307 that's driving me nuts

[86Olds442]

Ok guys, I really could use some ideas. I have the car running good, got the oil pressure issues fixed, and have a decently running 307. If you didn't know its an 86 vin 9 307, bone stock, 119k. I got the car non-running from the junk yard. Did the heads, timing chain, put a carb on it. (carb is newly rebuilt quadrajet by champion), fuel pump new. all emissions stuff is on it, new 02 sensor. Ok, she starts up and runs strong and good cold. Idle is decent. When rev'd in park, revs high, fast, and strong (at least when cooler) Drive it and use the gas pedal, and she intermittently majorly hesitates at about half on the gas, from about 2500 rpm thru about 3500 rpm. Then she gets up and goes. This randomly varies, but is never perfect. I notice a huge bog when the secondaries open. Let off the gas somewhat and it markedly improves. Sometimes it stumbles so bad you can watch the tach dip back a tiny bit as you're on the gas.

I notice when warm, and you go to start it, it cranks for a few seconds before starting. Might not be related, but my other cutlass's never did this, so I thought it might be relevant.

So my dilemma is how do I exactly figure out what is doing this? Should I suspect the carb is the issue, or look towards the distributor/ignition? Anything else too? Base timing is dead on factory spec. I've adjusted everything I could think of on the carb.

If any of you can give me any good ideas or testing techniques, I'd appreciate it. I don't just want to buy parts I 'suspect' are the issue and have it not help.

Thanks for listening and any help you can give.

 

[GP403]

sounds exactly like what happened to my 260 Cutlass back in the day. Look at replacing/rebuilding the distributor. The thing would do exactly what you say. Does it fire out the carb if you try and punch it? Replaced the dist. reset the timing and no more probs.

 

[olds307 and 403]

Check the base timing with the proper terminal grounded, beige and black wire disconnected anyways. Set your air door tighter to start, small allan wrench and small flat screwdriver needed. Go a 1/4 turn tighter untill the hard throttle bog goes away. Holley reman carbs have been one of the few reman carbs that aren't a total POS. There are Qjet experts out there but only a few mess with the CCC carb. Hopefully, you kept the original, it is a better carb to start with.

 

[86Olds442]

Check the base timing with the proper terminal grounded, beige and black wire disconnected anyways. Set your air door tighter to start, small allan wrench and small flat screwdriver needed. Go a 1/4 turn tighter untill the hard throttle bog goes away. Holley reman carbs have been one of the few reman carbs that aren't a total POS. There are Qjet experts out there but only a few mess with the CCC carb. Hopefully, you kept the original, it is a better carb to start with.

I wish I had the original from the vin 9. It didn't have it on it when I got it. I do have a non-rebuilt from my 85 307 parts car if I do need to replace this carb, I could rebuild that one.

Thanks for the input guys. I'll be on this tomorrow!

 

[86Olds442]

GP403 you nailed it. Finally got a good distributor from Advance, the first one went out while I was trying to set the initial timing after its install, and the second never even started the car, but the third time is a charm. It works well, smoothed out the idle and really helped the stumbling issue. I still can tell I have to adjust the carb a little bit better, but what a difference!

Now, here is my next question. At night when its probably 80 or so degrees, the car runs and maintains a nice 180-185 degrees. Get on it or climb a hill, the temp climbs to about 215 degrees. Leave the car idling forever, sit smack on 180 degrees. Drive it during the day in the heat and the sun, between 215-225 degrees, mostly sitting on 220. A/C on or off doesn't matter.

Facts, new HD water pump. New thermostat (STANT) 180 degree. New radiator stock replacement of HD cooling. New heater core. New flush and refill. Tried replacing fan clutch with good known unit, same issue.

What do I need to do here? I believe the engine is all original, and none of my 307's have ever done this before. My fear is going to a bigger radiator and not having good heat in the winter. Ideas Anybody?

 

[olds307 and 403]

Olds V8's are tougher to cool than some other motors. Try a high flow thermostat to start. Make sure the shroud is in good shape too. How many blades on the fan? Usually 307's are fairly easy to cool.

 

[86Olds442]

Olds V8's are tougher to cool than some other motors. Try a high flow thermostat to start. Make sure the shroud is in good shape too. How many blades on the fan? Usually 307's are fairly easy to cool.

Thanks. My T-stat is a Stant Superstat, and the fan is an original 5 blade clutch. Shroud is 100% in tact. I'm thinking it's going to end up needing a bigger radiator. Makes me wonder if this has ever been bored out....

 

[Bonnewagon]

It's usually the other way around, meaning airflow at speed cools the engine and the fan is hardly needed. Did you make sure there is a wire coil in the lower radiator hose? Without one the hose collapses at high suction and thus no coolant flow at high rpm's. Or if it's there then maybe a better radiator. I have a Rockauto aluminum unit with a 160* stat and it sits at 160* all day long even with the 90*s we've been having. A/C makes it go up to 190* in traffic. At speed, 160* again.

 

[86Olds442]

Mark,
Thanks. I have the same aluminum radiator you do. I do know the wire wasn't included in the new hose I bought, but the sales guy kept telling me that the way they are made, they don't need them anymore. Maybe I'll try and find one with a coil and give that a try. One thing about this car, nothing wants to be easy. LOL

 

[Bonnewagon]

Yeah, Scott, even a coat hanger that's been twisted around a baseball bat will do, it keeps the hose in shape under suction. I still don't know why they don't include them with a new hose.