Here is what I have. I agreed to buy a 88Firebird Formula, advertised to have a L98 in it. The car did not perform like it had that much tourque. Now he is saying it is bored to 350. I will not buy the car unless it has the 5.7 block in it, but just so I can explain to this guy that his head is firmly planted in his ***, I am looking to confirm that in any case a 305 wont go that big. I have no solid numbers, but I believe 327 or so is the largest you can safely go.
I have to drive from MA to southern NJ to deal with this guy, so any help would be appreciated.
Thanks,
Mike Demo


One of these days I will kill the dancing moron.....

 

The whole 305/350 thing has got to be the most common used-car lie going on today. Every car has a 350 in it during sale negotiation; but as soon as the money changes hands, about 95% of them magically turn back into 305s.

You cannot bore a 305 out to become a 350. Period. A 305 block has a bore of 3.736", and a 350 block has a bore of 4.000". As you can see, this would require boring the 305 out by .264", which is more than ¼". Since the farthest you can safely and reliably bore a 305 block is .030", and if you're lucky you can OCCASIONALLY get one to go as far as .060", it's obviously a lie.

You can stroke it, to a 334 (with a .030" overbore in addition to the longer stroke). That is very rarely done because it's economic suicide. It costs more to do that than it does to buy a 350 and just build it. Kind of like a few years ago, when McDonalds was accused of using ground-up earthworms in their hamburgers to "save money".... then it turned out that earthworms cost $4 a pound, but beef is $1.49 a lb or whatever. You do the math.

Look at the casting # on the block. If the casting # says it's a 305, odds are probably less than 1 in 100,000 that it's anything but a 305.

Personally, I wouldn't bother with any explaining; isn't worth the trouble. I let my wallet do that. I.e., tell him before you come, that if the casting # is a 305 you're not buying it (assuming of course that you don't want a 305 regardless of anything else about the car). You can look up casting #s at www.mortec.com/castnum.htm and maybe it would be a good idea to print it and take it with you.

 

A 305 cannot be "bored" or stroked to a 350. They are identical in some ways yet completely different in others. One of them being water jacket locations and such that limit the overboring. Ask him if you can get the casting numbers off of the block to varify. Chaces are it is another magical 305 that turned itself into a 350 when it came time to sell. Usually when the clock strikes midnight the motor will morph back into a 305 in the new owners garage. Casting numbers will keep you from getting burned by this guy. The largest 305 I have seen is a 334.

EDIT: RB beat me to it

 

Yeah I thought the same, but if I am going to be ripping new orfices, I want to make sure I am 100% on my info. This guy is telling me I bought the car as is, and part of the vehicle description was the L98. He said there had been engine replacement/ work, but he wasn't sure. I have to drive 5 hrs from my unit to go straighten him out. I will be bringing a 10mm wrench to move the wiper motor to check the block casting, and I printed out MOTEC's listing for casting numbers.
What size are the valve cover bolts, so I can compare those too. I doubt they will be 083's.
Thanks for the support, I am relatively new to this site, but it is an excellent resource.
Mike

 

The valve cover bolts are 1/2 if I recall but so they were the same ones found on every other centerbolt valve cover head. They aren't L98 specific.

 

Bring a T-30 torx bit with you just in case. That's what my donor motor used on the valve covers.
Have you asked the seller about the 8th digit on the VIN?

 

I checked it out, and it does come out as 305, which it would, since it is T5 equipped. As far as the valvecovers go, I'll have to find my Torx set,
Too bad some people can't be taken at their word.
Thanks for the help gents,
Mike

 

Another TGO success story...

 

Hey man glad to hear your back from iraq. Im currently stationed in Germany. Our turn for the desert is coming up. Anyway a couple guys have third gen camaros over here and I found a guy selling his. Its got the 305 which isnt what I want but I cant be too picky. I plan on dropping a 350 block into it when I get back to the wonderful states. Will everything external bolt up? I plan on getting new heads, new pistons, new cam.

 

Everything that externally bolts to the 305 can be used in the same manor on the 350. This includes the cam, heads and intake as well.

 

Well I pulled the valve covers and it was a vertical 081 head, big suprise... I ended up getting the car though, paid 2800 for it. Figured I already bought the parts to fix hte interior up, so may as well go with it. I dont know how long I will own it, but it will be a good car to practice on. Maybe for the 1500 or so it would cost to upgrade most of the engine, I will wait. Something will have to blow eventually, more reason to swap a ls1/t56 in....
Thanks for all the good info, i had to learn a lot real quick, and this site was crucial..
As far as the sandbox goes, good luck, I will probably get called up again this winter.....

 

i've got my 305 to stroke out to a 340.it can be done and safely too. mine is still going strong smoking every 350 it goes up against.