Clearancing needed for a 489?

[colonel]

Is there any commonly known things one has to clearance inside a 454 block when making it into a 489??

 

I used an Eagle 4.25 crank, Eagle 6.385 H beam rods and KB icon Forged pistons. Never noticed anything while assembling it and the people that did the machine work for me don't believe there is anything to clearance thus never said I should check anything.

 

The engine was always tight to turn around when I was putting rods in and dergreeing the cam and such but I never noticed that the tight spots do seem to be at the same point on the crank. Of course now there is a knocking noise throughout the engine which I had believed was lifter/rocker noise but that noise has been fixed and the other one still exists.

 

I did notice when I was putting engine together the counterweights and rods do clear the block but can't say as I ever looked at the inside of the rods to see it they were hitting the bottom of the cylinder bore.

 

So just wondering if anyone has experience with this.

[waupachino]

To my knowledge there is no clearancing needed to be done to the block when installing the stroker crank and rods. I'm running a 496.

[Daryl]

I recently built a 489 with the same crank and rods you have and I had plenty of room in the bottom end. I'm running diamond forged 21.5cc domes and Pro Maxx rec port heads. No clearencing to be done. What size of dome pistons are you runnin?...head and valve clearences checked out OK? I'm told some forged pistons may "slap" Just throwing out ideas.

[Mike 57]

I have done a few and never had to clearance a 454 block. I did have to notch a early 427 block.

 

Forged pistons knock when cold, but they should quiet down when the get warmed up and expand.

 

A couple of questions on the build:

What piston to wall clearance are you running?

What are the gaps on the piston rings?

Are the support rails for the oil rings installed with the dimples in the piston pin gap?

[colonel]

This is the piston I am using. Says 20cc dome. Should result in 10.6 cr with 115cc combustion chamber.

 

https://www.uempistons.com/index.php?mai...3834e0ec444e0ce

 

P-W clearance if I recall the build sheet info right was .0053 - .0055 depending on cylinder. Engine shop that did machine work installed rings and pistons on rods. I didn't want to screw anything up that way so can't speak to ring gaps and support rails dimples. Did follow shops advise on ring gap positions tough.

 

I pulled it all out again today and tore into it. Found no marks indicating negative clearances anywhere. Could only find a small score is cylinder 1 that seems to coincide with rings so maybe one of them broke or caught some debris somehow. Started moving the rods back and forth and when I got to front throw they wouldn't move. There was a gap but it wasn't even on parting line of #2 cap, .019 on one side and. 024 on other so it seemed twisted to me. Loosening off cap bolts didn't help. Had to separate cap and rod before they would slide. Bearings didn't seem right to me but were in the correctly and crank seemed to be fine with no odd marks.

 

Spoke with engine shop and was asked to check serial # on the 2 rods and caps on first throw. #'s on them ended in 8 and 0 which I had to look really hard to verify that but confirmed I had switched the caps likely after checking with plastigage then doing final assembly.

 

If you asked me if I was sure I did that all correct I would have bet the engine on it as I believed I was being so careful, double checking and going slow with no time pressure when I did this but I obviously I did it.

 

So I will haul it into the engine shop Monday so more experienced eyes can look it over and see if there is any damage to rods and such and hopefully all I need to do is replace the rod bearings and bolt it back up. Of course there is the issue of that small score in cylinder 1 too. I will see what they say about that. Maybe that will be more of a problem than the caps.

 

Still not sure how the cap mix up would make that noise though. Engine sounded like a diesel. I knew forged pistons made more noise than other ones like the hyper eutectic ones in first engine, but this did not sound right.

 

Engine was still sticky to turn by hand even with the first 2 caps loose and sliding on crank like they should. Guess that is why I will take it back to engine shop and see what they say. Don't do this every week so not sure what is normal and what isn't.

 

I wanted to do this myself this time as first engine I did for this car I let the engine shop assemble it rather than take it all home then bring complete engine back for dyno session. It only took a few hundred miles until the one set of roller lifters they put in upside down broke the tie bar and proceeded to eat up the cam and distribute the metal through the engine so I figured I would do it myself this time. It was my first full engine assembly and I learned some things along the way and some things happened that never happen to anyone else but this should not have happened.

 

Oh well. Sob story over. Get on with it and if you have to learn the hard way make sure you only do it once.

 

Hopefully I can get the problems solved easily, quickly and get it all back in the car so I can actually drive the car before winter settles in. Have a late summer going on now for about another week or so up here so will keep my fingers crossed.

 

Thanks for responses.

[waupachino]

Spoke with engine shop and was asked to check serial # on the 2 rods and caps on first throw. #'s on them ended in 8 and 0 which I had to look really hard to verify that but confirmed I had switched the caps likely after checking with plastigage then doing final assembly.

 

If you asked me if I was sure I did that all correct I would have bet the engine on it as I believed I was being so careful, double checking and going slow with no time pressure when I did this but I obviously I did it.

 

Still not sure how the cap mix up would make that noise though. Engine sounded like a diesel. I knew forged pistons made more noise than other ones like the hyper eutectic ones in first engine, but this did not sound right.

 

 

The Rod and Caps are machined as a whole, so if you switched them it completely changes the clearances and will lead to a whole bunch of issues.

[colonel]

It appears at this point that the rods are still in spec. Crank is no worse for wear so if that were the only problem it would be replace the bearings and put it back together.

 

The scoring issue though is what is the big problem. The rods being "pinched" on the crank has put some extra load on the thrust side of the cylinder and while #1 is visibly scored, #2 is also bad once measured. So the engine will need new pistons, it remains to be seen just how big. Shop will try and hone the problem cylinders to 4.29 and see if that clears it up and leave some room for a future rebuild should it ever need it. If they have to go beyond that then 4.31 it is.

 

They measured the pistons in there now (ic789.030 at 4.275) and they are as good as when they went it so are still useful to someone building a 489 so will try and sell them to help reduce the re-rebuilding costs.