74 440 bored .40 over
9.5:1 conpression
Comp cams extreme energy .488
Hooked super conp headers 3 inch duals
Edelbrock aluminum intake
750 holley classic carb
Orange ignition box and oem style distributor
4 speed
3:73 suregrip

I have been working on timing this car for a while now and no matter what I try it won't rev past 3200ish rpms unless it's in nuetral. I can rev all the way to 5k in nuetral but in first second third or fourth this thing won't go past 3200 or so rpms if kind of spits and sputters. I'm not sure if the timing is advancing too quick or what. I'm going to rev it to 3000 and set it to 36 degrees and see of that makes a difference. If the cam was out of time would I be able to rev it in nuetral? Very confused....

 

When in gear, can you exceed 3200 with part throttle?


Do you have a regular point distributor to install and try?


May be your cam went flat? With the valve cover off, you can observe the rockers and see if some of them barely move. If that is the case, you may want to not run the engine again until you replace the oil and filter. In fact, may be you want to remove the filter and open it up. If the cam went flat, it will really be full of metal.

 

WhenEVER you get problems like this you need to get things into "basics."

1........Be absolutely certain the timng marks are correct. This is a 15 minute job. Use a piston stop to verify the timing marks

2......Regardless of what advance curve is int he distributor, and where the initial is or was, this is a HIGH RPM issue. So yes, SET the timing for full advance, maybe 34 degrees

3......WHAT do you have for an ignition system, IE points, Mopar breakerless, MSD, etc? What have you done about trying to check the spark?

What do the plugs look like? Have you tried a different set of plugs? Do NOT just guess TRY a different set

Have you checked the coil wire / plug wires? Examined the cap / rotor?

Primary power to the ignition.......You sure you have good primary power? You checked? Is this a factory harness IE still has the factory bulkhead connector, etc?

IF SO I would temporarily "hot wire" the ignition direct to the starter relay battery stud and "make a run" to check


4....WHAT does it "sound" like? Snap and pop through the carb? Is it an even 'popping?" Have you had the valve covers off to check valve motion?

5....Compression check / leakdown check?

6.....What do you have for exhaust? Factory manifolds? Stuck heat riser? "Something else" stuck in the exhaust? (There's been everything from ice, in the winter, to collapsed rusted pieces of inner piping)

7........Flat cam.......Usually, this is only one lobe "to start" with and very noticable on one cylinder

 

Be sure the fuel pump is delivering enough and the float level is correct.

In neutral it will rev all day, under power it will use far more fuel. Sounds like it is drinking up whats in the fuel bowls and going lean.

 

years ago i stopped using mech fuel pumps. and went to electric pumps. and check that the fuel hose suction side does not have leeks. pumps will leek on the suction side long before leek on the pressure side. i had a 413 on a 300 L the steel fuel line had a rust hole in it. but was small enough that at low power needs would have enough fuel. but at higher power needs would pull air and not fuel. old crack suction hose can do this.

 

I checked the oil already and it looks very clean but let me open up the oil filter and see if I find something there. Yes I can rev al the way to 5000 in gear no problem it's when the car is under a load. Doesn't matter if the vacuum advance is plugged in or not the car won't go past 3200 rpms. I thought about the cam rounding off but if the oil is clean do you think that happened? This cam has been broke in already I ran this engine about a year ago but I had an auto behind it and I roasted the auto so I made a fun 4 speed conversion project out of it. I have checked the marks on the balancer already by putting the engine at top dead center and that's all fine. The plugs probably could use a change honestly which I'm going to do but the best way I can describe the driving is I feel like I'm ***** to the walls at 3 grand I touch that throttle with the timing light on it and it advances really quick. It's screaming at 3 grand. And when I hit 3200 ish it's like the car redlines and doesn't climb anymore kind of hard to explain. I also have checked the floats and fuel level that all seems perfect heck when I pulled the fuel line off the carb it squirted oil at me! I had just got done running it then though. Another strange thing it was idling and this just happened so you guys know. I was idling it and it sounds very strong but randomly started spitting and sputtering back fired here and there out the tail pipe I never had it back fire out of the carb. But the car cuts in then out so I shut it off restart it and it might idle a little longer then act up again. And my engine temperature doesn't matter when this happens because the first thing I though was vapor locking. 10 minutes later operating at 180 not a problem?! But still having crazy advancing issues or whatever this is. I'm starting to think the pick up coil took a crap. It's just a oem style proform distributor and I also reworked the whole ignition the other day with the orange box and single ballast new harness's and all and I know that's all fine because I checked that all again I figured the ignition box was failing but no it's fine. I really think it's my distributor sparking wrong.... And yes the car has all new fuel lines. Let me ask this. Is it normal to be able to run a car 36 degrees advanced at 900 rpms? Also after I took it for a cruise it was idling at 1100 and not 800 like I set it at.... It's timed at 12 now but I was told to twist the distributor until the car bogs then twist it backwards a little to set my timing. Sorry if my spelling sucks I'm typing on a phone. Thanks for the help guys.

 

I'm getting another distributor for it on Tuesday to see if it makes a difference. I saw another thread where a guy was having serious timing issues like mine I can go from 11-38 degrees at 900 rpms and I still has no high rpms. He also had revving issues and it turned out to be his pickup coil. I have a cheap Chinese dostributor I think also.... I bought that electronic ignition kit a while back and that's the distributor they gave me. This project has taken me about 2 years so bear with me I have to go back and dig up info when you guys ask specifics. Oh it has 906 heads if that matters!

 

Here is something you can do until the new distributor arrives. Check on fuel pressure. I had similar problems with my 440's (both of them, I think its the ethanol). However, in my case, since it takes time to consume the gas in the bowls, I would be able to rev on 1st gear all the way up, but it would stall at lower rpms with 2nd gear. In other words, the problem was not rpm specific. Also, it was very temperature sensitive. When it was hot outside, the problem was more serious. I resolved this by installing a high flow pump on one car, and an electric pump on the other (in series with the old mechanical pump).


Anyway, here is how you check fuel pressure. Get a T fitting for 5/16 fuel line, and install it upstream your carb. Get a long hose, and a fuel pressure gage from your local a-part store. Get the hose through the firewall and into the car. Then go and blast it out at full throttle, watching the gage. If your pressure goes under 1 psi under full load, then this is your problem.


From your description I doubt that's it, but that's easy to check. But I would check your cam first, because if that has gone flat, you do not want to be running the engine and do more damage.

 

I would try a different carb.. Are the secondaries opening ?

 

I will give that a try! I'll look into pulling the valve covers and watching the rockers move maybe I can spot a round one

Let me also mention I only put 93 octane gas in this car but I do know a few places around here where I can get 100% gas no ethanol it's not cheap but I might just try it. I also run an oem fuel pump mechanical of course. Is that an issue?

 

I thought the same exact thing I originally had a 770 street avenger on it so I pulled my other 750 holley off my other 440 and it's still doing the same thing

 

The OEM fuel pump may not be able to keep up. I would test flow volume and running pressure before changing.

 

Hey I hooked up a fuel pressure gauge and ran it and in park the psi was 5-6 then at 3k it was still basically a steady 5 barely moved. Then once the car got warm BAM it starts spitting and sputtering piping out the exhaust a little running horribly rough. I'm convinced it's the doitributor I will replace it with a curved oem style but in the future I want to upgrade to a MSD or? Since we are on this subject what is a good distributor or ignition? I was told to keep my vaccum advance for street driving reasons. I will mostly cruise with this car.

 

In all my fuel starvation problems, at idle or under no load the fuel pressure was always good. Only when driving under full power (or when very hot outside under high speed cruising) would I lose fuel pressure. So, in order for you to be able to draw a definite conclusion, you have to get the pressure gage inside the car, and drive it under high load. Especially, after it reached operating temperature. If your pressure always stays above, say, 3 psi, then this is definitely not your problem. But you have not confirmed that yet.

 

I should of been more specific. In first gear at 3 thousand rpms my car didn't go any lower than 4 psi. Then after wards idling it started spitting and misfiring running rough all that fun stuff. But a new update now it won't start at all! Cranks over that's it. I'll let it sit and see if it starts later.

 

Maybe I should also mention when my car seems to stop revving or climbing rpms while cruising I am by no means going anywhere close to full throttle. I have yet to even give this car full throttle. The most I have given it is half MAYBE! I give it maybe quarter throttle.... I put my boat around really

 

Fuel starvation problems normally happen at WOT or close to it.


May be your car is running too rich (?) You said when the car warmed up, it started misbehaving. ... and now won't start. Did you try starting it while depressing the gas pedal all the way down? If the car is too rich, opening the throttle allows more air to enter the cylinders, and the engine starts. Also, temporarily disconnect the fuel line from the carburetor (either block the fuel line or direct it into an empty container). If the car starts and runs for a few seconds with the fuel in the carb bowl, then may be your problem is too rich.


Problem with this theory is that you said you had similar problems with two different carburetors. But try it anyway, may be we will learn something.

 

I'll give your suggestion a try. I have 72 and 75 jets in my 770 carb originally they were 4 steps higher than that but I dropped them down and still had issues so I thought maybe it was still rich or I had other carb issues so I went to the 750 holley classic and that has whatever jets came in it from holley. I'll just wait until Tuesday to figure this out I opened up a 400 distributor I had laying around and it looks much better built than my crap Chinese thing

 

Yeah, well. The "rich" I am talking about is real-real rich (has happened to be before). I sort of doubt that wrong jets can really cause that level of rich, to the extend that the car barely runs. The rich level I am suggesting would be the result of a float valve being stuck partially open. When the engine is cold, it tolerates rich mixture, but not when it warms up. That usually happens as a result of dirt in the fuel, coming from a rusty gas tank. It could affect both carburetors. You should be able to see black smoke from your exhausts, if that theory is correct. (Actually, you should be able to see the black smoke if too rich, no matter what the cause is).


I can't see why your ignition, on the other hand, would run any different when hot. Why don't you get your timing light handy, and when the engine miss-behaves, just look at the timing and see if it is erratic. Just in case, may be you can swap coils with your other 440.


I assume that by now you have checked the valve motion, and there is no issue of cam being flat.


By the way, the 440 I just built for my Imperial is very similar to yours. I have a cam just one step below yours (.477 lift), but I have head work and larger valves. I have an Ederblock AFB 750, which I suspect is running a bit lean at WOT, so I have not seen the full performance potential. But it is running reasonably well throughout the rev range (from idle to 5000). I am surprised that I have strong low end torque to move the heavy car with 2.94 gears as well as it does.

 

Changing the distributor is a good idea, would like to hear results. Change only one component at a time to isolate problem.

 

the valve motion is fine. oil looks new nothing unusual there. i compared the quality of my old 400 distributor internals to my 440 internals and i cant get over how cheap the 440 one looks the arm on the back of the vaccum canister isnt the same as the 400 and i thought the 400 and 440 were the same distributor besides the 440 having a longer shaft being a RB engine. Now the pickup coil where the wires are soldered onto the coil itself under the cap they dont even have insulation on them it looks like its been covered in hot glue and dried the plate the vaccum advance moves that the pickup coil sits on barely moves compared to my 400. Heck i wonder if the pickup coil is even adjusted properly!

I have minor port work done to my 906 heads with the oem valves besides hardened valve seats. When i get this problem solved i may consider a set of stealth heads $500 per head assembled isnt a bad deal. I was originally going to use cast iron 915's but its a fortune to get the seats redone im better off going to aluminum the only reason i went with the 906 heads is because i found them with already hardened valves seats on a 440 i bought and the guy i got it from didnt know it was previsouly rebuilt so i paid $100 for a 440 with rebuilt heads and i cant remember what cam was in that engine.

What year is your imperial? I wouldnt mind seeing some pictures of it! i like the idea of a c body that can scoot. no one really expects it atleast where i live. The 4 speed conversion was tough but although the car isnt running correctly its still fun to drive around shifting. I even got the run around on swapping to a 8.75 rear end... but i managed it. i used a 73-74 b body rear housing its 3/4 inch shorter on each side but didnt affect me at all when i have an easy 12 inches of wheel well space to play with hahaha!

 

i will let you know tomorrow what happens! hopefully everything works fine

 

Glad the problem is not cam going flat.


I have never gone inside a distributor. So, I don't know how the 400 and 440 compare. But if the timing does not mess up, and if you have a strong spark, it should be fine. At any rate, I can't see why the distributor would not work so well when hot, but work well cold. The coil on the other hand ... it could.


The 906 heads are better than the 915's. The modern aluminum heads may have had some further improvements, and are lighter, but not as forgiving when the car overheats. I prefer the old iron heads for reliability. On a big car like yours, a few extra pounds won't make much difference.


I have two Imperials, both 68 model year. The 3xblack Lebaron with leather seats and 5 speaker stereo probably has had a cam upgrade before I got it, and two glass packs, and it runs fine. Smooth high speed cruising car. Sounds good too! The green sedan, that has the engine build, needs a lot of cosmetic work, but it will be a good dedicated high speed car, may end up winning a few high speed races. Both have the stock 2.94, and the LeBaron has a late model lockup converter. Don't really know how to post pictures, but I could email you some.


I was considering a 4 speed conversion too, but the torqueflites have a very good reputation, and the clutch would be out of character on a luxury car. Plus, the heavy clutch and the not so good ratios of the 4 speed scare me. But for a sleeper drag racer, a 4 speed may be fitting the character.

 

got the distributor in it works way better. by the way the vaccum advance canister and pickup coil on the old distributor was wrong and way off on the pickup coil adjustment. so its running way better i have a steady timing mark to work off of now. now! a new problem! the carb is running way to lean i think dont hold me to that. took it on the road and it started to jump i guess you could say whenever i hit bumps so now is this a float issue? run bigger jets? fuel pressure gauge still says the psi is fine. another thing the vaccum advance should be plugged into the port on the side of the carb right?

 

got the distributor in it works way better. by the way the vaccum advance canister and pickup coil on the old distributor was wrong and way off on the pickup coil adjustment. so its running way better i have a steady timing mark to work off of now. now! a new problem! the carb is running way to lean i think dont hold me to that. took it on the road and it started to jump i guess you could say whenever i hit bumps so now is this a float issue? run bigger jets? fuel pressure gauge still says the psi is fine. another thing the vaccum advance should be plugged into the port on the side of the carb right?

 

The discharge of the fuel pump should be 1 pint in 20-30 seconds at idle.

Holley fuel level is straight forward and You Tube videos can be found if your not familiar.

Test both before making changes.

 

I would suggest you go to one of the auto parts stores that loans tools & borrow a vacuum gauge & a timing light...

 

So I called a holley tech line today and explained the problem to him and he said it sounds like the fuel pump gallon per hour isn't high enough. Mine is 30 gph he said to get a 110 gph and that will solve the problem. I've been going threw my carb making sure it's all fine in the mean time and I was having some fuel boil over other than that I can't find anything else.

 

You said earlier that your fuel pressure never fell below 5 or 6 psi. That means that fuel starvation is not the issue, at least not yet (it might, once you start operating at WOT, but this is not your problem yet). If your carb bowl ever went empty, and the float valve(s) opened wide open, your fuel pressure would have been near zero.


Your problems are elsewhere.


Did you ensure that your engine is not running super rich? Did you check for black smoke in the exhaust when the symptoms show? May be have somebody follow you while test driving and watch these exhaust pipes. Smell the oil and see if you can smell gasoline residue, and/or see if the oil level is going up. (if running super rich, the excess gas accumulates in the oil).

 

I told him that I was getting 6 psi even at wide open throttle and he claimed that doesn't matter. I'm only pumping 30 gallons an hour vs 110 it's not supplying the carb fast enough. I have checched everything man I'm puzzled if he's not right I don't know where else to start. But I'll keep tampering.