Is there a proper order to tuning a edelbrock 1405?

I just read through your whole thread, so you are gappingplugs at .050 with a stock distributor? Are you still running points? even with a high output coil that is too much I think. I run .045 with a MSD box and blaster coil, and MSD dist.

I also read this
"I run 91 octane and this last summer I did have it at 8 degrees than I had to back it down to 6 to reduce/get rid of detonation. "

That just isn't right. I run 10.5:1 compression and on 89 octane sometimes, and dont get detonation even with 12 degrees base timing.

 

Ryan you also have aluminum heads

 

Ya now I do, but I've run pretty much the same timing setting even when I had my windsor heads. and everything 5.0 stang I have had I set the base timing at 12, i know its fuel injected but a good tuned carb should be able to do that timing also.

 

I'm currently running 0.045 gap with a mallory ignition, electronic distributor, blaster coil... I'm trying to change the dizzy right now having trouble stabbing the new one in... going to have to pull plug no. 1 to find out where I am again... the detonation is usually on light acceleration from 65mph up you know your cruising than you decide to give it a little more throttle, I'm currently using the lightest springs, I did have the medium ones in for along time than when I started this thread I started to try differant lighter ones... I just picked up a vacuum gauge yesterday so I'll check my vacuum once I get my distributor installed.

 

I understand Ryan and agree with you on the base timing setup I run around 12-14 with e7s and computer controlled as well and plan on doing the same with my current e7's. However I do believe that david is running smaller combustion chambered 289 heads and on a rebuilt 289 motor. Without calculating out everything he could be over his stated compression with iron heads and come into problems running our junk az low grade fuel.


Either way, there is something wrong in the carb or the advance is coming on to strong.

I believe he also stated that he has not played with the curve or been inside the disty, so it leads me right back to improper carb settings which have been altered from factory.

I do agree there should be able to get more base timing into it, I think the base timing being lowered is just a crutch for an improper setup on the carb.

I also think and have stated earlier that using a narrowband 02 sensor trying to tune is like pissing in the wind. And will lead you to this situation we have here with detonation or to rich rather quickly trying to rely on a useless gauge. Good gauge for flashing lights, but other than that useless in my book.

My best recomendation start adding fuel now before you loose a motor, by the time you actually hear detonation you are doing alot of damage to them pistons.

Add fuel, add timing, add fuel, add timing, get it close than either buy a wideband and continue to tune, tune at the track for acceleration, or put it on some rollers and tune.

 

So did this setup run good before and just recently acquire this problem?

With that ignition 45 sounds like a better gap then 50 or 55. But what distributor are you putting in? someting like an 86 5.0 electronic pickup and running it off the Mallory box, with or without the duraspark box? I tried running my MSD box with the Duraspark dist. without the duraspark box. Ya it worked and ran, but ran MUCH better once I ditched the duraspark dist and went with the MSD dist.

 

it's a duraspark distributor on just the mallory box... didn't think I could run both boxes. anyway I'm kinda stuck trying to get my dissy to engage the oil pump rod... when I rebuilt the engine I think I put the wrong end of the rod up... I guess I just lucked out the last time I changed the distributor and got it in the hole. I'm working on the car right now and getting on here when I decide to take a brake.

I forgot to mark down the numbers on the jets when I rebuilt the carb afew weeks ago...

 

If a dist came out then a dist should go back in. the drive haft to the oil pump is the same both ways, just there is a little keeper washe on the bottom to keep you from pulling the shaft up when you take out the dist. Sometimes when I can't get a dist to drop in i take my oil pump priming shaft down there and turn the pump just a tad to get the hex in a little different position to get it to mesh up to the new dist. if you don't have a prime shaft then you can use a 1/4" sock on an extention to get down on it. I think it's 1/4" if you have 1/4 drive sockets find one that matchs the size of the hole in the distributor shaft adn use a long 1/1 drive extention or a couple short ones to get down to the oil pump shaft. I'd tape the socket to the extention to make sure you don't lose it down into the motor. I've been in your spot before many times, seems everytime to do something with the dist it takes a little wiggling on the shaft to get it to drop back in.

 

I got it as far down as the metal colar right below the gasket is touching the block...

 

Got it running again, at idle my manifold vacuum is 13" and it goes up from there to about 20" or so. I did a process of elimination with the jets in my tuning kit (all the jets listed on the cardboard are in the box) so I'm currently running stock jets and rods in my carb, and the lowest inch vacuum spring (should probably be changed). I haven't adjusted the idle mixture for max vacuum yet.

f.y.i. I put the gauge on the distributor ports of the carb to see what they do.
The driver side port is manifold vacuum, it goes up as the RPM's increase and it'll drop if you gun it.
The passenger side port is ported vacuum which goes in steps like 0", 5", 10", 15", 20" or something like that and the only time it goes down is when you decress RPM's, when you gun it it does NOT change.

 

Thats good to know, I figured I was over thinking on that. I may have to try the other port on my truck and see how it reacts. Can't try it on my Maverick becuase i'm running the MSD dist with mechanical advance only.

Did you replace your old dist because you found something wrong with it or just process of elimination?

 

Hello

Sir one question.. recently I bought holley 0-80457S for a comet 5.0 and it's my first modification. Is not yet installed.

Do yo have any advise?

thanks.

 

Advise is as follows...Get it bolted on soon. It will most likely improve your performance.

 

thanks...

thank you!!!! but it is not necessary some special procedure?

 

when I disconnected the vacuum advace and ran only mechanical it didn't detonate so I figured my vacuum advace was defective, thats the main reason I changed it. While I was at it I changed the cap and rotor because the old cap was really corroded with white buildup and the rotor had a little on it, I might of been able to clean them up but I figured going new when I could would be a good idea. Also when I installed the distributor I set my base timing to 8 degrees, and used total advance on the way to work than tried the ported vacuum on the way back, neither detonated, so I'm using ported vacuum right now (more control over idle, total vacuum caused the idle to fluxuate abit). I also adjusted my idle mixture screws for max vacuum, not sure what I was doing but I ended up a 2 turns out (14.5" - 15" vacuum) where I was at 1-7/8 turns when I went off the tach only. I also changed the springs from the blue 3" to the orange 5" spring... I'm temped to goto the pink 7" ones but I haven't installed them yet. I hooked up the vacuum gauge to manifold vacuum and I was getting 14.5 to 15" and when I gunned it the lowest it went was 4" - 5", thats why I went to the 5" spring sence I don't know how vacuum behaves under load I thought that the lowest vacuum reading was a good place to set the springs, am I wrong?