I'm feed up. Time to ask for help!

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doogievlg

doogievlg

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My issue is a loss of power. First off let me give you my build.

360 .30 over
Eddie aluminum heads
Mopar .484 cam and lifters
Speed pro flat tops
Edelbrock performer rpm intake
Holley 750 carb
Mopar electronic ignition
Cheap 3000 rpm converter
3:55 gears
26 inch tall slick

15 initial timing
35 advanced at 2500

I first noticed it on my first trip to the track with my new motor. The car started cutting out real bad at about the 1000 foot mark. I assumed it was ignition related so I changed the plugs wires and rotor. This helped a very little bit. I took the car out and noticed it is still stumbling if i am cruising at about 35 and floor it. Stumbling to the point of complete silence. So I get back and think it's the fuel pump so I throw a guage on it. I am getting 6.5 lbs until I get to high rpm then it drops to 6 which isn't a big deal. I then switch to my edelbrock 650 avs thinking maybe it's the carb. The problem was still there. I wanted to make sure the car launched fine so I took it out one last time and did a fairly high launch...tach wasn't working so no idea what rpm I let off the brake. The car accelerated great up until 50 mph and then I could feel it loose some power but no stumbling or hesitation. At this point I am about to take my dad's carb off his car and put it on mine because I have no idea what else it could be. Just for laughs here is my time slips from when the car was cutting out.
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Thank you in advance for the help and sorry for the ignorance.
 
Cheap converter and "only" 15 initial timing jump out as WRONG.
 
RustyRatRod said:
Cheap converter and "only" 15 initial timing jump out as WRONG.
Click to expand...

It seemed to like being at 15. I plan double checking it again tomorrow to see how much more I can get. The converter wouldn't cause it to hesitate so badly though would it. I was under the impression it would be a more gradual slow down.
 
Valve springs?
I have the same problem with my 408 (same heads). The thing starts laying down and misfiring at about 4800 rpm. After checking fuel/timing/etc it dawned on me that it might be floating the valves. I didn't recall if the head guy put springs in when he went through them so I pulled one off and it's just a weenie single spring that Edelbrock ships them with. I am now waiting for the correct springs to show up from summit.
 
Alvin said:
Valve springs?
I have the same problem with my 408 (same heads). The thing starts laying down and misfiring at about 4800 rpm. After checking fuel/timing/etc it dawned on me that it might be floating the valves. I didn't recall if the head guy put springs in when he went through them so I pulled one off and it's just a weenie single spring that Edelbrock ships them with. I am now waiting for the correct springs to show up from summit.
Click to expand...

This crossed my mind when I was building my motor but I haven't thought about it at all since. Is there a way to tell if this is happening or is it just a replace it and see what happens kind of deal.
 
Your timing should be fine for WOT. If you have the orange box try a different one. Make sure the pickup to reluctor gap is set at about .008.
Are you running a air cleaner?
 
EL5DEMON340 said:
Your timing should be fine for WOT. If you have the orange box try a different one. Make sure the pickup to reluctor gap is set at about .008.
Are you running a air cleaner?
Click to expand...

Should I switch to chrome? I will check the gap and yes I am running an air cleaner.
 
You could, or just get a cheap napa one and try it out, if that ain't it you could try to bring it back.
 
Try a different box my orange did the same thing went to a stock box been running good ever since .
 
Thinking out loud (1) rotor phasing (if using vac adv which changes RP) & when you floor it you go to near zero vac which shifts the RP back CW (on a SB) which might be moving the rotor tip too far away from the cap terminal. the tip radial distance can be excessive also & they both add up & if the required voltage is greater than the available voltage needed to jump that combined gap then it will misfire (NAPA has a rotor with a .060" longer blade (MO3000 which helps with the radial gap/several options for the phasing (circumferential) gap correction. (2) vac leak. Holler what it (ends) up being. EDIT If using vac adv cap it which'll tell you if its a phasing problem and possibly if it is an excessive timing problem
 
Ha anyone purchased the MO3000 lately? Some were saying it's the same tip length as the regular rotors.....
 
Doin the math, 50mph =5622rpm@lowgear, plus TC slip. Timing was all in way back. Valve float/lifter pump up is on the table.
By 1000 ft you are probably back at 5600 to 5800, so it seems rpm related.
That would point to the ECU, or float. Or possibly a restricted exhaust.
Try 32*.My experience with tight quench and Eddies is that 35/36 degrees, is not/may not be, necessary.
But you seem to be talking about two different problems.
The stumble at 35mph(3936rpm@lowgear,plus Slip) could be nothing more than pumpshot or crappy fuel.

Your 60 fts look like mine. lol, well actually, yours look better than mine.
 
I was looking at switching to a chrome box and saw the rev-n-nator. Has anyone used this?
 
EL5DEMON340 said:
Ha anyone purchased the MO3000 lately? Some were saying it's the same tip length as the regular rotors.....
Click to expand...

Bought one a week ago from Napa.
They are 060 longer, and I even held it up next to a stock rotor to show someone the difference.
 
Unless you are racing at the 6000 ft level or towing a boat when you race, something is not right with the power output. Swapping out the orange box for a stock box is a good move. When I was plotting out my timing curve I found my orange box was retarding the timing on the top end.

If you get to the track with the new box and performance hasn't changed, I would add in 2 degrees more initial timing and watch your 1/8 mile and 1/4 MPH numbers. If the MPH numbers go up, dial in an additional 2 degrees more initial timing and make another pass. Eventually the MPH will level out. At this point back out one degree initial and make a pass to see if the MPH stays the same. If the MPH stays the same, back out another degree and make a pass. The goal is to find the least amount of timing that generates the highest MPH (HP).

Make sure you keep an ear out for detonation. Without knowing your dynamic compression and fuel octane it is hard to say how far you can safely go with the timing.
 
sledger
Did you catch that hes already got35*@ 2500, with a 3000 stall TC. Are you suggesting he go 35+2+2=39 total, with flat-tops and Eddies?
At 100 mph, his rpm is about 4600+TC slip.
Whats your thinking?
 
Are they open or closed chamber Eddies? Flat top pistons, but how far down the hole? How thick is the head gasket?

The orange box I had came with an electronic ignition conversion kit I bought from Summit Racing. When I plotted out the timing I was seeing the orange box back out 10 degrees of timing after 3500 RPM. The 35 degrees I thought I had turned into 25 degrees after 3500 RPM.

Bottom line is you need to run the RPM up to 4000+ to be sure the total timing is staying constant.

If you would have asked me a year ago what is the ideal timing for a SB Mopar I would have quickly responded 35 total. I ran a 340 back in the day and that was where it was happiest. Fast forward to the 360 I am running now with closed chamber EQ Magnum heads and thin .028 head gaskets. Granted, the factory cast, dished pistons are .088 down the hole and I am only netting 8.7:1 compression, but unless you measured it you don't really know where you are.

During a test and tune I played with the timing and was surprised at the results. My distributor has 22 degrees of mechanical advance and I original started with 16.5 degrees initial for 38.5 degrees total. I fully expected the car to slow down if I advanced the timing any more.

Initial Total ET 1/4 MPH
16.5 38.5 13.31 101.52
18.0 40.0 13.28 101.86
20.0 42.0 13.23 102.58
22.0 44.0 13.32 102.34

The magic number ended up being 20.5 degrees initial or 42.5 total.

In this case I might be more cautious to start and begin testing at 34 degrees total. I would then try 36 and see what the MPH tell me. If it liked 36, then try 38. If the MPH slowed going to 38, then I would try 37.

For comparison I run a 3500 stall converter (904) with 3.91 gears and 27" tall street tire (255R17)
 
The new box came in today and I finally broke down and forked out the money for a good tachometer. We have an engine to pull out tonight but then the dart will come over to my house and I'll throw the tach and ignition on.

I'm hoping to run the car a week from today and I'll take notes of rpm going through the lights to check on the converter and I will chart my timing adjustments and et results.
Money is going into my parts bank account aka my sock drawer, for a new converter. The current one is a jegs brand and it's been in the car for almost five years now.

Oh yea and I am running 110 octane fuel at the track just to be safe.
 
sledger
Im having a real tough time comparing your combo to the OPs. And I am unwilling to risk catastrophic failure for the sake of less than 1 mph.
So my recommendation to start at 32* stands.

Doogie
I run 87E10 full-load/WOT and 32* @750 altitude, an 3650lbs. Went 93 in the 1/8 on street tune. Just for comparison.
I made 4 runs that one and only time I ran it. Two runs were missed-shifts.There was something wrong with a third run as well. The last run was the only completed run, and so was good enough for me.My only reason for being there was for the timeslip. People were always pestering me to know how fast it was. Personally I didnt care. Thats not what I built it for. Never been back.

Good luck with yours
 
A 484 cam and letting the trans shift automatically is not a good way to go. The trans will likely shift way before the 484 is done pulling.
 
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