When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Originally Posted by 454Luvr
I've been gapping HEI-equipped motors at .040-.045 ever since HEI came on the market. I can't tell you what my reference was for doing that initially, but it would have an "official" document from a manufacturer. .
Thanks!!
I was checking around the web and thats the consensus and I'm going with .045.
I prefer to learn from credible sources instead of outdated opinions on carb size. There are many published sources that you can go to for an educated overview of carbs, these are people who live for this stuff. Here's one example of many I have read thru the years from a publication I subscribe to. I suggest that others on this thread would benefit from a subscription as an educational tool: http://www.google.com/url?sa=t&rct=j...ATbbtoAi4pv3IQ
Sorry to jump in on this thread uninvited but it seems like the right thread to ask my question. I have a 1978 Indy Pace Car with the L48 engine. The PO rebuilt the engine about 6000 miles ago putting in a more aggressive camshaft and a 1407 Edelbrock 750 carb on an Edelbrock Performer high rise aluminum manifold. Also there is an HEI ignition on the car along with a true dual exhaust system with an H pipe and NO catalytic converter. M y question is, is the 750 carb too much for this application? The car runs strong but I'm thinking that I'm using more gas than necessary. Would'nt a 1406 Edelbrock 600 carb give the same performance but use less fuel? Any thoughts on this would be greatly appreciated. Thanks.
IMO 750 cfm is right for your motor especially with that intake manifold. The Eddy carb will only flow enough to supply engine demands at any given load, and a 750 won't be a cork in the system like a 600. I wouldn't go out of my way to buy less carb, that makes no sense. And the capacity for flow has no impact on fuel economy.
IMO 750 cfm is right for your motor especially with that intake manifold. The Eddy carb will only flow enough to supply engine demands at any given load, and a 750 won't be a cork in the system like a 600. I wouldn't go out of my way to buy less carb, that makes no sense. And the capacity for flow has no impact on fuel economy.
SH-60B, I tend to agree with you about the 750 over the 600. Since I have no problems running the 750, I will stick with it. No sense in dropping a few hundred for a smaller carb. LOL. Thanks for your input.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Just an update since I completed my carb intake replacement.
So I cured the flooding, hot start issue with the air gap performer intake, phenolic wood block, the fuel pressure reguator and fuel line return re connected. For more horse from a cold air intake I installed the fresh air box for the L88 hood which also straightend out the factory dent it had when it was molded. The only issue it has now is a stumble under power when feathering the clutch at low rpm, guessing around 1500. If I get it up above 2300 and feather it out its okay.
I replaced the plugs and gapped them to .045. My timing is 36* all in around 2200-2500 rpm. I havent changed the jets or rods yet but increased the accelerator pump by moving the rod one hole. I plan on going to the stock 1405 rods/ jets soon but I am just starting on the garage remodel so it may be fall before I get there. My gas mileage is 16 mpg driving it like its rented so everything seems okay, maybe abit on the lean side.
Just wanted to update this thread. If anyone has more edelbrock 1406 experiences feel free to post them.
Last edited by Rescue Rogers; Jul 10, 2016 at 09:35 AM.
I havent changed the jets or rods yet but increased the accelerator pump by moving the rod one hole. I plan on going to the stock 1405 rods/ jets soon
Just wanted to update this thread. If anyone has more edelbrock 1406 experiences feel free to post them.
I used the edl 750 carb for 10 years. I had a carb boiling problem so I installed a 1/2 inch wood spacer. You said Phenolic which is black plastic and not as good.
The manual is poor and only gives you major % changes. So I got an online math Area calculator to really see how much flow area a rod and jet combo actually makes. Jet area minus the rod area = total flow area.
The edl rods are two steps so you can figure out cruise high vacuum flow and when you put your foot down the smaller diameter richer max flow. So do the math on their choices and you can see what they are doing and get an idea of how it works.
Then look at the rod and jet possible choices to buy and do the math. You can make very minor % changes to really dial in an edl carb.
You can buy the edl kit and dial in how fast the rods move up and down for the type of vacuum your motor operates under. Like you said a 1500 rpm stumble. You can cause the rods to go rich faster instead of speeding up the squirt rod.
I think that all in timing at low rpm is a dumb idea except for low compression non performance motors. You are firing so early that you are creating combustion pressure way before the piston reaches TDC. The motor is fighting it's self and you are hammering the rod bearings. It is just dumb
A correctly tuned dizzy has a high initial timing 14 -22 degrees. Where ever you get the smoothest idle with highest vacuum. Then all in somewhere around 3000 rpm
Plug gap is not .045 and set in stone as being perfect. The energy of your ignition and the quality of your plug wires resistance to arcing (blow through) determines max gap. crappy stock wires maybe .030 High powered Crane digital and super coil with Taylor 10 mm pro race wires .60 or .070 works fine with platinum plugs
