400? 455?

I was told the later year 455 blocks had more nickel in them and were great for a 500 hp application?

I also read somewhere that a 400 block was better to build because the smaller berrings were better for the crank?

I figure If I'm goign to dump $4000 in to a motor and have it built 'right' I'd start with the better block and setup I can get

suggestions?

Early 400 blocks were nickle content related. 428 as well. Most Pontiac machinists attest to 67-72 as being the best blocks.

whether you choose a 400 over a 428 or 455 depends on what your goals and budget are.

The smaller bearings produce a slightly less amount of heat. With the stroker cranks it makes the desicion even harder. I would look for a short cut to make the decision easier. Like if you could find a project engine that wasn't assembled but all the parts were bought. Not a box of rocks. Something with receipts and great parts. I saw a nice 455, new and ripe for the pickings that could have been bought for $3500. I would leave my mind open and look for deals. Sounds like you have a 'clean slate' to start with.

One give-away are small journal blocks drilled for 4-bolt mains. These were the blocks that were set aside for Ram Air and HO motors. This was done at the casting foundry after the blocks had been cast and inspected. (Only the "best" ones were set aside.)

As the produciton run neared its end, these blocks were used up for the more common 4-Bbl. applications. Most common (that I have found) are the YS & WT bolcks with late '69 & late '70 production casting dates. Neither of these motors have 4-bolt main caps, but many were drilled for them, attesting to their higher than average quality as deemed by the foundry.

Though you don't need the 4-bolt mains, these blocks were considered "better" at the time they were produced.

Just food for thought.

i pointed out in another thread that covers this subject. i reqad alot of mags and came across one i bought but never peeked at. it covers the topic of using a 400 block and converting it to a 455 using a stroker crank. the give all parts number, prices and a detailed build up on the subject. the cost is in your range and you will be able to source the 400 block easier than the 455 block.

andy

Here's an example of buying the complete deal. Right near your price range.

http://cgi.ebay.com/ebaymotors/PONT...Z018QQcategoryZ33615QQrdZ1QQcmdZViewItem

My car has a YS block in it of that era. I wonder whether or not it's drilled for 4 bolt mains.

I have 2 YS and one WT block, all drilled for 4-bolt mains, all cast in the middle of 1970 ("D" "E" and "F" casting dates.) All of them have 1970 400 block non-Ram-Air-IV casting numbers.

What is the block casting date?

I think they made a boo-boo when they listed the main, rod and piston clearances - .030" is a little much!

The rod and piston weights sound heavy to me too.

Do you guys think they are legit, or do they just know how to paint a motor real pretty? I've seen thier e-bay ads and have been tempted.

Well, I have a 76 455 block. Is this a good one to build? I'll have it pulled out of the car by the end of the week, will check numbers/ main caps

Well, the motor Jim listed sold in what, 1 day?

Looks like the guy who bought it will be putting it into a GTO

I saw that other one like it up with a buy it now for $3500. Just before the holidays and it just sat there. Last time I built an engine I started with a really nice used 428 and then dumped over $3K in it. That was a while ago and prices have almost doubled since then. These guys are not making money selling these engines for these prices. They must have either changed their minds on what they wanted or parting out someone's unfinished project.

PMI: I'm worse with numbers than at spelling. Where is the block casting date located? Saves me from breaking out the book or googleing.

The casting date is to the right of the distributor between the cylinder banks.

It's too grimy down there to deal with right now. I'll peek if I get around to cleaning up the area.

Merv -

Here's a picture of the casting date on the block. When I said the "right" side of the distributor, I should have told ya I meant as you're looking at it from the front.