My car originally came with a 307, but I was wondering how can I tell if it might be a 350 or not without yanking the heads? THanks

Read the engine number (on the deck surface in front of the passenger's side cylinder head). It won't spell out which engine it is, but I'm sure that someone here can decode it for you.

I was told that the engine in our el Camino (not the original) was a 350. The block is a '68 327 piece according to the casting numbers. The heads are '73s. Now, what do I have? I wouldn't mind finding out too.

Keith,
Some 68 4in bore blocks were used for all three: 302-327-350. So, just about your best way to determine what it is will be by the stamped code on the stamp pad, OR, remove a head and check the stroke.

a 307 has a smaller balancer than the 350- but i think 283's and lo-po 327's have the same setup as the 307.
that is about the only easy way to tell it isn't a 350 from the top, but balancers are interchangeable and easily swapped.
also, every different stroke crank has a different shaped counterweight at the back flange, but i don't know how to tell the difference. of course, the 307 has the same crank as a 327, so that might not be to helpful, either.
in the end, i guess you could pop off a valve cover and look for head casting #'s, and look up the stamped number on the pad next to the water pump.

You could get a rough stroke without pulling the heads. Pull a spark plug and slide something into the cylinder (a clean smooth stick or something) rotate the engine, mark the stick at the highest and lowest point in travel. Just try to keep it in the same place inside the cylinder for measurement. Measure the total distance traveled. If it is about ...

3.5" ----------> 350 or 305
3.25" ---------> 327 or 307
3" ------------> 302 or 283

Then checking the block casting numbers can give you the bore size and narrow it down from there.

Post back the letters at the end of the long VIN number string that should be on the little deck pad that is right above the pass. side top water pump bolt and we will decode it if it is still a virgin..

pdq67

OK there is one way to tell but only if these havent been changed. The 307 used a different motor mount than the other small blocks. The others had a safety feature that would not let the engine lift too far if the mount tore. It looks like a big T that would interfere with the metal sides of the mount so that it would only lift until this tee hits the sides of the other half of the mount. 307's were the only small block that came factory without these "T" tabs. (as I have read) although I have seen them on about everything because they are cheaper and will fit. So if you have these mounts chances are it may be a 307. Bill

Post back the letters at the end of the long VIN number string that should be on the little deck pad that is right above the pass. side top water pump bolt and we will decode it if it is still a virgin..

pdq67


two sets of numbers and codes here they are


C5S167007

V0506T F

get the casting number off the back of the block by the trans and i can tell you what the block is or originaly was.

two sets of numbers and codes here they are


C5S167007

V0506T F

First set of numbers......normally the first set starts off with a 1 instead of a C....maybe it's an old time thing? Can anyone please verify?

Otherwise: 5=year (1955, 1965, 1975, 1985....etc)
S=assembly plant (dont have codes)
167007=last 6 of the vin the car it came from

Second set of numbers:

V= Flint
05=May
06= 6th of May

Code TF comes up as a '55 265 or a '57 283.

I also tried just code F....again same thing...'55 265 or '57 283....

Post the casting number off the trans flange it'll help narrow it down....

C=Chevrolet Truck Div.
5=1975 model year
S=St Louis assembly plant
16007=Vehicle sequence number

T_F= For '75 trucks I find three possibilities:
TKF= 350/145hp 2bl
TZF=350/160hp 4bl LS-9
TMF=350/160hp 4bl LS-9

307's were not made in '75

Don't know what it is??

pdq67

get the casting number off the back of the block by the trans and i can tell you what the block is or originaly was.


Ill do this as soon as we yank the motor out.....


I bought the car a year and a half ago and they guy wasnt the original owner so there may be a different motor in it... Thanks for all the info so far, and I will post the casting number as soon as I can get to that part of the motor and see it(probably when I yank it out?) As for the exact spot it should be? Does anyone know or have a pic of this area so I can get the number back on here faster?

It's on the driver side top bell housing flange. If you get in there with a flashlight and/or an inspection mirror you can see it.

Might want to pull the valve covers and see what head castings you have as well. Think the 307's all came with heads using a 1.7" intake, 1.5" exhaust. If you have a head casting with 1.9" valves, it's more than likely a 350.

It's on the driver side top bell housing flange. If you get in there with a flashlight and/or an inspection mirror you can see it.

ok here goes GM 3970010

that is all I got is there more somewhere else??

Good news you have a good block number that is a 69 - 80 302,327 or 350 2 or 4 bolt main. If all checks out on the inside stroke it!!!!!!!!!

You can look that number yourself here http://www.mortec.com/castnum.htm

I took off the valve cover on the drivers side and got these numbers

GM 51

3927185

F19 8

Use the same site and you will find your heads 69- 76 302,327,350 70cc chambers. Just continue to scroll down

Bill

Use the same site and you will find your heads 69- 76 302,327,350 70cc chambers. Just continue to scroll down

Bill
Is there anyway to check which it is without measuring the stroke, and without yanking half the motor apart? Thanks for this great info by the way! Jeffrey

a 307 has a smaller balancer than the 350- .

This motor has a huge balancer Im talking at least one inch thick

from what i have found and if it has a monster balancer i would asume its a 69-80 truck 350 with either 2 or 4 bolt main. It dose have the same casting numbers as a 69 z/28 302 4 bolt main and a 69 truck 327 2 bolt main when you pull the engine pull the oil pan and at least it will narrow it down by the main cap bolts or get some pics of the balancer and crank posted and others could tell for sure exactly what it is!!

I would agree, it is most likely a 350. There were just many more made.

The 307 used a different motor mount than the other small blocks. The others had a safety feature that would not let the engine lift too far if the mount tore. It looks like a big T that would interfere with the metal sides of the mount so that it would only lift until this tee hits the sides of the other half of the mount. 307's were the only small block that came factory without these "T" tabs. (as I have read) although I have seen them on about everything because they are cheaper and will fit. So if you have these mounts chances are it may be a 307. Bill

Depends on the year. ALL small blocks (and, I think, the big blocks, too) came with the crappy mounts up to '66 or '67. GM had a very extensive recall campaign because of the number of broken mounts causing serious damage/deaths.

'68 to '73 307's used -185 heads too!

pdq67

yeah pdq67 but that engine casting number was never a 307 only 302,327 or 350

Gotcha guy..

pdq67

Borderbum it sounds like you have a 1975 350.

As I posted earlier the partial vin stamp is for a for a '75 truck.
That means it was a 350 originally.....

Thank you for the replys, I will post a pic of the balancer in the next day or so, so you guys can tell me for sure, I wanted it to be a 350 to tell you the truth, cause I wanted to be able to have a good core 350 to build my first engine with and I couldnt get one any better,,,,,just needs resealed and Ill add a good cam etc and Im in business. thank you all for the info and I will get the pic of the balancer tomorrow.

http://www.t-mobilepictures.com/photos/photo11/d7/10/8bc5d240f9b3.jpg?_rh=4q6kpv5hhevure2jhghxqlgi2

here is the pic of the ballancer, this is the big sucker that is used on the 350s right?? Thanks

In the thread above some were waiting for my pic of the balancer on the motor to make sure it was a 350...wonder if anyone else can help out if these guys are off somewhere. Thanks. Jeff

My car originally came with a 307, but I was wondering how can I tell if it might be a 350 or not without yanking the heads? THanks

3 pages of replies??? come on guys, this is VERY simple.

Borderbum, just crank the car and pull out into the street, and stomp the gas pedal. If nothing happens, you have a 307.

3 pages of replies??? come on guys, this is VERY simple.

Borderbum, just crank the car and pull out into the street, and stomp the gas pedal. If nothing happens, you have a 307.

HAHAHA you are not far off for sure...My motor 350 or 305 or 327(due to the codes we have come up with on the motor) has no compression anymore...I think we are down to the last bit of information that will spell out if it is a 350 or 305/327 with the size of the ballancer......

bump

Looking at the balancer it looks like a 350. Now it is time to disassembly the motor to make 100% sure. Time to get dirty :D

Bill