The Money Pit

I've been toying with the idea of trying annular boosters in my carb.

Got a 254@.050 flat tappet solid cam, pulls 6-8 inches vacuum at 1000 rpms in gear. Idles with the fenders shaking,.....and I love it. The 406 pulls to 7000 rpms, tons of power ,.....once I get it going. My only complaint is low speed cruise. It feels a little soft below 3000. And as luck would have it,...over half my 40 mile commute is country back roads, where by the nature of the road,..you're doing 40-45 mph,..or about 2500 rpms with my 3.70 gears.

I've read online some have had great things to say about annular boosters, and I got a quote from Quick Fuel to rework my carb. Before I take the plunge, I was wanting to hear from anyone in my similar situation, that converted to annular.

The other option is a roller cam,....but that's more money than I want to spend right now, and in my opinion, I'd be loosing power compared to what I now have.

elle88

on my L88 type engine i switched from a 800 holley dp with downleg boosters to 850 holley with annulars. the bad manners at low speed are still there but there was a slight improvement with annulars.
before going for a different cam, maybe it worths the try

427Hotrod

Annulars generally help with *too big* stuff...like everything I do! Big heads, big cam etc.

Dominator circuitry in a 4150 carb helps it feel stronger also.

Have you played with timing curve? A LOT of initial can help things.

JIM

The Money Pit

Went through a ton of timing curves,...ended up 36 degrees locked out, no vacuum advance at all.

I was running a Vic Jr intake,..and swapped to the RPM also trying to bring back some low end.

The ironic part of all this, ....I had so much low end before I couldn't hook if I wanted to. So I went too big on the cam swap,....and now I'm hunting for a little more low end. Go figure............

v2racing

I also run a vacuum advance hooked to ported vacuum. I use an adjustable vacuum pot with an adjustable limiter I made. I run 16 degrees initial with the vacuum limited to 6 degree so just off idle it is at 22 degrees. It runs around 40 degrees cruise @ 3000 and 34 degrees WOT. Your cam has more duration and your vacuum is lower than mine, so it would probably like even a little more initial.

Have you tuned the carb. I use a digital wide band AFR gauge and a vacuum gauge so I can set up the AFR's at idle, just off idle, cruise and WOT and also where I want the power valve to open. Between tuning the carb and ignition it really gave my motor a much friendlier attitude on the street.

v2racing

What is the rest of your build? How much compression do you have?

The Money Pit

I forgot my sig wasn't on....Sorry cr is 10:1

The cam has 108 LC,.....also helps my problem

v2racing

With your compression being almost 2 points lower than mine and if your intake lobe is installed at 104 degrees, your intake valve closes 1 degree later (@ .050") than mine. My roller will be much narrower at advertised duration though. You will need more initial timing to try and help the off idle and bottom end power. I would say you could use like 22 degrees initial timing and that should help. You will have to limit the advance at the distributor to keep from having to much timing when it is all in.

Myself, I think you could really improve the manners of your engine with a roller cam with wider lobe centers and less timing at .050". Your can still get more area under the lobe curve with a roller and more lift. You would be able to tame the street manners and make more power at the same time.

cardo0

Annual booster? Where do get one of those? My bank account needs one ASAP.

cardo0

TimAT

Dial in a couple degrees of cam advance?

pauldana

fwiw..., I had a Mighty Demon 750 annuler on my 383, it ran fantastic.....period.

Now my new build i am going with an EZ-EFI 2.0 by FAST. very excited about it, uses a wideband O2 for adjusting at A/F, looks like a carb, an takes the place of the carb... very excited to get it.

The Money Pit

When I had the 406 out last July to make some minor repairs, I almost wanted to advance the cam a bit,..but at the time I was into so many other projects, both time and money were an issue. I didn't feel comfortable just advancing the cam without pulling the heads, rechecking valve clearance with clay, and so I left it as it was. From what I've read the difference in timing changes done like that are pretty minor.

pauldana,

How radical was your 383?
Though I don't consider my 406 to be Pro Street, or anything,,..it's far from stock. There is no doubt I have a "cam" when people ask. The fenders shake, it sounds like a race car.
With that comes the "drivability issues" normally associated with big cams. I spent a year tuning the carb to get it to idle in gear without stalling........Now the car will start dead cold, idle in gear indefinitely, pull 7000 rpms, ....and my spark plug color is tan. So I think my tune is pretty good overall. Just got one area to tweak,...and that is why I'm considering annular boosters.

The roller cam option will be the last thing I try. In my quest for the ultimate smallblock,..I wanted an engine that had hotrod qualities. The idle cackle, the high rpm potential, and a little bling just for show. A big block would have been easier to make 500 plus horsepower, but would have required many more changes up front to get in the car. I built what I have over many years, one part at a time,...and by keeping the smallblock, was able to re use all the parts I bought in the past, for every rendition of the engine to present.

427Hotrod

Just depends on what roller cam you get. I did a 388" for a buddy with a 248* SR on a 109 LSA. It screams and I was very surprised how easy it drives. He busted his 5 speed and stuck an M-20 back in it for awhile with 3.36's and the thing will idle away from a light. It has 215 cc heads and a single plane intake.

I did a 400" with a different 248* SR..but also on a 109* LSA. It made 555 HP at 6300 RPM or so and will pull hard past 7000 all day long. He drives it everywhere with a TKO and 3.08's.

I'm betting you could take a good chunk of duration out of it with a tight LSA and do well with the right lobes.


JIM

The Money Pit

That SR cam might work..........Maybe even on a 106 LC.
Do you have a dyno pull with the 400? I'd love to find out things like idle speed/ vacuum levels at idle too. The magazines only care to show off the power,....but you still need to actually be able to drive it.

When I'm ready to go roller,..it'll have to be solid for sure. Love my rpms!

pauldana

I busted the crank, it was a Skat cast crank i believe rated at 500hp

The last dyno was 440tq and 460hp at the rear.

So i am now building a 427... I would like to see 650hp out of it, but most believe it will hit about 600-625hp...

I have done a tone of research for a carburetor of this new build.... and EVERYTHING i read was positive about the EZ-EFI 2.0 system by fast... they have a less expensive version, the EZ-EFI, and its good to 550hp. your "carb" will always be on perfect A/F tune automatically, your gas milage will improve by 2-3mph, starts easy cold or hot, ... its just the end all of carbs as i see it... an amazing system....

My old build, .... before the crank snapped.
Engine: 383 SBC gen 1 (original block)

Custom Cold Air Intake with ram air design by D&C designs
with moroso intake and K&N filter
Barry Grant Mighty Annular Demon 750 Carbarator
Edelbrock RPM intake manafold
Dynomax tuned ceramic headers
Custom 2 ¾” duel exhaust with X-pipe by D&C designs
Borla mufflers
Fluid damper harmonic balancer
Skat crank
10.5:1 hyper pistons
chromoly rings
Edelbrock signature series RPM roller cam
Comp-Cams hydraulic roller lifters
Comp-Cams 1.52 magnum roller rockers
Comp-cams Beehive springs
Comp-Cams push rods
World Products Sportsman II heads
Heads and intake manifold were sent to Valley heads in So-Cal for race porting, polishing, and port-matching
HEI MSD ignition
March under drive aluminum pulleys
Canton Racing oil pan

MotorHead

I put in annular boosters in my 825 Drag Race Demon years ago and did notice more bottom end tq and response, there was enough difference to trip my butt dyno so I liked them better than the downleg.

Now that being said if you are into hardcore racing at the 6500+RPM the same car would probably beat it in a 1/4 mile race, but where do you do most of driving ?

It's a definatley "do" in my opinion and I did it when 99% of the HP carbs came out of the box with downleg boosters, after all they are racing carbs. Now we are starting to see carbs being sold with your preference.

Same carb same car but in drag racing your looking for every 1/10 sec and the down leg would probably win but I wouldn't say buy much more than doors length

The Money Pit

Wayne,
I think you nailed it. My "toy" is all street,......though sometimes I fracture the rules and "play",.....so the big picture from me is a torque curve I can drive. Hence my choice in RPM intake over the Vic Jr I was running on it before. If I wanted to,....I could put the Vic Jr back on, swap on the 1 7/8 inch headers.....wide open,....and hit the throttle.

73C34me

My 383 with a 254 degree solid cam likes 32 degrees initial timing. This provides 10" vacuum at 1050 rpm idle in neutral (manual trans)

BOOT77

I run a custom annular booster carb since last fall. I had BLP install the boosters into a 750 hp mainbody. Still my combo is odd. I just built another 750 carb for my other car with downlegs and I planned on swapping it to compare, but I don't expect the downleg to work better with my combo. What makes my combo odd is I am using shorty headers, low stockish compression, a 106 cam and my motor runs really cold.

I was gonna swap carbs because with my new drag radials the car was just chirping the tires off the line. Be a great time to tell if the annular had more torque on my combo vs the downleg. I'm pretty sure the downleg won't be better but if I don't test it out, it'll bug me. I was hoping to have tested it already, but I messed up somehting and now I gotta fix that. When it's fixed I might have to retune the carb some before I swap to be sure the test is fair. Still it'll be a few weeks before I comparre and that doesn't help you right now. All I can say is when I got my annular booster mainbody my tune was still too far off to make a honest comparison vs the downleg it had on the time. But the car runs great and my plugs look perfect.

427Hotrod

This actually was a "Magazine Build" I did for Corvette Enthusiast. The 3 tests shown are with a ported 2x4 intake with WCFB's, a Dart Dual Plane with 750 Holley and a Weiand Single Plane with same carb.

Cam was a 248/248 single pattern based on the intake/exhaust restrictions I knew he would end up with in the car (he kept the 2x4's) to replicate the look of the original 283/270HP in his '61 Vette. Out of the box Dart 200cc SHP heads. No massaging of anything..the point was to pull it out of the box, assemble it all and dyno it like anyone could do.