can you make a gm 305 block a 350?

15

Asked by Jun 04, 2009 at 07:55 PM

Question type: Car Customization

25 Answers

12,375

No you can not - Nice Try though

15

well that shows how much you know about gm because the 305 and 350 blocks are the same the only difference is the length of the stroke

1 of 1 people found this helpful.
7,635

same block but the largest displacement out of the 305 can get is 34x ci. cant reach the 350 ci with a 305

1 of 1 people found this helpful.
12,375

Main Bearing journals are a differnt size and will not fit a 350 crank A 350 block is a 4 inch bore a 305 is NOT and cannot be bored out to 4 inches as the coolant chambers are too close SO NO I say again it cannot

1 of 1 people found this helpful.
75

wat are you guys talkin about the blocks ARE the same and a 305 CAN be made to a 350 but its not worth the effort when u can buy a 350 used cheap and a crate for a RELE affordable price please if you dont know wat ur talkin about dont post

7,635

Lmfao!!! Dude just stop before you embarass yourself further. You couldn't be more wrong!!!

1 of 1 people found this helpful.
75

if im soo wrong then why do i know a guy who did it? he had a 350 with a hole in the block and a 305 with bad crank and he used the 305 machined it and re assembled it using the 350 internals(305 block only) he didnt have the money to buy a motor and he had the equiptment to machine it himself so it cost him $0 so YES it can be done with a little machining and i stand by my word that it is NOT worth it

2 of 2 people found this helpful.
12,375

Sorry you are confused - There is no way you are going to bore a block 1/4 inch to fit the 350 pistons As the previous person said GIVE up - Your wrong. ;b The bore on a 305 is 3.75-78 - 350 is a flat out 4.00 inches Do the math My Assumption is the bad crank was milled down to fit the journals of a 305 ( lot of metal but I suppose it can be done ) You would have to cut both mains and rods to 305 specs and he used all the internals of the 305. Would be my guess making of course another 305

1 of 1 people found this helpful.
12,375

Jeff - You asked a question Do not pretend to know the answer Bore Stroke Rods and Mains Diameter are all different

1 of 1 people found this helpful.
7,635

Lmao. I love listening to people talk out of their ass. There's 3 possabilities here. He lied to you, you're lyig to us, or you misunderstood what he did. Google the question. You will find that a can be made into something like 34x ci butnot 350 ci.

12,375

:) - I agree - Its a stroker 340 yer thinking of

1 of 1 people found this helpful.
7,635

yep. this guy is basically saying you could turn a 305 into 383 using his logic lol.

12,375

I have a stroker 434 in my Race car :) A Ton and a half does 12.33 @ 111mph ... Not bad for a heavy car and factory fuel system :) I am done with this topic Take care Chase

75

sorry to all i just called him and it was a 327 block as he later found out at the time we thought it was a 305 becuz that is wat we were told it was

1 of 1 people found this helpful.
45

No.

7,635

The 400 ci block is much different. The 2 inside cylinders on each side are closer than the outside cylinders. Spacing isn't even and it creates problems for boring the engine out in many cases.

1 of 1 people found this helpful.

remember mexican blocks have off set bores. dont get them

40

All of you are partially wrong. 350 and 305 cranks are the same. as long as you have same journal family. 350 has a 3.48 stoke and also 305. the only thing that seperated them is bore size. the 305 crank has weight removed for balancing purposes . Chevy 302,327&350's are all same blocks but not 305'. a 304 can be stroked to a 34x sumthing. depending on boring sizes availible

4 of 4 people found this helpful.

I hope you can help me, you can replace a 305 by 350 Chevrolet, thank you very much for your help

10

Jeff is completely wrong everything in the 305 and the 350 are the same exc. bore 350- 4" and 305-3.736. Rods are 5.7,stroke 3.48,main journal 2.45 and rods are 2.10 this is for both 350 and 305. As far as boring it to 4" the sleeves might be to thin. May work for awhile or may be to hot. Not with the investment in my book.

1 of 1 people found this helpful.
10

Yes you can bore a 305 to fit 350 pistons it's done all the time but no it does not make it a 350 but it dose make a decent little engine so if you don't have a certification in mechanics or have no clue what your talking about shut the fuck up the blocks are the same the only difference is stroke and hole size 305 is 3 3/4 holes and a 350 is 4 inch but is basic same block it's just like the Ford 289 302 and 351 Windsor they now Chevy made a 307 and there is a difference there

1 of 1 people found this helpful.
10

305 and 350 are only different from valves and bore size. 305 has a 3.760 in bore 350 has a 4 in bore. safety you can bore a 305 over .060

1 of 1 people found this helpful.
5

You can make a 305 mimic a 350. You will have to put titanium sleeves in it though. The real problem is a 350 is a 4 bolt main designed for punishment. a 305 is a 2 bolt main you will rip the crank right out of the block if trying to punish it. The titanium sleeves are really pricey then having to pay for the machine work also pricey. Not is it not worth it but you will take something that will marginally be good, spend a lot of money to make junk.

LOL Kris 350 has 2 or 4 bolt main . i wish all 350 were 4 bolt main !

20

Ok here is just what I've seen with my own eyes at home. I have both a 1987 305 and a second gen 350 engine at home and both where disassembled. What I did was put the rods and pistons of both engines next to each other to see the differences. The only difference I took notice of is the fact that the rods are of the same length and same type only the pistons of the 350 are bigger meaning that the bores of the 350 are bigger than the 305, they both use the same crank. This is not what I read or heard, it's what I've seen at home myself. Both engines are 2 bolts main. In any case it is risky business to try and bore out a 305 to 350 because the walls inside won't last long is you did succeeded in doing so. The pressure inside the block is very high making the engine vulnerable. So think twice what you want to do because on the long run over boring the 305 will cost you more both in money and time. It is better to safe your money and when you have it together buy a 350 and modify this. Mr. Engelhardt .

2 of 2 people found this helpful.

Your Answer

Shortcuts

Car Customization Experts

  • #1
    Tom Demyan
    Reputation
    6,170
  • #2
    F_O_R
    Reputation
    4,260
  • #3
    COMETGUY61
    Reputation
    4,060
View All

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.