I have a 1979 that came stock with a 305. I have been torn between rebuilding the 305 and keeping it stock and replacing it with a 350. What I am trying to find out is will a 350 bolt up without needing to change mounts, etc? If so what year 350s are compatable? Also are the 305 and 350 blocks the same other than the obvious differnce is engin bore, stroke and hp? Are parts interchangable?

Thanks, Jim

external they are the same. The only difference would be between years of block more than displacment. About 79 most block change to a pass side dip stick and 86 and newer have a different flywheel and the heads and intake can be different. A goodwrench 350 engine would be perfect and if you painted it the same color it would be difficult to tell.

Here is how I would do this!!

Buy a 350 core motor and build it like you want while you drive the 305 and then switch them over a weekend!! A low strong tree limb, a ton come-a-long and a Buddy will do fine!!

Done it several times except one was my junk 301 and the other was a .060" over 409 "W" motor and the other my 406 SB!!!!

pdq67

Up to '92, they will physically bolt in. Only thing to watch for is dipstick, which isn't really a problem. Just make sure you have the correct flexplate and dampner, and it's easy!

Great, and thanks for the input. It sounds like any 350 up to a 92 will fir right in. I assume this also means the alternator, ac brackets etc will all mount the same?

The alternator, ac brackets and pretty much anything from the front of the engine will bolt up fine assuming you are using your current intake again.
But, if you use a 87 and up engine the flywheel from your engine will not work. In 87 they changed the flywheels, and the rear seals from 2 piece to 1 piece. Also in 87 they changed the heads to the centerbolt style valve covers, and also slightly changed the way intakes bolt up. Your starter should still work though.

Actually even the new vortec motors up to 99 in the trucks will bolt right up but the valve covers and the intake have changes but with the right intake everything else will bolt up.

The Small block chevy made very few changes from it's start in 1955 up to the 90's LT/LS based engine.

55 had no side motor mounts

56 to early 70's used "pad" style motor mount.

After early 70's the motor mounts went to "clam shell" mounts and stayed that away.

55-68 used "short" water pumps. Those also use diff acc. mounts for alt., etc than the 69 and up long water pump.

55 to 73 used points, 74 up used an HEI dist.

69 up used long water pumps.

Some where in the late 70's (not sure when) GM changed the alt. mount alittle. 1 had the top alt. bracket bolted to hole in front of intake, the other had it on a stud at the water neck.

Also late 70's early 80's the oil dip stick changed from driver's side to pass. side.

80's brought on quite a few changes. 1 the carb's and HEI's was now computer controlled,

mid to late 80's went to sep. belt/pulley system

87 changed to roller cam, 1 pc. rear main seal, diff bolt angle on the 4 center intake bolt holes, center bolt valve covers.

The over all out side size never changed untill the LT1, LS1, etc (90's)

So any 1956 to early 90's small block will fit in your car.

you can swap all your parts, mounts, etc onto any of them engines.

Thats one of the great things about chevy engines.. Parts will interchange through out the whole run of that gen engine family

<font face="Arial,Verdana" size="2">Originally posted by 1978LT:
Up to '92, they will physically bolt in. Only thing to watch for is dipstick, which isn't really a problem. Just make sure you have the correct flexplate and dampner, and it's easy!</font>

Actually as far as a small block goes it goes later than that. For example a LT1 will bolt right in. and that was all the way to '96
like others I have heard the vortec mototrs have the chevy bolt battern too

<font face="Arial,Verdana" size="2">Originally posted by badazz81z28:
Actually as far as a small block goes it goes later than that. For example a LT1 will bolt right in. and that was all the way to '96
like others I have heard the vortec mototrs have the chevy bolt battern too</font>

Yeah, all these replys are true, especially the '99 Vortec engine. I was trying to save the good man any gried http://www.nastyz28.com/ubb/wink.gif I was thinking carbbed, which you can't do to an LT-1 without the expensive intake. The Vortec engine, however, would really be the ticket! Already set up for a roller cam, the awesome Vortec heads....if he can only find one http://www.nastyz28.com/ubb/wink.gif

Yes, I think they finally sold the last original type, L-48, 350 motor last year in a cargo van or something like that so the old motor is no longer being used/installed from the factory even though you can still buy crate motors!!

I personally think they obsoleteted the greatest engine in the WORLD, but that's just my opinion!! What did they make, 60,000,000 of them over the years, all sizes??

pdq67

I don't know I have built a lt1 and now have a lsi Trans Am they both run hard. It is just what you are used to. Fuel injection is great and other than a little cost for a tuning program they can easily tuned. I kinda like being able to tune from the drivers seat.