Guys,

I need a bit of direction. I have read the threads related to a 305 to 5350 TBI swap, but have not been able to get an accurate and clear answer. Motor is installed, the only mods are Performer Intake, shorty headers, 3" exhaust with flow through CAT and muffler. I have ordered a new ESC and knock sensor for a 350 from GM, my question is about the PROM in the ECM. Can anyone tell me if my ECM (which has a SERV. No. of 1226865 ) allows for a different PROM? Must I use a chip for a 350 c.i.d ? If so, what is a good choice since it looks like Fastchips is no longer around. I bought this Camaro Camaro Sport Coupe back in 1985 and have dragged it around the countryside for years, and Corona gave me time to work on it. Your advice and direction is appreciated.

 

No, the stock chip works fine for that. Not ideal maybe, but not "necessary" to change it.

You used to could get chips for the computer carb system from several vendors, that gave a little better timing curve and a few other minor tweeeks like that. It's real slow, dumb, stupid, limited, old, and Stone Age; if you're accustomed to think in terms of modern cars and the options for tuning them, try remembering back to what your smartphone looked like in 1978, compared to 2020, and you'll get a better idea of what you're working with. http://www.antiquetech.com/?page_id=674 Note that it had128 BYTES of RAM... not gigabytes, not megabytes, not even kilobytes... BYTES.

The 305 in your car would have been the base model, low-perf LG4. Getting the chip out of a L69 car would make a noticeable improvement. Those aren't too easy to come up with nowadays though.

 

Thanks for the info, some of this stuff is so confusing. Not to bore you to tears with a long story, but this is a project car I started working on years ago, and the new motor sat in the car untouched for probably 10 years. Getting it to start was tough, but it did finally and then I discovered my intake manifold never really sealed and I ended up with coolant in the crankcase. Cleaned it all out, replaced the corroded intake and then learned I needed the knock sensor and ESC module. Back when I initially decided to rebuild the Camaro I purchased 2 hot chips (dunno why) and I have them still in the boxes. One is a Hypertech 305 HO Thermomaster and the other is a Superchip #8501-A but they both appear to be for a 305 based on the little stickers although I am sure I planned on the 350 from the onset. So, why they are for a 305 I don't know.

Would it be beneficial to install one of these or am I best just leaving it as is? I am already over budget and still need a little face lift on the car but it is in overall pretty fair shape with just a small area of surface rust. So, where I can save a few bucks I am eager. Thanks again

 

I'd try either of those chips, see if you notice a difference after running the stock chip for a while. likely the only significant difference is the timing which is probably more aggressive in the aftermarket chips.

the computer controlled part is really not able to tell the difference that 45 ci makes. it provides feedback control for the ccc-qjet's mixture control solenoid by varying duty cycle. as long as the 'mechanicals' of the ccc-qjet are adjusted for the displacement change, the computer's feedback loop will be the same.

 

Sofa,
How would I know if a chip was an L69 ? This is all a bit new to me, sorry for too many questions. Are there specific numbers to search? Can they be burned still?

 

Naf,

Can you give me a bit of insight on what changes would need to be made on the carb? I used the original fuel pump as it was pretty new back then, and the carburetor is a Rochester rebuild that is purportedly already adjusted, but it is newly installed too. I appreciate the guidance on this stuff as I am learning the swap comes with a bit more issues than I planned on, but I know it will be worth it to get it going again. The car has not run for many years but I recall how much fun it was on the road. The last thing I need to do is to replace the U-joints, and then the car will be entirely rebuilt with the exception of the rear end, which looked super good when I opened it up.

 

the idle air bleed will need to be adjusted to provide an adequate range of mixture control for the additional load. the idle mixture screws may need some adjustment as well. the rich/lean stop settings will likely be good.

the goal will be to get the dwell for the new motor in the sweet spot where it has the optimum range for adjustment rich or lean. I can help walk you through when you get there.

 

You will need the special tools to make these adjustments. They are nearly impossible to find now. They sometimes pop up on ebay.

 

Easiest way I know of to come up with a L69 chip, is to find a Monte Carlo SS in the junkyard.

I hate to be a buzzkill but my only brother died in one of those. A 87.

The tools are not hard to make.

 

You already have the Hypertech 305 HO Thermomaster chip. I was going to offer mine, but you already have, most likely, the same one.

EDIT: the chip I have is a JET Powertech # 18411 S. For 1984 305 ci LG4 / Auto trans / CCC carb
# 18413 S would be Jet's chip for the same but with the 305 HO L69 engine.

From Summit:
JET Stage 2 performance chips/modules will improve the performance of your car or truck with very little work. These chips have been programmed to deliver peak power increases under hard throttle conditions, such as towing and wide-open throttle. They offer a full range of DST programming of the air/fuel ratio, ignition advance, and transmission, and are fully track and dyno-tested to ensure the most possible power without affecting day-to-day drivability.

Stage 2 power chips/modules must use the following for proper performance:

* 180 degree thermostat
* 91 octane or greater fuel
* Free-flowing exhaust

 

Thank you for the recommendations. I think I will pop the Hypertech chip in and see how it goes!

 

If you need to adjust the carb: https://www.thirdgen.org/forums/carb...ml#post6305614