trying to sort out things for a new motor for wagon. 1st block in way was 77 or 78 400 bare block. took it to machine shop and was discussing options for stroker. he checks bore and it is already .020 over. he says it won't be a good choice as it is only .020 from where he wants a low deck stroker to be, bore wise. do i need a new machinist or is he correct. will be street motor. not sure on cubic inch or anything else at this time. thanks in advance.

I don't really know what he is saying. If it's .020 over and it needs a bore job, 440 Source (and probably others) has .035 stroker kits.

Does your machinist own a sonic checker?

not sure on sonic checker but i looked at 440 source and saw .035 kit. maybe i'll take it to another machine shop to see what they say. thanks for reply.

If I was you I would have that block sonic tested by a good shop before making any choices on using it or not
It is very possible it is useable but you won't know until it is tested
If it will have less than .120 thick anywhere in the cylinder walls after boring and honing look for another, better block

My 400 block (73 230 std web casting) is .040 over.... don’t understand what the problem is. “Only .020” from where he wants it”.... first: what does that mean??? Second: why would that stop him from going there?

Are you sure you’re understanding him properly?, or are you sure he’s understanding what you want to do?

The shop is probably telling you that the bore size to too much to hone to the next size and too little to bore. That makes some sense depending on what equipment he has. The real question is what is the wall thickness. If it is a thick block then no problem. If it is a thin block then it is junk so go find another 400 block. Only the sonic checker knows for sure.

i revisited the machine shop and andy f is exactly correct in what he stated. so on to another block. thanks all and happy holidays.

That is why they pay me the big bucks to answer questions on here.

I guess I still don’t understand the problem exactly.

The common bore size for those blocks is 4.375.
If it’s currently +.020 the bore is 4.363.
.012 is not a problem to hone out at all, unless you’re using a hand held type of hone.
Any power stroke hone would make short order of that job.

Now, if the wear at the top of the ring travel is already beyond 4.375, then you’d really want to sonic test the block first, and use a larger bore size(4.380 or 4.390). But then you’re likely looking at custom pistons as well.

I'm curious as to why a machine shop wouldn't be able to bore a block out. I understand Andy said the machine, so I guess my question is what is the machines problem/ or lack of ability? rbkt65 if youd be interested in selling that block please contact me.

My source kit came with 4.380 pistons

i look forward to everyone's answers for all the questions that i ask, no matter how stupid the question i ask. at almost 69, i still learn a lot from all of you. thanks again.

My guess is that it is due to the equipment that the shop has. If you went to a different shop then you might get a different answer. Does the shop you're talking to have a Mopar torque plate? If they have a torque plate and a power hone then they should be able to put the torque plate on the block and hone it to size. But I wouldn't do that until you have the block sonic checked. Sonic check, order pistons and rings, then power hone to size is the order I'd go.

There is a big difference between a machine shop and a performance engine builder. I’ve been building engines and learning about performance engines since 1976. Fortunately for me, my mentor was a very good performance engine builder that built his own Super Stock engines as well as others in this division. He kept buying state of the art equipment and always advancing his knowledge. He had a good business when he retired. Fortunately he sold it to a good young fellow that has followed in his footsteps. He has the only shop still around because he has learned and gives the customer a great product. Some of these shops are old guys that never learned the patience to build it right or just wanted to get it out the door cheaply. I’ve dealt with one or two of those. Get a new shop.

I've built a bunch of 400 block motors with 3.750 stroke up to 4.300 stroke crankshafts, all but the first one where sonic tested by me after having the first block crack the #1 cylinder wall on the camshaft side of the cylinder wall while breaking in the cam on a engine dyno it was right at .035 thick after prying apiece out of it while I having it bored out for a ductile iron sleeve
That block was not salvable due to much core shift on the drivers side
What I have found in the past on bore size is the lack of a good set of piston rings after you get above 4.380 bore size 4.440 bore size rings are available but not many stock blocks will be safe at that size
My first pump gas 400 stroker motor (511 C.I.) I built for myself ended up with four ductile iron sleeves in it due to deck damage between the #4 and #6 cylinders due to a blown head gasket torching that out, #1 and #7 had to much pitting in them to clean up at 4.375 bore size so I had the shop sleeve all four at the same time due to not being able at that time to find another block in SO CA back in 2001
That motor made a bunch of power and took a lot of abuse by me on the track and street on pump gas, it had a set of ported big valve 906 heads with 9.25 to 1 compression ratio to start with and it made 612 HP at 5500 RPM and 644 Ft. Ls. at 4500 RPM with a low deck six pack. I ended up swapping heads several times and crankshaft stroke once to 4.300 stroke (517 C.I.) to make it make more power, it ended up with a set of Indy SR M.W. intake ports with a 400-3 intake and a 1050 CFM Holley Dominator, that combination made 727 HP at 7000 RPM and around 680 Ft . Lbs. of torque with 10,78 to 1 compression using Oregon 91 octane non ethanol pump swill. That combination ran a best of 9.993 at 134.+ MPH corked up with the air cleaner on in my old street Duster weighing 3450 Lbs. with me in it, it ended up being way faster than I expected
Test, test and test some more, don't be afraid to try something different to make more power My current S/P bracket 400 cold weather block that I bought form AndyF on here ended up only needing being bored to 4.350 to straighten out the bore That motor has pushed my 1970 S/P chrome moly tube chassis Cuda (2750 lbs with me in it) (517 C.I.) to 5.50 at 120.+ MPH in the 1/8 mile and 8.886 at 150.+ MPH in the 1.4 mile so far
IHTHs

I see rings listed for: 4.380, 4.385, 4.390, 4.395, 4.400

That's good to know, which company?

Total Seal

Thanks