Any tips on tuning Edelbrock 1412 800 cfm Performer?

[AR67GTX]

My otherwise stock 440 has a 1412 Edelbrock 800 on it that I picked up used years ago. It's a little ragged in off idle transtition so I bought a kit to put in it. I suspect that a rebuild and setting all the adjustments to spec will greatly resolve this but I also want to see what is inside it right now in terms of jets and metering rods in case it was tampered with before I picked it up.

Does anyone know what Edelbrock originally installed in these carbs?

Also, based on a stock 440 (cam, heads, pistons, exhaust, etc) has anyone found any metering rod or jet changes that it responds well too?

Thanks

 

[lewtot184]

i've got a friend with a 427 corvette with the 800avs. the avs jetting is a little richer on the primary side than the regular 800. i started doing some serious tuning on the vette last fall to cure off idle transition problems. i ended up going about 15% leaner on the primary cruise side and down sized the squirter. i haven't messed with the secondary jetting yet. currently the carb has a .110 main jet and a .073x.047 metering rod combo up front. squirter was down sized to a .024. remarkable difference! before the car would not take off in first gear smoothly, after tuning it will take off in 2nd gear smoothly (close ratio 4spd). i think most of the edelbrock carbs are baised to the rich side, probably to work on a small block chevy. larger engines don't need the extra jet area.

 

[lewtot184]

when i started to go after my friends 800avs i thought i'd do the same to the factory avs on my '69 r/t. so i made a cheat sheet of jet and metering rod area to figure a more precise jet change rather than just poking around with jet numbers. i also used some known combos that worked and factored those in with respect to venturi area of the carb.

 

[AR67GTX]

That's interesting that you went to a smaller size squirter to cure on off-idle stumble. I ordered an Edelbrock tuning kit so I can experiment with a couple different squirter sizes.

Thanks

 

[lewtot184]

for street tuning big squirters don't work.

 

[AR67GTX]

Just realized that the tuning kit doesn't include any different size squirters so I guess I will see what is in it now when I tear it down.

 

[AR67GTX]

I disassembled my old 1412 Edelbrock carb today and checked out the parts.

According to the Edelbrock website stock calibration consists of the following:

Main jets .113 inch
Secondary jets .101 inch

Metering rods .071 x .047 p/n 1453
Squirter .035 inch

What I found in my carb:

Main jets .113 inch
Secondary jets .095 inch

Metering rods .071 x .047
Squirter .035 inch

So with the exception of the secondary jets, the rest looks stock. The secondary jets look leaned down considerably. The .095 jet is shown to be used in 600 cfm carbs according to the Edelbrock website and are 8% lean from stock per the website.

http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

I guess I will change the secondary jets to .101 jets to get back to stock calibration. I can't see leaning out the secondaries that much. The smallest jet the Edelbrock tuning kit includes is the .101 jet.

Again, if anyone has gone through this with a 1412 Edelbrock (800 cfm) carb on a stock 440 I would be interested in hearing what you tried.

Thanks

 

[Meep-Meep]

Personally for your stock street driven car I'd go with a smaller carb. 650 - 750 CFM. You may end up chasing some demons with that 800. OEM carbs were about 700 CFM but that's probably not wet flow. Carter never really put out CFM ratings for the OEM stuff, but comparing to the later Comp series AFB's, one can make estimations based on throttle bore and venturi size.

 

[bigmanjbmopar]

I had one of those, tried several different jets / rods combos. the stock config makes the carb run rich and does not lean out well. Thinner rods and stiffer springs did the trick, you also want to make sure the floats are spot on with the instructions, 7/16 drill bit depth? can't remember. that makes a big difference, also I got the dual feed line so both sides of the bowl got gas equally, this helped when stopping hard or turning hard etc.

Lastly, put a phenolic spacer under that carb. 1/2" or more if you have the room. Todays gas boils out and evaporates fast so you need to keep it cool as you can.

Lastly lastly, fuel pressure. make sure you do NOT give it more than 7 psi or it will act stupid and stumble and fall one after the other off the line.

Good luck, but based on your environment and driving you just have to play with the jets and rods but only after the basics are down like said or that eddy is just a boat anchor. good luck... this message will self destruct in 10 seconds.....

 

[AR67GTX]

Thanks for the replys. I've had this 1412 carb on it for about 10 years and I have an old small bore AVS with worn out throttle shafts that was on it when I bought it. I'm probably not going to buy yet another one for it if I can make this one work at all. If they tend to run rich I can take it one step leaner (2%) on the primary side per the Edelbrock manual. That should be pretty close to what lewtot184 used above in post 2. The smallest jets I have for the secondary side in the tuning kit are the .101 jets (match factory delivered jeting) unless I leave the .095 jets (8% leaner) in it.

I had a 1/2 inch phenolic spacer under it until I installed the correct 67 air cleaner lid on it (had to use an AVS base plate to match the carb) and that put everything too high to clear the hood pad so I had to remove it. I recently picked up some 1/4 inch spacers by Holley for another car and I might see if one of them will fit.

Thanks

 

[lewtot184]

use a .110 primary jet with your 71x47 rod and install the .101's in the back. as for the pump nozzle you can do a simple test. looking down thru the top of the carb slowly open the throttle. if fuel does not squirt out into the venturi, vs just dribbling down the side of the venturi wall, the nozzle should be down sized. on the 800avs i worked on i changed the check ball in the pump circut to a larger ball and cleaned out the casting flash around the slot that supplies fuel to the pump well. i also raised the floats slightly to make sure the pump well always had fuel.

 

[amike95]

Personally for your stock street driven car I'd go with a smaller carb. 650 - 750 CFM. You may end up chasing some demons with that 800. OEM carbs were about 700 CFM but that's probably not wet flow. Carter never really put out CFM ratings for the OEM stuff, but comparing to the later Comp series AFB's, one can make estimations based on throttle bore and venturi size.

I have a stock 383 in my 69 RR and run a Edelbrock Performer 650 with no issues.

 

[AR67GTX]

use a .110 primary jet with your 71x47 rod and install the .101's in the back. as for the pump nozzle you can do a simple test. looking down thru the top of the carb slowly open the throttle. if fuel does not squirt out into the venturi, vs just dribbling down the side of the venturi wall, the nozzle should be down sized. on the 800avs i worked on i changed the check ball in the pump circut to a larger ball and cleaned out the casting flash around the slot that supplies fuel to the pump well. i also raised the floats slightly to make sure the pump well always had fuel.

The above sounds like a plan. If I can dig up some .098 secondary jets locally would you suggest that over the .101 jets??

Thanks

 

[lewtot184]

i wouldn't go any smaller than the .101 for the secondaries.

 

[AR67GTX]

I got the carb rebuilt and back on with revised jetting. Man, I had forgotten how bad carburetor cleaning smells over the last few years. It permeates everything. I took it outside and I think it stunk up the entire neighborhood. But, it still has a slight bog or hesitation from a stop sometimes, until thoroughly warmed up. Once it was adjusted, wamed up and I put 5 or 6 miles on it I pulled over to a stop and nailed the throttle and it responded instantly and spun tires/roared through first and well into second very strongly with no hesitation. I think the hesitation when not fully warmed up is either from the choke not being entirely optimized (it's a manual choke carb that I swapped parts from a Mopar AVS to make functional as a factory choke) or the 800 carb is just a little too much for a stock 440 as some have suggested. I think it's running a little better.

Thanks

 

[lewtot184]

the 800 isn't too much carb. the factory 440hp carb and the 800 have nearly identical total venturi area. the primaries on the 800 are larger than the 440 avs but nothing that can't be tuned. you just need to tune the accelerator pump circut and off idle primary mix.

 

[AR67GTX]

the 800 isn't too much carb. the factory 440hp carb and the 800 have nearly identical total venturi area. the primaries on the 800 are larger than the 440 avs but nothing that can't be tuned. you just need to tune the accelerator pump circut and off idle primary mix.

I forgot to mention that I did carefully set the accelerator pump settings to the Edelbrock manual. The accelerator pump puts out a strong discharge from the squirters. I can't remember when I had the intake off about 10 years ago if I blocked the heat risers or not. It definately seems to make a difference in how long the the car has warmed up. I never put any pressure on an engine until the oil temperature is coming up but occassionally I get a little bog just leaving a stop light at moderate throttle for the first mile or so. Once it's good and warm and got a few miles on it, it drives very smooth and strong. I think it may just be a warm up issue and choke adjustment, particularly if the heat risers are blocked.

 

[bigblock]

A smaller carb would be better for the street. Also never tune try to tune a cold engine.

 

[dvw]

Move the pump rod to the hole closest to the pivot. I have fixed more than a few by doing this.
Doug

 

[lewtot184]

I forgot to mention that I did carefully set the accelerator pump settings to the Edelbrock manual. The accelerator pump puts out a strong discharge from the squirters. I can't remember when I had the intake off about 10 years ago if I blocked the heat risers or not. It definately seems to make a difference in how long the the car has warmed up. I never put any pressure on an engine until the oil temperature is coming up but occassionally I get a little bog just leaving a stop light at moderate throttle for the first mile or so. Once it's good and warm and got a few miles on it, it drives very smooth and strong. I think it may just be a warm up issue and choke adjustment, particularly if the heat risers are blocked.

you need to refer back to the pump squirter test i mentioned. the squirter providing fuel in the air stream at very light to slow throttle movement is the key. a large squirter will only provide the correct volume when there is fast/long throttle movement, like at quick WOT; drag racing stuff.