I'm putting together a 505 with Indy EZ heads from Porter racing with a solid roller cam spec'd by Dwayne with a repo cross ram intake. My plan is to get a pair of Edlebrock 750's. My question is should I just buy 2 from Jegs?Or is there someplace or someone to set up a pair. I have never ran dual carbs or the edlebrocks. This is going in my 64 strip/street car looking for 10.50s. Thanks Mike

I'd go smaller than the 750's. Edelbrock sells the 500 cfm carb calibrated for dual carb applications so that is what I would use. That gives you a total of 1000 cfm which should work fine with the cross ram.

Mancini or Hughes can sell you the correct linkage kit which is designed for the Edelbrock carbs. Using the Edelbrock carbs saves you a ton of money over trying to find the factory correct parts.

Did you read this article?

http://www.moparts.org/Tech/Archive/bb/80inches.html

Yes i did. I have linkage already just need carbs yet. I'm not sure 500s would be enough Dwayne said 750s. Looking for 625 hp to get my 64 in the mid 10s

Dual 500 cfm carbs can easily support 625 hp. I'd use the smaller carbs for something that is going to be street driven. You can go with 750 or 800 cfm carbs if you want. The air valve secondary is pretty forgiving in terms of over carbing an engine.

64 Max wedges had 750's from factory. All the max wedges I do for big hp street or strip I use the 750"s You will need to jet them right out of the box because they are way to rich. leave the rods stock and use .104 jet in primary and .082 secondaries to start and get you in the ball park.

this!

Thanks for the info! The car will only see a couple hundred miles a year on the street.

If you buy the Edlbrock carbs. make sure and don't buy the smog ones with the electric chokes , buy the Hi Po versions with the manual chokes I've used both versions both on street hemi and M.W. motors, the non smog carbs. are way better out of the box I would use and follow the secondary jetting recommended in the old Mopar drag manuals

I was looking at the 1407s. I will google the drag manuals. Thanks

the '64 3705 carbs are identical in size to the 1407 and would make an excellent choice. the 1407's will be too rich and need a metering rod and jet change for base lining to factory specs. i believe this to be factory specs.

.104 jets for primaries, .066-.052 metering rods. secondary jets, .063 choke side, and .089 throttle side.

Thanks think I will try 1407s.

If they actually flowed 500cfm....Those eddy 500's only flow 350cfm or there abouts. I would run 750 or bigger manual eddy carbs with all the choke stuff removed.

Max Maniac has a couple of Eldelbrocks for sale, real good pricing

With an extra 80 cubes and 200+hp over a stock 426, I don't know that I'd drop the jetting all the way down to what came in a stock MW carb.
I'd rather err on the rich side to get it going.

I ran a 498 with two 750's on a Stage 1 cross ram with the the jetting called out in the old Mopar Performance tech sheets from 1990 to 2002. Even had to solder one jet closed and redrill, as I remember it was .068.
Doug

The cubes and HP should have nothing to do with the jetting, if anything the stock jetting might be too rich.

lewtot184 has the best suggestion, the stock 3705s flow about 700 CFM.

Huh.

The factory manual calls for extreme cross jetting but when I ran my MW setup I used Edelbrock carbs right of the box and they were close enough. By close I mean the plugs looked okay, the EGT's were fairly even and the widebands were okay. Not sure what the factory guys were looking at when they cam up with their recommendations but with a 500 inch shortblock sucking on that cork of an intake I wouldn't start with their old info.

I ran dual 800 Eddy carbs on that first engine but later on I switched the engine over to dual 500 cfm Edelbrock carbs and made roughly the same amount of power. Which is why I wouldn't have any issue starting off with 500 or 600 cfm carbs. They have plenty of airflow to support 600 hp from what I've seen on the dyno.

On the two stroker motors I dynoed that had Indy heads and a x-ram intake with edelbrock 750 carbs, when jetting for best power, I ended up with jetting quite a bit richer than the as delivered edelbrock jetting.
One was 675hp, the other was 745hp.

One of those came to me with torched head gaskets from being run too lean.....and those carbs were richer than stock as well.

i hear of people going to very large jets in big cube n/ss engines using afb/edelbrock type carbs. i've always wondered about that and my thoughts were; has anyone ever taken the plugs out of the fuel passages and checked them for restriction/flaws/size? after all the jet is just a restriction device and when that gets reduced big time wouldn't that indicate a possible problem somewhere else? are the cams so large that they can't create a good pressure differential? is plenum volumes excessive?

Although the ede 750's and the last of the carter 750's were both made by weber, and both came with the same jets and rods, they did not provide the same a/f ratio when run on the same motor back to back.
Subsequent disassembly and inspection showed definite differences in the calibration with the air bleeds and clusters.

No way would I assume that the jets for an OE MW carb would be optimum for an aftermarket similar version of that model carb just because the throttle bores and venturii are the same size.
In the same way not all 750 Holleys are supplied with the same jets, or would require the same jets, to achieve equivalent a/f ratios on a given engine combo.

[quote=fast68plymouth]On the two stroker motors I dynoed that had Indy heads and a x-ram intake with edelbrock 750 carbs, when jetting for best power, I ended up with jetting quite a bit richer than the as delivered edelbrock jetting.
One was 675hp, the other was 745hp.

One of those came to me with torched head gaskets from being run too lean.....and those carbs were richer than stock as well. [/quote
Were they the stock mani or aftermarket, my jetting comment was based on the stock mani. Some of the NHRA Maxie stockers are near the 650 HP range and not varying far from the factory jetting that was right for the maybe 400 they made stock. I'm guessing cam design, aftermarket head and mani ports and large headers make this a different animal. I could be wrong but IMO that motor that burned the head gasket had some other issue if it required much larger than stock jetting.

The 750 Edelbrock carbs have been known to have AF problems. Tuner did a long (even for him) explanation a while back on the issue. It had to do with the size of the air bleed as well as a crimp in the emulsion tube.

I've run the 800 carbs on a number of stroker motors. They do tend to be lean and putting big jets in them sometimes doesn't help until the needle and seat are enlarged.

So I'll say the Edelbrock carbs can be made to work but sometimes you'll end up spending a full day chasing your tail when working with them.

I looked back in my notes and what it says on my 505 cross ram engine was that the 800 carbs worked fine out of the box. But when we switched over to the Indy ram the carbs needed to be jetted up significantly. So that is just due to the difference in the intake. Something was messing with the signal on the Indy ram and the carbs required a lot more jet to deliver the same amount of fuel.

the one 800 avs i've spent a lot of time with had .110 needle and seats ootb. for the application it was used in it was jetted stupid rich. the 800 had the large open emulsion tubes vs the 600's swagged down tubes. the 1407 750 edelbrock i have came with .093 needle and seats and after measuring all the air bleeds in the primary clusters they were near identical to the 4618s avs i use on my 69 r/t; big exception was idle jets.. the 750 i have uses a straight open emulsion tubes like the 800. there are some recommendations from mopar to solder up the small holes in the emulsion tubes. i think the performance community has had holley stuck so far up their rectums for decades and can't get their mind around something different. i guess tomorrow i get off the couch and star "drilling" one apart to learn more.

The car I mentioned with the old jetting had over 700 passes when it was sold, ran another 2 years with that setup. Car was sold again and I lost track of it. My current 572 with Indy X-ram Eddy 750's usually runs 113 pri/110 sec with stock rods. I did drill the secondary cluster feeds last fall to .120" as they were around .075" if I remember. That along with 116/113 seemed to help a little but the air was pretty good. As far as being lean it runs the same MPH (148) with the Eddys or a pair of Pro-Systems Holley 750's. I clean cut with the Holley's and the plugs looked perfect. 300 passes, rod bearings and rings looked excellent on tear down. If it's lean it sure hasn't showed it.
Doug

116/113 jets is way richer than some on this thread are recommending, but that's in line with where I ended up with the ones I had on the dyno.

On a 557 with the Indy intake I was at 119 on all 8 holes with the performance series Carter 750 carbs.
Again, I was jetting for power.

Honestly though, I'm all for people finding out what works best for them.
The main point of my initial post on this thread was to just encourage jetting on the rich side "just in case".
The ramifications of taking that approach is a little less costly that finding out you're way too lean.

The Edelbrock 750 has 1 major problem and that is the length of the primary booster is shorter than it should be. Any early pre Carter/FM 750 will have the correct longer booster if you want to compare.

From memory when i compared the both the longer booster activated the primary flow sooner.

Heres an Eddie 1407 thread at Speedtalk:
Edelbrock 1407

I would look to the NSS guys for guidance as thats their bread and butter.
Also heres a write up from Dan Dvorak on AFB's. Well worth the download price $1 for what he knows.

Carburetion: A maximum performance treatise
Hope this helps

Hysteric

Thanks for the link.....a lot of interesting info there.
Answers some questions as to perhaps why some of those carbs just can't seem to be sorted out with normal tuning methods.

When I get a chance I'll read through the stuff from Dvorak.

Great read! We need more posts like this on Carter/Eddy carbs.

As far as the boosters go I know some Demon carbs have that issue like the King Demon I just converted to a 2-circuit for a 1000+ hp BB Chevy. The booster is too high in the venturi making the depression point less than desireable and a weaker signal needing more fuel when the boosters are active and making it richer down low..............

Thanks for the links good info. I'm going to call Dvorak about his carb synchronizers and any other info I can get from him.

Are you stuck on AFB`s? Can you run Holleys?

I can run Holleys. The AFBs look more period correct. Not that most people would know. I have thought about holley might be easier.

I know some haul azz w/the AFB/E-brocs and agree they look more "correct" but I still love the easy tunability of the Holleys and they just look meaner to me...........

I agree with you! I have more experence with holleys but none with dual carbs. I have a little time yet to decide for sure. If I was smart I would put a single Dommy on it.

I think w/properly calibrated duals, the distribution would be better but a Dommy gets it done everyday for many...........

A single plane intake with a Dominator will make 100 hp more than a MW cross ram on a race type engine. When you think about it that means that the cross ram intake is destroying 100 hp of potential power but keeping the air and fuel from getting into the cylinders at the right time. I know that people love the look of the cross ram but sheesh, 100 hp is nothing to sneeze at. Plus the single 4bbl setup costs less and weighs less.

On a different note, a GOOD t-ram intake will make more power than a single in most applications.............NOT cross ram............

I knew the cross ram would cost me big power. I have the cross ram, linkage and bolts already so I will use it. I would like to try a single setup just to see the difference. What intake would you suggest? It is a 440 base 505 with ez heads by porter racing and a solid roller cam 264/270 dur @50 110 lobe sep and .631 lift. Thanks Mike

I run a heavily ported Victor 383 w/an adapter that`s blended nicely into the manifold and a Thumperized HP-1050.............

As mentioned Dan Dvorak is the man on a cross ram. I run the earlier Federal Mogul AFB carbs, they have a few minor differences. My 3200 lb NSS car ran a best of a 10.00 with the old cross ram, I could never get it faster, and Dvorak said that I was wasting my time trying. Two other guys in NSS are at the same ET and nothing seems to make the cars go any faster. Put a homade inline manifold with same carbs on mine and it ran 9.78, When setting up your fuel system the needles and seats are the main restriction, I machined little windows in the seats and drilled the air horn to make them dual inlet. Really improved the stability of the airfuel readings.

As long as your heads have the stock Max Wedge size or ports look at the Indy single four intakes, 440-2 for the RB with 4150 carbs and the 440-3 for the dominator carbs, 400-2 and 400-3 for the low decks. I don't know of anyone testing the new Edlbrock Super Victor 440 M.W. intakes yet, they may be a decent choice also

How much ET are we talking about the 100hp loss with the factory crossram? I can run 10.20's thru the mufflers with these small
air cleaners on. Curious how quick I could go with a single plane and dominator.

Probably pick up to 9.80 or 9.90 if you added 100 hp. I'm assuming that you currently weigh about 3600 lbs?

The problem is that then you are just another guy with an Indy intake and a Dominator. Having a cross ram looks cool even if it costs a bunch of hp.

9:70's in 3300 lb. in. Nss car stock xram 750 edies.

Originally Posted By Smoparmike

I knew the cross ram would cost me big power. I have the cross ram, linkage and bolts already so I will use it. I would like to try a single setup just to see the difference. What intake would you suggest? It is a 440 base 505 with ez heads by porter racing and a solid roller cam 264/270 dur @50 110 lobe sep and .631 lift. Thanks Mike

duration is wrong for a cross ram engine that will work with a short runner single plain intake. cross ram should be the other way around. 270 intake 266 exhaust

not disagreeing with you but the most we have ever seen on a dyno (stock eliminator engines) going from a cross ram to a single 4 is 45 hp that with changing cam shaft.

Sounds very reasonable for a stock eliminator engine. The engine where I saw 100 hp increase was 505 inches with Indy heads. The stock intake was very restrictive at 505 inches so the flow increase bigger when we switched to 4500 intake. The OP in this thread has a 505 inch engine so that is why I was using that number.

My motor is 499ci , little Ez 295 cnc w/2.25 intakes, small comp roller .620/.620 272/276@.050. 750 eddy's done by Dvorak . 5400 ati converter w/ 4.30 gears. Launch at 2200 shift at 6200. Weighs 3500lbs w driver.

The engine I was working with was fairly similar to what you have. It was 505 inches and 13:1 compression. It made 620 hp with the cross ram, 705 with the Indy X ram box intake and 740 with a 440-2 intake and a Dominator carb. I think we changed cams in there too. I was using a cam that is a little bigger than what you have. Here is a link to one of the articles. The MW article is also in the tech archives:

http://www.hotrod.com/how-to/engine/mopp-0709-cam-carburetor-modifications/

I'll just throw this out as an untested counterpoint to the 100hp loss from the factory x-ram.
I dynoed a 12:1 RB499, ported Indy -1's, .650 lift roller, 2-2 1/8 headers, OE stage II manifold, FM carter 750's.
It made 675hp like that. I didn't test any other manifolds on it, but I just don't think there was another 100hp to be had out of that motor by installing a 440-3 and a dominator.
I suppose it might have made 775hp, but I know I've built "better" motors than that before that didn't get there.