Ok well my buddy has an IROC that he was told was a 350 TPI and I am pretty sure it is not. So where on the heads do I look for the casting number, and what is the head number for the 305 TPI's. Thanks guys, I know has been posted alot, but nobody ever really explains the casting numbers.

 

To be absolutely sure, you need to check the block casting number to tell whether its a 305 or 350. Look at the driver's side rear of the block directly behind the head and you'll find the #. Also, you may see a big "5.0L" or "5.7L" cast into the block underneath, or maybe not. There also could be a "305" or "350" cast into the block, or maybe not. You'll be best off to get the casting numbers and go to www.mortec.com Also, check the 8th digit in the VIN to see what the factory put in it. You'll have to take a valve cover off to get the head #.

 

If the car is all orginal, in the trunk open that little storage compartment with the lock, on the inside should be a list of codes, they are options on the car. If the car was a true 350, somewhere in the codes it will have " L98 ".

 

can someone please explain how to do this, like step by step, I've never worked on engine internals so I'd like to get it right. I've been told that my car was a 5.7, but being the fourth owner of my car, and with no one knowing what the first guy did to it(presumable the guy who swapped in a 350) but the person I bought the car said that the mechanic said it was a 5.7L. So, I'd like to check this for myself. Thanks guys.

 

If its original, the rpm guage for a 305 redlines at 4500 versus the 5500 redline on 350 engines. Could be wrong but thats what I have seen.

 

LnealZ28 just explained it step by step above.

 

do you need to remove anything to do this? i was looking "on the drivers side rear of the block" and could not find it. when you say "behind the head" you mean "farther toward the firewall then the exhaust headers" correct? or do you mean below the headers? do i need to remove my headers to do this?

thankyou for any clarification you can give on your allready pretty clear instructions.

my "5.7 350" just dynoed 172HP/249TQ. got me thinking

 

Its in the picture above. The shiny area is the head surface of the block. So... just behind the head, at the head gasket level, before the trans, thats where its at. The last 3 of the number is cast into the sides of the block between the freeze plugs. You should be able to figure it out from there and mortec's site. May need a cloth or towel to clean off any debris, sludge, etc.

 

i have been crawling around under that hood with a maglight and i can't find anything. my car is fully assembled.. do i need to remove anything to find these numbers?

 

Doesn't GM still put an engine SN on the front of the block?

 

http://www.mortec.com/location.htm

 

I think that I will add more confusion:

I have a 1987 L98 (350) IROCZ. I am the only owner.

My factory block is sitting on the garage floor. I jusy went out to check it for numbers.

The block casting number is located on the face of the block just behind the cylinder head on the PASSENGER side.. The number can be read from above the remote coil. The number does face upward, and the number is 14093638. You might have to move some wireing harness stuff around a bit to read the number.

On the DRIVER side, I have GM5.7L and nearby is F127. I think that the F127 is the casting date of the block. These numbers are located on the block just behind the cylinder head on the dvr side and also face upwards.

So check the VIN number is verify what engine was factory, then check the block numbers to verify what block is currently in the car.

 

If the engine is orignal try checking the VIN number (8th digit )
8= 350TPI
F= 305TPI

 

The VIN only tells you what it left the factory as, not necessarily what it is now.

 

yeah, my vin code 8 car just dynoed 172 HP. THAT is why i am investigating this. it appears as though some jackass may have put in a 305. i do know i have 305 headers... that will be remedyd soon.

so i do not need to remove the coil to see the numbers. wicked! thanks. i'll go investigate that right now.

 

ok, when you say "remote coil" you are talking about the coil that has the 9th spark plug wire on it right? the one right next to the distributer that feeds ~48K volts to the distributer cap. thats where i looked. i moved all kinds of things, i even pulled the coil out, there is nothing there. is it under the bracket? even if it was right near there it would be on the cylinder head not the block.

i don't supose anyone has a usefull picture of a block casting # do they? the one posted above lets me know what it looks like but it is so close in that i cannot tell where it is. sorry to be so inept, i am not a mechanic, and my engine is still in my car as it is a daily driver. if anyone could give any more help that would be great. i would realy like to know what engine i have.

EDIT* also there appears to be some confusion about what us non-mechanics mean by "step by step" for me "next to the whatever, there ya go" is not "step by step". i'm looking for instructions like, "look at top of engine, remove plastic thing at rear of plenum, unscrew coil, remove lower coil bracket where it goes into cylinder head...." that kind of "step by step". i know thats alot to ask, but hey once it is done realy well, i promise to take like four realy good pictures and post them, that way if anyone ever asks this again we will have the diffinative thread on the jubject we can link them too (or yell at them to search for)

 

The block extends beyond the cylinder head in the rear.

 

in order to see any of that portion of the block you are refering to do i need to remove anything? will this be at the same level (height wise) as the cylinder head (part intake comes through) or the exhaust headers? when people say "heads" i get confused, as "heads" could be cyllinder head or headers. i ask because as was looking around before there was a "cliff" and then another surface extending toward the firewall, i saw nothing there, though i will admit i was under the impression that was not where they were so i was not looking as hard as possable. i think i'll go re-investigate that area right now.


thanks for your continued attempts to make me understand this Apeiron. eventualy i will find it (i hope).

 

oh, ok. after going out for another look i remember why i did not investigate that area clearly. in order to see the area you are refering to i will need to move the master engine wire-harness, this requires removing the coil bracket from the cylinder head, completly. and i will also need to pull the hose out of the top of the heater core. is that what i am going to need to do?

if so it will have to wait a bit, i don't have a stardrive big enough to fit the bolts that go to the coil brackets, i'll have to do it at my dads house.

 

Your on the wrong side. Driver side. Behind the head. You dont need to remove anything. Just dig and look good.

 

"heads" are cylinder heads, not/never headers. Headers are headers. - Should be driver's side. Right up "against" the firewall. Its below the head, at the level of the mounting surface of the head. As in actually on the engine block, right where your transmission bellhousing bolts up. - also, you said you have "305" headers...this looses me because 305's and 350's use the same headers. Everything is the same between a 305 and a 350 except the bore size of the block. All other hard parts are the same.

hard parts meaning actual engine components.
- note: 305's have smaller ports/chambers in the heads, I'm just talking generals....

 

172rwhp out of a basically stock 350 TPI w/ mileage is not very far off. You have to remeber these things only made 245 flywheel hp brand new, which was atleast 14 years ago, 18 for your 88....

 

sorry, yhat was the headers/heads thing again. i was told by a guy in my carclub that t might have 305 heads. i'll ask for clarification on that.

 

well, ok. i found somthing it was in the described location on the drivers side. it says I267. i had to move some sparkplug wires out of the way, unplug the vaccumme line to my break booster, unplug the bellshaped thing next to the distributor (would have been easy if i could remove it) and twist my hand into positions *** had never intended to scrape the grease of of it. there was also an AIR line in the way that i would have just removed if i could, as my AIR is disabled anyway. sucker is bolted down good. anyway i'm off to that website to find out what the heck this means.

 

oh.. it means my STILL UNKNOWN block was made on sept 26th 1987. well it stands to reason that it is the original engine then. thats good news. i would still like to find out for sure though.

this image is from mortec.com


you can quite claerly see the casting number in this image, i was looking at that blury number on the far right, at an angle. the place where this number is located is COMPLETLY covered by an AIR tube. it may be posable to see this casting number if i pull the valve cover...... maybe. other then that it is completly imposable on a fully put together car with all the factory options. there are just to many things blocking every angle.

has anyone ever seen the casting number in this location with there engine in there car in full running condition? if so what did you have to remove? please help me

 

My car with an original 305 (now has a 350) had a dash gauge stock with a 5500 redline, i read somewhere it was becuse they put a hotter cam in some of the engines...possibly the stock L98 cam.

 

Have you tried a flashlight and a small mirror?

 

holy crap that is a good idea! i even have a small mirror. it is on a teliscoping pen thing. like one you would have a magnet on to grab screws from behind your work bench. i've never even pulled it out of the box. dang dude thanks. i'll try that tomorow in the daylight. the only thing i think will hinder that is that i had to rub the casting date for like five minutes with my finger nail to get the oil off of it to read the danged thing. to tight of a space to get a rag or brush into. but i'll give it a shot.

 

hey xopher, was it a mustang dyno or a dynojet you dynoed on? If it was a mustang the numbers are always lower than what you'd typically expect.

 

dynojet. my carclub (www.cascadecrew.org) had a dyno weekend. i think all in all we put 12 fbodys up. and a 2004 hemi dodge ram.

 

huh yeah that's strange. Was it standard calibration or was it calibrated for tire friction as well?

but that's strange you only pulled 172. im usually seeing L98s at like 195 or so.

 

i don't know.

 

Did you get any torque figures? Or does the dyno only give HP with the engine in the car? Just curious.

 

I was at a mechanics shop one time looking for parts and saw a black gta up on wheel stands, I asked the guy about that car to see if they were parting it out and he told me how it was a 350 tpi and they just pulled the engine to put in a c4 corvette, I checked the vin and the sticker under thee hood and sure enough it was a 305 tpi. Somewhere in Florida there is a c4 vette running around with a a 305 tpi

 

A sadder thought is the stock LG4 Corvettes running around in California.

 

172 HP
249.1 LB/FT

my air fuel ratio was pretty much dead on where it was suposed to be too. little rich at idle. never got to lean though.
it was 52.06* outside temp when i ran.

 

Engine spec's on a 5.7 should be (stock) 230hp, 300ft. lbs. torque W/TPI. A 305 is 190 & 240. I'd say your figures are pretty consistant with a 305 and a good set of headder's. Any luck with the mirror yet?

 

have not tried it yet. been working on my 2.8. and can't find the mirror. also, the headers are STOCK. so they are not "good headers" or anything. the only things not stock about this engine are things removed (ac delete, air delete).

 

If they're stock, then they're not "headers", they're manifolds.

 

Not sure how easy they are to see on the TPI engines, but the suffix code (guaranteed the Mortec link with number locations shows it) is typically a better bet than casting number, as it tells you more about the engine as built.

Casting numbers work, sometimes, but suffix codes aren't used in a multitude of applications like casting numbers. They are sometimes "recycled", but it's not real common.

 

Stampings also get lost if the deck is milled in a rebuild.

 

I have an '88 GTA with a confirmed 350, and it put down a whopping 176HP, stone stock. It also turned a 14.7 in the quarter. That's all right in the ballpark.

On the drivers side, in back of the valve cover. down on the "deck" of the engine. You will need a mirror, and probably need a can of brake cleaner and a rag to clean it. Look for a 5.0 or 5.7. So many variables, either could be producing that HP, but the torque makes me think it's probably a 350.

 

can't you tell by the size of the harmonic balancer?

 

BONZ

The LB9 305 came with 2 different cams. (roller)

small one int dur 179@0.050 lift .350

large (or larger) int dur 202-207@0.050 lift up to .415 (I think. depends on years)

The tach yellow line started at 4500 or 5000



just FYI



Art

 

pretty quick here the "manifolds" are going in favor of some tubage

 

Unfortunately, the tach is a terrible way to determine what cam was in the car. GM was not consistent on what tach they installed with what engine, my 86 is a prime example of this (supposed to be and was a peanut cam car). 5500 redline, and its the original tach and cluster. Another member has the same car, same options, 5000 redline.

 

Have you ever crawled up under the car??Blocks origionally in that era had the last 3 casting numbers of the block in big numerals on the side of the block(usually upside down too).627 for a 305 and 638 for a 350.Ive even seen 305's stamped 305 on the side of the block and some 350's that say 350.

Jack it up and slide under and look for big numerals on the drivers side of the block(easier to see than pass side) between the oilpan and the head right behind the motor mount(toward the rear of the block).