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]

GET UNDER THE CAR AN

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.