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4 barrel problems
https://slantsix.org/forum/viewtopic.php?t=40115		 Page 1 of 2
Author:  jonbob562 [ Wed May 05, 2010 9:36 pm ]
Post subject:  4 barrel problems
i have a 63 dart with a 225 in it
its got a set of clifford headders and a four barrel offenhauser manifold on it and im running a four barrel eddelbrock on it.

when i get up to higher rpms or when i jump on the gas its popping and seems to have too much gas, i tried jetting it down and it didnt really change.

any ideas what it could be??
Author:  hellion_locdogg [ Wed May 05, 2010 10:11 pm ]
Post subject: 
Popping or back firing is usually a sign of being lean. So you must be running a 600cfm? I think that is a tad large for a slant. I'm running a Holley 390cfm vac sec. I got tired of guessing and got a wideband o2 sensor w gauge.

,Cliff
Author:  jonbob562 [ Thu May 06, 2010 12:14 pm ]
Post subject: 
Yeah its a 600. Where would be the best place to pick up one of those 390s or a carb that's similar?
Author:  Joshie225 [ Thu May 06, 2010 1:11 pm ]
Post subject: 
The Edelbrock 500 is a proven piece on a 225. You can make your 600 into a 500 with the primary boosters, jets and rods from a 500. The jets and rods you can buy easily. I don't know if Edelbrock will sell you the boosters or not.
Author:  jonbob562 [ Thu May 06, 2010 3:13 pm ]
Post subject: 
I've got the kit that comes with the jets rods and springs, I've never changed boosters in an edelbrock before. How would I go about doing that? Also does anybody know the rod, jet, spring combo I would use?
Author:  Joshie225 [ Thu May 06, 2010 3:14 pm ]
Post subject: 
The boosters come out after removing the top of the carb and two screws from each booster. You will need the jets and rods for a 500 as shown in the 500 user guide available on Edelbrock's web site.
Author:  Fopar [ Thu May 06, 2010 4:51 pm ]
Post subject: 
500 CFM uses .086 primary/.065 x .052 rods, secondary .095 use the orange springs under the rod pistons.
This should be good for a starting point.
Author:  ceej [ Thu May 06, 2010 5:13 pm ]
Post subject: 
I've run the 390 and 600 Holley 4160's, and the Carter set up as a 600 and as a 500.
The Holley carbs are a royal PITA compared to the Carter/Edelbrock. Get a set of 500 cfm boosters, and jet right on the base Edelbrock curve per Fopars post.
Put the stiffest primary metering rod springs you can find in it. That will cause the enrichment circuit to come in sooner and avoid a lean out condition. Check to see what color the metering rod springs are and let us know what they are. By bumping the spring rate up, you may be able to use the 600 as is while looking for the 500 cfm primary boosters.
The metering rods must be pulled out prior to removing/replacing the top cover on an AFB anyway. You may find that the stock accelerator pump setting needs to be changed as well.

Have you done any internal modifications to the engine?
What kind of instrumentation do you have for tuning? Air/Fuel? Vacuum? A tach? These are three very useful tools when installing a four barrel on a slant six. I'd rate them as neccessary, not optional. :D

CJ
Author:  jonbob562 [ Thu May 06, 2010 6:10 pm ]
Post subject: 
No internal modifications yet, its all stock besides the 4 barrel, manifold, clifford dual headders, x-pipe and pair of flowmasters. I've been wanting to do a cam and lifter kit but I haven't had the money. That's next on the list. The stiffest springs I have are the orange, I'm ordering the jets and rods tomorrow.
Author:  Joshie225 [ Thu May 06, 2010 6:19 pm ]
Post subject: 
Before you go changing the cam I would put big valves in the head, port the head a little and have the head milled to get the compression ratio up to 8.5:1. It's more money than a cam and lifters, but it will get you more power.

Don't order jets and rods unless you're sure you can get the boosters to make your carb a 500. If you can't get the boosters you can't use the jets and rods.
Author:  ceej [ Thu May 06, 2010 6:25 pm ]
Post subject: 
2X Bump the compression up. I like 9:1 or better.

What transmission do you have?

CJ
Author:  jonbob562 [ Thu May 06, 2010 7:00 pm ]
Post subject: 
I believe I have the 904, doesn't the 727 have a bulge in the pan? The pan's small and square. Its a three speed push button. And how much am I looking at spending for porting and putting bigger valves??
Author:  Aggressive Ted [ Thu May 06, 2010 7:56 pm ]
Post subject: 
Not much, maybe $200 max...that would include shaving the head, bowl porting, new valve guides, hardened seats, valves and a port match.
Author:  jonbob562 [ Thu May 06, 2010 8:55 pm ]
Post subject: 
i cant find the 500 cfm boosters anywhere.
any ideas??
Author:  Joshie225 [ Thu May 06, 2010 9:00 pm ]
Post subject: 
Quote:
i cant find the 500 cfm boosters anywhere.
any ideas??
Did you call Edelbrock directly?

You'll probably end up with $400-$500 into a head with new valves, guides, hard exhaust valve seats, and all the machine work. My machine shop bill was $355, I supplied my own valves which were about $70 and I did my own port work. I reused the stock retainers and picked my best set of used springs. Don't forget gaskets!
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