Sbc 305 build with factoey bottom end

[pagrunt]

thought of finding me a th350 but Ive heard it take modification to the crossmember

A TH350 would directly replace the TH200 only needing to run the vacuum line for the modulator. Uses the same driveshaft A TH400, TH200 4R, TH700R4/4L60 would need another crossmember unless that TH200 in the car is actually a TH200 4R but I don't recall you saying it's a 4 speed transmission. Also the TH200 4R uses the same driveshaft as the TH200.

 

[GuysMonteSS]

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

Well,you wont know unless you start looking.
Local junk yards would be a good place to start,also Kijiji, Craigslist and eBay might have them.
Remember the old Hotrodders proverb,"If you want to play,you gotta pay" LOL
Another one is "Speed costs money,how fast do you want to go ??"
Guy

 

[Gonzo1970]

I have an original 1986 Grand Prix with the 305 4bbl / 200R4 / PegLeg Rear.

It's only got 50k on it, so there is no real reason not to run the 305. All I plan on doing was letting it breathe (headers, intake (with EGR, keeping OBD1)) and just go..

Ive contemplated getting more power out of it, but ultimately decided not to, because at the end of the day, you will have more money into a modded 305 for less power than putting less money into a 350 making more power.. as its been said, there is no replacement for displacement..

So, what I decided to do is Work Backwards.

I am going to put 28 Spline, Auburn 3.73 Posi in it, then beef up the 200R4 to handle 400/450HP, and run it. That will give me a little more low-end, and it won't be obnoxious on the highway RPM's (with the 200R4's 4th gear) and then I would be ready for if/when the 305 goes t*ts up.. At that point, I would be inclined to mildly build a 400 poncho (350-375HP), and at that point, everything behind it would be Bolt-It-On because its Ready To Go.

It's all in perspective, and the long game. All I did was choose to prepare the rest of the drive train for something beefy up front.. Its not like a built 200R4 and 3.73 Posi would have any issues with a weak 305 in front of it...

I thought that would be better money spent preparing the rest of the drive train to get rid of the 305 than beefing it up for its inevitable replacement.


*tosses two cents on the table*


-Gonz

 

[SSpev]

build the 305. hod rod and car craft has done just what you want a few times. I did a couple too. cam, compression?, intake and headers will get you there. 300+hp.
cam is critical, not to big. maybe 268/208 .470 lift. max. you probably have 58 cc heads. Compression bump isn't really needed at this level or easy. you could do some pocket work on the heads. exhaust is most benifit. throw on some roller tips. cheap headers and I'd be done. 👍 More HP more money. More reliable more money.

 

[Wageslave]

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 an EFI, 230 hp. I would go with the 625 Street Demon since spreadbore Vortec intakes are very hard to find.

My thought was the TBI cam is made for low end torque and while it is pretty low-lift, the cam lift vs. effect on an engine scales up somewhat as the displacement goes down. Combine that with the low compression and the unknown but probably blah heads, buying a new hot cam wouldn't be best value for money.

Either way, a cam would be about item #3 on the list of things that a 305 needs to be fast. It needs port work to make the best of those unknown heads, it needs higher compression pistons to make better use of that small bore size, then once the framework is in place go with a better cam.

 

[84dragcutlass]

There is an episode of engine masters and they had a little 305 when they put it on the dyno it was around 350hp i believe and there really wasnt all that much done to it. Cam and heads. So it can be done from the little engines.

 

[Ratty86cutlass]

Lots of screen shots being taken for notes thank you all!!!.

 

[Clone TIE Pilot]

Do you know what year and model Chevy PU the 305 came out of? Like Chevy 350s, 305s came in several grades. Some 350s are worse than some 305s in factory form.

G bodies and F bodies used the same carbed 305s, the 140 to 160 hp LG4 and 180 to 190 hp L69. Quick look online shows 80's truck 305s made 130 to 175 hp. Big varience in starting points.

 

[Ratty86cutlass]

Do you know what year and model Chevy PU the 305 came out of? Like Chevy 350s, 305s came in several grades. Some 350s are worse than some 305s in factory form.

G bodies and F bodies used the same carbed 305s, the 140 to 160 hp LG4 and 180 to 190 hp L69. Quick look online shows 80's truck 305s made 130 to 175 hp. Big varience in starting points.

Preetty sure its a 82 or 83...came out of a 4wd I buddy of mine gas a book you can look gm engine codes up in and tells you the power specs..

 

[olds307 and 403]

My thought was the TBI cam is made for low end torque and while it is pretty low-lift, the cam lift vs. effect on an engine scales up somewhat as the displacement goes down. Combine that with the low compression and the unknown but probably blah heads, buying a new hot cam wouldn't be best value for money.

Either way, a cam would be about item #3 on the list of things that a 305 needs to be fast. It needs port work to make the best of those unknown heads, it needs higher compression pistons to make better use of that small bore size, then once the framework is in place go with a better cam.

The numbers are horrible for the TBI cam, his stock 305 cam would make more power. Those motors were actually overrated at 210 hp, supposedly more like 180 hp.