[Mjohnson23]

Are these cranks drop in ready out if the box now? I had read in the past that they needed work/ clean up in the thrust area? Just wondering with a $280 price tag online if they had improved in the last couple years

[1971WARBIRD]

I would buy one from one of the business's that advertise here. that way you can have them check it out first. I live right by Ohio Crank and have used several of theirs with good luck. I have used forged though.

[Half-Inch Stud]

I had a Cast 455 Eagle crank drop- in (2007) & still good.

[Transporter]

Since we are talking about cranks, what about the Scat products?

[Cliff R]

I've only installed a couple of the "drop-in" cast cranks, since introduced we use and prefer the forgings. When first introduced the cast cranks had some issues, mostly "rough" machining, and not sized correctly on the journals. Didn't matter where you sourced them out from, they would need some work before they were actually "drop-in".

The first one we attempted to use ate up the thrust bearing and the rear seal right on the dyno. During assembly the surface finish didn't appear that bad, but it was, and we had to remove the crank and hand polish those areas.

Same deal with the "H" beam offshore connecting rods, very few sets were "drop in" right out of the box, mostly needing opened up slightly for the pins to fit thru them.

Jump ahead to a couple of years ago, we assembled an engine with a complete rotating assembly from Butler. The cast crank they supplied was spot on everyplace, highly polished journals and for the rear seal, didn't need to touch it anyplace or get oversized bearings, etc. The "no-name" "H" beam rods were fine for fit/finish as well. The entire rotating assembly was truly "drop-in".

I think you'll see more or the latter with current production parts, as they have had quite a few years to work out the "bugs" with them.

We just finished a 455 assembly yesterday, the rotating assembly was from PPR (forged crank). Fit and finish were spot on, didn't have to touch the crank, connecting rods or anything else, just check all the clearances and put it together........Cliff

[Transporter]

Originally Posted by Cliff R

I've only installed a couple of the "drop-in" cast cranks, since introduced we use and prefer the forgings. When first introduced the cast cranks had some issues, mostly "rough" machining, and not sized correctly on the journals. Didn't matter where you sourced them out from, they would need some work before they were actually "drop-in".

The first one we attempted to use ate up the thrust bearing and the rear seal right on the dyno. During assembly the surface finish didn't appear that bad, but it was, and we had to remove the crank and hand polish those areas.

Same deal with the "H" beam offshore connecting rods, very few sets were "drop in" right out of the box, mostly needing opened up slightly for the pins to fit thru them.

Jump ahead to a couple of years ago, we assembled an engine with a complete rotating assembly from Butler. The cast crank they supplied was spot on everyplace, highly polished journals and for the rear seal, didn't need to touch it anyplace or get oversized bearings, etc. The "no-name" "H" beam rods were fine for fit/finish as well. The entire rotating assembly was truly "drop-in".

I think you'll see more or the latter with current production parts, as they have had quite a few years to work out the "bugs" with them.

We just finished a 455 assembly yesterday, the rotating assembly was from PPR (forged crank). Fit and finish were spot on, didn't have to touch the crank, connecting rods or anything else, just check all the clearances and put it together........Cliff

Cliff, aside from finishing issues, how well are these cranks for the rod throws being same height, I had been reading about a couple of cranks that had piston heights at TDC different across the banks?

[J GLASGO]

Eagle cranks are at best 50% drop in. Even if purchased from one of "our"venders. I don't think they are checking them at all. Scats seem to be machined better and is what we use if at all possible. Triple check everything,and never count on someone else doing their job properly.

[Skip Fix]

The Eagle 4" 409 forged crank I got had almost 0.001 taper on the journals. One of the Pontiac Ohio billets I have was similar and the filet was too thick for normal bearings so had to be turned-although now they carry thinner Mahle bearings for that reason.

Never trust any crank to be drop in.

[Cliff R]

Early units were off some for journal size, taper, out of round, poor finish, and stroke. The stroke was the least of the issues with them, as they were less than .002" off with the ones that I had here to check. For a variety of reasons, including difficult to balance (CAT and Scat units), I bad mouthed them when the first came out, and typical of most things that folks buy into, took heavy criticism for it. There are also enough catastrophic failures with them to avoid them completely for big power. Probably fine to 500hp or so, but I would just move up the forging instead, and sleep better at night. The forgings have also been much better for fit and finish. We built one of the first engines with them when they first came out, it still survives as over 700hp now for nearly a decade, been freshened up once.

To date, including the engine we just finished yesterday, the forgings have been excellent. Haven't had to do anything to any of them, although I think the most recent unit took away WAY too much material at the oil feed holes on the rod journals. There is no need for anything more than a slight chamfer there, you don't have to cut a 1/2" "slot" across them.....FWIW.....Cliff

[PONTIAC DUDE]

Finished cranks have improved drastically over the past couple years. Most of the current issues is the end user not knowing about bearing widths, bearing tang fit, bearing upper and lower shells, Pontiac oil feed issues to address, side clearance and a host of things. It's the knowledge thing. Not trying to alienate anyone just from observation on the boards and assemblies brought to me.

Most think that because one can do a stock rebuild that any build is OK to attempt.

[gtofreek]

Originally Posted by Cliff R

Early units were off some for journal size, taper, out of round, poor finish, and stroke. The stroke was the least of the issues with them, as they were less than .002" off with the ones that I had here to check. For a variety of reasons, including difficult to balance (CAT and Scat units), I bad mouthed them when the first came out, and typical of most things that folks buy into, took heavy criticism for it. There are also enough catastrophic failures with them to avoid them completely for big power. Probably fine to 500hp or so, but I would just move up the forging instead, and sleep better at night. The forgings have also been much better for fit and finish. We built one of the first engines with them when they first came out, it still survives as over 700hp now for nearly a decade, been freshened up once.

To date, including the engine we just finished yesterday, the forgings have been excellent. Haven't had to do anything to any of them, although I think the most recent unit took away WAY too much material at the oil feed holes on the rod journals. There is no need for anything more than a slight chamfer there, you don't have to cut a 1/2" "slot" across them.....FWIW.....Cliff

X2!!

[pippintook]

Just a heads up - if you drop in the crank , you might want to consider balance. If the eagle crank was zero (or neutral) balanced...it should be used with a zero (or neutral) balanced flywheel...many pontiac engines will have an "offset" (ie. non zero) balanced flywheel..in ideal world it would be nice to get crank balanced with your rods/pistons/flywheel

[400 plus]

X2 Another thing I found out the hard way buying cheap mismatched parts. LOL Thanks Jim

[jonmachota78]

so "drop in" at least assumes after balancing with reciprocating assembly?
I can see a balanced reciprocating assembly being drop in......
but how can a CRANK itself ever be drop in? really?

[gtofreek]

Sometimes the counterweights are slightly bigger and hit the boss on the block near the front. The block needs to be clearanced just a little in these cases.

[pippintook]

good point about the counter weights..forgot about that...Butler Pontiac has some good pics on their web site for this

http://www.jbp-pontiac.com/tech.html

"...4.25 OR 4.500 CRANK CLEARANCE
This picture shows the only area that normally needs to be clearanced to put either a 4.25" or 4.500" stroke crank in a Pontiac 400 block- although any new part should be installed and all clearances checked prior to final assembly because of factory production variances..."


I guess that 'drop in' crank is becoming less and less ..drop in...