Hey guys, I piked up a 1987 IROC-Z with the 305 TPI with the auto. I haven' thad time to check the RPO codes yet so I'm not sure about the ggear ratio.
But anyways, right now it's got 197K miles, and it seems to run great; while it won't even touch the LS1 performance wise, I'm hoping to make it into a low-14/ high 13 second car at the least, while retaining the 305. What kind of modifications should I do, discounting FI and the 335 kit? Thanks in advance.

 

I'd do a good tuneup and a timing chain before I did anything big. just go through change plugs clena all the wire terminals and stuff. run throught some fuel injector cleaner, then do with some stuff you make it breath(air filters) then a catback and headers.

 

I know I wouldn't waste any money on a 335 kit.

 

If I had the money for something major like a stroker kit, trust me, the LS1 has called dibs on anything serious.

 

If you get a new timing chain, it's a perfect time for a cam change. Luckily you have TPI and not an LG4 so your performance capabilities are a lot better than mine were. Start with full exhaust. I believe you emailed me concerning all this, correct? An easy way to determine your gears, do 70 mph in D, if your tach reads 2730 rpms you have 2:73s and so on. Now with low 14s/ high 13s in mind, you might want to go w/ 3:73s, your mpg might decrease, mine didn't. But remember stock TPIs stop breathing past 4500 rpms and 3:42s would be your best choice if you don't do mods to the TPI. You'll probably have to buy new heads as well, seems the S/R Torquer heads are among the most popular for 305s. And a higher stall TC would be a good idea. This will all be costly, but I would think would put you close to high 13s. One thing I've learned make sure you pick all your parts to match your power band and you'll perform a lot better.

 

It's foolish to start dumping money into bolt- on parts
for your 305 with that kind of mileage. It won't hit the goal the parts would suggest and may mechanicialy fail.
Leave the 305 as is, and enjoy it. Start building a well planned out 350 from scratch.
When it's all done, pull the 305 and install the new motor with
all the goodies along with a good exhaust system. You'll be able to sell off the good used 305 core then.
You're just looking for dissapointment, otherwise.
Which would you rather have an expensive wimp, worn out 305, or a reliable tiger under the hood?

 

I just noticed how many miles you have, depending on your situation, I wouldn't invest too much into the 305 without rebuilding it. Or like mentioned plan out a 350 buildup. You can still get full exhaust and have it bolt onto a 350, atleast you'll get some power out of the 305 for now. Just be sure to order exhaust that will be used for the power band of the 350 or 305 rebuild.