Right now I have a 305 TPI... I was wondering, if i bought a few mods, would I be able to use them after I swap a 350 TPI into it? What mods, if any, would or wouldn't be able to? Thanks a lot guys.

 

the 305 and 350 TPIs are the same with the exception to when they switched to speed density, i assume you plan on keeping the MAF system in which all you have to do is get the #24 injectors, 350 ecm and whatever you plan on getting done. if you plan on going with a bigger camshaft yoyu dont have to worry about reprogramming the prom but if you want to is your decision.

 

ok, thanks iroc.

 

Just to kind of follow up on what was mentioned, I did this swap a little over a year ago, and it was pretty much a direct swap. The only things I replaced was the Knock Sensor and the PROM. Evidently the knock sensor for a 350 listens at a different frequency than the 305 knock sensor. Also, just to clarify, it's just the PROM you need to replace, not the whole ECM. I'm betting that's what IROC meant, but I wanted to make sure you knew. And some may argue about bigger injecters. I'm still using 19# injecters they seem to work fine w/ an adjustable fuel pressure regulator, but I do plan on swapping bigger ones in later.

 

Along with the 350 Knock sensor, you should really get a 350 ESC module too, 24# injectors will be overkill. Just get the stock 22# ones and you will be fine, and yes it is just a 350 prom you will need.

 

I agree, When I swapped in a 350, I used everything except the injectors and the chip plus the knock sensor.

 

I just not a week ago swapped from 305TPI in my 86 trans-am! and the knock sensors were left the same and the injectors were upgraded to 22's but that is really no matter. The ECM was also left the same and it will fly. I soon hope to put gears heads and a cam in it! I had heard that I needed to swap to a 350 knock sensor so I went down to my local parts store and looked up the part # and it said engine code 8 and F for 86 to 92, I then went to another parts store and the same . I then went to my local GM dealer and ran the #s and came up with the same knock sensor , go figure.

 

Perry,

Just a few things. First, I'm really suprised that the 305 chip is running your 350, if you change it over, I'll bet you'll get a nice boost in overall performance. IIRC, the 305 and 350 chips have different fuel and spark tables. Second, there is a difference in the knock sensors. A few years ago, many of the parts houses were mistaken, and were giving out the same sensor to both 305 and 350. There are a few threads about it. I looked up the part numbers for both at autozone and ac-delco (but these aren't being carried for some reason), but here ya go:

AutoZone 305: SU121
AutoZone 350: SU154

AC Delco 305: 213-89
AC Delco 350: 213-90

 

If you change the chip you should change the injectors as well. The chips are programmed to the injector size. A 19lb injector with a 350 chip is most likely going to be too lean.

 

Thanks for the part #s for the 350 knock sensors. I'll get that changed. I do plan on changing to a propper prom but money was tight so I just ran it, we hooked a tech 2 up to it and it seems to be running real fine with the 22# injectors the car doesnt seem to want to add much fuel to it, I agree the timing curve will really help, I just wanted to let you all know that it will run and run pretty good but not optimum as you said. I now have a little over 650 miles on the new motor and we drove it to the city (ok city) and back (about 120 miles) it entered closed loop fine (even with a 160 deg stat) and never had a hitch. I am looking forward though to the custom chip I have ordered I'm sure it will give it quite a bit more pick-up.

 

No problem on the part numbers. How do you like the difference power? I couldn't believe it when I did mine, and to top it off, I get better gas mileage too.

 

Right now the biggest difference I have felt is the torque of the 350 is ungodly compared to the 305 that was in this car. The car feels alot closer to my 4th gen when it was stock. Now I just gotta add the cam and heads I have ready ,since its broken in and of course the tune. I have a set of ported 041 GM heads with bigger valves and the whole 9 yards plus a crane cam (218/218, 454/454, 112-was free so I cant complain). I'll let you guys know how it runs down the track hopefully this month.

 

ok, thanks for all the info guys. I've got one more question though since all you guys that did engine swaps are already reading this.

About how much time & money went into getting your engine's swapped? (including the price of engine and parts you needed to get it running nice.)

- Tyler

 

Old saying "IF YOU HAVE TO ASK, THEN YOU CAN NOT AFFORD IT". Or let me put it this way, you will be nickle & dimed to no end.

 

I've put about $4000 under the hood, and I don't even want to talk about the labor. It took me two weeks to take the old one out and put the new one in.

 

About $15k (not including labor) & still going.

 

The actual motor swap cost me the core price machineshop bill and rebuild kit which total was a hair over 600$, not the nickel and dime part is where it gets you, this sensor is bad that sensor etc, the doo hickey here doesnt work or fit right. then after all that youstart modding the thing....lol

 

LOL! Yeap the $$$ goes fast. I spent lots converting the L98 TPI into my 85 Monte SS, plus the engine had a complete rebuild, I'm in the $3000 range and climbing.... But all well worht it in my eyes.

 

My swap cost me in the neighborhood of $2500. All work was done by me except the machining.