LOL.. marriage teaches you that there are some places you just don't go!
Hi YR, You might try spinning the oil pump when you have the timing cover off. If there are no plugs behind the cam plate I bet you will see oil squirting out. I did this and that's what happened to me (flat block and plate). Is it a lot of oil? No. But it will probably make a mess with the cover off. Does it cause a big oil pressure loss? Not in my experience. I ran without plugs behind the cam plate and did not experience low oil pressure. But, during a cam change I spun up the oil pump with the cover off and noticed oil squirting out (40+ psi on the gauge). I put the plugs in before wrapping up my cam change. Just my experience.
I took my own advice on my suggestion to YR. I'm working on my own stroker 340 and was doing some test fitting of parts and such. I went ahead and bolted on my oil pump, pan, added some oil and spun the oil pump with a drill. This is with NO galley plugs, just the cam plate (4 bolts). With 5-30 oil and 50 psi on the mechanical gauge I hooked up, there was only a small amount of oil escaping behind the cam plate. It didn't make a big mess like I expected (or remembered from the past). Instead, it just dribbles down the front of the block. My guess is maybe 1 cup of oil a minute. Other setups might be different. A plate with only 3 bolts might "leak" more. Just my experience. I'm still going to install the plugs.
Thanks for doing this; it is some extra work and I appreciate the effort.. very much! But there is a matter that is making the resulting leakage quite misleading.... the oil is not hot and so the viscosity is waaay off. Kinematic viscosity for that 5W30 oil will be around 80 at room temp, and around 60 at 100F, but the viscosity will drop like a rock to around 10 at 200 degrees F. So such leak tests are not valid with the viscosity that far off from actual operating conditions. Folks don't fully appreciate the extent of the viscosity changes as temps go down.I took my own advice on my suggestion to YR. I'm working on my own stroker 340 and was doing some test fitting of parts and such. I went ahead and bolted on my oil pump, pan, added some oil and spun the oil pump with a drill. This is with NO galley plugs, just the cam plate (4 bolts). With 5-30 oil and 50 psi on the mechanical gauge I hooked up, there was only a small amount of oil escaping behind the cam plate. It didn't make a big mess like I expected (or remembered from the past). Instead, it just dribbles down the front of the block. My guess is maybe 1 cup of oil a minute. Other setups might be different. A plate with only 3 bolts might "leak" more. Just my experience. I'm still going to install the plugs.
I assume you meant 'front gallery' plugs? Now that is interesting... made me go look at my unmolested '68 273 block.... no plugs in the front. So just the plate in stock form.I have never seen a virgin block with the freeze plugs in.