307 upgrades

[King_V]

Cold starts with the Q-jet, or really most Rochester carbs since at least the late 70s, have generally been easy. Even with the temps as low as 0 degrees F, it was always, on the first start up of the day (or any time where the engine itself is COLD):
- Floor once, release
- Start car.
- Wait a few seconds, tap gas to bump down the idle speed slightly (it'll still be fast idle, just not AS fast)
- Give it about a minute or so.
- Tap gas again - idle may or may not drop further
- Drive (gently until completely warmed up, or at least until idle is down to normal "warm" idle speed)

That's of course when everything is working as it should.

 

[DoubleV]

Yea. I looked on google on gunning a carb and all it said was fuel an air ratio. I pump the gas 2 times turn the key no start, pump the gas again 2 times and still no start, pump it 1 time after and then it find starts.

If anyone has any tips on running it would be great!

Hard starts with carbs are more common today because of todays fuel but generally you should be able to get things working OK. Does your hard starting happen every time, only when it's cold, or only when it's hot?

If it happens when the engine is cold ( sitting out over night ), it can be caused by fuel leaking out of the carb. Sometimes the fuel can even siphon out through the carbs inlet. That can be caused by not having the fuel filter installed properly ( or at all ) because it acts as a 1 way check valve when installed correctly. I've also heard a bad fuel pump can cause this too. Pour a little fuel into the fuel bowl of the carb before starting it in the morning. If it fires right up then you probably have your fuel leaking out of the fuel bowl when it sits for a while.

If it's hard to start only when hot, it can be an incorrectly functioning choke or fuel percolation.

 

[Dripz1985]

I looked today and I have the 5a whatever it is.

 

[86-blk442]

5A heads are the earlier 307 heads. They have "normal" sized ports and can accept aftermarket intakes and such.

 

[ronbz455]

You need my 403 olds engine but you will still have the same carb symptoms but more power!

 

[86-blk442]

You need my 403 olds engine but you will still have the same carb symptoms but more power!

Are you selling the 403? I'd be interested depending on location!

 

[jetsetw31]

The 5a huh? that's actually good news. A good tune will wake it up for sure. You can get parts for it that will work on the 307 and the 350 or 403.

 

[ronbz455]

Yes I'm in Indianapolis, In and I want to spend my money on the Buick 350 so the 403 Olds is for sale. Crank is .010 .010 and polished and the 403 block has been checked for cracks and needs bored and decked because of some rust in the cylinders and the deck has coolant deterioration so with flat top pistons it would be a killer engine but if you put a big cam in it I would go with the block girdle cause it will have a lot of power.

 

[ronbz455]

Here is a pic of the crank.

 

[lg1200]

Quit wasting money on old carb'd motors. Go get a 5.3 or 6L from the yard and swap the cam and valve springs with something mild like the z06 for the 5.3 and get 350rwhp. Fuel injection is the best way. Take it from a guy whose built a $3500 402HP dyno'd Gen 1. You can do this whole swap for under $2000 and you'll like this setup way better than a rebuilt Olds 403, 350, 455 etc..old motors are great but an avg 9-5er gets alot more for his money going newer..and BETTER. But if nostalgia is your goal then chase it with a mindful eye on your dollar in ratio to gains in HP and performance. You pop your hood and it's a nice tucked LSX swap then the nostalgia guys will have to give you the pass. I've seen it too many times for the BOP sticklers..The 6L gawd has spoken.