LT1-LT4 Modifications - block filling

How many have had to do any filling of the block for clearance issues going to a 4" crank??

anybody not had to fill?

A vendor was offering these for awhile and posted some details here like using small journal crank/rods to improve clearance. Do some searching and you will find it and I think it would help.

while researching my 396 build I read a good article on chevy high performance about a 396 sbc build & it stated that 4 out of 10 blocks fail the pressure test on a 408 build Yeah stroker rods & such will help but any way you cut it Its still a 4in stroke Find a shop that builds a lot of strokers

while researching my 396 build I read a good article on chevy high performance about a 396 sbc build & it stated that 4 out of 10 blocks fail the pressure test on a 408 build Yeah stroker rods & such will help but any way you cut it Its still a 4in stroke Find a shop that builds a lot of strokers

After my machinist fit the rotating assembly in my 396, he told me there was enough meat to get a 4" in there. It would be close, but there was very little shift in the block. I don't think you can get ARP L19 bolts to fit so they will have to be something smaller, even the 2000's will be a close fit, but it really depends on the block.

I think most shops recommend a short fill at least. Only to completely make sure they don't hit water.

I have an ultrasonic thickness gauge but was trying to decide if i wanted to go 3.75 or all out to a 4".... block filling isnt a problem but if many haven't had to fill then i def will go 4".

Go for the big 408 IF you have 2nd thoughts go 3.875 instead of 3.75 The 396 combo helps tame those big cams just a LiL better than a 383 :) Just my 2cents

keep us posted on how long it lasts. i have only read rumors that LT1s exceeding 396CI are not long for this world. i know of 2 local 396's that take regular beatings plus street duty that barely break a sweat so knowing those extra cubes are more than a novelty would be nice.

keep us posted on how long it lasts. i have only read rumors that LT1s exceeding 396CI are not long for this world. i know of 2 local 396's that take regular beatings plus street duty that barely break a sweat so knowing those extra cubes are more than a novelty would be nice.

I daily drive my 396 when the weather is nice, I beat the shit out of it no problems. I have LT1s that are .040 and .030 you need to sonic test them if you want to go crazy. You can go .060 but you have to check that. I sonic tested .140" wall thickness between cylinders and .240" thickness the other way. Also my block had almost no core shift.

Some people say .100" is the min wall thickness, however if you hardblok fill it you can make the wall paper and still get "some" runs out of it.

Here is a few pictures of my 396, the machinist had some fun on the rail sides, you don't have to take this much out for a 3.875, but a 4" is another story. I believe this was done on a bridgeport.

^ i am speaking in terms of exceeding a 396 and holding it together as well as a 396

Here is a few pictures of my 396, the machinist had some fun on the rail sides, you don't have to take this much out for a 3.875, but a 4" is another story. I believe this was done on a bridgeport.
Are you running a small base circle cam? What rods?

^^^ ah.. good question....

Are you running a small base circle cam? What rods?

No special cam, its one of Bret's super secret grinds. Rods are off the shelf 6" Eagle H-beams with ARP2000's in them, 4340 Eagle 3.875 crank. The pistons are Mahle.

No special cam, its one of Bret's super secret grinds. Rods are off the shelf 6" Eagle H-beams with ARP2000's in them, 4340 Eagle 3.875 crank. The pistons are Mahle.
I can't remember what Eagle rods I had, but the place that built my block didn't want to use them and recommended Compstars. The rod bolt profile was significantly shorter and allowed for less clearancing.
Did you have any problems with using a pilot bearing/bushing with the crank? The hole for a bearing/bushing is oversized on the one I bought (problem with a batch of their crankshafts) and their answer was to use either a knurled bearing or an oversized bushing.

I can't remember what Eagle rods I had, but the place that built my block didn't want to use them and recommended Compstars. The rod bolt profile was significantly shorter and allowed for less clearancing.
Did you have any problems with using a pilot bearing/bushing with the crank? The hole for a bearing/bushing is oversized on the one I bought (problem with a batch of their crankshafts) and their answer was to use either a knurled bearing or an oversized bushing.

The pilot bearing wasn't too bad for the eagle crank, balancing the crank was a pain in the ass thou. If I was to do it again, I probably wouldn't buy any eagle stuff. If I didn't have a shop in my pocket it would have cost me a ton of money to get it all balanced out.