I was out cruzin 2 today with a friend of mind who has been having some trouble with his Edelbrock 600... Looks for another answer on his problems. I am a Holly guy so can anyone help !

a. While idleing or stop as soon as he give it gas it seems like it wants to stall or sometime backfire.

b. When the car first start up .. with the elec choack on and the engine idleing high .... seems like both exh pipes by the manifold get Cherry Red untill he hits the gas to bring the idle down...then okay.

I was going to mess with the mixture screws but was alittle unshure.

Hope I can get some advise for him .... Thanks.
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"Big Al" Liebmann
"Righty Tidy..Lefty Loosey"

Charter Member: Dipstick Street Rod Association
Technical Advisor - Barris/Kind Chrysler City Coup'e Kustom

BTW ... It is a PERFORMA 600 CFM
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"Big Al" Liebmann
"Righty Tidy..Lefty Loosey"

Charter Member: Dipstick Street Rod Association
Technical Advisor - Barris/Kind Chrysler City Coup'e Kustom

This a vacuum advance distributor?
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Anyone can restore an old car, it takes a man to cut one up.

Electronic dist...no vacume
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"Big Al" Liebmann
"Righty Tidy..Lefty Loosey"

Charter Member: Dipstick Street Rod Association
Technical Advisor - Barris/Kind Chrysler City Coup'e Kustom

Electronic dist...no vacume
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"Big Al" Liebmann
"Righty Tidy..Lefty Loosey"

Charter Member: Dipstick Street Rod Association
Technical Advisor - Barris/Kind Chrysler City Coup'e Kustom

bIG AL, don't touch those mixture screws! When the carb is on high idle w/choke, it's on primaries and the mix screws are not at play.

Here is a manual site that will help you http://edelbrock.com/automotive/eps_intro.html

You got to make sure the timing is correct first and tell us more about the motor. How high is the vacuum....or better yet is it more a stock cam or a performance cam. This tells me alot so I can help you.....I have put too many of these in to count! If it's more a stock cam and pulls alot of vacuum, the transfer circuit springs need to be changed to silver (see manual) instead of the ones that came with the carb....and it real easy to do if you get a tuning kit. This will make sure that the hesitation when transitioning will be crisp.

Vacuum advance set up is also key. Setting the initial at 10 or more, then plugging in the vacuum advance on full time vacuum is the ticket....you should see at least 20 something at slow idle. Keep the rpms of the motor below 900 or the primaries may come in and screw up the idling mixture.....how does it idle without the choke when warm
? If it doesn't have VA, then put more timing in....at least 14 or more.

The idle mix screws only affect the idle circuit when just sitting idling. You can set the high idle rpms with the secondary mechanical screw on the drivers side...the one that kind of points down and to the front...see manual. The other mechanical screw is for regular idle.

The cherry red exhausts on high idle, is telling me that the primaries are tooooooooo lean. A jet or rod change is necessary and since I don't know anything about the motor I can't help much, but again the manual will tell you the procedure.

After we determine more about the motor, then we can discuss pump setting, which could be part of the problem as well.
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Steve Jack
Engineering & Marketing Technologies
ConceptOne Brackets and Pulleys

Steve,I noticed the "Conceptone brackets and pulleys" deal and I'm wondering: Do you have a bracket to mount an alternator on a SBC with "Fuelie" style heads. No holes in the front of the head. The Allen Grove style low mount won't clear my steering. I'm undecided on headers or manifolds right now. This is for a '60 ElCamino.
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I know the pix supposed to be of me, but I didn't wanna scare anyone!

47......nope, I am even having to pull the "fuelies" off my 57 that have no accessory holes to put new Edelbrocks on for my new Conept One kit!

Sorry.
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Steve Jack
Engineering & Marketing Technologies
ConceptOne Brackets and Pulleys

Steve, as we're on the subject of Edelbrock performer carbs, I'd like your advice before I buy
one from SRS for my 305 sbc powered deuce hiboy. I'll be running the '79 305 completely stock for now but will upgrade to s/r torquer 305 heads & a mild Comp cam in the future. The intake I'm
using is a Weiand action plus & ignition is a stock HEI.
My question is can I use the 600 CFM version of this carb or am I better off running the 500. I
prefer a manual choke either way. Fuel economy is not a priority, but I do want crisp throttle
response and decent driveability. RPM's over 5000 won't happen very often as my roadster will
be a cruiser.
Any suggestions/ words of wisdom will be more than welcome... thanks Ed.
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Hotrods forever...

Actually, you are right in the middle. If you were to leave your stock cam in I would deifinitely say a 500. But with a little more top end, the 600 will fit too. If it's throttle response tho....the 500 is the way to go. It will go on right out of the box and probably only need a tweak for a cam change as long as it's not too agressive.


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Steve Jack
Engineering & Marketing Technologies
ConceptOne Brackets and Pulleys

Thanks Steve... much appreciated feed back. I'll probably go with the 500 then. The cam I'm
looking at (as suggested by the COMP CAMS tech guys) is grind # CS XE256H-10 which has the
following... lift of I - 447 & E - 454 and duration @.050 of 212 Intake & 218 Exhaust.
BUT, does this cam fall into the "too aggressive" catagory?? or will it be ok with the 500 cfm unit?

Thanks again... Ed.
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Hotrods forever...

I run the XE series all the time. The cam specs are within your 500CFM window.
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Steve Jack
Engineering & Marketing Technologies
ConceptOne Brackets and Pulleys

More questions, Steve! .....In your post above you said the cherry-red exhausts were indicative of a lean mixture.

Please explain why a lean mixture cause an increase in EGT?

I thought (mistakingly?) that retarded timing and/or a rich mixture would cause the fuel to continue burning in the exhaust manifold, thus raising EGT. Also, that a lean mixture or advanced timing, would cause the fuel to burn inside the combustion chamber and cylinder, where most of the heat would be transferred to the coolant.

I realize there are variables affecting flame propagation, and my above thoughts are obviously general simplifications.

Please explain the basics, and tell me where my thoughts went astray. I'm here to learn, and I have an open mind. ......I also suffer from CRS, so I may just say, "Now, I remember!" LOL

Bruce.....there is a balance of timing and fuel burn that needs to be managed in any engine.

You can get fuel to pass into the exhaust pipes to be combusted there, and that does make things hot, but 99 times out of 100 the reason exhaust gases are hot is the mixture is too lean. A richer mixture actually offers less oxygen per unit volume available to burn when all else is set up correctly. The more Oxygen, the hotter the fire. So, without getting into a big long chemistry lesson, the leaner the mixture, the hotter the the combustion temperatures. These hot gases escape and make the headers/manifolds very hot to the extent of sometimes glowing!

The advancing of timing is done for anticipating and optimizing combustion chamber flame front arrival with piston position/travel and is a good thing which allows most of the energy on the piston to be expended on the way down. If not, you get the preverbial detonation. Retarding the timing will in affect, make the crux of the flamefront arrive in time to work against the piston. This is how to make alot of heat because the explosion is happening, but alot of energy is being wasted. Therefore alot of heat is needlessly generated.

Hope this helps some, sorry to be brief, but all the time I had this afternoon.

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Steve Jack
Engineering & Marketing Technologies
ConceptOne Brackets and Pulleys

Thanks, Steve!

I believe too much advance will try to keep the piston from getting to TDC. This leads to knock. The burn should be done at approx. 16 deg after TDC. http://www.hotrod.com/editorial/article.jsp?id=43300
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Mike J
Unchartered DSRA Member
If it ain't broke, fix it anyway...

Mike, you are right on with the tooooo much advance thinking. It will lead to detonation and working against the piston.

Thinking about what you posted, I just suddenly realised that I misspoke in my prior post, thinking that I was commenting on "advance" instead of "retardation" and in a hurry as indicated. Oops. ...but anyway, retarding the spark allows the crux of the flamefront to be wasted, literally missing the curtain call for spark at the optimum time. The advance will work against the piston.

Actually the amount of advance needed to optimize your curve is dependent on several variables. As you have pointed out and we all agree that peak cylinder-combustion pressure should happen just after TDC. To find this, alot of tuners will advance the static timing until detonation is found and then back it off a couple of degrees. This is optimizing the curve with the given combinations instead of just guessing. Such things as cam (peak cylinder pressures), timing, fuel octane, mixture, combustion chamber design all play into flame front propagation.




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Steve Jack
Engineering & Marketing Technologies
ConceptOne Brackets and Pulleys