Having a bit of an issue with a new 428 build

[BigBlueOvalFan]

428 PI keeps flood stalling and is running a bit rough (not smooth and a bit jerky).  I have other big cam FE's and it's a noticeable difference. It's a new build and basically stock 10.5:1 with 390GT heads and a lunati cam .554 lift/292 duration.  It runs fairly well when first fired after sitting overnight and/or cold and only has a small miss but after a minute or so as it starts to warm up, it acts like it's flooding and dies at idle.  If I keep the rpm at 2500 + it cleans out but still has a small miss.  When taking the rpm up to clean it out, it stumbles like it's loaded up but hasn't backfired. I have a pertronix unit with a new msd coil. I'm running an older edelbrock 2x4 aluminum intake with newly rebuilt carter/weber type carbs from carb junkys.  Jim over there helped me reset the curb idle and a/f idle mixture correctly but I think the damage had been done to the plugs by previous starts/runs.  I did notice upon removal of the plugs that they were in there only finger tight, don't know if that could be a contributing factor.  I also still have the small port on the side/top of the cast exhaust manifold that is not in use for the choke at the moment but don't know if that is a contributing factor either.  It hasn't been out on the road yet as I'd like to get it to idle correctly first. 

My vacuum gauge reads 9-11lbs depending on the timing and idle (would this be average for the cam ?).  Any spark plug recommendations would be helpful since these look to be gone, something I could pick up at the local auto parts, NAPA, O'reilly, Pep Boys, etc.

Pics attached.

Any suggestions/help would be greatly appreciated. 

Thanks, Jim

[NIsaacs]

It sounds like your timing is too slow. What is your initial and total? Is the distributor mechanical or vacuum advance?

Nick

[cjshaker]

More info would help. What are the .050 numbers on that cam? Solid or hydraulic? Have you driven the car at all yet? Did it do this from the beginning, or was it worse before the carb adjustments? Any more info would help track the problem down.

I ask about the cam because that vacuum seems a bit low. What is your initial and total timing, because that can have a big effect? I asked about solid or hydraulic because I wonder what your lash is (if it's solid), or how you determined pushrod length (if it's hydraulic), to make sure your not hanging the valves open a bit. I asked about if it was like this from the beginning because if the carb was really rich, it may have just fouled the plugs beyond help and a new set may cure it. I think the 45's should work ok on most stock type builds.

The port on the exhaust manifold will have zero effect on any of this stuff. The plugs do look a little fouled from being over rich, and often times they will not recover once the carb is adjusted correctly. I think I'd start with a fresh set of plugs and see how it acted then. If that doesn't cure it, it'll be time to start trouble shooting and going over the finer details like timing, lash, possible carb or ignition issues etc. It would also be worth your time to disconnect any vacuum sources (except for the distributor) to eliminate any possible leaks. If everything cleans up, re-connect everything and see if the miss comes back.

Edit to say that, in your picture, the vacuum advance isn't hooked up. Is it still that way? That will have a big effect on idle quality and vacuum readings. If you try and compensate for it being unhooked by upping the idle speed and mixture, it just gets you into different problems with the carbs.

[RJP]

I would check fuel pressure. Carters [aka Edelbrock, Weber, etc] do not tolerate alot of fuel pressure. Unlike a Holley that can handle 6.5-7lbs. the AFB type only needs 4-4.5 lbs.

[BigBlueOvalFan]

It sounds like your timing is too slow. What is your initial and total? Is the distributor mechanical or vacuum advance?

Nick

I only set the total at about 3000rpm at 34 but had to back it down to 32 because of a hard start.  The dizzy is vacuum advance but I didn't hook it up, probably should.

[BigBlueOvalFan]

I would check fuel pressure. Carters [aka Edelbrock, Weber, etc] do not tolerate alot of fuel pressure. Unlike a Holley that can handle 6.5-7lbs. the AFB type only needs 4-4.5 lbs.

I've read that about these carbs and wonder if the combination of low vacuum and high fuel press may be causing the fuel rich issue. I'll be checking my fuel pressure next and will install a reg if needed.

[BigBlueOvalFan]

More info would help. What are the .050 numbers on that cam? Solid or hydraulic? Have you driven the car at all yet? Did it do this from the beginning, or was it worse before the carb adjustments? Any more info would help track the problem down.

I ask about the cam because that vacuum seems a bit low. What is your initial and total timing, because that can have a big effect? I asked about solid or hydraulic because I wonder what your lash is (if it's solid), or how you determined pushrod length (if it's hydraulic), to make sure your not hanging the valves open a bit. I asked about if it was like this from the beginning because if the carb was really rich, it may have just fouled the plugs beyond help and a new set may cure it. I think the 45's should work ok on most stock type builds.

The port on the exhaust manifold will have zero effect on any of this stuff. The plugs do look a little fouled from being over rich, and often times they will not recover once the carb is adjusted correctly. I think I'd start with a fresh set of plugs and see how it acted then. If that doesn't cure it, it'll be time to start trouble shooting and going over the finer details like timing, lash, possible carb or ignition issues etc. It would also be worth your time to disconnect any vacuum sources (except for the distributor) to eliminate any possible leaks. If everything cleans up, re-connect everything and see if the miss comes back.

Edit to say that, in your picture, the vacuum advance isn't hooked up. Is it still that way? That will have a big effect on idle quality and vacuum readings. If you try and compensate for it being unhooked by upping the idle speed and mixture, it just gets you into different problems with the carbs.

Doug,

The .050 #'s are 230 in/ex. I included a copy of the cam card on my post as a gif that you can open and see all the specs. The cam is your basic hydraulic.  I have not driven the car yet, It's been a 5 year long rotisserie restoration and this is the first time it's been fired.  The first fire was cam break in/ring seat and I held the throttle open at about 2000rpm with some blips here and there.  After about 10 minutes, it started to get hot and developed a leak on the backside of the water pump so I shut it down.  It never had the chance to idle and produce this issue until I repaired the water pump.

I only set he timing at full at around 3k rpm at about 34 then backed it down to 32.  I haven't hooked up the vacuum advance but probably should and then reset the timing correctly.  Please let me know what you think the initial and full timing should be.  When I first fired the engine, I didn't pay attention to the a/f idle screws and the front carb which is secondary had them out 10 turns which is real rich.  I think you may be correct that these plugs are toast and a new set may fix the issue. I'll be trying that today along with setting the timing correctly.  I checked my push rods by rotating the engine manually until I noticed closed valves and then checked to see if the push rod would spin with my finger without having play.  I didn't run across any that were tight or with play.

The engine/carbs sat after being rebuilt in 2013 in a fairly dust free condition and all fuel associated items (tank, lines, pump, etc) are all new. I pulled the meter rods and noticed that the underside of the cup where the spring sits in was dirty with black grime and I wonder if that's just from the spring or if I have a needle/seat issue with debris or a float that's sticking. I'm also spewing a bit of water with carbon from the tail pipes but I think that's normal considering the fouled plugs and not being driven.

A couple other notes;  most of the plugs were only finger tight, don't know if that was caused by using antiseaze or if the loosened up after it got warm. Also, when I ran a bore scope down the runners, the ones I could, the head to manifold match is great on the top and sides but the bottom has a large shelf where the manifold is much lower and the bottom of the runner just runs into a 1/2" or better block of cast iron.  I attached a pic. Don't know if this could cause any of the issues I'm experiencing. I just got off the phone with a tech from lunati and he stated 13-14lbs would be good and that I'm low.  He thought that, as you guys have, that it's wise to set my timing first which may pull up the vacuum which would in turm pull down the metering rods.  He thought that it sounded like the carbs are setup with too heavy a spring for the cam and low vacuum condition I have, especially with 2 4bbl carbs and that the carter/afb is notorious for requiring more vacuum to close the circuit. He suggested a tuning kit for the carbs and using a much weaker spring if the timing adjustments didn't get me to the 13-14 lbs of vacuum.

I'll report back after I install the new plugs and reset timing.  I just don't want to have to do it again as changing plugs requires me to remove the driver valve cover and that's a whole bit of contortion of wrists and skinned knuckles going on, lol.

[cjshaker]

Your timing is WAY off. That's what caused it to get hot and have low vacuum, and is probably the cause of the miss. At partial no-load throttle, that engine wants timing. It needs to be up around 38*-39* total with the advance disconnected. Initial will fall wherever it falls, but if it's too far advanced and is hard to start, you'll have to get into the distributor or send it to someone who can set it up properly. Typically, with an untouched distributor, it'll be anywhere from 12*-16*, depending on how it's currently set up. 14*-16* initial is usually a happy place to be. Remember to set your timing with the advance disconnected, then hook up the advance. It'll run MUCH smoother and cooler.

Anything you do at this point will be useless until you get that timing up. Is there something wrong with your advance canister? Severely retarded timing is VERY hard on an engine, heatwise, so get that taken care of first.

As for taking the valve cover off, it probably isn't even an issue since your timing is the problem, but I've found a very long 1/4" extension with a swivel and socket taped on the end (so it won't pull off and drop down into the 5th dimension), works very well. I can get to all of mine this way except for the bottom rear corner on the drivers side, under the master cylinder. And that's on a Mustang, which is tight no matter what covers you have.

Edit: The finger tight plugs obviously aren't a good idea, but probably not the cause of any of your problems. Of course they should be tighter though. And your port mismatch isn't really an issue either. Lot's of dyno tests have shown that on a typical mild street engine, it won't make a big difference. If you ground the heads to match, you'll either grind through or make a huge divot in the port, which would be counter-productive. I wouldn't worry about that. Also, the water is PROBABLY normal condensation in the exhaust. I wouldn't worry about that either unless you notice your water level lowering. If it was going through the cylinders, your plugs would show signs of it and I don't really see that in the pics.

[mike7570]

Somebody needs to mention it -   
Your engine compartment looks too good to be using the out of place Edlebrock carbs, get some Holley's

[BigBlueOvalFan]

Somebody needs to mention it -   
Your engine compartment looks too good to be using the out of place Edlebrock carbs, get some Holley's

Thanks for the compliment, wish the Holley's would fit on this manifold.  Got a good deal on this setup but it's turning into a real headache.

[BigBlueOvalFan]

Your timing is WAY off. That's what caused it to get hot and have low vacuum, and is probably the cause of the miss. At partial no-load throttle, that engine wants timing. It needs to be up around 38*-39* total with the advance disconnected. Initial will fall wherever it falls, but if it's too far advanced and is hard to start, you'll have to get into the distributor or send it to someone who can set it up properly. Typically, with an untouched distributor, it'll be anywhere from 12*-16*, depending on how it's currently set up. 14*-16* initial is usually a happy place to be. Remember to set your timing with the advance disconnected, then hook up the advance. It'll run MUCH smoother and cooler.

Anything you do at this point will be useless until you get that timing up. Is there something wrong with your advance canister? Severely retarded timing is VERY hard on an engine, heatwise, so get that taken care of first.

As for taking the valve cover off, it probably isn't even an issue since your timing is the problem, but I've found a very long 1/4" extension with a swivel and socket taped on the end (so it won't pull off and drop down into the 5th dimension), works very well. I can get to all of mine this way except for the bottom rear corner on the drivers side, under the master cylinder. And that's on a Mustang, which is tight no matter what covers you have.

Edit: The finger tight plugs obviously aren't a good idea, but probably not the cause of any of your problems. Of course they should be tighter though. And your port mismatch isn't really an issue either. Lot's of dyno tests have shown that on a typical mild street engine, it won't make a big difference. If you ground the heads to match, you'll either grind through or make a huge divot in the port, which would be counter-productive. I wouldn't worry about that. Also, the water is PROBABLY normal condensation in the exhaust. I wouldn't worry about that either unless you notice your water level lowering. If it was going through the cylinders, your plugs would show signs of it and I don't really see that in the pics.

38-39 seems a bit much, are you certain ?.  The lunati tech said 24 with the vacuum disconnected but I'm more apt to listen to the guys here that know the FE. 

Since I had to pull the export brace and valve covers off which is a chore in itself, I decided to run some tests.  Compression test first shows Cylinder#1 = 175, #2=165, #3=170, #4=155, #5=180, #6=170, #7=165, #8=175.  #4 concerns me and these numbers are cold as getting this thing warm and then trying to pull plugs is a recipe for burns.  I also ran a leak down and no cylinders showed more than 5% loss.  I ran a fuel pressure test and have 6.5-7psi which some say is too much for these carters.  I read on the HAMB that a couple guys that run the carters suggest no more than 3-4 psi as well as RJP here on this forum and one guy used a spring loaded needle/seat that is usually used for marine and off-road conditions and it seemed to stop the excessive fuel at idle.

I plan to clean the plugs, test them for resistance, shorts, ect and set the timing correctly and see if it can pull enough vacuum to close that idle circuit.  Jim at Carb Junkies was very adamant about setting the curb idle first by turning them over and adjusting until the long slit was just a small square and then not to touch it.  He said to let the timing correct my idle speed to no more than 800rpm which doesn't seem to work very well.  I may also have a clogged needle/seat and plan to pull the air horns on these carb and use some compressed air just as a precautionary method.  A visual inspection didn't reveal and bent push rods, loose rockers or anything out of place.

I don't think it's just timing, although it's probably one of the issues for sure.  I have a feeling it the fuel pressure which is blowing past the needle/seat. 

Any other ideas and/or suggestions on how I should move forward are greatly appreciated.

[unclewill]

I run 12 initial/36 total with no problems on pump gas.

[fryedaddy]

i dont know if you or anyone else has mentioned it,but have you checked the float levels in the carbs,they could be too high causing gas to go to places it should not

[BigBlueOvalFan]

i dont know if you or anyone else has mentioned it,but have you checked the float levels in the carbs,they could be too high causing gas to go to places it should not

Good cal, I'll be checking that as well when I pull the tops off.

[Falcon67]

Somebody needs to mention it -   
Your engine compartment looks too good to be using the out of place Edlebrock carbs, get some Holley's

I'll mention that I run two Ed 600s on a SBF tunnel ram and have no issues.  I have a fancy 750 DP on the dragster and have had nothing but issues with that POS all year.

As noted, Ed fuel pressure should be max 5 lbs. 

>38-39 seems a bit much, are you certain ?
The SBF is locked at 36, the 351C in the Mustang at 38.  I use PMGR starters and dial back 10 degrees in the ignition for start retard.  No problems and the motors really like it.  The only exception is the 351C in the dragster - the fast chambers in the heads like 28.