olds 307 to olds 350 swap.

Discussion in 'General Automotive Tech' started by zzzizxz, Mar 19, 2016.

  1. zzzizxz

    zzzizxz Well-Known Member

    Joined:
    Jun 21, 2013
    Messages:
    663
    Likes Received:
    44
    Trophy Points:
    93
    Wagon Garage:
    2
    Location:
    Cincinnati, Ohio
    Since we're now talking about the CCC, do you just mean that I can't use the Q-Jet I currently have on the 307 when I upgrade to the 350, or are you saying I can't use any CCC? Didn't the 350s also use CCC Q-Jet??
     
  2. zzzizxz

    zzzizxz Well-Known Member

    Joined:
    Jun 21, 2013
    Messages:
    663
    Likes Received:
    44
    Trophy Points:
    93
    Wagon Garage:
    2
    Location:
    Cincinnati, Ohio
    I've always pumped while cranking. Why do you say you want to pump before, but not during? I almost never have the car fire right up without pumping, even if it has been driven the day before. Sometimes I have to pump 6-9 times before it ends up firing.

    I had the carb rebuilt last year, and the car runs better now than it used to, but I still have to pump when starting.

    Also, since you've rebuilt these carbs, When the car is cold and I start driving, I get a slight hesitation on acceleration at about half throttle. It only happens within the first couple minutes of starting in colder weather.
    Does this sound like something you can troubleshoot across the net?

    Thanks!
     
    Glide-Aways likes this.
  3. Glide-Aways

    Glide-Aways Well-Known Member

    Joined:
    Sep 21, 2008
    Messages:
    1,443
    Likes Received:
    83
    Trophy Points:
    123
    Wagon Garage:
    2
    Location:
    San Diego
    zzzizxz's symptoms and experiences are almost identical to mine, but I live in So Cal, so I don't have the cold weather variable. Also, I have not had to pump numerous times so long as the wagon was driven the day before; two pumps before cranking and it would catch. My hesitation experience has been at barely ΒΌ throttle, if that; cold or well-warmed up.
    But to Joe's point, I've never had to (or should I say been tempted to) pump the accelerator WHILE cranking the engine until acquiring this wagon (my first 307). Joe pointed out to me earlier in this thread that I was wrongfully attributing this experience to the mere fact that this engine is the 307. Joe's right. I think I was just looking for a scape goat in my frustrations.
    I have since spoken with my mechanic to get an update on my wagon. He seems very familiar with GM carbs (judging by the other cars that seek his help). At this point he has essentially rebuilt my carb. Because my wagon sat more than it was driven most of its life before finding me, many of the rubber parts/seals have deteriorated just since (because) I've been driving it; the old rubber elements can no longer tolerate the heat of the engine. (I've put a few hundred miles on the wagon since getting it in January.) In my infinite wisdom, I forgot to talk with him about the CCC part of all this. I'll be seeing him again on Monday. In the meantime, I will be reading up on the CCC in my GM shop manual. Thanks again Joe for your wise words!

    Matt
     
  4. joe_padavano

    joe_padavano Well-Known Member

    Joined:
    Feb 9, 2010
    Messages:
    786
    Likes Received:
    135
    Trophy Points:
    117
    Wagon Garage:
    5
    Location:
    Northern VA
    Because the fuel needs to be in the intake before you start cranking. If you read the owners manual, it will also tell you to pump BEFORE cranking.

    No Olds 350 was ever built with the CCC system. The 350 gas engine went out of production in 1980 and the CCC system was phased in on the 307s in late 1980. The ECU fuel map and ignition advance map are set up for the 307. The 307 carb is jetted for the smaller motor. The 307 carb also has a stop on the secondary air valves to limit opening to 70 deg instead of 90 deg, to limit airflow for the smaller motor.

    It is possible to rejet and reprogram the CCC carb and ECU to accommodate the larger displacement. Others have done that. You need to be able to program the PROM.
     
  5. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

    Joined:
    Apr 21, 2014
    Messages:
    14,928
    Likes Received:
    2,950
    Trophy Points:
    710
    Location:
    New Braunfels, TX
    If your mechanic has the set of carb tools for the CCC Q-Pukes and a scan tool to read MC solenoid dwell, as well as an exhaust gas sniffer, there's no reason he can't get it to be within CARB spec and still be a lively performer.
     
  6. joe_padavano

    joe_padavano Well-Known Member

    Joined:
    Feb 9, 2010
    Messages:
    786
    Likes Received:
    135
    Trophy Points:
    117
    Wagon Garage:
    5
    Location:
    Northern VA
    ^^THIS! The problem is that there are almost no "mechanics" left today. They are all parts-replacers who simply read codes and replace the parts suggested by the error code. That is NOT diagnosing a problem, and the feeble computer on the CCC system can't monitor most of the trouble points. It is far more likely that the car will have a problem that isn't monitored by the computer and thus won't set a code. This is where skill and experience come in.

    I've also found that once properly adjusted, the CCC system works very well. Unfortunately, few people have the skill or patience to adjust it properly. Hell, few people can even rebuild a carb anymore. I'll add that if your mechanic did rebuild the CCC carb, unless he also verified that all vacuum connections were good and then followed the adjustment process in the CSM exactly, it still won't run right.
     
  7. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

    Joined:
    Apr 21, 2014
    Messages:
    14,928
    Likes Received:
    2,950
    Trophy Points:
    710
    Location:
    New Braunfels, TX
    That's why I 'interned' at a shop that specializes in carb rebuilding--so I could learn those carb skills. But I have dealt with so few carbs since leaving there in '02, that it takes me some time to remember proper procedures when I do have to deal with one.
     
  8. zzzizxz

    zzzizxz Well-Known Member

    Joined:
    Jun 21, 2013
    Messages:
    663
    Likes Received:
    44
    Trophy Points:
    93
    Wagon Garage:
    2
    Location:
    Cincinnati, Ohio
    So this begs the question, how will installing a 350 affect the car?

    More importantly, how will not having a CCC affect the car?

    Would I just be better off rebuilding the 307 I have in it now?

    If so, what can I do to increase both fuel mileage and power? I know those two are usually mutually exclusive, but right now I'm averaging about 9 city, 11 highway, both of which are significantly lower than I should be getting.
     
  9. joe_padavano

    joe_padavano Well-Known Member

    Joined:
    Feb 9, 2010
    Messages:
    786
    Likes Received:
    135
    Trophy Points:
    117
    Wagon Garage:
    5
    Location:
    Northern VA
    Go back and read Post #3 in this thread.
     
  10. The Stickman

    The Stickman Well-Known Member

    Joined:
    Nov 26, 2008
    Messages:
    1,316
    Likes Received:
    9
    Trophy Points:
    111
    Wagon Garage:
    3
    Location:
    Lehigh Valley pa
    Ok posting just about my own experiences. My first 307-350 swap was with a $400 Ebay engine. It had been modified but the guy that bought it thought a 350 was a 350 and found that an Olds 350 wouldn't fit in his Chevy truck. So he put it on Ebay and I was the only one to bid. His loss my gain. Loved that engine and it came alive even more when I put a shift kit in the 200 4R and could manually shift it to take advantage of the cam that was in it. My second 307-350 swap was in my friends Buick hearse. Her 307 swallowed a valve and holed a piston. So I litterally pulled an Olds 350 off the garage floor that had been in a converted Chevy diesel pick up. It had a huge difference and the car now is driveable where you don't slow down going up long hills. That being said we are looking at doing fuel injection very soon. We have most all the parts and just need to start wiring things up. We will be running a 454 TBI with 2 inch bores and 80lbs injectors. This TBI is a 670 cfm unit where the 350 TBI engines used a 450 cfm TBI. We have an adapter for on the Edelbrock Performer intake. We will be using a Megasquirt that I bought long ago. I have heard from people that have used stock GM computer and wiring harness with a TBI and CCC distributor for a complete EFI system even on 403's.
     
  11. ross

    ross Well-Known Member

    Joined:
    Dec 10, 2008
    Messages:
    600
    Likes Received:
    20
    Trophy Points:
    75
    Wagon Garage:
    1
    Location:
    Chicagoland
    I just skimmed this thread so please forgive me I'm way off base I'm attempting to answer what has already been done.
    I'd be VERY suspicious of such a mileage claim on an engine that been out of production for decades. Very few people would bother to rebuild such an engine either. The price asked is insane too, installed or not. Anyone who still has a set of SAE wrenches ought to able to R&R that lump in a few hours.
    I agree with your wanting to dispose the 307, it's a turd. The 350 ain't much better in my opinion, just a bigger lump of the same stuff. Any Buick, Pontiac or Cadillac will bolt up to your trans. The Buick 350 is a sweet engine, vastly superior to the Olds IMHO, A Cadillac will be under stresssed and will probably deliver good economy if you don't get too happy with your right foot. The Pontiac is the most ancient of the bunch but has very good aftermarket support.
    If you DO decide to swap in a different brand motor be sure to get one with ALL the brackets and accessory drives.
    Lastly, the CCC carbs are a bear to get right and require a few special tools to adjust*. They are another primitive emissions device that was dumped quickly.
    My advice is to go back in time with a "conventional" carb(regular Qjets are great) or employ a modern EFI system.
    * I still have mine, should you insist on this tack I'll lend them.
     
    Last edited: Apr 14, 2016

Share This Page