Cold Blooded FE...Part Two

[Bluedog]

OK, I finally mastered getting the cobra started when the engine is cold using some of your great techniques suggested. I sure miss a choke! However, the engine still dies at idle (even after it's warmed up) at a stop light or when I come off the freeway off ramp. I have to goose the gas pedal slightly to avoid stalling when stopped.

I'm using a Holly 750 on a stroked 427 Shelby block FE. The float levels and power valves look good. However, the carb pulls fuel through the booster at idle which it shouldn't do. It's running a little rich at idle. The cobra has been on an engine and chassis dyno so the carb should be dialed in.

Any idea on what's up with my Holly 750? Thanks!!!!

[Portoman]

Try checking for a vacuum leak somewhere. You could also try running the car without a air filter and see if it idles, it sounds like it could be starving for air. Also check your spark, you may have a weak spark and it could be not burning all the fuel causing it to almost flood the engine and die. Sorry I dont know the specs of your engine, so thought i'd just give a suggestion. Hope this helps abit.

[RICK LAKE]

Bludog what is the fuel pressure you are running? How where the floats setup on the carb? Cold motor or hot? You have no picture of the top of the 750 carb, do you have the 2 vent tubes in the top? If the level for the floats are high the gas will suck out of the vents at idle or high vacuum in the motor. Power valve does not have alot to do with the idle curcuits. If you have a propane torch and get the car running at ilde, hook a hose to the end of the torch and use a small end on the hose like a tire inflator and run this around the base of the carb. If the idle of the motor or the motor smooths out, you have a leak. Check your PCV valve for working correctly too. You don't need to run more than 5 1/2 pounds, of fuel pressure and the gauge on the fuel rail maynot be that accurate either. Holley needle and seats bounce with any more that 6 psi pressure and this may cause you a idling problem. Try backing off the pressure to 5 psi and set the carb floats up hot with the motor off and the fuel pump running. MAKE SURE you have rags to catch the fuel or the clear site glass plugs for check the fuel level. If you don't have clear site plugs for the carb, get a set before you do any adjustments. Without a choke, and if it is cold out you will have cold start problems. If the carb is a double pump, double feed, Pump once to the floor and it should start. Pump pedal twice if the carb is a single pump. If your fuel pump is on a switch, Turn on to get pressure and fill carb, then shut off until car is running. This will keep the flooding to a minimum and washing down of the cylinders on cold starts. Rick L.

[Michael C Henry]

How much ignition advance timming are you running? I started with verry little advance and had to open the idle screw a bunch to get it to idle. Once I actually checked The ignition timing and adjusted the timing up to 12° to 14° BFTDC. That same idle settimg had the engine just roaring. I have a Mallory HyFire VI ignition system. It has the abillity to program a set amount of start retard. It only affects the timing under 500 RPMs. So when starting, I'm not working against preignition when starting.

[wtm442]

Originally Posted by RICK LAKE

If you have a propane torch and get the car running at idle, hook a hose to the end of the torch and use a small end on the hose like a tire inflator and run this around the base of the carb. If the idle of the motor or the motor smooths out, you have a leak. Rick L.

KABOOM! I would never use a flame next to a running carb. Just spray the area with a little starter fluid using one of the small red straws to pinpoint just a little fluid at the areas of a suspected vacuum leak. If the idle increases RPM, you found the vacuum leak.

[427 S/O]

Warren is absolutely correct........

[blykins]

Guys, I don't think Rick was talking about using an open flame.....he meant just hook a hose to the torch so you can turn the valve on and get propane from it...not actually lighting it....same idea as using starter fluid, WD-40, etc. to find vacuum leaks.

[767Jockey]

Rick's no dummy - I'm CERTAIN he meant use the propane un-lit, as a source of fuel to be ingested into the vacuum leak which would burn, raising or smoothing out the idle, therefore pinpointing the source of the leak, just like starter fluid would without the possible mess.

[RICK LAKE]

Sorry Guys, I don't see anywhere where I was lighting the torch?? DON'T LIGHT THE TORCH!!!!! Sorry Bluedog Too many lawyers on this forum. My bad. I did stay at a Holiday inn last night Rick L.

[wtm442]

Rick
I guess I was sniffing something when I posted.

[RICK LAKE]

twm 442 with the picture of your car and other half, I am surprised you have time to even get on the CC site. Rick L.

[RICK LAKE]

twm442 I would NEVER use starting fluid around any motor except to start it. You are right are KABOOM with a motor running and a possible poor spark plug wire insolation of the outter cover. I have found that WD-40 doesn't always help with the finding of a vacuum leak, in some cases it swells gaskets or seals and stops the leak until it drys out or burns off. Carb cleaners are better but back to the hot motor KABOOM thing. Saw a kid working on a hot motor looking for a leak and sprayed everything, 2 seconds later he was missing eyebrows, part of his beard, and front hair line. Lucky he didn't loose a eye. I try and find most leaks with a stephoscope and my ears. I use the propane as a last trick. How is the flounder fishing in Quincy?? My dad used to go every year and did well. They now have limits on the fish?? They do down here but it is OK for the commercial to go crazy. They get a limit in tons, we get 5 or 7 fish. Cheaper to buy the fish at the fish market than go fishing on a charter boat. CG loves to check boats for over catching the limit and impound everything. 3-10 grand fines are being handed out in some towns, 2 guys lost there boats to the state for repeated law breaking. Stupid people, loss a 30-50 grand boat over $100.00 of fish at market price. Rick L.

[wtm442]

Originally Posted by RICK LAKE

How is the flounder fishing in Quincy??:Rick L.

Not bad. I can fish for them off the rocks about 1/4 mile from my house. But most people fishing off the shore go for stripers. I remember when the min length was about a foot. Now if the fish is shorter than a yardstick, just throw it back!

Sorry for the hi-jackBluedog. Did you fix the problem yet?

[Michael C Henry]

For the cooler parts of life try another carb wth a choke.

[Keithc8]

Bulldog give us a call about the carburetor. It should not have fuel going by the boosters. This sounds like either to much fuel pressure or some trash in the needle and seat holding it open a little bit. You need to check the timing and the float levels after the engine is in the car. You mayn have fowled the plugs with the carburetor bleeding over and this will make it hard to start. Check the heat range of the plugs as well. We would be happy to look at the carburetor or to trade for another one. Thanks, Keith

[Bluedog]

Thanks everyone for your great suggestions! I'm still on a business trip but when I return, I will be able to fix the carb once and for all. Keith, I will give you a call later this week.

[jdog]

This is the main reason I had my engine built & installed by a local shop.

They would be looking for the vacume leak!

I know Keith, George and many others, do a great job of building these engines but, there's so much more than the original build to consider. Like what if, .................(fill in the blank) happens?

I wanted my engine builder local so we can talk face to face.

jdog