2.4L main caps

[AshTsi]

The 2.3L strokers have clearance issues with the connected main caps. Can you use the main caps out of the 2.4l 4g64 engine in the 4g63 so you wont have a problem with the main caps clearance? Or is there a difference like oil pickup or something else?

 

[GVR4592]

I think they're interchangeable, you would need a line hone afterwards though. I don't think it's worth doing because you lose a lot of rigidity with the mains not being connected. Just clearance that caps and call it a day.

 

[absolute_DSM]

Its definately not as much of a PITA as you think. If youre building a 6 bolt, you can take the 1-2 and 3-4 girdles and clearance them like I did below with a dremel and carbide. Ive never stroked a 7 bolt but clearancing would be the same. Doesnt take any time at all but is needed to keep the assembly rotating properly.

EDIT - (Also, if building a 6 bolt, dont forget to grind on the block a bit on the #3 cylinder... Ill just throw in another pic below)

Like Luke said, putting different main caps on an engine would require a line hone by a machine shop which can incur some unwanted cost on the build.

And for your question, there shouldnt be a oil pickup problem. But, if you are using ARP main studs, the 3rd point for the oil pickup (located with a nut on a main stud) wont even be able to be used anyways, it will have to be cut off.

 

[GVR4592]

That's a good pic, I'll remember that for the next time this question comes up.

 

[absolute_DSM]

That's a good pic, I'll remember that for the next time this question comes up.

Gimme a carbide with an air powered dremel and I can do wonderful things.

I almost wonder how much is too much, I pretty much guessed. Ive read through Dans (project_tsi) build a few time (back when he built his 2.3, because its fairly similar) and noticed his clearancing of the caps and block so I went off that. To my knowledge, he doesnt have any problems!

 

[GVR4592]

I think it might be a little overkill, but it's not to the point where it might break. Dan's going back to a 2.0, but I think it's due to breaking drivetrain parts, nothing to do with the engine build.

 

[rconlon67]

If your assembling your bottom end and you do not do any clearancing, and the assembly rotates freely..Do you still need to do clearancing?

Will there be a certain amount of flex that might make the rods hit the main caps if they do not when cranking by hand?

thanks,
Ryan

EDIT:I'm putting together a 2.3L 6-bolt

 

[GVR4592]

That's a good question. Usually .005" is enough clearance for the big end of the rod, assuming you don't spin a bearing or lose a rod bolt at some point.

 

[Black94DSM]

If your assembling your bottom end and you do not do any clearancing, and the assembly rotates freely..Do you still need to do clearancing?

Will there be a certain amount of flex that might make the rods hit the main caps if they do not when cranking by hand?

thanks,
Ryan

EDIT:I'm putting together a 2.3L 6-bolt

Yes. You need to make sure you have at least .080-.100 of clearance. If it dont hit now by freehand spinning it sure thats fine...but think of what happens when you put 7,000-7,500 rpm to the crank/rods. Things do stretch a little. I clearanced my mains caps to what I said as a percaution.

Looking at the picture of absolute_DSM's main cap, that looks to be what I had for clearance too.

 

[GVR4592]

Yes. You need to make sure you have at least .080-.100 of clearance. If it dont hit now by freehand spinning it sure thats fine...but think of what happens when you put 7,000-7,500 rpm to the crank/rods. Things do stretch a little. I clearanced my mains caps to what I said as a percaution.

Looking at the picture of absolute_DSM's main cap, that looks to be what I had for clearance too.

Aluminum rods won't even "stretch"(I believe the technical term is elastic deformation) .100 on the small end of the rod, that's extreme overkill for a steel rod on the big end.

 

[Black94DSM]

I don't think we are on the same page here, I'm talking about the clearance from the rod end cap/bolt area to the main cap bridge.

 

[GVR4592]

We're on the same page. I'm saying that a steel rod isn't going to stretch enough to cause interference issues with a tight tolerance like .005".

.080-.100" is a lot of clearance and extremely overkill. The most I've heard of is .005" with a high revving steel rod engine. I was comparing an aluminum rod as an extreme example of overall stretch. They will "grow" a lot more than a steel rod at high rpm, and even with an aluminum rod you wouldn't need anywhere near that clearance.

 

[Black94DSM]

We're on the same page. I'm saying that a steel rod isn't going to stretch enough to cause interference issues with a tight tolerance like .005".

.080-.100" is a lot of clearance and extremely overkill. The most I've heard of is .005" with a high revving steel rod engine. I was comparing an aluminum rod as an extreme example of overall stretch. They will "grow" a lot more than a steel rod at high rpm, and even with an aluminum rod you wouldn't need anywhere near that clearance.

Wow, ok. I've never heard of that tight of clearance. I just dont see how a large peice of hairs worth of clearance is enough. To each his own.

I'm more cautious when it come to any type of rotational clearances.

 

[AshTsi]

Thanks for all the input guys especially the pictures, Really Helpful!!! I was gonna get a Main Girdle, so i have to get it line honed anyways, but if its not worth it to just go with the 2.4l caps then I'll just grind the standards. Plus it wasn't as bad as i had thought it was going to be.
Thanks again guys
~Ash