85 305 to 350 tbi swap questions.

[dyeager535]

CCC will have a three wire TPS plug on drivers side front of carb, faces forward (and IIRC, slightly downward). As far as I remember, nothing but CCC got TPS. Can't necessarily use the MCS to ID a CCC carb (plug on passenger front top of carb) as there were various other things used in that location. Even guys that know CCC typically don't know much about the truck abominations. Some of the truck setups are fairly rare, I've seen I think one non-CCC truck carb that had one of the odd valves/wiring where the MCS was on the CCC carbs. US GM *cars* got CCC starting in 1981, and as I understand it, that was all cars. Trucks it started in '84, maybe '83 AFAIK.

http://www.cliffshighperformance.com/tech_qjet_history_5.html Pencils in that pic indicate the TPS (on right) and MCS.

More complex than fuel injection, and none of the benefits.

I'm converting my '85 Cutlass over to EFI and have just started digging back into it. Kind of neat about CCC is that much of the wiring is already there for EFI...Baro/MAP sensor, CTS, TPS, ECM controlled distributor, etc. I assume with a little bit of thought, you could use existing CCC wiring for much of a TBI swap. If I'm lucky, the car and the truck fuse panels will swap though, as I grabbed a complete '89 K5 harness that I intend to use in it.

 

[jkeys0218]

Its definitely a ccc. Well atleast it was until i put the new one on

 

[dyeager535]

Go figure! Originally a 305 truck as well?

Unfortunately I don't have a wiring diagram from that vintage, or I'd check and see how the ECM gets power. Should be pretty easy to tap into if you want to go that route for now, just disconnect it and check the connector for 12V bat and 12V ign. I know so little about those setups that I'm not sure they even have both. TBI does.

I assume it's located above the glove box under the dash, like the ESC module and TBI ECM was later, which will be good if it's a "standard" size GM ECM, as the TBI one will fit in the holder as well in that case.

 

[jkeys0218]

Yea the 305 is original. Im not worried about modifying the existing wiring. Its in bad shape and the new engine has its own wiring

 

[jkeys0218]

Ive decided to replace the currant tank with a baffled one and use the stock fuel pump for that tank. Anyone know what tanks will fit? Like i know my 95 truck had a long skinny one out side the frame. Did suburbans have the short/tall ones? What about the 90s fullsize blazers?

 

[dyeager535]

Only K5's. There is a "tall" and "short" tank, but the short ones are pretty uncommon. I can't recall if they were even offered '87-91.

Used tanks unfortunately are often not a good option. The baffles inside are plastic, held to the bottom of the tank by small press on spring clips, which tend to break the plastic, so the baffle wallows around. Even vehicles not involved in wrecks can have this problem, and the issue isn't going to get better as the tanks get older.

Pretty sure my replacement came from these folks: http://www.spectrapremium.com/products/fuel_tank.html

If you search back here a bunch of years, you'll probably find posts by me and others...so far haven't heard of an aftermarket company that makes a tank with "good" baffles in it. Due to the design of my tank, I try not to let it get below a half of a tank. Probably overly cautious, but there are holes in the sump...great for letting fuel in, also great for letting it out. Factory was very different, and while it breaks because it's plastic, no way the fuel would run back out.

Edit: BTW, just did a little searching on the tank baffle "issue", and apparently the Buick GN crowd ran into the same thing I did. Found a thread from 2007 where someone said they had talked with spectra at that time, and the baffles had been changed. Someone confirmed they received a different style baffle in their spectra tank, the earlier tanks used the baffles just like my K5 tank does. I bought mine well before 2007, so perhaps the K5 tanks are fixed as well. One can hope.