help!

Hi everyone. First of all, a happy new year to you all. I am a new member, and was wondering if someone could help me. I live in England, and have just bought a 1980 t top trans am that started out life as a 301 turbo. The engine has long gone, and is fitted with a motor from a 1973 pontiac, and is coded XY. Could someone tell me what size engine this is? It sounds awsome, and has that lovely "I'm about to cut out" sound on tickover! Also, the transmission has an irregular shaped oil pan, and an elecric kickdown. does anyone know if this is a TH 350 or 400??? Sorry to sound a bit dumb , but info on these great motors is a bit thin here! Thanks, Alan.  

What is the head code as well as the block casting number the head code is located on the center exhuast port and the block casting # is located on the right rear of the block.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Alan, it would seem you have a nice combo there. If the motor is in fact from 1973, the XY code indicates either a 215hp or 250hp 455 originally equipped with an automatic trans. It should have 4X-1H heads with 114cc combustion chambers and 2.11" intake and 1.66" exhaust valves with pressed in studs. In stock form it has aprroximately 8:1 compression ratio. If you have the electric kickdown, the trans is a Th400, possibly the mate to the engine (your car came with a Th350-square pan with one corner cut off).
This combo should work nicely with the 3.08 gears that were standard on turbo TA's, if the cam is original a swap to something a little more aggresive and a nice free flowing dual exhaust will make this engine really fun. I can't imagine how many looks you get driving that around England, it must be a blast!
Steve  
A little help... 'cause we don't all have to learn the hard way!

Hi. Thanks for the reply, and the much appreciated information. I had a look at the heads, and they do have 4X stamped on them. I have a HUGE tin full of receipts for bits done and fitted, but they dont state anywhere what size the engine is, just applications 350 to 455. What I do know is (according to the receipts) it has an Edelbrock Performer RPM camshaft fitted, an Edelbrock Performer manifold, a Holley 800CFM double pumper carburettor (with a huge chrome air filter that goes through a hole in the hood) the pistons I think are 10:1 compression, (as that is what is stated on the receipt) but the part number is missing in sections, and again has the wonderful applications 350 to 455. I have tried to GOOGLE the number that is readable, but it returns no results, so not entirely sure.  Hooker headers that go to a balancing pipe (I think thats what its called) then onto a pair of cherrybomb silencers, then exit the car just before the rear wheels. Mind you, the word SILENCER is a joke, the car is deafening and sounds like a dragster! But you are right! I DO get some looks, and the car IS a blast!! Thanks again for all your help, Alan.  

It is most likely a 455 if you get the casting number off the right side back of the block I can tell you for sure.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Hi. Thanks for your reply. I have looked all round the rear of the block (as much as I can), including using a mirror, and can't find any numbers. To make matters worse, the block and heads have been painted a blue/turquoise colour, and I would assume this was done when the block was out, as it is a good job done of the painting!! Would all pontiac engines have this casting number, and if I scrub away with a wire brush, do you think it might become readable? I dont really want to "scrub up" the block if the number might not be there. Thanks again, Alan.  

If you look at the side of the block around the freeze plugs, there will be the number 455 cast in the side of the block, or 350 or 400. The block casting number is on the pad next to the distributor behind the valley pan as well as the date code.
Steve  
A little help... 'cause we don't all have to learn the hard way!

Hi guys. Sorry for the delay, but I had to go to London on family business, then my internet connection went. Anyway, back to the point. I have looked all round (as best I can) and all I can see is the following...On the LHS of the block, it says E (or) B053. On the RHS it says 485428 (last number could possibly be 3, but almost positive it's an 8) Hope this helps, and sorry for being vague but obviously the block is in the car, and it is difficult to see clearly. On another point, I have accuired (free) a set of heads I am assured are from a Pontiac. They have the cast number 7BS (or) 7B5 on the centre port. Do you know if these are indeed Pontiac heads, and are they better than the 4X heads already on the block???
Thanks guys, Alan.  

It is a 1973 455 215/250HP 8.1CR and came with a 4bbl carb.
As far as the heads there aren't any pontiac heads codes 7bs or 7b5 that I could fined are you sure of the code.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Hi. Sorry for the delay again, I live in Norfolk, but had to go to London for a while, so couldnt get round to looking properly. Anyway, I have cleaned up the heads, and the casting number on the centre port isnt 7bs (or 5) it is in fact 722!  As I said, they look like pontiac heads, but cannot be sure. They are very grubby, (hence getting the number wrong first time round) but they look in good shape. They have all the valves and springs etc, so if they are better than the 4X heads on the engine at present, it shouldnt be that much trouble to fit. Thanx for your help, Alan.  

Alan, it appears you have hit the jackpot! The 722 heads are 1969 Ram Air IV(4) heads! They have 71cc chambers with 2.11" intake and 1.77" exhaust valves and round exhaust ports. Assuming your 455 has .030" oversize flattop pistons, stock deck height and uncut heads, you will have 11.91:1 compression ratio! That's race engine territory, however, you may have dished pistons which depending on the design will lower the cr considerably.
Since you don't know the piston numbers, the only way to know short of a teardown is to locate a shop with a borescope. This will allow the technician to look into the cylinder through the spark plug hole to see what piston design you have. This is important due to the octane requirements of an engine with almost 12:1 cr. If you have flattops, you definitely need race gas, even with dish pistons you could be treading very close to the threshold on pump gas.
By the way your headers must be round port designs as opposed to d-ports, so if you have to replace them be sure to get the right ones. Regardless of all the above, this must be a wild ride, I am envious!
Steve  
A little help... 'cause we don't all have to learn the hard way!

Alan, I just read this thread.  It sounds really interesting.  Good find!  I wish someone gave me a pair of ram air heads.  I am curious to know how the project is going.  Let us know when you can.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

Hi. I have managed to get the car to a garage, and the guy has told me that the pistons are "flat top" design. He said that he couldnt find any "readable numbers" on the pistons, so said that they most probably are stock. I showed him the receipt that I have for the pistons, and he said that he couldnt be sure if they were fitted or not, and maybe the guy who owned the car before never fitted them. He did also add, however, that he is not used to working on American cars/engines, and should take it to a specialist. I have now ordered a head set off of a site on ebay, and am just waiting for it to get here from the states. I use super unleaded petrol in the car, and it runs fine! It is the same petrol that is used in old classic cars that have high compression engines, so should be ok. If I fit the 722 heads, will the compression ratio only be 11.91:1 if it has indeed had the 10:1 comp pistons fitted (as per my receipt that I have) and if the pistons are stock, what would the compression ratio be then?
Thanks for all your super help (again) Alan.  

Most pistons are rated for a specific combustion chamber size so without any manufacturer or part number you would be pretty much guessing. 11.91:1 CR is extremely high as street engines go, when you consider that only the highest performance musclecar engines got 11.5:1. Other things come into play as well, such as piston-to-deck height measurement, head gasket compressed thickness (and therefore volume), actual volume of the combustion chambers (they may have been milled). All of these things can stack up to create higher or lower CR than the standard "book" measurements and can even vary from one cylinder to the next. Ideally, all cylinders should be machined to get them as close to equal as possible, much like balancing the rotating assembly or porting the heads to get equal flow.
Assuming the pistons you have are stock or replacement flat-tops, the compression should be nearly 12:1 and the 10:1 rating would be for the same pistons used in conjunction with larger chamber heads.
Steve  
A little help... 'cause we don't all have to learn the hard way!

That is a nice find. Getting a set of ram air IV heads does'nt happen everyday!! I had a lucky experience myself with an old 70 GTO. Baught it as a parts car. ( body was very rough) To my supprise when I got it home and did some # checking I had just purchased a 70 Goat with a 68 ram air III, with the three speed and a 3:55 posi rear-end all for $200. The kids dad was sick of it in the yard and said it had to go that day. Glad I was the first one to stop by!!