When i go to put headers on, i will be able to see the exhaust ports. are 350 ports bigger than 305 (specifically L98 v Lb9) ? Is there any other way to tell displacement other than casting numbers (decked block) and pulling the heads.

 

If you know the engine is original, check the 8th digit of the VIN #. A 350 will be an '8'.

 

It was an L98 car, but the motor was rebuilt. Chances are that the original motor did not get switched with a 305 either fradulently or accidentally, but im paranoid...

 

The exhaust ports will be the same 305-350. The only ways I know of is to trace the casting numbers(mine has GM 5.7 on the rear of the block on the drivers side bank) Some have numbers elsewhere also. That, or you gotta pull the heads and measure the bore. Some people claim the 305 uses a smaller balancer, but I've seen 305's with the big balancer also. Sorry, but I don't know of any other ways. maybe someone else??

 

speakin of exhaust ports, the bigblocks had oval ports and sb's have rectangular square ports corect?

 

Not always. Some BBC heads had "D" shaped ports. Many had rounded or oval ports (exhaust). Some SBC engines had "D" ports and some had oval ports. It all depends on the head casting.

 

related question... how can you tell if your engine is a 305 or 350, ignoring the vehicle vin??? (my engine may have been replaced) is there an eaiser method than getting in their with a flashlight and a couple mirrors to get to the # on the block?

 

May not be simpler, but you could always unbolt your tranny mount and jack your tranny up to the floor (which inturn tilts your motor up in the back) and then look at the back of your block it might give you enough space to see the block casting #. Maybe that is too much work.

 

.....oops double post, damn back button

 

Casting number aare usually reliable:



Check the number at www.mortec.com

 

Hey Vader. Thanks for the pic... one thing i couldn't figure for sure though... What precisely is that pic of? (whereabouts on the block?) is the # in some abscure place i can't see with the engine in the car?

thanks


Edit:

I found it , never mind.

I got a 305

 

See the flywheel? Here's another hint: The dial indicator is over the #7 cylinder. You should be able to see it without disassembling anything, just a little contortion.