Dirty 307

Hi, i am in Perth, Western Australia and have a 307 chef engine. i bought it without a carburettor on the manifold but it did have a loose rag on top. i have since covered it properly, however that was several years ago- i now want to put a carby on it and get it started. What can i do to ensure no contaminants are in there, like dust or dead mice. is it far better to remove the intake manifold or can i get away with a blow out with compressed air. Any other tips on starting an engine thats been sitting for a while. the engine looks good and i was told it has done about 8000kms since rebuild. any help appreciated as I’m a cheapskate and want a running engine for as little money as possible.

Led inspection camera

Probably using a powerful shop vacuum on the intake ports couldn’t hurt either. I had a Chevy with a 307. They are tough, nearly indestructible motors.

The boroscope is a great idea if you think you would use it again. But you either have to go somewhere to buy it or order it on line and waif for arrival. I’d pull the intake manifold, inspect the visible areas, and clean as required. You might see something you don’t like and continue disassembly, and you could miss the problem you want to further investigate if you left the manifold on. BTW, have you turned over the engine by hand lately?

Used motor is a crap shoot. 100% chance it could have been abused by former owner. Was it stored outside? Did any water get in? Does it have distributor? Pull intake and inspect intake ports in heads. Are you going to use intake on motor? Or swapping out motor and reusing some parts from old motor? Don’t know where it is going.

Ahh, the old 307 could swallow a handful of rocks and still be fine…but seriously, I don’t think pulling the intake manifold would help you much. There are still going to be valves open on both heads, and if something did fall down the intake it could just as easily have fallen into a cylinder. If it doesn’t look like the intake has been leaking I’d leave it alone.

As cheaply as possible? Pull the spark plugs out, spray some penetrating oil in the cylinders, turn the engine several revolutions by hand to ensure it spins freely, install it in the car, crank the engine with the starter but without spark plugs until there is oil pressure, then spark plugs in and fire it up.

I would suggest pulling the intake, oil pan and valve covers for a close inspection and after turning the crank a couple of revolutions run a leak down test. Bolting on a carburetor and installing the engine to attempt to start it seems like a poor crap shoot.

Oh @“Rod Knox” where’s your sense of adventure? He said the engine only has 5000 miles on a rebuild and he wants to do it as cheap as possible. Leakdown test? He probably doesn’t have the equipment to do that anyway. It’s an old Chevy, what could go wrong?

I wonder though, does the distributor turn counterclockwise below the equator? Sorry, couldn’t resist…

A 307 costs the same to rebuild as a 350. It’s just a poor combo of parts to produce a smaller displacement motor to achieve minor fuel economy gains. Too bad it made less power and got worse mileage than a 350.


Is this 307 installed in a vehicle . . . or is it on an engine stand?

If it’s installed, I’d definitely drain the fuel tank, even if that means removing it first

The old fuel probably won’t ignite, and might actually cause problems

Use fresh fuel

Is this engine capable of running regular, unleaded pump gas?

If I were on the cheap I would run a magnet down the intake runners as far as possible in case a nut or small bolt found it’s way in, then blow the intake runners out with compressed air to clear any vermin nests, a shot of oil in the cylinders and turn it slowly by hand a few revolutions. I would also loosen the oil pan drain plug and see if any water weeps out first, if not then no water got into the motor via the distributor hole. Crank it a few minutes without the plugs in to circulate oil once again and then throw some fuel in it and cross your fingers.

The only thing I will add is just how certain are you that the engine has been rebuilt and rebuilt properly?

I’ve heard some of those “rebuilt engine” stories over the years with a number of them stretching the truth on the rebuild claim.

If its on an engine stand, I’d turn it upside down and blow out the intake. Then hand turn the engine very slowly just in case something is in the cylinders.