Cruizin Uncle Bob

Had problems with engine heat, after two good flushings, a new radiator, water pump, fan clutch, new bypass thermostat, a change in ignition timing, and adding redline water wetter and JB radiator super cool seems I have made a marked difference in the running temp. Now, when cold, with a couple of pumps of the throttle, it starts every time, once the engine comes up to temp and you shut it off, when you try to start it cranks off with two pumps of the throttle, runs about 10 seconds and dies, then you have to pump the throttle like crazy and hold to floor to get it to light off. Starter turns over really good, not sluggish as if a timing issue. My theory is the fuel is vaporizing in the line with the under hood temperatures. Need some ideas if anybody got some. Was thinking of re-routing the entire fuel line and possibly insulating some how. Any suggestions would be greatly appreciated.

MDchanic

Why are you pumping it when hot?

You describe pumping it, then holding it open. These two moves have opposite purposes:
Pumping actuates the accelerator pump and pumps raw gas into the manifold, which can be helpful when starting a cold engine.
Holding the throttle open is what you do when you flood it, to clear the excess gas out of the manifold.

Sounds like you're flooding it, then clearing it.

- Eric

droldsmorland

No idea what year & engine you have so Im referring to a stock 68 442 or H/O with 400/455 here...But should apply to what you have for the most part. If you do discover you're having "heat-soak" problems with your factory 400/455 with a QJet and iron intake & exhaust manifolds, which it sounds like you are to me, try placing a 1" insulator under the carb. If it still persists try blocking off the heat riser crossover in the intake. With 1/4" holes drilled into said block offs (one per side) the cold start system can be left intact. If you really want a cold blooded creature remove the thermo flap in the drivers side exhaust manifold and disable the heat stove thermatic vacuum flap in the air cleaner too...Completely solved my hot start problem.

joe_padavano

Before changing anything, have you confirmed that the choke is functioning correctly? If it is, then percolation may be an issue. Try an insulating spacer under the carb.

Cruizin Uncle Bob

already have a spacer under the carb, which is now a summit 750 cfm dual feed not a Q jet.

Cruizin Uncle Bob

agreed opposite effects but that's what it takes to fire it off, bought decided I bought a money pit

joe_padavano

And I assume that's a nice, conductive METAL spacer, right? I'm talking about a non-metallic insulator to prevent heat soak into the carb fuel bowl. Since now you've told us you have a non-stock carb, I'll ask again: Is the choke working correctly? Is it an electric choke? How is it wired up?

Cruizin Uncle Bob

yep it's a nice conductive metal spacer which transfers the heat, will check on a phenolic spacer, and the choke is electric, not hooked up yet tied open, and I will hook it up. Have not had any problems starting cold, as temps here are in triple digits during the day.

MDchanic

Are you sure it's a fuel problem and not a spark problem?

- Eric

aussie oldsmobile 98

hey uncle bob , my v8 rambler dids the same thang, did every thing ....turned out the fuel pump was" how ya going" .. low fuel pressure, even would make my car overheat as was runnin to lean , and was a real mongral to start when warm/hot ....bought a new high vol pump no problems fore the last 10years ....

Cruizin Uncle Bob

well, installed a new fuel pump, problem is still there, not but about 1-1/4 turns out on the air screws on carb, seems to run good there, any further out seems to have no effect. May have to re-jet, this car seems to be really testing me, I just give out, never give up though thanks for the feedback.

Cruizin Uncle Bob

well I feel it is fuel, the engine had an HEI distributor in it and it went belly up about 3 months ago, had a lot of slop in the shaft and reluctor went out, so I replaced with MSD ready to run distributor and the matching coil.

joe_padavano

Look, the mind reading still isn't working, and you've been VERY slowly giving us the details of your car, many of which are EXTREMELY relevant to diagnosing your problem. How about you back up and give us ALL the details so we can provide useful troubleshooting suggestions.

So far we have a Summit 750 carb (I assume that's the Autolite 4100 clone?), a metal adapter to the Qjet intake, a non-functioning choke, and an aftermarket HEI, with a problem that occurs on days with triple digit temps. Is there anything else about the car you can tell us, particularly the things that are NOT stock? For example, how is the fuel line run? Is it metal or rubber? Do you have an inline filter? Etc, etc.

Cruizin Uncle Bob

Ok, the car is a 1970 Olds 442, which I bought without interior, with 455 engine, 4 speed manual trans, 12 bolt rear with 223 gears(yes I pulled the cover and counted the teeth), stock exhaust manifolds, dual exhaust, stock intake manifold, not sure about camshaft,engine had been rebuilt a few years ago but not sure how many miles are on it since, original fuel lines ran through the frame with rubber hoses at each end connecting to the fuel tank and the stock fuel pump. A rubber line leaves the fuel pump goes through a clear plastic in-line fuel filter then connects via rubber hose to metal dual feed carb connector, which I have insulated with a small heat wrap. The carb is new Summit dual feed, 750 cfm Holley clone(was told by Summit it uses all Holley internals) with electric choke and vacuum secondaries. It does have an aluminum adapter under it which I realize is probably adding to the problem. Could not find a phenolic adapter. The fuel tank was new when I bought the car. The engine temp now runs about 170 degrees on the highway after all the money I pumped into the cooling system, new radiator, new hi-volume water pump, new fan clutch, am running a 160 degree bypass thermostat, and the bypass neck from the thermo housing back to the water pump has been blocked off internally. I have the rally pack gauges in dash, but also added a second temp gauge for comparison and that is what am using for temp readings. I also installed Vintage air surefit air conditioner system and did away with the old R12 unit as it was junk anyway. The AC has been charged and cools well running down the road but engine heats up to about 200 Deg. at idle with AC on. Added a 16" pusher fan in front of the AC condenser. I have eng. timing set at 12 Deg. as I do have an original service manual on CD and recommended timing was 8-12 Deg. depending on fuel carb etc. The vacuum advance does work. The car originaly had an HEI distributor which I assume the other owner put in, it failed and I installed MSD electronic ready to run distributor with the appropriate coil.

Run to Rund

12 deg. with vacuum disconnected is good. Check the choke when the engine is warmed up and you are going to start it--the choke must remain fully open even after you open the throttle once and then close it.

MDchanic

Are you sure 12° is okay with HEI?
With the reduced mechanical advance range of the HEI, timing might be retarded overall, leading to increased engine heat, and possibly contributing to hard starting.

I agree that with 12° base timing while cranking, the engine should be easy to start, though, all other things being equal.

What's the centrifugal advance at about 3,000 RPM, just out of curiosity?

- Eric