Hello all,

I recently installed a pair of the marine Edelbrock 1409 carbs on a pair of small block Chevy marine motors, and they start and run well, but I don't think I am getting full power from them.

The secondaries do not appear to be opening until I get to the max rpm setting, and the boat does not seem to want to rev like it did before. I am assuming I have some sort of an internal jet setting that should be changed out to make things work better.

The motors are 327F flywheel aft, with 210-hp. My questions is, has anyone else experienced this, and if so, what can be done about it.

Thanks,

Jay

That carb is actually intended for more motor than you have. I'm not sure what the true needs of a 210 at 4000 would be but I would guess it is in the 400 cfm category rather than the 600 cfm like the Eddy.

The 1409 appears to be an almost perfect replacement for the 427 big block, but the small block just will not suck enough air at a given rpm range to take full advantage of the 1409.

Rather than guess, I recommend you call their (carb) tech department and talk to their in-house expert. There may be a change of jets or something that will tune the carb more specifically to your motor. With the big diameter openings cast into this carb, jets may only get you part way.

Good luck,

Tom

A vacuum secondary carb is designed to only open the secondaries as needed for proper air flow. Opening them too soon or too wide will reduce performance by allowing the airflow through the venturis to drop below the desired limits.

If the motor seems lazy all of a sudden, look at ignition/timing first. As Tom said, a 327 is gonna have a hard time opening the secondaries except a full throttle and high rpms. BTW, opening the secondaries on my 450 cfm Holleys on 302 Fords only picks up 200-300 rpms.

When the 427 draws air through the 625-cfm Carter AFB that was the stock carb from Chris Craft, those 4-bbl secondaries will open when called upon. However, when the small block calls for power, there does not seem to be enough of a suction demand from the motor to open them, as I have experienced much the same issue you note on your motors. I can hear them opening, but not until way up on the top of the rpm band, just as you have noted. I have not removed the air cleaner to watch what is happening, but that is next.

If you talk to Edelbrock, that would be one real nice bit of info to share here on the forum, please keep us posted.

Regards,

Paul

Hi Jay,

The one thing you can check easily if you
have not already done so, is to make sure your throttle linkage is opening all the way.
Simply remove the flame arrestor,open the throttle all the way. The primary blades should be sraight up.
Push on the secondary air valve to make sure it's not binding. Do this with the engine off, BTW.
Are your WOT RPM's over 4000?

Greg

Hello all,

Thanks so much for the responses. Greg, I am able to get up to a max of 3800 rpm but I have been told I should be able to go higher without any problems with the motors. I think I was able to get more rpm with the old carbs before the swap. They have right around 1,000 hours, good shape, pampered, and now with new carbs. I will check the linkage.

LJH

Many other factors affect rpms. Bottom and propeller condition, timing, carburetor inlet air temperature, wind, even water depth. I picked up a couple hundred rpms by removing the restrictive flame arrestors. However, do check and make sure you're getting full throttle, and make sure the air valves move freely.

This morning I decided to call Edelbrock tech center due to the fact that we have a lot of 1409 marine carb action here on the Forum, just to hear it from them.

VERY INTERESTING comment about the size of the carb versus the size of the motor.

The guy said the small motor may not be creating enough vacuum to actually open the secondaries on a 600-cfm carb, which is what I believe I am experiencing with my Skiff motor (also a 327F, but with higher compression than the stock 327F). They don't appear to be opening much until I'm already reaching the 4000 rpm mark.

The guy said, "can you actually see them open"? I said, "no, I've been just listening to them, and it doesn't sound like they're opening".

He said it was important for them to open, in order to potentially avoid a lean running condition. He said I should look at the plugs to be sure I'm not running lean.

I inquired about what could be done about it, and he said I could drill out the counterweight on the air door at the secondaries (see part # 42)





The tech guy was kind enough to email me this diagram showing how to drill out the weights, to make the secondaries kick in quicker on a smaller motor. Ohhh boy, I'm DANGEROUS now!




I thought I would include the following chart from Edelbrock, to be helpful in any future carb discussions.


Here is their full Carb Owners Manual, in PDF form, 1.8 MB, in the event anyone wants to see lots of metering rod and jet combos that might help your particular running scheme. I'll be looking over that info too, but for now I am intrigued with the drilling of the counterweights.
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

Regards,

Paul

Yes this brings back memories of hot rodding and I had overlooked this neat little trick. Don't drill out too much weight, or you'll be driving around with the 4-bbl open all the time, lol. I saw the note about pinching the hole shut if you added solder, but you really don't want anyting flopping around in the carb that could potentially dislodge and get sucked into the motor.

So where do you think you want to hear those 4-bbls open up? I would think you would want to run up to around 3200 to 3500 before they flop open. That way you'll have 500 to 800 rpm of 4-bbl action. This is good stuff. Careful with that drill.

Tom

Uh, hmmm..something doesn't sound right about this. First, plug reading is only accurate if you run full throttle, cut the ignition, and turn off the engine immediately. Lean? Why? If the carb is calibrated properly, but the engine simply isn't big enough to open the secondaries, what would happen on a big engine that was not turning enough rpms to open the secondaries..would IT be lean also?

Worth a try, but don't expect miracles. also, ask yourself why your rpms are down in the first place....

Well I certainly don’t discount the BS meter is a useful tool, ha, as a reality check is always good.

I don’t know about Jay, but I ran mine at WOT intentionally long enough to know what it felt like. As I got into the high range, I kept pushing the throttle forward until I got to a point of diminishing returns, backed off a little and it seemed to give a bit more smoothness. I didn’t get any lean popping as in fuel starvation.

I am no expert at all with the AFB, as I'm especially accustomed to the SU and Zenith Strombergs with the vacuum operated dashpot, where you need to run at a steady speed under load, read plug, and then you know what the needle is doing to you at that rpm. If you are lean at that rpm, you select a needle that is tapered a little more at that segment of the lift, and that provides more fuel at that specific rpm. I ran several solid lifter motors in my former life with those type of multiple carbs, high compression, ported, hot cams, with a totally custom stage of tune. After reading plugs at low, mid, high, and ultra high rpm, you would eventually get a motor that was totally tractable over the entire range.

The AFB style carb just doesn't work that way at all. What I think I found with my 327F+ was a flat spot up around 4000 or just under, and it didn’t appear the 4 bbl was acting like a 4-bbl. Based on my limited experience with a less tunable carb like the AFB, it feels like a lean condition. I can’t select an adjustable needle like a SU or Zenith Stromberg, but I can cause the butterfly to open a bit sooner. What do you think, Bill? Do you think the motor is producing what it can as a 2-bbl, or should I be getting something from that secondary set of carb ports? Granted, opening the secondaries may just choke out the motor at high rpm by dumping a lot of fuel in, without the compression and cam to handle it.

The guy I talked to today was at the following number, Tech Line Only: 800-416-8628

If you talk to him, the motor I'm running is 8.5:1 and probably a 250 hp version of the 327. Jay is running the 8.0:1 marine version at 210 hp.

Comments are welcome!

Regards,

Paul

SU?? You're dating yourself, OLD man. Actually, a very efficient carb, self compensating for alot of variables.

In my experience, AFB's and Quadrajets are somewhat self compensating also. The secondary throttle plates are mechanically connected, but don't flow any air until the air valve opens. Once the air valve opens, flow drops again because of the extra area of the open venturis. I would think this would cause a kind of fluttering or oscillation of the air valve, since it is simply hanging in the air flow. Sometimes the flat spot is the transition/opening of the air valve, that is probably not real steady at that point. since there is no accelerator pump on the secondaries, a short term lean condition occurs. Nothing serious, but creates that flat spot. Holley "double pumpers" have an accelerator pump on the secondaries to address this problem, but they're mechanical secondaries. However, the Holley spread bore is an air valve system with a pump.

The carbs are pretty much designed so that the primaries are not overloaded before the secondaries open. The air valve controls the metering rods, so only as much fuel flows into the secondaries as is needed. Often the secondaries are set to run a little fat, which is desirable. Carbs use air bleed jets to control the fuel curve, in addition to jets, emulsion tubes, and metering rods.

Other factors affect full throttle on a marine engine..restrictive exhaust and restrictive flame arrestors. The first thing I'd do is check for total advance of the ignition, then remove the flame arrestors and try it again.

It's quite probable that the engine will make about the same power just on the primaries, since the carb is much bigger than needed. Even on my 302 Fords with 450 cfm Holleys, disconnecting the secondaries only drops the full throttle rpms a couple hundred. I've got manifold vacuum gauges on my boat, and full throttle is still so close to zero I can't read it.

I'm not all that old, by the way!

I was one of those guys who grew up respecting American iron, but knowing I could generally get from Point-A to Point-B quicker in something lighter with a little less power, that could actually go around a turn instead of run like the blazes down the quarter mile.

My Grandfather had a Ford dealership and I always saw a lot of big powerful iron, but never got much of a chance to drive any of it. I eventually found out just how fast a 1960 Fairlane 500 would go with the 240 cubic inch six and three on the tree. It would go 105-mph flat out. Although my family had big block V8s, I was never permitted to drive one, ha ha, which may be the reason I am here today, so "thanks Dad", for selling that Galaxie with the T-bird hi-po motor!

Instead, I got a 1965 Alfa Romeo several years old in good condition, which gave EVERY INDICATION of being a sewing machine on wheels, for girls. However, upon taking that car into the mountains of Central Pennsylvania to college at Penn State, I soon discovered that a car built in Italy could downshift and stand on the gas into hairpin corners when all my friends in Triumphs and Healeys were having to brake. That Alfa became the terror of Central Pennsylvania, ha ha.



I have the distinction of having outrun a 429 big block Ford in a 1600-cc 5-speed Alfa Romeo, ha ha. I will neither confirm nor deny whether or not the 429 was in a police car or not. Driving the little Alfa was like rowing a boat and going nowhere (with the long shifter and gutless motor). What it would do, however, is go around a corner so fast it would make you peel your eyeballs off the window, and it tied for the best handling car of 1965 (with the Lotus Elan). It also had something the English cars didn't have at the time, and that was a soft suspension, which made it a real terror on dirt roads where the "429 event" took place, leaving a rooster-tail a mile long at night, and throwing in a few acute corners, lol. That car had a Solex carb, by the way. Mind you, this was back when racing on back roads was a lot more socialy acceptable than it is today, but no less dangerous, and it was a dumb thing to do. I am fortunate that I never got hurt, nor did anyone I associated with get hurt in cars.

I then graduated to faster cars, such as a Volvo PV-544 Sport, which looked like an egg on wheels, but had a fully ported and polished head, hot IPD cam, double valve springs, headers, and yes, a pair of big Solex carbs that came off a Jaguar. Hey, they fit, I did the needle adjustments, and that car (with it's 411 rear end) would scream to 6500 rpm so fast it would make wonder how the motor stayed together. Here is one in the photo below, owned by Jay Leno, same color as mine, but I'll bet mine was a LOT faster, ha ha. It would eat BMWs with regularity.



It wouldn't handle very well, but it had something I had not had much of before, and that was lots of power in a light weight car. I never broke anything on it, old Volvos are built like tanks. It would run up to 100 but ran out of rpm there.

Then came the TR-6, which I modified with a Kastner cam, fully polished and ported heads and intake, additional big Solex carbs after I pushed the Zenith Strombergs to their limit (vinyl diaphragms in the latter, metal dashpots in the former), and the now infamous 8-speed transmission. I have the distinction of outrunning a.......well lets just forget about that one for now.

I added overdrive switches on all four gears. First gear was a joke, but second gear was NO JOKE AT ALL, as the car would squat down and scream for another 500-rpm with the flip of a switch. That car had a great motor, but it didn't have much of a suspension. After bending that car in half, I took the cam and cylinder head and installed it on my 1974 TVR, and also installed the 8-speed tranny. In addition to that, I added three side draft Weber DCOE carbs, and that inline six would light up like a blow-torch. Now I had power AND handling. I still have that car, and you and anyone else would swear it has a hot small block in it the way it will stand up and run. I not only embarassed a small block Corvette one day, I caught and passed him so convincingly after he got a head start, ha ha, and we both had witnesses in the car. Here is an identical model to mine, same color too.


From there I moved on to faster and better handling cars, but none of them had carbs, they all had electronic fuel injection or and/or turbochargers. I am a lot more proficient in working on a German L-Jetronic system, than I am a Carter. It's not really that I am so old myself, har har, but the fact that I love older things, like Austin Healeys and Jags, and of course the fuel injected water-cooled Porsches too (running three of them now).

Had I started into small block Chevy or Fords at the onset, maybe moved up to big blocks, I would have learned a lot more about raw power, but I would have never experienced a car that would stop, or go around a corner. Naturally, the new Corvettes are an exception to the rule, and they are just now incorporating some of the things one of my 1983 autos has, such as a rear transaxle, but still not the 4-wheel steering via Weissach rear axle of that 1983 928S.

Ah well, so much for the past. I now have 5 big block V8s four Fords and one GM, 5 small block V8s one of which is an all aluminum SOHC injected version, and a host of exotic 4, 5, and six cylinder cars, a tractor and a few weed eaters and a Hercules or two. It's tough keeping up with everything, I know a metric 13mm versus 1/2" box wrench, but don't seem to remember what fork to use when we go out for dinner.

regards,

Paul

Well, I can relate. Had a 544 Volvo for a while, had a tr-6 i took in trade for some real estate (my only British car, I think), Porsche 912, 66 Shelby Mustang..a real one. 300sel 6.3 Mercedes. Datsun 510. Formula Vee.

You spund like the ideal sucke..eeerrr..person to for a project car. Ever heard of a Steadman? Me either. Anyhow, it's a replica of a Jag SS100. Got a buddy who has one, sorta. Frame, XKE rear axle assembly, right hand drive XKE front end assembly. Real cheap. The British guy who designed/built 'em has a shop a couple bas from mine. Small world.

Anyhow, that's my story. Been playing with stuff and tweaking cars for decades. It's all about paying attention to the details. Marine stuff is so conservative, there's always room for improvement without sacrificing durability.

Bill

Yup, I'm a sucker allright. Sometimes the truth hurts, but being able to admit it and talk about it is the first step in doing something about it.

You combine being a sucker with boatitis, you got one sick puppy on your hands, lol.
(but what a way to go!)

Regards,

Paul

Thanks for all the comments guys. This gives me some things to look for, for sure. I'll look into the linkage to see if throttles are opening all the way, and I'll check that timing. I also realize one engine that is not performing right, will cause both motors to show a lower rpm as the one drags the other one down a bit.

Paul, if you decide to drill out the counterweight, I would be very interested in knowing if it makes any difference in the way your motor runs. Please post an update if you do this.

Jay