What kind of webbing is this 400
 

OK guys is this average,weak or good main webbing for a 400? Looks average to me, but I didn't have another block to compare with.

Looks to me to be the thick version.

Looks like a great candidate for 4-bolt splayed caps. Got any pics of the lifter valley?

I'll get some tomorrow Brian.

what is in the lifter valley that differentiates block to block? thanks Brian

Sorry but...........
 

looks to be the thin casting block. support under the main caps in the area under the cylinder bore. Pics are too far away. Need pics closer to the cap mate area under the cylinders in #2. 3 & 4.

I have found 4 basic 400 casting blocks. Need to take pics before I build and sell them all to customers and put on my website?

What's the date code by the distributor.

From what I see it would be good for a bacic 455 conversion with a mild cam or a 350/375 hp 400 combo.

That works for the 455 blocks and still have to check other ares on the 455's. But if Brian tells, I'll have to kill him. LOL.

I'll take some closer, but you can see the #2 main cap front and back side area.

It has less meat in the main webbing area than a 68 block or a 72 junk block I have laying around. I you look at the first pic you posted, you can see a 'step' where the cylinder ends, toward the middle of the block. Neither of mine have that but have metal there.

P-dude, I have a thin web 400 I was considering installing your stroking kit on, so I take it that it works fine? I would be looking for substantially more than 375 horses, though!

Is it possible to weld it up for more strength?

Here's closer Ken

Jeff can you snap a picture?

here's lifter valley on a 72 HO block

I wouldn't recommend that block for any higher hp applications. No support under the cylinder bore to the pan rail. But for a mild rebuild as i stated above shouldn't be an issue.

birdzz:
I wouldn't do the 4.250 deal with that block. But a 455 conversion with 9.0-1 compression, under 375hp and 5200 rpm won't be a problem.

FWIW: You can run real low 13's making 350/375 hp in basically stock chassis car.

Just bottom fill the block, deburr the block, ARP studs and have the line bore checked.

Dude, you may have just solved some of my problems with the mains on my sprint boat

All centred around #2 which looks like where Skips pic was taken. My block looks the same in this area. Using factory mounts at the front (either side of #2) the mains were moving around alot and cracked the cap outboard of the dowel on this side

Can you confirm if the "thicker" blocks have more material along the pan rail (shown "A" on my marked up version of Skips pic) Mine has "bosses" for the mount holes as per the pic also which wouldnt be visible if there were more meat there. I know the 58 etc blocks have more meat here and are looking for one here for a new boat engine build as we dont need a starter mount or any factory side mounts

Also does area "B" differ ? My current block (73 YT code) appears a little thicker here ?

Any help figuring this out would be great

Forgot to post pic (cheers Skip)

I was thinking the B area was the area toi lok at. Although I had a 70 block that to me didn't look much different, and the caps actually looked thinner to me.

My 72 455 block is on a roll araound with a pan so I can't look at it.

Anyone else got block pics??

Here are some pics from my spare 67 400 block. How is that look?

OK to me the 67 has meat all the way to the dowel whereas this block is just to the bolt area. The rails are thicker under the bore but I would think the main cap area is the more important area. Kins of subtle differences.

Skip, I also have 2 70 blocks at my dad's house. If you want I can get pics later on. To me, I really dont see much difference.

Definitly alot more meat along the pan rail below the bore in the 67 block compared to my 73 YT block (area "A")

On mine the bosses for the motor mount holes show up clearly and the rail is thinner

Hmmmmmmmmm

I posted a long time ago about the merits of the 67 block.
Maybe this post will clarify some of my thoughts in that area.

Tom V.

So is a 67 considered to be among the strongest 400's? I ask because I want to build a (relatively) bullet-proof shortblock (and I'd like to stay with a factory block) in the near future to support cranking up the boost on my 6-71 and possibly adding a bit of squeeze too.

I went out and looked at all my blocks,all had thicker bulkheads than Skips block,most are early '70's (1-350,3-400's,1-455) blocks,one of them,a '70 YS 400 block was obviously thicker and cast differently from the later blocks,it looked more like the '67 block pictured by SergeF,but it still had some slight differences from that one too.

I tried to take pics but most turned out terrible,I'll take more tomorrow and post 'em,I'll try and get the year,and block casting #'s as well.

I'll dig thru my stored pics too,might have a pic of the bottom end of the 455 I dropped into my firebird not too long ago.

Gotta go,need sleep...:sleep:

Two blocks here, an early '67 "WT" - #9786133 ... and an early '75 "YJ" - #481988.

Comparring them side by side I noticed some VERY interesting differences, particularly in the parting lines. The two blocks look the same but the molds were structured quite differently. I'll post some images later today after another project is finished.

Here's a couple pics of the block from my race car. It's a 1969 block.

Looks like the material out to the dowels vs the bolts is the biggest thing showing up.

You guys have me nervous now! I just finished building my early 1975 400 block,I thought it had the thicker webbing,now Im not sure.Ill post the date code later if anyone could help.The motor is already done so I guess it would only be for peace of mind at this point.I did fill the block and stud the mains,looking for around 550-600 hp keeping it under 6000rpm.

My '70 YS block looks to be virtually identical to the pics of Jeff Walker's race block.

The bottom end on the '70 YS is still assembled,but that's the spittin' image of the casting it uses,his pic is better than what I'd get,really did'nt wanna break it down just for this deal,so that pic saves me some effort.

Only visible difference is the '70 block has the extra motor-mount bosses.

I'll be back with those pics a bit later.

My block(actually a brand new one) is a 76 casting made in 77, and the same casting my original 78 TA 180 hp had. I wanted opinions before I said what year it is. I'm glad we have some pictures to compare what areas are different.

I just looked at my date code again- I165 and casting # 500557.It looks like it was made in sept. 1975,I misread the code before.Dude could you chime in on this,I was planning on racing this one.

500557 is not the thick one. I have one with the same casting number, and it's got good thick cylinders, but not thick under the caps!! I was planning on using mine to race too, but discovered I have to look for an earlier one.

I really don't know about the date and run of the blocks.
I just go by looking at the webbing area. You will also notice that some blocks have the same meat under the cylinder and have a wider casting to meet the cap. In other words I have seen some blocks that are narrower then the cap and some that are the same width. Some that are wide then cut narrower right after the cap area on the block to the pan rail.

As far as how much abuse a certain thicker casting block will take over another. Your guess is as good as mine. ;)
But bottom filling, deburring and studs to offset loads can't hurt.

Most I have encountered split right up the middle to the camshaft or from the dowels to the cam.

I selected a block that a machine shop had and held for me for 3 years. I was ready to start on that engine, dropped the pistons & caps off, and when I went to pick it up it was a different block then I had originally picked. Mine's a 77 block, and the cap area is narrower then the thickness of the caps. I filled it to the bottom of the freeze plugs, studs & 4 bolt aftermarket caps, and I'm going ot throw it in my driver with a 3" stroker kit & e-heads. I'm going to spray it with a 150 shot and cross my fingers! Oh well, it's what I ended up with, and don't feel like throwing it in a corner. Think it will last if I don't put slicks on it?

You guys act like the thin block is a BAD thing...

Here is my '75 block from this spring. The motor was two years old...

The car is my daily driver mid/high 12 second 3000lb car. Fairly mild really..

-Abone.

http://img.photobucket.com/albums/v7...missnchunk.jpg

Good luck. I have split 2 of those kind of blocks. Not trying to be a smart a$$ but, Personally I don't know why the shop 4 bolted that block? Makes it even weaker in that area.

when did they stop makin the the thick version block? i have a late 72 400 that i makin a 416 stroker

I have heard 1974...but I dont know. I do know that a '74 block (may be a '73) that I have appears to have more meat than the one Skip posted pics of.

Well,,,after some frustration with my digicam I'll post my pics.

First set is my race cars 400:
casting= 481988
date code= D093
Code= XN
application= '73 230 HP,A/T,4bbl.

Next,spare 400 bare block w/caps:Valley is the same as race 400.

casting number= 481988
date code= l053
code= YH
application= '74 190 hp,A/T,2bbl.

And for now my spare 455 block,bare w/caps:

casting number= 485428
date code= ?183
code= YU
application= '74 250 hp,A/T,4bbl.

I'll get some pics of the YS block up later,the lighting back there is giving me fits and I had to take about 40 pics of each to get usable pics,so the batteries are getting low.

HTH.

My '74 455, pics are not great but maybe you can see something i cannot.

Looks like the same basic casting as my bare 455 block, casting #485428,the Pete McCarthy bible says that casting was used '71-'74 in non H-O or S.D. applications.

Also the PM bible says the change from the #481988 400 casting,to the #500557 casting was mid year '75.
The "late" (post #485428,'75 and up) 455 block info is a bit more sketchy though,I think that's that "double top secret" info Brian and Dude cryptically refer to from time to time,though I do recall Brian let that info out on another board somewhere once,but damned if I can remember where,so I cant prove it... :-ohwell:

But I did get the "gist" of what to look for,maybe I gotta go out to my friend's place,he has a bunch of core motors around and see if I can dig up some pics and blow the lid off that,,,ahhh who am I kidding,,,too damn lazy for that,,,at least till it cools off around here....

500557 blocks were so bad, Pontiac went back to the 481988 for the 78 Trans Am. I'd only use a 557 block for a very mild application. We actually run one in my son's 67 GTO with a RA IV cam and 6x heads. Runs high 12's but makes me nervous!

Pontiac Dude - Exactly my thought, why the heck did they work it and put caps on it. Like I said, I selected a block, was a 69 casting, waited 3 years, and when I dropped the stuff off to have the machine work done, they did that one. Not even going to go into it, and I'm sure it was a mistake. Someone else must have gotten my block though. So you say to bail out on the block then? Would be destine to grenade? What power level do you think I can get away with? Just do another block?

Flamedabone - What were you doing when that let go? Hammering it? Spraying it? Was that a 4.250 stroke engine? And the block was sonic/mag'd when you put it together? Doesn't really look like 4 bolts/studs would have helped that?

Im pretty upset I put the time and money into my '75 block now,I guess I could swap the rotating assy into my '70 455 thats in my Lemans and is pretty much street duty now-its due to be freshened.What do you guys think,roll the dice or spend more time and $ to build another motor?

Mine is a 500557 with a 77 casting date. It is the same casting number as my original 1978 TA motor also. Ol Pinion Head said that is the most common casting he has seen pulling motors through 78 except for the TA 6.6 motors,eventhough McCarthy has different ones listed for later years.

Even that 74 looks stouter to the dowels.

I can't tell one what to do with their stuff already done. Not my call.

But I would never 4 bolt that kind of block if a customer brought me one. I would send it back out the door or tell him to keep it for a mild 455 conversion or mild 400.

It might last one pass or 100 passes or 1000 passes. I'm not Carnak. LOL.

I just got done pulling apart my 400. This is a 76 block. It's cracked in the exact same place as flamedabone's pic. It looks like the pieces would interchange. LOL

I'm shopping for a block as we speak. If anyone has a 68-71 400 2-bolt block, std bore they want to get rid of, let me know...