is it a 305 or 350?
 

i just got another iroc and it originally came with a 305 tpi auto, but the guy i got it from wasn't sure if when the engine was rebuilt a 305 was put back in it or a 350? so i just wanted to know how could i check and see if it is a 305 or 350

Re: is it a 305 or 350?
 

There's a casting number on the side of the engine block. There's also a 5.0L or 5.7L on the back by the distributor, if its a newer model roller block. Once you get the casting number, go to http://www.mortec.com/ and search for the number you found.

Re: is it a 305 or 350?
 

The casting number is on the rear of the block right above the bellhousing on the drivers side. There may or may not be the engine size cast in it there.

For the most specific information take a look at the front passengers side of the block directly in front of the head. It may be hard to see or paint or rust has it covered up but there are numbers and letters there, get them and post here and we can tell you what you have. Mortec.com is ok but theres some discrepancies in some of their info.

Re: is it a 305 or 350?
 

If they bought a rebuilt engine it probably didn't come with injectors and ECU

Re: is it a 305 or 350?
 

im pretty sure everything from the 305 was used, probably even the injectors. the only different thing would be it that it is a 350 instead of a 305

Re: is it a 305 or 350?
 

You can also check the head casting number. This is relatively easy, as all you need to do is remove the valve cover. It is not the most accurate way though, because they might have put 350 heads on the 305 for all you know.

I would say the only REAL way to know is to get a mirror and check on the block on the drivers side against the firewall. You can try the "Tom Hanks in Saving Private Ryan Mirror on an army knife with a piece of chewing gum" method. (Man that was long-winded). But in all honesty it's gonna be hard to see in there, mirrors are your best bet.

And don't get the casting number backwards. I don't want to see you back here tomorrow morning with a thread entitled "MY IROC HAS A HONDA MOTOR?!?!?!" or something to that effect :p

Re: is it a 305 or 350?
 

you may already know this. or maybe already done it but the engine number on the drivers side at the rear of the block then u can research it, or even call chevy to verify

hope this helps
Douglas

Re: is it a 305 or 350?
 

When the question is asked: Is it a 305 or a 350 the answer 99 44/100% of the time its a 305. :rolleyes: And the seller just dosent know what was installed. Dumb answer and same for the buyer.

Re: is it a 305 or 350?
 

I bought a perfectly good 305 from a guy that wrecked his K5 Blazer for $125 and it turned out to be a 350 with 2.02 valves, so until you check you really never do know. Another guy bought a 283 and it turned out to be a 327, so until you check the numbers you never know.

Like I said before get the numbers off of the front of the engine, passengers side right in front of the head. Thats the most accurate and descriptive numbers on the block (actually you need the letters but tell us the whole series)

Re: is it a 305 or 350?
 

In the late 80s my ex brother in law bought a "283" from his neighbor for $75 to replace the 6 banger in his 72 Nova. It was in a 4 door Chevy II, engine still running good at ~ 80k miles, body trashed. He borrowed my hoist, I went with him to lend a hand. We yanked the engine without the powerglide. As soon as I saw the back of the crank I said "that's a 327!".

My bro in law's face at that instant = :eek:

His neighbor's = :mad:

Me = :D

Re: is it a 305 or 350?
 

Lol thats priceless.

The guy I bought my IROC off of is actually a really great friend of mine now. When I told him that he sold me an IROC with a 350 for 1700$, he nearly crapped himself. He told me that if he would have known, he would have kept it. So I made him an offer for $3000, but he still refuses ;)

Re: is it a 305 or 350?
 

350 heads wont fit on a 305, the valves interfere with the cylinder walls

Re: is it a 305 or 350?
 

i might just buy a 350 chip for it and put it in and if it runs better ill asume its a 350 and if it doesn't i guess i got a 305

Re: is it a 305 or 350?
 

Guess again. 1.94/1.50 valves will fit just fine with the 305's small bore. Its the larger 2.02/1.60 valves that wont fit.


Changing the chip wont tell you a thing. I doubt it'd be enough to notice.