Gotta get this sorted out!

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KnuckleDuster

KnuckleDuster

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Ok, here's the deal...
410 ci 360
Stock Edelbrock 63cc heads 60779
Cast MP 4" crank
SCAT H-beam rods
Wiseco Protru 20 cc pistons
Felpro 1009 .030 head gaskets.
Comp 7958-16 pushrods
Crane 99378-16 lifters
Comp Pro Magnum rockers with MP rocer shaft shims to correct side to side valve contact
Edelbrock 7576 Air Gap
B&M 10230 flexplate (internal balance)
Carter M6902 fuel pump
Stock original Chrysler distubtor with new magnetic pickup and rotor.
New cap and Taylor Spiro-Pro wires
Accel 8320 cap and rotor kit
MP 3690715 distributor drive gear
Hedman 78050 headers
Rollmaster bollet timing set with MP tensioner
Mopar branded MSD 6AL
Comp XE285HL (20-228-4) cam
Turbo Action "Tight 10" 3500 stall converter (17805-ST)
NGK FR4 plugs
(I 'm sure I am leaving something out, just ask.)

Problem I am having-
Was running a 1413 800cfm carb and it was bucking about 3800-4000rpm. Still ran 14.4 @101mph.
Been trying to cure mainly via carb.
Checked float height and drop, blew out all passages. Tried to richen with rod changes. No dice!
Swapped on a 1406 that I rodded and jetted to 1405 specs with pink springs.
No more bucking, but if I stab it from a 30 mph roll, it stops pulling at 3800rpm and falls flat until I lift and then takes a few seconds to recover.
If I gently, gradually ease into the throttle, or nail it from 60mph (2800rpm) , no problem.
This leaves me to believe it is fuel related. Also, stab it fom a dead stop and lift, it wants to die. Brake hard for track turnoff, same deal...
I have searched the net but can't conclude if it's some design flaw with Edelbrock carbs, or if it could just be an ignition issue, or just something I am missing?

I am thinking of going to a Holley type carb, but want to nail down the root of the problem before spending cash.

Yes I will plumb a fuel pressure guage to see what's going on at rpm under load first, but whats the best method of doing that? Bring the hose out ny hoodscoop? That's about 5-6ft of hose.Is there a good isolated guauge you guys might reccomend for permanent install?

Are these Carter pumps known to have problems?
Mine is about 10 years old and at times has sat for months while I ironed out bugs or upgraded stuff on the car, I haven't smelled any gas in the oil, but maybe sporadic use caused diaphragm damage?
 
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Could be low initial timing, Could be pump shot "try the closest hole on the pump lever to the carb", Could be the primary rods step up springs are too weak.
In what condition are the plugs?
I like Holley style carburetors, but let's try fixing this one.
 
If you check for fuel pressure, check volume also.
i don't know the specs, but the equation should be that the pump fills a gallon in x amount of time, or quart, or whatever volume you want to use. You may want to put an electric pump on if you find that it is the pump, go full race equipped. I copied these specs from Summit on the Carter M6902 fuel pump:
Free Flow Rate:120 gph
Maximum Pressure (psi):6 to 7.5 psi
Im thinking GPH is gallons per hour, you should be able to fill two gallons a minute.
 
Sounds like its running out of fuel supply. Check between pump and carb inlet for restrictions, restrictions from tank to pump, blocked pick up, blocked filters.
 
"stock mopar distributor". Your engine is compeltely changed. The stock timing curve will nto be the best for you. You need to recurve it to limit the centrifugal advance, quicken the centrifugal advance, and reset to add initial - I like about 18° initial and 12-14° centrifugal. If the vacuum advance can be set to work with your cam and not surge - use it.
Once the timing is set, THEN you can start messing with the carb.
 
Timing is limited with an FBO plate.
21 initial 35 total, all in by 3000rpm.
Sorry, told you I was fogetting somethiing.
I also put a new rotor in, checked cap for carbon tracking, and routed plig wires for cylinders 3&5 and 8&4 over 1" away from each other. Pliugs are new, will pull a couple in the morning and snap a pic.
Was running FR5, but when I ran the engine in the dark I was seeing four or five sparking around the base at the head,, and.they looked lean or too hot judging by a chart I found, so I stepped down one heat range to rule out too hot of a plug.

I changed the few bits of rubber hose from tank to steel line with stiff fuel hose because of age and worrying about collapse under suction.
Running a clear plastic Wix filter before the pump and a 40 micron Edelbrock filter between the pump and carb, 3/8" sender and hard line to pump, 6an braided nylon from pump to carb through a Quick fuel regulator with 5.5psi at idle.
 
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KnuckleDuster said:
Timing is limited with an FBO plate.
21 initial 35 total, all in by 3000rpm.
Sorry, told you I was fogetting somethiing.
I also put a new rotor in, checked cap for carbon tracking, and routed plig wires for cylinders 3&5 and 8&4 over 1" away from each other. Pliugs are new, will pull a couple in the morning and snap a pic.
Was running FR5, but when I ran the engine in the dark I was seeing four or five sparking around the base at the head,, and.they looked lean or too hot judging by a chart I found, so I stepped down one heat range to rule out too hot of a plug.

I changed the few bits of rubber hose from tank to steel line with stiff fuel hose because of age and worrying about collapse under suction.
Running a clear plastic Wix filter before the pump and a 40 micron Edelbrock filter between the pump and carb, 3/8" sender and hard line to pump, 6an braided nylon from pump to carb through a Quick fuel regulator with 5.5psi at idle.
Click to expand...

I would swap in some known good wires on any wires/plugs seen arcing outside. Make sure the plugs are tight.
Make sure you have a good engine ground, ignition box grounded. What's the number on the plug?, BPR5EY ?
 
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I have a braided ground strap running from the back of the passenger side head to the firewall.
NGK FR4 5155 is all it says on the box.
Ignition is bolted onto driver side inner fender on the vibration isolators per MSD insructions.

Tried to upload a pic of the FR5's I pulled out, but Photobucket is crapping out and not sure how else to post it from my phone.
 
KnuckleDuster said:
I have a braided ground strap running from the back of the passenger side head to the firewall.
NGK FR4 5155 is all it says on the box.
Ignition is bolted onto driver side inner fender on the vibration isolators per MSD insructions.
Click to expand...
Those plugs they call hot and very hot fr4/fr5, those are hotter than the 4/5 heat range lead on. Try the NGK gr4 stock 340 replacement or if colder the bpr5ey. What compression do you have and havvvvvve you done a compression test?
 
You majorly changed your opening post, start over time...
NGK plug heat range is colder as the number increases , higher the number the colder the heat range, the lower the number the hotter the range.
If you have spark arcing, fix that first.
Post a pic from your phone, look on the message box and it will have an add photos button above the more options button, post some spark plug pics. 600cfm is tiny for that motor.
 
Haven't in a while, last time all were between 175-180 cold.
Calculated SCR is 10.1:1
No leakdown test as of yet.
Lifter preload is set at 3/4 turns which if I remember correctly come out to about .040 with my adjusters.

The 600 is the only other carb I had to test with, it's not staying on there. The 800 will go back on soon.

If I hit the photo button it asks for a URL...???
 
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Yeah, I did but it keeps saying my phone memory is too low. Too many pics and apps I don't want to delete, and my phone is not moving stuff to my SD card like it should. I'll try photobucket again tomorrow. Used to be a good pic host but it's gone to crap lately.
 
KnuckleDuster said:
Yeah, I did but it keeps saying my phone memory is too low. Too many pics and apps I don't want to delete, and my phone is not moving stuff to my SD card like it should. I'll try photobucket again tomorrow. Used to be a good pic host but it's gone to crap lately.
Click to expand...
I don't run fr4/5 so I can't tell you they are the right plug...but by their discription, they are too hot for that dynamic. You are running near what I am for cylinder pressure, I'm at 185psi. So what are you 11.1? Static?
 
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KnuckleDuster said:
Those are 13/16
Have to use 5/8 in Edelbrocks
Click to expand...
Yeah I always space that.
A lot'a people say they for some reason seem hotter than a the number shown, I scratch my head at that.
How do you know that it wants 35/36 total timing? Have you tried backing it down to 32-34 ? Need to see those plugs....
 
Just for fun try closing your plug gap down to about .035-.040 if it isn't there already.
The higher the cylinder pressures, the more the spark will try to go somewhere else, and from the sounds of how the motor acts on acceleration it may very well be too big a plug gap for it to jump under that load.

You did say it craps out under sudden load, and if you ease into it the problem is not as bad.
The more throttle you use, the more pressure in the cylinder so...
Couldn't hurt to try it as a diagnostic and see what it does.
 
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I made the mistake of thinking the NGK heat ranges weren't backwards, lol...
On the other hand I had some brand new Chanpion R9YC's from who knows what in the garage, so I tried those in between the FR5 and FR4, car ran like total crap!
But I digress...
I ran Autolite 65's with a Holley 750 for a while. My Dad and I played around with the timing, just by ear, and ironically enough, the car ran the best it has ever run that day!
Here is a short video from that day.


Unfortunately, the carb was vacuum leaking at the throttle shaft, so I shelved it. Might just buy a new baseplate and run it....though the Proform and Quickfuel Blaclk Diamond carbs have quite an allure.

Guys, to be honest, I keep coming back to thinking this is carb related.
I pulled the 800cfm Edelbrock back apart, and found that while the float height was correct at 7/16, the drop was only about 3/4, not the 15/16- 1" called for. Sunday when I'm off I'm gonna reinstall the 800 and see what happens.If that goes badly I'll try some other plugs gapped to .035. I have been gapping .045 since that's what MSD calls correct for my box. If that doesn't help I'll cut a new set of Accel Super Stock wires I have laying around.
Is there any reason a Mityvac would be inaccurate for compression testing?
I would like to do a leakdown test, also.
Should I just invest in a real tester?...or just rent one from the parts store?
Also planning to install an AFR meter if If I can spare the cash after some dental bills on Tuesday.
 
As long as the arcing plug issue is fixed (not usually plugs - but wires/boots) then yeah, keep chasing the carb.
 
Hey Moper, these Taylor wires only have 3k on them, but. 5&7 burned on the header, so I reused some old Accels. It was the cylinders with the Taylors that were sparking though.
I could just barely see them in pitch black, wasn't very obvious.
I was thinking the plugs were fouled from overheating issues I was having, plus idle mixture and timing being all over the place while I was working out bugs.
What's your take?
I don' t mind using new wires, just curious...

I wish Taylor would make a set with 6 straight and 2 90° spark plug boots! Thinking about contacting them, as many people that run headers with clearance issues on those cylinders, you'd think at least one wire company would offer a set with mixed boots?
 
KnuckleDuster said:
Hey Moper, these Taylor wires only have 3k on them, but. 5&7 burned on the header, so I reused some old Accels. It was the cylinders with the Taylors that were sparking though.
I could just barely see them in pitch black, wasn't very obvious.
I was thinking the plugs were fouled from overheating issues I was having, plus idle mixture and timing being all over the place while I was working out bugs.
What's your take?
I don' t mind using new wires, just curious...

I wish Taylor would make a set with 6 straight and 2 90° spark plug boots! Thinking about contacting them, as many people that run headers with clearance issues on those cylinders, you'd think at least one wire company would offer a set with mixed boots?
Click to expand...
call then or whatever...but change your plug wires, then we can help you.
 
If you're having a problem with wires getting burnt, get a set of these:
ProtectBoots.jpg


Boot protectors. I run them on my setup. I can pull the plug boots immediately after turning the car off they keep the wires so cool. Any engine shop/speed shop should carry them.

Pull all your plugs. Pull all your wires. Get new plugs, start with something like RC12YC or autolite 65's. Most guys start with these for small blocks. Should holdup just fine to your compression but if not you can go down colder one plug at a time. Gap at .035-.040. Apply anti-seize to threads. Install finger tight. Then give them up to 1/2 a turn with the wrench, it's recommended half a turn for those plugs, but that's on iron heads, so be careful on aluminum, they take a little less torque. Now get new wires. Matched set. 8MM or bigger. Use dielectric grease and grease the boot (NOT the contact inside, just the boot). This will help them slide onto the plugs. Make sure you feel a SOLID positive clip onto the plug. You can't miss it. It's a distinct click feel. You probably can even hear it. Make sure each wire clicks on FIRMLY.

This will eliminate any chance of sparking/arcing or whatnot. That at least get's rid of that problem. Show us your old plugs. So we can see what they look like. Then we can see if your other problems still exist.
 
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