Thinking of switch to a big block and I have read and read and read....a lot of guys say things will or will not last, but I want to hear from guys who have done it or are currently doing it, not just what the word on the street is. What block, low deck or rb? Caps, girdle, hardblock- some of those, all, or nothing at all? How fast or how much power and how long did it last?

I'm not looking for a low rpm grunt motor, but something that will make power wherever it wants to make it. Looking to run atleast 11:1 compression, and good cylinder head to make it all work, packed up in an a body in front of a glide or turbo 400. I understand a stock block is on borrowed time, but I would like to know how many are doing it and how long they borrowed time for

Real world experience- good, bad or lucky is all welcome! No b.s., just experience

We have three running 512's and a 526, all in stock blocks....

The 526 clipped off a 6.99 in the 1/8th on pump gas last week on an 11" slick in an almost all steel 65 Plymouth street car. Has ported reworked OEM heads too. Roller cam with over .600" lift 10:1 compression and a 4.10 gear....It has a girdle and my old 1000cfm carb. 440Source kit...RB block.

We also have two low deck 512's....Mine has the light weight 440Source kit and is around 10.8:1 with my Indy EZ1 heads and a .660 lift solid roller cam. Its light, and fits in my A-body better than the 512RB it replaced. Also has a girdle...Got a few 6.20 passes on it, and lost a couple pushrods and pulled it to go thru it. Should go 6.0's on pump gas. We will know next week.

The 512RB I have had in my car for 7 years. It was 10.8:1 pump gas with Indy EZ1 heads and the same cam as above. Went a best of 9.70 at 138.5mph with the Thumper carb 1050. Also runs a 440Source kit with a girdle.

Keep the revs under 6500 and they will live. Shift above that and cap walk is an issue.

Excessive RPM is the biggest killer. I have had my 500" RB to 6.8s in the 1/8. Been together 11 years with a couple of freshenings. Pump gas street car that gets the occasional KOS test at the local track.

Both my back to back 9.70 passes pushed the 512 into the 6700rpm range. I just rebuilt it, and cap walk was very evident on the middle caps.

Freshened it all up. not sure what I will do with it yet, but might end up in my Cuda if the Hemi sells.

Similar for us here downunder, have a 528 12-1 roller cam RB with 440 source crank, half fill, indy top in my 71 Barracuda full street trim just went 10.1 135 @ 3800 ft and 3750lb, 7100 rpm through traps, engine is around 5 years from fresh and lots of street miles.
547 RB 11-1 with half fill, indy top in Aussie Valiant around 3500lb best and last run 9.99 135.

I have split one block, it had the above 440source rotating assy in it but at the time we were spraying a 200 shot of gas into it running 9.2 @ 145

440 +.030 over. Indy 440-1 un ported, Alum rods, light piston. Stock main caps. .660 roller cam. With two plates stacked went 9 teens at 3600lbs. Still got it

With boost, you should be able to go mid 8's or mid to low 5's in the 1/8. Boost is usually easier on the short lock than nitrous,mat least a turbo

Keep it out of detonation, use a light reciprocating assembly. Use a turbo 400 for a low Buck trans as they are pretty stout in stock form. Use an electric shifter to go right to second off the trans brake. 1.48 and 4.10 rear is a great SLR. Also using the turbo 400 with a jw bell, uses a GM style converter, which is almost always cheaper than a Chrysler converter.

Not looking to boost it at this point...all motor with some spray maybe. I didn't realize I can't turn more then 6500 thoughand how bad cap walk could be doing so, that's something that may turn me away from it all. I know the low deck is stronger and fits better in the a-body, but the 440 seems like it would accept more cubic inches. I am not opposed to a half fill and aluminum caps since I currently have a half filled SB that sees over 7k and runs quite well teasing it with small amounts of spray and a way wrong converter...but if I really have to be super cautious about pushing it then it kinda defeats the purpose of changing engines for me. I really want to move towards more cubic inches and speed up, not change over and do the same as where I already am. That said, having the same performance but on motor alone would be awesome.


I have 2 glide cores so that's probably the way I'll be going even if I don't build a BB, the t400 seems like it would be harder to fit, but I haven't looked into it enough.


I appreciate the data and input so far guys, please keep it coming along with your opinions too...after all experience is great because it teaches you, so I'm all ears to what you guys have learned through it.

541 RB block with hardblock and main studs. Alum rods, 440source 4.5 crank and pistons. Been 5.90s on motor with Indy - 1

I'm efi so it has a good tune

Mine is a 68 383 block out to 496 with the Hughes main girdle, 440 source 4.250 crank, 4.31 bore.

Indy EZ heads hand ported, solid roller cam, 12-1 compression.

Has been together for around 10 years. Best pass 6.36 @ 107 in an all steel 65 plymouth. Also still a street car so I do drive it around a decent bit on the street.

I've built several 518 C.I. 400 blocks(4.375x4.300 stroke) and one 526 C.I.(4.380x4.375 stroke) 440 stock block, all had ductile iron main caps and ARP main studs. The 526 was built before I knew how thin the stock RB block main webs are
I will never build another stock 440 block with any longer stroke than 4.25 and only if it is a pump gas street motor that won't be ran above 7000 RPM I will limit the power with the heads and cam.
On building a stock block race motor I would start with a 400 block that sonic tests okay first and then add good main caps and studs and good heads That is for a build that will make near 900 HP on race gas and be shifted before 7800 RPM
Any more power or RPM above those numbers add a good after market race block
My next race motor built for me will have a Koleno block with 4.500 bore and a old 4.250 stroke Bryant top fuel crank(full counter weights ) offset ground to BB Chevy rod journal sizes and increased the stroke to 4.375. B1-MC heads with titianum valves and custom ground solid roller lifter cam shooting for 8500+ RPM
Hopefully it will make north of 1100 HP N/A on race gas or E85

I wish I would have bought a aluminum low deck block for my 512 street car, I want to boost it but don't want block carnage.

I put 30 psi on a stock block lol

AWESOME!! was it your daily driver in a 4100 lb pig & for how long ?

Nope! just a race car. Lifted the heads at 143 MPH IN THE 1/8. at 3100 #

Bottom end is still together.
Bought an Aluminum block and didn't look back. Now I run it harder lol

Stock block with a big arm is a gamble - sometimes it works good and lasts a long time. I think the key is a light weight - well balanced rotating assembly (less than 2200 grams) good fasteners everywhere - aluminum main caps - keep the compression below 13-1 and don't twist above 7000 RPM. But in the end it is a gamble - I have seen many stock blocks for no reason crack clear up through the mains and split the block in two.

Mine was only 500 cubic inches but it made it 275 passes running 8.60's in my daytona without any tricks. When I took it apart it was cracked up through the mains. Was still running strong when I took it apart for a freshen job and found the crack. If I ever built one again with a stock block (which I never will) it would have aluminum main caps.Now if I only wanted it to run mid 9's or slower no-adder I would do another stock block.

This is what it's looking like, a gamble...I understand anything stock block is a chance for things to go sour, but it almost seems like the small blocks can actually take more power....or maybe there are just more BB stock block carnage stories.

They work great if you keep the Revs down...Shift it like a pro stock and it won't last long.

Well I dont have over 500" but it just depends on how fast you want to go. I currently have a 451" 440 with aluminum Edelbrock victors unported , super Victor intake, Holley HP 950, .590 flat tappet cam, steel crank and Eagle H beam rods in a 3200# Challenger that has been 10.70s. Just pulled it out to freshen up haven't had any issues been together for years but I don't get to drive it as offen as I'd like probably has done more sitting than driving over the years but so far been a great combo.

Probably going to end up selling it when it gets out of the machine shop if anyone is interested... probably gonna jump ship and go Gen 3

I built a 535, which is 4.50 stroke 4.350 bore 440 block. It lasted four years till the crank broke. I did not rev it high though, 6,200 to 6400 max.
One VERY good thing you can do would be to buy a center weighted crank, then add some of the better bandaids like studs, aluminum caps, etc. A center weighted crank puts the balance weights where it is best, at the opposing forces, not making the block carry the loads to other bearings. I run one, and saw improvements in cap walk problems .