Ignition or fuel issue?

Hey everyone, I'm new to the forum. I've been beating my head against the wall trying to solve my issue... Here it is.

1976 Corvette

496 BB stroker 10.1 : 1 comp.
th400 trans
quickfuel 850 carb
quickfuel reg set to 7psi
quickfuel hp155 pump
msd 6al box (replaced)
msd pro billet distributor (noticed rust on pickup, have not replaced yet)
pt# 8361
msd hvc blaster coil (replaced)
ohmed all superconductor msd wires and they check out 40ohm/ft
new ngk plugs gapped .040
timed 36 deg total advance 18 in motor 18 in distributor

Car ran great for about a year and a half in Chicago. Moved to Florida (Tampa). Drove the car for a couple days and it started acting up...
From a stop, if the car idles at a light, if I leave the light hard it sounds like it is breaking up. Accelerate through 3rd and the motor chokes and dies. Can't even feather the pedal to keep it going. Need to stand on the accelerator to get it fired up again. Spits fuel out of the primary vents of the carb.
Also, noticed when sitting at idle in park, it is fine. When I bring the Rpms up around 3000 the engine sounds like it is dropping a cylinder and the rpms drop sharply about 3-500 rpm and never regain through acceleration.

Would rust on the magnetic pickup inside the distributor cause something like this?

For the longest time I thought it was a fuel issue... The car originally had a mechanical pump. The first thing I did was replace the mechanical with an electric one. No change. Replaced fuel line. No change. Added a heat shield to the bottom of the carb, no change. Sent the carb back to quickfuel to be rebuilt, no change. Replaced plugs multiple times, no change. Ran new ground from battery to frame, battery to bell housing, 2 straps from frame to engine block (cast iron heads) no change. Replaced 6AL box, no change. Replaced the coil with a Blaster 2 coil, no change.
Short of replacing the distributor or carb, I don't know what else to do besides rip the interior apart and rewire the whole car.... Or go EFI! I should be able to figure this out... I won't stop till I have!

Ideas???? Please help me figure this out! I've been at this for almost a year and have spent way more than I wanted to all for no reason so far!

Check your distributors mechanical advance, make sure it is not binding or sticking.

Spits fuel out of the primary vents??

First off Chicago area has different fuels than other areas of country-----

A holley carb won't hold 7 psi pressure------electric pump? turn off to see if it will clear up---- sounds like you are flooding it out pretty bad

Quote:

---

Originally Posted by jerry clayton

A holley carb won't hold 7 psi pressure------electric pump? turn off to see if it will clear up---- sounds like you are flooding it out pretty bad

---

You guys kill me with your fuel pressure settings. No modern 4-bbl carburetor needs more than 5 psi to keep the bowl(s) full. You need VOLUME, by using large diameter lines (1/2" or larger), but you do not need high pressure. All that will do is to overpower the needle and seat and allow the pump to blow raw fuel into the intake manifold, creating a tuning nightmare for you. :eek: This is not EFI, where more pressure will support more horsepower.

.

I agree with the Inspector. You do not need to hear much more than the system psi and that gas is coming out the bowl vents to understand that you are flooding the engine. The other tip is having to hold the throttle wide open to get it to re-start. I think that you may also have pre-ignition issue due to poor gas. Have you read your plugs? Pull your plugs, keeping in mind with came from which cylinder. I'll bet you will see black deposits on the center insulator and they may even be wet. Take a look and they will tell you all you need to know. Google "Read spark plugs" and you will get great photos that will help. If this has been going on for a year, you may have to reset the floats and check the needle valves as they may be off at this point. The rusty pick up may contribute somewhat to the misfire issue but you have to fix the fuel issue first.

It's no skin off of my nose, but vetteguy76 posted his lengthy explanation and question, then two minutes later logged off and has not been back. This means that he's not yet read any of the four responses unless he's lurking w/o logging in. Not a problem to me, but maybe we need to give him time to come back and respond to what's been suggested. Maybe he's one of those "instant gratification" guys who expects an immediate answer to any question, but maybe he just went home to visit Mom for Christmas.

Well I found an article for him. http://www.crankshaftcoalition.com/w...ng_spark_plugs
Fun to talk about any way
Happy New year!

Quote:

---

Originally Posted by twolaneblacktop

Well I found an article for him. http://www.crankshaftcoalition.com/w...ng_spark_plugs
Fun to talk about any way
Happy New year!

---

Thanks for addressing the reading of plugs. I usually do that also, but failed to mention it this time. I like to suggest a Longacre lighted 10X loupe and making a full-throttle run, then going to neutral, chopping the ignition and coasting to a stop, where the plugs are pulled right there. Idling or driving after the full-bore pass will re-color the plugs and the plug reading is worthless.
Longacre Racing 50884, Longacre Tools and Pit Accessories | Longacre Racing

.

I doubt this fellow is coming back. He probably asked the same question on 10 other forums and liked the answers he got somewhere else.

.

Well, for me I do not care if he returns or not. It was very enjoyable to think about his issue, knock the cob webs out, and discuss the issue with you folks. I am an old drag racer that has been away from the sport for twenty plus years. My son saw the old photos and fell in like with the strip. He built an 88 super coupe himself. I made sure that it went straight when it went, did not catch fire, and that it stopped when it needed to. Don't know how I raised a ford kid......

Quote:

---

Originally Posted by twolaneblacktop

Well I found an article for him. http://www.crankshaftcoalition.com/w...ng_spark_plugs
Fun to talk about any way
Happy New year!

---

I just realized that article was written by Mark Ritter, an old friend from Atlanta, aka Cobalt327. :D

.

He's a check writer

Hey everyone, thank you for all the responses! I am a Realtor in the Clearwater Beach area and I focus on property management/rentals and I have been swamped right before the beginning and just after the new year with check ins and check outs. This is the first chance I have to respond to everyone. First Happy New Year! And I am so grateful that all of you have taken the time to share your experiences with me! I have not had a chance to mess with the car too much... Since I have posted my initial Thread, I have changed my magnetic pickup in my dist. which was rusty. I have also replaced the msd 6al box with no change in issue. Quickfuel has told me to run the carb at 6.5 - 7psi. In speaking with the techs there, I question their competence. I have tried to bring the car up to 3000 rpm (in park) while the motor is chugging and shutting the fuel pump off and low and behold the car smooths out. I plan on dialing down the fuel to around 5psi. I also checked my power valve this morning which is a 5-6. The car has 9in of vac at idle in drive (th400 trans). I will be replacing the valve with a 4-5 either tonight or tomorrow. The plugs have been fuel soaked the last few times I have changed them. It's been extremely frustrating dealing with this issue for the past year... however I have learned so much about the other components of the car! I love hearing feedback from others... I am not afraid to say I don't know that much about cars but I am learning!!! I will post an html to photoshop of my build. This is the first car I've built. The only things that were done for me was the engine and trans were built by professionals. I have done everything else myself.

Corvette by jpalasky | Photobucket

Please let me know if the above link works!

Well son I have to say that based on your posts, I think you have more money than sense. Quit spending money and put your brain in gear. You have fuel squirting out the vents, wet plugs, and clear symptoms that the carb is loading up. You are dumping fuel down the carb and choking the engine. Take The Inspectors advice and install a fuel pressure gage. Adjust fuel PSI to 5. I believe that the carb is damaged. Find a local carb shop, they still do exist, and have them review the carb or IF you want to spend some more money buy your self a real HOLLEY.
At that point you need to look at the distributor. How did you get dampness in the distributor?? Is the cap in good condition? After you fix the fuel issue look for a vacuum leak.

The link works.
Nice car!

Hmmm...

It's usually the people posting that don't give enough time for response.

It's actually amusing to me to see the members ran out of patience first.

Ha ha. I love this site.

Hot rods 4 ever!

vetteguy76,
Welcome to CHR. My approach would be to get a pressure gauge piped into the system and set your fuel pressure at the carb at 4.5 to 5 psig and see what that does. I believe that you've been lifting the needle off of the seat and flooding your carb, and the fact that you're blowing some fuel out of the primary vents is reason for concern for an engine fire. Hopefully reducing the pressure is all you need, especially considering that you had the carb gone through by the QuickFuel guys. Once you get the float level right then you can read the plugs to see if you've got jet issues with the 1200' change in altitude. That will involve making a hard run, shutting down the engine as soon as you come off the throttle and coasting to the side of the road to check a few plugs. You don't want to bring it down into the idle/mid-range before checking, but first things first, get your fuel pressure right.

As for the rusty pickup, you've moved from Chicago to Tampa (you didn't say if you drove the car or if it was trailered), where the daily relative humidity is pushing saturation. I expect that with your problems (started a couple of weeks after arriving...) you've made a bunch of start/stops without the engine getting up to temp enough that the distributor cooks off any ambient moisture, and if you barely get it warm then it's going to condense moisture as it cools. You may have to take the distributor apart and clean it out, but again first things first. Fix your fuel problem before your 'vette becomes a pile of flaming fiberglass by the roadside.
Hope you'll stick around and let us know what you find, especially details of the fix. You'll get there.

I'm thinking that your move, and the probability that the car doesn't get driven much are contributing factors to this problem you have.

First thing, address that carburetor; the subject of fuel pressure has been well discussed. I would either find a good set of instructions and a top level rebuild kit and refurbish it yourself, or find a carb pro to do it. Carbs need to be "kissed and hugged" from time to time just to let them know you still like them. If they sit too long without being worked out a good bit and heated up to good operating temps, especially with the low quality of today's gasoline, things in them, like o-rings, seals, and gaskets dry out and start to leak; they will do that over time, anyhow, but not as quickly, if you run the car enough on a regular basis to get it good and warm for a fair amount of time - think a ride on the interstate at traffic speeds for at least a half hour or preferably more.

The same train of thought goes for the distributor; it has rubber parts, seals, and venting devices that in good shape, seal it and prevent water or moisture from getting inside or collecting there. Over time, the rubber and other materials in these seals will dry out, probably crack, and let moisture or water get in, or won't vent the distributor to let accumulated condensation get out, and then you get problems. I would just take it apart and clean out the inside and spray it down with WD40 and wipe it out well, and put a whole new "rebuild kit" in there, including a new, fresh cap; check any grommets or other openings through the distributor body, too, to see that they are sound and sealing correctly.

That is a nice car, and it needs to be driven and worked out often to keep it in good shape.

.

I have figured out the problem! I have 3 points in my fuel line where I have psi gauges... one directly after the fuel pump, one at the fuel reg and one at the carb. Here is what I did.

Set the fuel psi to 5psi. replaced the 1cyl plug. set the float bowl level to just above the bottom of the sight glass. rejetted the carb 78 on the primary and 84 on the secondary. started the car and it seemed worse!!! Then, I noticed when I accelerated, the choke closed! The harder I accelerated the faster the choke was closing. I can't believe that all this time it was the choke. I turned the choke adjuster so the choke was under spring tension holding it open. I took the car out and it ran good. Pulled the 1cyl plug and it was white... time to work on the jetting! That's easy enough!

Congratulations! Gotta feel good to have found the main problem and making steps to having it done-done! Thanks for coming back with the update, too, and hoping that you'll continue to post as you home in on the final adjustments to get the 'vette "Floridized".