Bad Block News Today

Got the call from Matt Hensley today. My 400 Block didn't sonic good. Imagine that. I got one more block to try. If it don't check out good. I think I may go Gen 3. I'm not gonna go fishing for 400 blocks in hope of finding a good one. So I may have a Molnar 4.25 crank and rods with Diamond -24cc pistons ProGram 2 bolt caps a Dwayne porter specd small solid lifter cam with HYlift Johnson lightweight edm lifters for sale. Which with a set of 240 TF would make a awesome 512 street engine. Will see in a week or so. Man Im bummed about the block situation.

How bad is bad on the sonic tests?

The block was standard bore with 3-4 cylinders in the 70 range. Which Matt said was as bad has he as seen. Not seen the sonic sheet myself. But I will take his word for it. And that was. He would not use it for this build. For a stock rebuild job maybe. For a stroker no dice.

If you can come up with a good block that only needs one or two sleeves to fix, I would go for it. There is no way a gen 3 will match the power per $$ considering you will take a bath on what you have, plus you will have to buy gen 3 stuff.
Keep looking for a good 400, with the loss on your current parts in mind!

Yeah I know and agree. Just bummed. Was gonna have this engine rollin together. Then I get this news. Like I said I have another block and a line on 2 more. Will see. Very frustrating though. Oh and until I get a block thats good. You go to the end of the line.

If he is saying that you have .070 thick now I would junk that rascal also
I had one of the first 400 block I built ended up having .030 after boring it on the cam shaft side of the block on all four cylinders on the driver side , it split the # 1 cylinder on the dyno
I bought a Dakota 1000 sonic tester after that and I use .160 minimum on the thrust sides and .130 on the non thrust sides as a minimum before boring

Yeah I'd say keep your chin up and keep looking for a 400 block, especially with the point that you're at and all the good parts you have

That's what Matt said also.

Im trying to stay positive about it. Just not sure how many 300-500 dollar swings I wanna make at blocks.

So sleeve it and move on, it's done all the time. S/F...Ken M

That was just the worst cylinder numbers. I think the other cylinders. While not that thin. They were just not where he would like them to be. Im just gonna go with Matt on this. If he is not confident with this block for this build. Im not either. But I agree. I don't have a problem with sleeves. But I don't think that was a viable option with this particular block

I have an early 7/71 400 block. 4

Standard bore, 4 holes checked thin, one was .083.

Well you know what. Both blocks I have are 71 230 blocks. Not that the 230 matters. But if this other early block is thin. Next one I get. I will get a later block. See how it checks. Matt said it's a crap shoot. He seen them thin and thick through all production years. Talking to Matt about the 230 thick main web blocks. Thick main webs won't help thin cylinders.

Was there or is there a year that is a better block than other years without said problem. I have a 400 motor also and think it was cast in 71 or maybe it came out of a 1972 Vehicle. Just hanging on to it in case I ever make a stoker out of it but likely will never happen. Has anyone done a study on what 400 block are better than others, year, mold it came from stuff like that.

I think Mopar Action did one back in the day (It was on 440 blocks but probably still applicable to 400's) and they found the later blocks were cast thicker and more consistent, but were of a slightly softer grade of cast iron. I'd look for a later block and try your luck there

Andy F has or had a article on his web site about that. It was along those lines you talking about. I think Im gonna look for a later block. Gonna make a call tomorrow to a guy close to me. See if he may have a block or 2 gabbaged away.

to me the earlier blocks are too much of a crap shoot for finding a thick block for the money some guys want for them,, I bought two 1975 530 blocks from two different people and both sonic'd out excellent(over 280 non thrust and over 300 thrust) and as far as the cast iron, my machinist told me that my block was as hard of material as he has ever tried to machine ,said it was much harder than any chevy or ford block.

Im thinking you maybe correct. Got a call in now for one and a line on another.

I have a 76 block. I’m glad I built it when I was 25 before all the haunting tales of this is too thin for a stroker stuff.... my engine guy built it and it’s been together for 2 decades.

I used a 76 block. Don’t remember the numbers, but it was by far better than the 71/72 blocks I had at the time. Over the years, the bores did get a bit barrel shaped. Never any issues with the “thinner” main saddles. If I were to build another, Id sleeve it and run a smaller piston. The weak part of the blocks in my opinion is the cylinder walls. I used that block from 1992 until I sold the car in 2006. First year it was together made 776 hp on the dyno. When I sold it it was making over 1100hp.

All 440 block, regardless of the year cast, are no where near as good as a decent 400 block for building, trust me on that
You need to remember that not all magazine writers are real hot rod guys with hands on experiences that know something about what there writing about, I've seen that personally time and time again

I’ve ran 440 blocks for years without concrete or sonic checking them. One 440 block (Stroker) cracked up thru the mains after 275 eight second passes and was found when I tore it down for rebuild. Sometimes you don’t want to know how bad things are. Lol 😂

Bummer man hope it works out

Factory blocks are always a crap shoot. That is why I refuse to pay more than a few hundred bucks for a core engine. The year doesn't matter and neither does the HP stamp. You just have to buy the blocks and spend the time to clean them up and then you find out if it is good or not.

Good news is that 400 blocks are still fairly easy to find. I'm sure you could find one within a week on craigslist.

Cab, I wasn't espousing the benefits of a 440 block over a 400 block (there are none, the 400 is a better foundation to build on for sure). I was merely pointing out Mopar Actions experience, in an article written by Ehrenberg (sp?), that the later blocks were thicker and more consistent. Yes they were 440 blocks but I imagine it transfers over to the 400's as well. If I remember correctly they tested around 20 blocks. Love him or hate him Ehrenberg seems to be at least a legit car guy who gets his hands dirty

All the stock RB blocks are a lot thinner in the main webbing under the cylinders down to the main bores than any of the stock 400 blocks made
I've heard of a lot more 400 blocks having severe core shift than the early 440 blocks but when you crack a cylinder wall or the main webbing that block sis toast, correct?
I would much rather crack a cylinder wall and have that cylinder quit working and find it right away than end up running over the crankshaft due to the main webbing falling out on the track or on the road
I've had one 426 M.W. block crack the main webbing and seen several 440 blocks that had done that also, no 400 blocks crack the main webbing so far

Yep, that’s why I said the 400 block is better. No one is telling him to use a 440 block. Only linked the MA article to show that later blocks should be thicker in the cylinder bores

Like it was said before just sleeve it my old R block had 4 sleeves in it

I'll tell you my block story. I've ran 570ish HP 440's for years (10.20's 3400lbs) and had a lot of luck with them. I'd split a cylinder or a main web once in a while and machine up another old block and use all my guts. After 18 seasons of this,(3500+ passes) I got the urge to go faster finally.

I thought about going Gen3 and did all the math. The engine build is about the same if you're starting from scratch,but the Gen3 you have to change the trans,buy headers,oil pan, trans sheild,a thousand dollar intake, the MSD box etc and it all adds up.

I went with the low deck 511 stroker since I had one of the good 230 blocks with the thick webbing I had been holding onto for 20 some years.You could see the core shift in the front cam tunnel bore. The block was good and thick, except right near one of the upper head bolt holes it was under .100" so I decided not to use it.Went through 3 other blocks before we found one that was suitable,the thinnest spot we could find was just over .200" thick.

Pump gas motor, no fill, Indy -1 heads and it ran good, 9.70's but it didn't last the full season and it split #1 cylinder down low on the thrust side.I finally found another usable block recently after checking 3 more. This one is getting a half fill and going together using all the same parts.

I kind of regret going low deck, the stock block has it's limits and the aftermarket block situation is not good. I think it's possible there might be some more choices coming up for the RB, but not the low deck.Looking back, if I had it to do over again I would probably go Gen3. The stock block is pretty stout, and there are so many around it's like 440's were in the 80's, dime a dozen.

I've got a 77 400 block I bought yrs ago & it sonic tested well. Been in storage at a local shop for years. GLad I didn't get an early version.

you think the long stroke and shorter rods had more to do with the failure than the extra power?
what rod length were you using?

See, that's what I was thinking as well, but what do I know.

(Personally never went over 3.75 until I got an aftermarket block, now I'm going way up to 4.500...but the reason for the 3.75 was much more about being broke, and much less about being smart)

Got a line 2 blocks. Little bit of a road trip to look at them in the Carolinas. Guy from on here MSGd me he has one. But it's in Oregon. Nothing local. Which sucks because I passed on 2 a while back. In regards to my build. Pretty confident if I can just find a good block. I should be safe block wise. It should never see over 6000. Though component wise it could go over that easy. Basically this gonna be low rpm tractor like torque engine. 100% Street manners engine with OD. I do appreciate all the input and advice from everyone.

My first pump gas 400 stroker 511 C.I. motor ended up needing four sleeves in it, two due to the block being blown out on the deck surface between # 4 and 6 and two on the other side(#1 and #7) due to bad pitting that boring it to 4.375 wouldn't clean out
I already had the 6.800 long BB Chevy type H beam rods and custom forged Ross dished pistons along with the Ohio Crankshaft CO 4.25 stroke low deck crank and I couldn't find another good 400 block so I went with having four ductile iron sleeves installed and I never regretted doing that I also had a set of Mopar brand Ductile iron main caps installed with ARP main studs
I beat on that motor from day one and it exceeded all my expectations and never let me down, Fast TOO
One of the past members on here, R.I.P. Dan couldn't, wouldn't believe me when I posted the first dyno testing results when that motor had a set of ported with big valves BB 906 heads with 9.25 to 1 compression ratio and was 511 C.I. with a low deck eddy six pack set up on it. That combination made 612 HP at 5500 RPM and 644 Ft. Lbs. torque at 4500 RPM on CA 91 octane pump swill
I ended up changing to four different sets of heads and ended up changing the crankshaft from the original 4.25 stroke to 4.300 stroke to raise the pistons up from -.025 down to zero deck to raise the compression from 9.25 to 1 to 10.29 to 1. I kept the same block,cam shaft, rods and pistons and I swapped the heads and intakes only after the crankshaft change the second year.
It ended up with a set of Indy SR Max wedge port size heads and a Indy 400-3 intake with a 1050 CFM Holley 9375 non HP Dominator carb. on it which made 727 HP at 7000 RPM on a DTS engine dyno on 92 octane Oregon pump swill in Klamath Falls, OR which is at 4300 ft. altitude
I now have several other 400 block stroker motors that I built and I'm looking forward to using on the street and at the track
BTW, that motor had a custom ground Com Cams solid roller cam that liked to RPM, I have shifted that motor with the 440 type heads and six pack at 7800 RPM and it wasn't slowing down on the RPM gain per second in second gear I ended up trying to shift it between 7000 to 7300 RPM from then on
That stupid motor didn't follow any of the normal rules for six pack motors, but it wasn't a normal six pack motor either
Don't be afraid to experiment

You guys can send me all these scrap blocks. I’ll find a use for them

I'm in Morristown and I have a 400 I'd like to get rid of.

I just bought two blocks today for $375. A guy on CL had a 440 block for sale for $200. Went to look at it and he had a second block that he also wanted to sell. Both are standard bore and super clean. He works at an engine shop and ended up with more blocks than he had space for.

Sent you a PM if you don't see it shoot me a call Im in Rogersville number is 423-921-4975 or send me your number

Good for you Andy got to tell you im jealous lol my area is dead right now for blocks it seems or they are just not putting them on CL or FB marketplace right now

Where is TN are you ? I’ll look and see if I can find one.

https://pittsburgh.craigslist.org/pts/d/avonmore-chrysler-400-engine-blocks/6788206442.html

https://pittsburgh.craigslist.org/pts/d/washington-mopar-parts/6821428094.html

Knoxville

Matt Hensley and his dad are as fine and trustworthy of guys as i have ever met
You are getting good advice.