318 std piston quench with aluminum heads?

[33IMP]

Drive down the road at a speed that gives a very noticeable vibration. Note rpm.
Then, when stopped, rev and hold that rpm in neutral. Vibration? It's in the engine/trans. Smooth? It's something that moves when moving at speed. ( driveshaft, u-joints, pinion angle, tires/wheels)


And with twelve to one pistons, I'd be shopping for some .125 thick head gaskets.

 

[340inabbody]

honestly, at this point i can't keep up with what's going on. so thanks for somewhat clarifying.

the thread is about a 318, then you're on about a 360 and now it's something on a 340. in the future, my suggestion would be if you want pointed advice is to ask clear and concise questions and not muddle up a thread with a bunch of information that's not pertinent to the original ask.

here's my thought: i would eliminate any and every possibility from the drivetrain before suspecting the motor (aside from a bad harmonic balancer).

if it has 12:1 pistons i'd assume a performance build and therefore a forged crank-- factory or otherwise. but like they say: trust but verify

however... the balancer *should* be the tell tale sign.

so you're not off your rocker, it's just a super round-about way of getting there.

Thanks. Yes sorry for the confusion. Normally I don’t post like this. I am doing two things. One trying to determine what is causing my vibration by eliminating drivetrain which I stated and also see if the 318 is decent enough to put in if I can’t fid the issue and decide to swap the motor.

Focussi g back to the 340 vibration in the car. There was no harmonic balancer when I got the motor. So I couldn’t tell much and I didn’t know about the internals until after the engine was in. I have learned a lot since then about the motor. I just don’t know for sure what type of crank is in there until I see it. I do feel a vibration when revving the motor in park. So it points to the motor. I should have also mentioned that before.

I hope tomorrow I will be able to work on it and verify the crank type.

 

[340inabbody]

Drive down the road at a speed that gives a very noticeable vibration. Note rpm.
Then, when stopped, rev and hold that rpm in neutral. Vibration? It's in the engine/trans. Smooth? It's something that moves when moving at speed. ( driveshaft, u-joints, pinion angle, tires/wheels)


And with twelve to one pistons, I'd be shopping for some .125 thick head gaskets.

Thanks yup I just did the engine run up in park and I get a vibration. Honestly it wasn’t clear before but now seems to be. So this is why I want to see the crank.

 

[Illahe]

Thanks yup I just did the engine run up in park and I get a vibration. Honestly it wasn’t clear before but now seems to be. So this is why I want to see the crank.

Get under the car and take a peak at the crankshaft flange you may get a hint. The cast vs forged may have a different shape flywheel flange. I can take a look a a couple of 3.31 cranks tomorrow.

The pistons are likely heavier than oem. Perhaps someone has the weight of those trw slugs.. Your flywheel should have several large recesses drilled in the back of it if your crankshaft is cast. Or a scalloped flex plate, if the torque converter is neutral balance.

Precision torque converts web site has photos of the different flywheel weigh configurations too.

What is your cylinder pressure on gauge? Additionally, we had a cross fire on some plug wires that caused a pulses felt in the automatic transmission until we rectified the situation. Something to think about.

 

[340inabbody]

Well 3 separate tries to pull my oil pan no go. There is not enough room without pulling the coolant lines and probably the headers. All bolts are off and it’s free but my be hung on a baffle and needs to move somewhere to get free but no room to maneuver.

 

[mygasser]

you could pull the k member bolts one at a time and replace them with studding or longer bolts so you can lower it to gain more clearance to get the pan out. you might get just enough and there's only one way to find out, lol.
neil.

 

[340inabbody]

you could pull the k member bolts one at a time and replace them with studding or longer bolts so you can lower it to gain more clearance to get the pan out. you might get just enough and there's only one way to find out, lol.
neil.

I don’t think it’shanging up on the K member. Remember, this is a bbody. It seems to be hanging up buy something from the inside, but I’m not sure.The front is coming down and is clear to move forward. I just can’t pull anymore forward because there’s something hanging up so it may have to go sideways to get unhung? This is why I think I need room to maneuver laterally. But it’s very tight on the sides.

 

[mygasser]

that'll be the oil pump pickup and/or pump itself.
i recently removed the pan on a ford fe and it wouldn't clear the pickup. the pan came down 2" ish which was just enough to squeeze my hand in with a wrench to unbolt it. that was the easy part, bolting it back on was great fun through that little gap. you should be able to do similar on your car if you can get your hands in the gap.
neil.

 

[340inabbody]

that'll be the oil pump pickup and/or pump itself.
i recently removed the pan on a ford fe and it wouldn't clear the pickup. the pan came down 2" ish which was just enough to squeeze my hand in with a wrench to unbolt it. that was the easy part, bolting it back on was great fun through that little gap. you should be able to do similar on your car if you can get your hands in the gap.
neil.

No room only comes down 2” in front and 1/16 in back. I am screwed…..

 

[340inabbody]

Welp PITA I finally got the oil pan off. The passenger header needed to be loosened and shoved over and I was able to finagle it around and down. The 340 windage tray also made it more difficult. The trans coolant lines were also a problem but just able to clear with interference to the pan to get it by.

Next step to remove the windage tray.

 

[340inabbody]

So the windage tray uses the 4 main cap bolts? Seems like a piss poor way to have to mount sheet metal. Any risk I should be aware of removing what appears to be #2&3 main cap bolts? The cap should stay in place if it’s good right?

 

[junkyardhero]

So the windage tray uses the 4 main cap bolts? Seems like a piss poor way to have to mount sheet metal. Any risk I should be aware of removing what appears to be #2&3 main cap bolts? The cap should stay in place if it’s good right?

a picture would help immensely here.

however, the stock windage tray mounts to the main bolts with small 3/8's or 7/16's head bolts. no need to disturb the main bolts in that application.

 

[toolmanmike]

So the windage tray uses the 4 main cap bolts? Seems like a piss poor way to have to mount sheet metal. Any risk I should be aware of removing what appears to be #2&3 main cap bolts? The cap should stay in place if it’s good right?

There are small bolts that screw into the 4 main cap bolts.

 

[340inabbody]

There are small bolts that screw into the 4 main cap bolts.

View attachment 1716494818View attachment 1716494820

Thank you guys! Makes sense!

 

[340inabbody]

So I don’t see a parting line yet. Will bump the starter to rotate the crank. Any indications to you guys if this is internally balanced or not? Cast or forged?

 

[junkyardhero]

*spidey senses tingling*

 

[340inabbody]

*spidey senses tingling*

View attachment 1716494863

A castle nut on a con rod ay? Good catch. Looks like that’ll be the connecting rod bearing that I’ll check while I’m in here. But can you tell me is this a cast or forged crank?

 

[340inabbody]

It’s forged! Therefore must be internally balanced. That must be my problem in 1973. This was a cast crank and somewhere it was changed to a forged crank and internally balanced when it was rebuilt. I have to change my external balancing to neutral.

 

[junkyardhero]

Un castle nut on a con rod ay? Good catch. Looks like that’ll be the connecting rod bearing that I’ll check while I’m in here. But can you tell me is this a cast or forged crank?

yeah, that's... uh... to borrow some industry parlance: no buneo

sorry i can't help on the crank, the pictures aren't super clear. the best place to see it is on the front of the forward most con rod throw. though all the con rod throws will exhibit it, the main caps kind of obscure it making for a difficult picture.

 

[340inabbody]

yeah, that's... uh... to borrow some industry parlance: no buneo

sorry i can't help on the crank, the pictures aren't super clear. the best place to see it is on the front of the forward most con rod throw. though all the con rod throws will exhibit it, the main caps kind of obscure it making for a difficult picture.

Thanks. The parting lines are huge! That’s a tell tale sign it’s forged. A cast crank would have a think line. But I am just learning about this stuff and only seen my 318 which I just learned is also forged for the exact same reasoning.

 

[Newbomb Turk]

Thanks. The parting lines are huge! That’s a tell tale sign it’s forged. A cast crank would have a think line. But I am just learning about this stuff and only seen my 318 which I just learned is also forged for the exact same reasoning.

View attachment 1716494874

Yup, that is forged.

 

[340inabbody]

*spidey senses tingling*

View attachment 1716494863

Ok not sure but the builder must have lost the correct nut and used a castle nut geeze. Thanks @junkyardhero for catching that!

What are the specifications on the correct nut? Is it 3/8-24 grade 5? Is there anything special about this nut?

 

[Illahe]

FWIW this information is on the site: 318 vs 340 forged crankshafts. Look at the photo in post # 70 then refer to the following description.

273 and 318 cranks are generally the same. The 273's and 318's balance to the same bobweight.

340 cranks are different in that the 2 end journals are drilled out with large holes to take out some weight from inside of those 2 end journals for counterbalancing the heavier piston/pin/rod combo of the 340 engine. So while the bearing dimensions and stroke are the same for the 340 as the other 2, the balancing as it came from the factory is not the same.

 

[Bewy]

I wouldn't be worried about a castle nut. It actually has more thread engagement, spreading the load over more threads. I wonder about the other nuts. The domed shape is often a sign of a pinch nut, that pinches the thread to remain tight. If they are pinch nuts, that will have some effect when torquing the bolts.

 

[junkyardhero]

I wouldn't be worried about a castle nut. It actually has more thread engagement, spreading the load over more threads. I wonder about the other nuts. The domed shape is often a sign of a pinch nut, that pinches the thread to remain tight. If they are pinch nuts, that will have some effect when torquing the bolts.

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