Sbc 305 build with factoey bottom end

[Turbo Zach]

Correct me if I am wrong, but I do believe that the transmission you have will not bolt up to a small block Chevy. It is a probably a BOP bellhousing. Where you are going to gain the most horsepower from a 305 is the pistons. Flat top pistons and a better cam is your best bet to make a engine run like you want.

 

[79 USA 1]

Turbo Zach.....you beat me to it. Transmission looks BOP.

 

[565bbchevy]

I guess he will need a trans adapter plate.

Chevy-to-BOP GM Turbo-Hydramatic Transmission Adapter Plate

Turbo-Hydramatic GM Transmission Adapter Plate Adapts 1966-up Olds, Buick, Pontiac, & Cadillac Turbo 350 and Turbo 400 (TH350 or TH400) automatic transmissions to 1962-up Chevy engines (or vice versa). Will also adapt a 700R4 to a '70-'77 Pontiac 455 (however will not work on the smaller...

www.speedwaymotors.com

 

[Wageslave]

A 350 TBI cam (with new lifters of course) and some flat top pistons would make for a cheap but stout 305. 1.6 rockers would help even more if you wanted to do a little port work on the heads to get them to flow better.

Regardless, if you have it out of the car then you should at least plastigage the bearings and make sure everything is in spec. I would hate for you to put in an engine, just to find out that you have crap oil pressure.

Another thing to watch for is that TH200 transmission. They are not as terrible as everyone makes them out to be, but they are not as strong as a TH350 and having to push a 2.14 rear gear puts a lot of strain on them. If you start adding more power to the equation, then the transmission may not live too long. Consider swapping rear gears OR swapping to a stouter transmission as funds allow. Swapping to a set of 2.73 or 3.08 gears is going to have a bigger effect than you might think on performance and economy.

 

[Ratty86cutlass]

Correct me if I am wrong, but I do believe that the transmission you have will not bolt up to a small block Chevy. It is a probably a BOP bellhousing. Where you are going to gain the most horsepower from a 305 is the pistons. Flat top pistons and a better cam is your best bet to make a engine run like you want.

Yes it is a boo u already knew this but for 80 bucks you can buy a bop to chevy adapter

 

[GuysMonteSS]

Consider swapping rear gears OR swapping to a stouter transmission as funds allow. Swapping to a set of 2.73 or 3.08 gears is going to have a bigger effect than you might think on performance and economy.

X 2 what Wageslave said.
From a google search I just did,the TH200 has a 2.74:1 first gear ratio.Combine that with your 2.14:1 rear gear ratio gives you a very poor SLR,or Starting Line Ratio.
Using the Wallace Racing SLR calculator with a 26.5 inch tire gives you a SLR of 4.28.
Closer to a SLR of 9 would be a huge improvement and would be a big "kick in the pants".
And,AFAIK,some Vortec heads will bolt on to your 305,although specific intake manifolds and valve covers must be used,and the heads will need to be milled to keep the compression up where it needs to be.
I copied and pasted this from HotRod Network;
"The Class Of The Heads
Chevy 305s came with only 1.84-inch intake and 1.50-inch exhaust valves. Fortunately, there is an effective upgrade available in the form of ’96-’97 Chevy truck L31 Vortec heads with 1.94-/1.50-inch valves. The cast-iron heads’ intake and exhaust ports are similar to the late-model Corvette aluminum LT1 heads, but unlike the LT1 heads, they bolt onto conventional small-blocks. The Vortec’s greatest improvement is on the intake side, which is why we chose the dual-pattern cam with its slightly larger exhaust lobes.

There are several minor hassles when using Vortec heads. First, they have a unique intake manifold bolt-pattern requiring a dedicated (and more costly) GM or aftermarket intake. Also, early small-blocks must switch to ’87-and-later center-bolt valve covers and late-model guided rocker arms. The heads’ 64cc chambers must be milled to avoid compression loss on a 305, and the larger-diameter chamber outline requires 350 head gaskets, which could also cause reduced compression. To solve this, we milled the heads 0.045-inch and used thin 0.015-inch head gaskets and got just over 10.0:1 compression. We had no detonation problems on the dyno even with 89-octane gas."

A set of these heads and a matching camshaft will be a step in the right direction.
I am not a big fan of Comp Cams,but I do like the Bullet Racing line of cams;

Bullet Cams

Bullet Cams specializes in camshafts and valve train components for serious racers

www.bulletcams.com

Your best bet would be to call and talk to one of the experts there,Tim is who I would ask for.
Matching valve train components are also recommended.The wrong valve springs could destroy a new engine in a hurry.
Guy

 

[olds307 and 403]

Why would he want a factory TBI cam? Those motors were turds for two reasons, the swirl port heads and awful cam. Even the Olds 260 had a better cam! There are 305 Vortec heads on EBAY which are rare. In factory form with whatever cam they had and EFI, 230 hp. I would go with the 625 Street Demon since spreadbore Vortec intakes are very hard to find.

 

[Ratty86cutlass]

A 350 TBI cam (with new lifters of course) and some flat top pistons would make for a cheap but stout 305. 1.6 rockers would help even more if you wanted to do a little port work on the heads to get them to flow better.

Regardless, if you have it out of the car then you should at least plastigage the bearings and make sure everything is in spec. I would hate for you to put in an engine, just to find out that you have crap oil pressure.

Another thing to watch for is that TH200 transmission. They are not as terrible as everyone makes them out to be, but they are not as strong as a TH350 and having to push a 2.14 rear gear puts a lot of strain on them. If you start adding more power to the equation, then the transmission may not live too long. Consider swapping rear gears OR swapping to a stouter transmission as funds allow. Swapping to a set of 2.73 or 3.08 gears is going to have a bigger effect than you might think on performance and economy.

Well I have heard they are an anemic transmission and I had planned on rebuilding it anyway...the guy I got it from said ut was good when he pulled the 307 but I would rather just go ahead and rebuild it....ove thought of finding me a th350 but Ive heard it take modification to the crossmember and the slip your has too be changed too the correct spline count and after all that if i didnt spend the money to rebuild the unknown 350 id have the possibility of having a bad trans...so I figured rebuilding what I got would be my best bet....now what about thus I got a 700r4 i know for sure works good I just took out of my 88 chevrolet??? Any thoughts on that.

 

[Ratty86cutlass]

X 2 what Wageslave said.
From a google search I just did,the TH200 has a 2.74:1 first gear ratio.Combine that with your 2.14:1 rear gear ratio gives you a very poor SLR,or Starting Line Ratio.
Using the Wallace Racing SLR calculator with a 26.5 inch tire gives you a SLR of 4.28.
Closer to a SLR of 9 would be a huge improvement and would be a big "kick in the pants".
And,AFAIK,some Vortec heads will bolt on to your 305,although specific intake manifolds and valve covers must be used,and the heads will need to be milled to keep the compression up where it needs to be.
I copied and pasted this from HotRod Network;
"The Class Of The Heads
Chevy 305s came with only 1.84-inch intake and 1.50-inch exhaust valves. Fortunately, there is an effective upgrade available in the form of ’96-’97 Chevy truck L31 Vortec heads with 1.94-/1.50-inch valves. The cast-iron heads’ intake and exhaust ports are similar to the late-model Corvette aluminum LT1 heads, but unlike the LT1 heads, they bolt onto conventional small-blocks. The Vortec’s greatest improvement is on the intake side, which is why we chose the dual-pattern cam with its slightly larger exhaust lobes.

There are several minor hassles when using Vortec heads. First, they have a unique intake manifold bolt-pattern requiring a dedicated (and more costly) GM or aftermarket intake. Also, early small-blocks must switch to ’87-and-later center-bolt valve covers and late-model guided rocker arms. The heads’ 64cc chambers must be milled to avoid compression loss on a 305, and the larger-diameter chamber outline requires 350 head gaskets, which could also cause reduced compression. To solve this, we milled the heads 0.045-inch and used thin 0.015-inch head gaskets and got just over 10.0:1 compression. We had no detonation problems on the dyno even with 89-octane gas."

A set of these heads and a matching camshaft will be a step in the right direction.
I am not a big fan of Comp Cams,but I do like the Bullet Racing line of cams;

Bullet Cams

Bullet Cams specializes in camshafts and valve train components for serious racers

www.bulletcams.com

Your best bet would be to call and talk to one of the experts there,Tim is who I would ask for.
Matching valve train components are also recommended.The wrong valve springs could destroy a new engine in a hurry.
Guy

Ive also rwad about the vortec heads but i hear the carbed intakes for those heads or a bit more pricey then a conventional old sbc intake manifold

 

[bracketchev1221]

I would go for it. If you have a 305, then build it. But I would take the heads off and see what you have for pistons. It is not overly difficult to build a 1 hp/cu in engine with available parts.