OK, here is my story. I am getting around to restoring my beat 305 TPI 86 TA. I know enough about engines to get by pretty well in a conversations, but have no real experience with rebuilding them. I have an uncle who is more than competant who will be helping me with the work so that I can learn. Here is my dilemma.

Do I keep the 305 and build it up, or go for a 350? Here is what i am dealing with. The car will be a weekend driver. It will probably never see the track, but I want something that is pretty fast. I also want to keep it drivable.

Will I be able to get any kind of meaningful power out of the 305? If not, I assume the next logical step is the 350. More questions then.

If I move up to a 350, do I go crate, or built it myself (this is where my uncle comes in)? Each crate motor I see says not for post 1975 vehicles. Am I an idiot for worrying about this? Do I have the same emmissions hangups even if I build one myself?

If I build it myself, any recommendations on good head / cam / intake / carb combos? The car has stock gears (not sure of the ratio), and is really setup for highway cruising. I would want good low and midrange power. I really don't have any idea what parts to choose to achieve that. Hoping someone else can give me some pointers.

This basically boils down to power and budget. I don't have a ton of money to spend, so I don't want to pour it into a 305 if I will just be unsatisfied with the result. If I go with something larger, I need some advice relating to the emmissions stuff, and which parts to go with. Hope this all makes sense.

Thanks,

Jeremy

 

I would go 350 no question. The 305 isn't a bad motor. I had alot of fun and made it to be pretty quick. The 305 and 350 are the same except for bore size. IMO most performance parts (heads cam etc are designed around the 350 but will work in a 305.

I personally never worry about emissions but that is on you.

If you go with a crate you won't need to worry about combination. The motor should include instructions on the type of gearing/converter/carb/header size required.

hope it helps.

 

First, let's define "restore". That typically means returning it to factory-like-new condition. Since you're talking about the possibility of a 350, I'll assume what you really want to do is "fix up" your car.

Assuming that is true, I'll say what I've been saying for a couple of years: For the same money, you can make a 305 faster than you could if you bought a 350 to put in your car - up to a point.

Actually a couple of points. Moneywise, that point comes when you start spending money on the 305 shortblock. Put simply: don't do it. Cam, yes. Heads, sure. But, if it needs rings, pistons, and/or bearings, give it up and get a 350 to build.

The other point is when you get to the max emissions-legal 305 power. Of course, getting more power will require more cubes, so that's when you go 350.

A lot can be done to a 305 that will reap good gains w/o changing the engine. The first weak point is the exhaust - get headers, high flow cat, & cat back. The next is cam - get a nice computer-compatible cam from Crane or Comp (mine is probably a little too big for the typical TPI). The TPI should have the plenum & base ported, and shorter/bigger runners (larger TB also an option, but probably not required yet). Get an adjustable fuel pressure regulator, too. After than, ported heads or World S/R Torquer 305's (pocket ported at least). Since all of this would be required to get any power out of a 350, that is why I say you can get more power out of a 305 for the same money than you can by installing a 350 - because you don't have to buy an engine. It will all be emissions-legal, too.

After that point, you're looking at a 350 shortblock at least. Crate motors are available to fit in an '86, but they aren't simple "bolt-ins", that's why you see the stuff about '75-earlier. However, I have a bud who put a ZZ3 in his '90 RS, converted it to speed density TPI, did a butt-load of other modifications to it including custom PROM work, and goes through emissions with a fast-pass because the levels are so low. It runs low 14's here (which would be 13.0's at sea level). You aren't going to get a 305 to do that in emissions-legal form without power adders, but he's got about $12k in the engine system, another $3000 in transmission and suspension mods. Something tells me you aren't in that league, but it gives you an idea what can be done.

 

Should also address a couple other points in your original post.

Don't go carb. The only emissions-legal carb is computer controlled, and switching over to that is more money and trouble than you want to get into. But, if you really want to do that, we can talk about a TPI/CC-carb system swap.

With more cam, gears and higher stall converter are key to improved off-the-line performance. That will add to the overall cost, but again, it would have to be done to a 350, too.

As to being disappointed with mods to a 305, a little over a year ago Popular Hot Rodding (and one of their sister publications, I believe) did a dyno test of a fresh 305 shortblock with stock-like cam, comparing fresh stock TPI heads with 3-angle valve job to pocket-ported World S/R Torquer 305 heads. Both tests used long-tube 1-5/8" headers. With nothing else changed, the World heads pulled 50 HP more than the stock heads. Believe me, you can feel 50 HP.

 

I live in CA, so emissions legality is an issue for me.
I bought this crate motor.
http://www.goautocenter.com/300hp_tpi_1987-89.htm
It passes smog in CA as a 305.
It's got twice the power of the 305 that my car came with.
It's reliable enough for my daily driver.
I've put Almost 20,000 miles on it since installing it last December.
-Rich-