can you make a gm 305 block a 350?

95

Asked by Jeff Jun 04, 2009 at 07:55 PM

Question type: Car Customization

37 Answers

19,185

No you can not - Nice Try though

4 people found this helpful.
95

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

9 people found this helpful.
15,975

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

5 people found this helpful.
19,185

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

10 people found this helpful.
305

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

10 people found this helpful.
15,975

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

5 people found this helpful.
305

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

11 people found this helpful.
19,185

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

9 people found this helpful.
19,185

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

5 people found this helpful.
15,975

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.

3 people found this helpful.
19,185

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

3 people found this helpful.
15,975

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

2 people found this helpful.
19,185

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

3 people found this helpful.
305

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

5 people found this helpful.
15,975

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.

2 people found this helpful.
170

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

17 people found this helpful.
40

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

4 people found this helpful.
80

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.

8 people found this helpful.
40

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

4 people found this helpful.
30

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

3 people found this helpful.
25

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.

2 people found this helpful.
40

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

4 people found this helpful.
50

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 .

5 people found this helpful.
60

For everyone that is guessing about the size of 305 and 350 is the bore size and here is my proof https://youtu.be/0K1yGXct_sg

6 people found this helpful.
10

yep go to junk yard get set of old 350 pistons take block an pistons have it bored an honed to those pistons use semi decent rings never those no gap ones and dont road race it or circle track it but will get you around an for road trips k o an dont use a high volume high pressure oil pump sbc dont need them just a good stock one engine live longer the high ones will put all the oil up in heads and starve the bottom end and rods when its cold out sbc dont need much oil but does need some k

1 people found this helpful.
20

the rods, main ,crank are the same you cannot bore a 305 1/4 inch their is a lot people that don't what the hell their taking about

2 people found this helpful.
50

If you really want to, you CAN make a 305 into a 350. It would take a lot of machining and come custom parts. It would have the same bore and stroke as a Buick 350: 3.8" bore and 3.85" stroke. You would need to start with a 305 block, a 400 crankshaft, and a set of small journal small block rods. The block would have to be bored .060" over to a 3.8" bore. The crank main journals would have to be ground down to 2.45" to fit the 305 block. The rod journals would have to be offset ground from 2.1" to 2.0" (early small journal size) to make a 3.85" stroke. The pistons would have to be custom.

5 people found this helpful.
20

Can u fit a 351w crank and pisrons into a 350. Instead of all the non sense what you can and can't do. Give me measurements to why you can't. Cam as well. Using 350 block and heads.

2 people found this helpful.

A Ford crank into a Chevy engine? Nonsense!

1 people found this helpful.
30

Proof that 90% of this country has their head up their butt. Science and Math are dead. As mentioned above the 305 and 350 are the same except for the bore. Yes you can make a 305 a 350 but you have to have the right block. With the 305 being the "Corporate Engine" of the 80's, There were more 305's than 350's and low budget race teams were forced to use the 305. They could finish to 4", but that was the last rebuild on that motor. As also mentioned above avoid the Mexican blocks, the bores are cast offset. Improvements where made, not good for the Hot Rodder. The casting is thicker on the major thrust side. Wow sorry this as old as Redbull in the states.

3 people found this helpful.
20

You can go as high at 339 on a 3.75 stroker crank and a 0.060 over bore.

2 people found this helpful.
10

yes it's possible, they make crank kits and you'd need to get the correct heads which require a special gasket set, but if you're gonna spend all that money getting the kits needed to do it why not go buy a 350, or better yet something bigger.

1 people found this helpful.

Some of the most idiotic answers Ive ever seen. A 350 & 305 have the same 3.48 stroke rods, crank and large journals. all sbc 68 and up are all large journal so the crank will interchange but a 350 has a 4.00 bore and the 305 is 3.736 so the blocks are the difference.350's are both 2 & 4 bolt mains there is even a rare Canadian 305 truck block that has 4 bolt mains casting# 361979. You can bore a 305.060 over but you still a long way from 4.00. Before you start name calling know wtf you are talking about or do your research. You know who all I'm talking to.

Tu eres el idiota , y mira por qué, scat 4" crankshaft, 5.565 rods de chevy 400 ,3.736 pistons de 305 stocks 1.560 deck to wristpin ,eso da 350.61732352

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