Inliners International Forums General Discussion Hi Performance Edelbrock 1406 (long post)

I have a relatively stock 250. It has split headers and a Pertronix conversion kit in it also. My problem lately has been my one barrel carb. It's just giving me fits. It's a remanufactured Roch. BV carb and I've been through it twice (one rebuild & once tryting to fix this problem). I'm continually getting a backfire through the exhaust, jerking, leaking, and lack of performance. I can't figure out what the problem is.

I should have an Offy 4 barrel intake heading my way, and I already have a 600CFM Edelbrock carb sitting around. I also have the two barrel adaptor for the stock intake. My main question is, what do y'all think is the best option? I hate to buy another one barrel only to put a 4 barrel on later. The main concern with the Edelbrock is if it will work well with my application. I know I'd have to retune it, but I'm wondering if it would be worth it. Sorry for the long post, but I just don't know what to do. Thanks for any help. John.

The 600 will work,probably be somewhat rich as is. Tom Langdon can no doubt tell you what jets and metering rods you need to get it dialed in.I once borrowed a new 600 edelbrock and put it on a 250 on an offy manifold.It worked ok,just rich.

The 600 should work fine. I had a single 600 on a mild 292 and it ran great. We have to have smog checked annually and it never failed to pass.

If you do not have the original book that came with the carb, it is on Edelbrock's website. It has a chart that is a good basis for tuning including jets and metering rods needed based on what the motor is doing.

Thanks guys. I have the owner's book, but I was just curious what other people had run into. I'm going to have to work out a spacer, since the linkage on the carb hits the manifold with it mocked up. I'm going to get a rebuild kit and go completely through the carb. I'm planning on rejetting it, and running different metering rods and step-up springs. I really don't want to dip into the secondaries unless I put my foot through the firewall. This is for my daily driver, so I'm hoping to get around the same gas mileage or better. I was getting around 13 MPG, which is a combo of highway and around town. Thanks. John

bigchevy,

You have a setup similar to mine. You'll need a 1 inch spacer to set the carb up higher. You can find the spacer at AutoZone or Advance (see picture).



-magic mike-

magic mike, you're just the person I need to talk with about this. What type of screws did you use for the bottom adaptor, and did they interfere with the spacer? What CFM carb do you have? Also, how are you going to setup your throttle cable?

I've got to figure out what the best way to hook up my trottle cable will be. This is on my '68 C-10. I'm also going to lean out the carb I have. I'll probably start out at 6% lean on both the Cruise and Power modes, and see how it goes from there. Thanks for the help guys. John

Another question for y'all. The carb is an Edel. #1406, which is a 600 CFM elec. choke 4 barrel. I was wondering if the calibration kit for the #1405 (manual choke 600 CFM) could work for the #1406. The kit for the #1405 has a wider range of jets and metering rods. Just curious.

#1406 kit---- EDE-1487
#1405 kit---- EDE-1479

I may end up getting the #1406 kit first, and maybe later getting the #1405 kit. Just curious. Thanks. John

Here is a view from the rear driver's side of the engine. Here you can clearly see the fabricated throttle linkage setup I have. They're just a few scrap pieces of 1/4 inch aluminum. I have a Lokar cable threaded through the bottom and the spring attached at the top. This setup did not work well with the Lokar cable because the cable bound inside the sheath from the heat from the headers. I went to Pep Boys and bought a much cheaper vinyl cable. It was much more flexible than the Lokar cable and shorter too. So I threaded it over the top instead of the bottom and have been running happily ever after since. My carb is the 500 cfm Edelbrock. It's a pretty good match with the 292 - a little bit rich out of the box. The 292 is .060 over for 301 CI. Cam is a little hotter than stock (.464I & .490E lift - 194I & 204E at .050) but the pistons are stock. So I'm sure the 600 cfm will be a bit too much for your 250 in stock form.

The adapter plate I bought from Tom Langdon came with screws. And they don't intefere with the adapter. They're low profile, flat top screws. They actually recess just beneath the surface of the plate.

The worst part about my throttle setup now is that I don't have enough cable travel distance to open the secondaries or set the automatic choke. But I have enough acceleration for my needs. The 292 spins the tires with very little effort. Lots of fun. If you're ever in metro ATL let me know and I'll show you my setup.

-magic mike-

The bracket you made only attaches to the one carb bolt? Do you remember the part number of the Lokar throttle cable, and the one from Pep Boys? We don't have one here, but I can cross reference the number. Also, do you know what the two threaded holes on the back of the intake are for? I'm going to get some pipe plugs to take care of them, but I was just curious.

Also, how much leaner did you jet your carb? Thanks for the help. John

The fabbed up throttle cable bracket attaches to both rear carb studs. You just can't see it from this shot. And I don't have another pic that does show it.

I haven't changed my carb any. It's right out of the box. This carb would be a perfect fit right out of the box for a stock 283 or 327 so it's just about right for the 292.

My HEI distributor has new components and the timing has been advanced a little to help performance. I get no black smoke on revving the throttle or at idle. A little on startup. I could probably do a little better by stepping down the primary jets one step and/or a metering rod and spring change but for now I'm going to leave things as is.

Sorry. I don't have any numbers for either of the cables. The Lokar cable was the 24 inch stainless braided type and Pep Boys (or autozone, whichever I bought it from) only had one type of black vinyl throttle cable. Runs about 20 bucks.

I'll try to get a shot of my new setup when I get a free minute.

-magic mike-

Thanks for the help. I'll see if I can't "be like mike" and fab up a bracket like that. Hopefully I'll order all my parts soon and get the intakes swapped out. Also, what type of intake gasket did you use. I've got a metal one from P.A.W, but I wasn't certain if it would be the best. Thanks. John

I used the FelPro 9786 one piece intake/exhaust gasket. I also used the stock cast iron "clamps" to hold the headers and intake in place (see pics). The header bolts were just to short in the middle and allowed too much movement. I did use the header bolts, however, on the ends. So far it works great. I did a paper test to check for leaks. I kept working on tightening, loosening and retighting everything down until I couldn't slide a single sheet of paper between the intake/exhaust gasket and the manifold. If the sheet of paper can pass between the gasket and manifold (intake or exhaust) then you will have leaks! I used black hi-temp silicone around the intake manifold and nothing around the headers. Whenever I remove the headers or intake in the future I'll probably use hi-temp copper RTV between the gasket and exhaust headers just for extra assurance.

-magic mike-

I just used the high temp copper RTV on both sides of my intake gasket. I don't think it's leaked, but then again I haven't done a paper check. I haven't noticed any popping like my 327 did when the header gaskets blew on it. I'm using the stock bolts and clamps except for the end ones. Basically it's the same setup as yours.

I was also wondering if you had tried the throttle brackets that have a built in base? I think everyone makes them. It actually bolts under the carb just like a spacer, but it has an arm coming out that the throttle cable attaches to. Thanks. John

Something like this
http://static.summitracing.com/global/images/prod/large/sum-g1419.jpg

I'll probably use that felpro gasket. Also, did you have any problems with the flange thickness between the intake and headers? Thanks. John

That piece would probably have made my installation a lot cleaner looking. And would have solved my throttle problems. I'll have to look into one of those. Thanks!

I had no flange thickness issues, but did have clearance issues between the two. I ended up grinding away a portion of the header flange (the portion that separates the two inner tubes from the single outer) to allow the intake and exhaust manifolds to center each port. A few tries at the grinding wheel fixed this.

-magic mike-