im curious as to what kind of gains can be expected with upgrading a 305, ie cam intake exhaust, Im debating whether to build the original 305 that is in my trans am or swap in my LT1, however i dont want to hear swap in the lt1 and be done with it. I just want advice if i decide to keep the original engine in the car. I'd like to keep the same 416 heads that are on the engine to keep it as original as possible. Also can some people recommend cams and such that are effective in 305. This is not going to be a strip car and will probably only be driven once a week so high horsepower is not a huge priority, just want a fun street car

 

cam,intake,exhaust upgrades sure made a big difference for the better on my '82 z28 original 305 and mine was the old 8.5 C/R LG4,original 86 LG4 should be 9.5 C/R IIRC.The cam i used was a mild one-just a little hotter than L69 H.O.cam,ran strong up through ~5500 RPM instead of going lame above 4500 like it did in totally stock configuration

 

Every dollar you spend on 305-specific upgrades is a dollar you could put into the LT1. Or an L31. 305s just don't give quite as much return on investment. But headers and exhaust will help your 305 now, and your LT1 or L31 later. The LT1 is a lot more work, and a bit more cost, compared to the L31, for very little extra reward. Mostly just saving 50 pounds.
Some '86 blocks have provisions for roller lifters. But you must pull the intake manifold to check. Good chance to upgrade the intake manifold. If it can take the rollers, then you can upgrade the cam now to something that'll also work in the LT1 or L31 later. The LT1 requires a longer dowel pin in the front of the cam, but most LT1 cams let you push the pin in more, if it proves necessary, to run in non-LT1 SBC, '86.5-up.
Something like the GM HOT cam would be too much for your 305, I'd start with something like a 212/218-114 480/487 if your block will take the HR stuff, and you still have the computer controls. But then you need springs. Still, it would be a good street midrange cam in an LT1 or L31.
If your block doesn't have the provisions, then I wouldn't do a cam swap, the same money will buy an L31.

 

the Lt1 is already built, fresh shortblock, cc503, crane gold 1.6rr. so im not worried about getting parts that will fit the LT1 except the exhaust, and i may still put the lt1 in the car, im just trying to get as much info on what i can do with both engines and decide whether i want to keep the original engine and upgrade it a little or just yank it and put in the LT1

 

Figure out how much HP it'll take to make you happy. Getting a 305 to 300 HP is easy. And can still get good MPG and pass emissions. Getting a 305 to 400 takes too much to be worth it.

 

300Hp is all I'm really looking for. I don't want anymore than 350hp

 

so looking into it more and im thinking i might run the 305 until i am ready to put the LT1 in and then just pull the 305 and store it, keeping the original engine to the car. Im also thinking of using the LT1 as carb so i can retain the carbed style the car originally came with

 

Good plan that lt1 will make you more happy then that 305 would ever do. They are jus turds.

 

4 basic choices are more cubic inches, better heads, bigger cam and more compression. There are so many options for the sbc it will make u dizzy fast. How much u spend and what changes u want to make are entirely up to u.

Really the best way to do this is make a chart of what u want and how much u want to spend that way to make a realistic budget. But if your resourceful and patient u can find some real bargains for the sbc in the used or unused new parts.

Reading u want to use your heads and block then an inexpensive pocket porting with a thin head gasket and a larger cam should get u close to 1hp/ci. That should keep the cost less than $500. Well u will want headers and intake also but again those parts are found anywhere u look. Always important to match your cam to your compression so when u have the heads off measure all the volumes to nail your c.r. numbers.

One last thing is most including me think the smaller displacement blocks (like 283 through 305,307) are only good for restorations and numbers matching collectibles. Myself i would rather have fun tearing my car up and drilling holes where ever i want them. So to me a 400" block would be what id look for - but thats for me, not u.

Good luck and hope this can help some.