# 455 Casting/Block codes



## PPCRO (Jun 15, 2013)

Hey all -new to the crew. Just picked up a 66 Goat a few weeks ago and I'm trying to pull up as much info as I can on it. The engine is a 455 that was sent away 13 years ago to get built up by Rock and Roll Engineering. The guy I bought it from didn't have a build sheet but was able to provide some pretty solid information on the parts used. I also contacted RRE and they were able to dig up a cam card and a few dyno runs from the build but not much else. I'm now working on identifying the block. It's a YH 9799140 code engine, which from everything I've seen is a 1970 block used in a B-Body with a Turbo 400. Problem is, depending on where I look, it is identified as having either a 2 bolt or 4 bolt main. I would think since I had the block and casting numbers it would be pretty cut and dry but I guess not. Thoughts?


----------



## pete78 (Jun 14, 2013)

that block casting code stands for...

- Y = automatic transmission
- H = block made month, august
- block is 455cid from year 1970

Horsepower and Torque (from internet)
The 1970 to 1971 Pontiac 455 generated 325 and 455 foot-pounds of torque. The 455 High Output generated 335 horsepower and 480 foot-pounds of torque for 1970 and 1971. However, power steadily declined beginning in 1972 when Pontiac reduced it to 300 horsepower and 415 foot-pounds of torque. In 1973, a 250-horsepower 455 with 370 foot-pounds of torque surfaced along with a 455 Super Duty, which provided 310 horsepower and 390 foot-pounds of torque. By 1976, the 455 was limping along at 200 horsepower and 330 foot-pounds of torque.


----------



## jmt455 (Mar 26, 2012)

pete78, the YH code is not the date code. The date code is located next to the distributor mounting boss.

The YH is the engine code that, along with the block casting number and the casting date, identifies the block as a 1970 Model Year high-compression 455 for full-size cars.
As far as I know, those were originally built with 2-bolt main bearing caps.

The Engine ID pages at Wallace Racing-Drag Racing Pontiac powered Firebirds,Trans Ams and Dragsters are very user-friendly and have a lot of good info.

If you're really concerned about the mains, you should probably drop the pan to check them. Many 2-bolt main caps had provisions for 4-bolt attachments. You might find that yours have been drilled and tapped for 4-bolt main caps.


----------



## pete78 (Jun 14, 2013)

okay, thanks for correcting this. 

here is list for those codes
http://www.bassettracing.cz28.com/custom3.html


----------



## Instg8ter (Sep 28, 2010)

The main caps were drilled for 4-bolt mains and only tapped for two in the block i believe. Really no need for 4 unless you plan on making above 600 HP. Rods were the weak point in Pontiac motors, don't think they were making the forged aftermarkets back then and the forged SD rods were hard to come by, so you probably have re-con stock rods. If it ain't broke don't fix it, meaning if its running and still has good compression, drive it and start saving your penny's for the next re-build. Do you know how many miles are on it? What were the dyno numbers? You should keep a hard redline of 4800 RPM with stock rods and a 455 block.


----------



## PPCRO (Jun 15, 2013)

Thanks all. Just curious more than anything. Some sites I have seen identify the block as one of the few 4 bolt 455s Pontiac built. The motor was professionally rebuilt 13 years ago so it may very well have had 4 bolt caps put on if it didn't have them already. It made 515/546 on the dyno at that time. I don't race it so I'm not super worried but wouldn't mind knowing either way.


----------



## BearGFR (Aug 25, 2008)

Always start with the block date code first to ID the model year, then go from there. This is because Pontiac sometimes re-used the remaining codes in different years on vastly different engines. More than likely, the only way to tell for sure will be to pull the pan and look. Unless you plan on buzzing it well beyond 6000 rpm, it's not going to matter anyway. Pontiacs ain't chevys. Their 2-bolt caps are stronger/better than the chevy 4 bolt caps.

Bear


----------



## Instg8ter (Sep 28, 2010)

nice Dyno Numbers, should be a beast...no worries on the caps. Drive it and enjoy!!!arty:


----------

