500 CFM for my Fastburn 385

[TheRoaringEagle]

i was reading a book on holley carbs and there was a calculation on how to find the best cfm rating for your engine. c.i. times max rpm all divided by 3456.

so i got about 587 cfm from entering 350 and the factory recommended max rpm 5800. with about a 85% v.e. it goes to 499 cfm. is this right?

i read somewhere that the recommended carb for my crate motor was a 750 cfm holley. what am i doing wrong?

[68Formula]

1) Reality, an oversize carb can show hp gains on a dyno, but street response and lowspeed torque are a different matter. Oversizing the carb to get good max hp numbers is a good marketing tool.

2) With the efficiency of these heads and camshaft combintation a VE closer to 100% is possible.

A 600 - 670cfm would be a good street carb.

[TheRoaringEagle]

thanks for the suggestion! i was also wondering if you would recommend using a 4160 holley to start with. i've heard that holley's are not the best for the street, but i still would like to have an upgradeable carb, and i feel like holleys arethe best for that

[68Formula]

I'm not sure why someone would say a Holley carb is not a good street carburetor. Perhaps they mean a double-pumper and not a vacuum secondary? The Holley carburetors do tend to run a little rich out of the box, but like any carb this would be improved with proper tuning. I prefer the Holley for it's simplicity.

I'd recommend getting one with secondary jets rather than the "plates" if possible. In some cases I've lucked out with leaning only the primary jets was sufficient to improve the air/fuel ratio across the secondary open range as well, so changing the secondaries was not even necessary. But every engine is different.

Granted there are others that allow more tuning range (even offered by Holley) that allow changing the power valve restrictions and idle bleeds, etc., but for 98% of the applications the 4160 will give you enough tuning. Sometimes having too many knobs to change can get you into more trouble anyway. When you consider that some circuits will also affect (to a lesser decree) the calibration during different stages (idle, cruise, acceleration, WOT), there is enough to do already.

[TheRoaringEagle]

thanks for the suggestions and tips!! i want to start off with a 4160 and maybe later add the secondary metering block kit later when i get more comfortable with tuning

btw, is the metering block and metering plate the only difference btwn a 4160 and a 4150?

[68Formula]

Yes. The kit should include a longer transfer tube because the thickness of the metering block.

[PARKERRS]

I'm running a fast burn 385, and I used an Edelbrock AVS #1813. I had to lean the jets and rods according to thier chart by 8% and it runs great. I'm using 1 5/8" primary try-y headers with d-port flanges made by Stan's headers in Washington state. We made seven dyno pulls on it after setting up the carb and distributor and it was the most repeatable engine that I have ever saw. On the dyno it made 416HP and 440 ft. lbs. well over what GM rated it out of the crate.

[TheRoaringEagle]

parker, have you tried the hot cam kit?? i wonder how much hp that would put out!!

[PARKERRS]

No, but it's a thought I've had. I was really pleased at the extra output over what it was rated at and I just finished assembling the car about a week before the turkey run so I've only got about 100 miles on it. I thought I would run it a while and see how I like it in this configuration first.

[TheRoaringEagle]

btw parker, i am almost ready to install my 385 into my camaro, and i was wondering if you had any tips before i do so?

the engine is pretty much ready to run out of the box right? (less wires, carb, and other accesories for me)

thanks!

[PARKERRS]

I bought the turnkey package and had them swap the holley for an edelbrock. Bought it from Sallee Chevrolet on the west coast, they have an in-house dyno, so I had them uncrate it and do the break-in on the dyno so it wouldn't ruin the ceramic coat on my new headers. So when I recieved it the timing was already set along with jetting already in the ballpark (had to lean it one step because I used headers with smaller primaries than the dyno headers) even the choke and idle, fast idle had already been set. 6 pulls after break in run and all within less than 1/2 hp or 1/2 ft. lb., extremely repeatable engine. Final figures on dyno were 416 hp and 440 ft. lbs. it is making 400 ft. lbs. by 3000 rpm. So far I love this engine really grunts down low and is almost istantanious, can't wait to open it up after everything gets about 500 miles on it to seat in.
as far as tips it's just a straight forward small block install, the only thing that required extra attention was header selection. Be careful about your choice of headers, the d-port exhaust is the hang up. Some headers with 1 3/4 primaries or larger will actually hit below the machined sealing surface on the port and the headers will leak at the bottom of each port, others will only seal by about 1/8 of an inch(which wasn't acceptable to me) the best fit I found out of the box was Doug Thorley try-y's but the right collector didn't have sufficient clearance between it and the floorpan. I wound up having a set made by Stan's headers in washington state, they have 3/8 d-port flanges and 1 5/8 primaries which fit and seal perfectly, you just tell them you are using d-port lt-1 style heads.These are also a try-y design and have excellent ground clearance.Watch out on some of the 1 5/8 primary headers because the flanges squeeze the pipe and wind up covering part of the port.Also I suggest header gaskets for an lt-1.
In case you were wondering I bought and shipped everything across country to Georgia because it was cheaper than the local GM dealers would sell it, even after paying shipping, plus Sallee had the dyno service in-house.

[TheRoaringEagle]

hey am i going to have major issues if i use my non-d-port hedman hedders i used on my old camel hump heads on the fastburn heads? it looks like it won't seal very well, but will seal... i don't know, i overlooked my headers as an interchange part and used up my budget for other parts. could i do this for a few months?

also do you know by chance if 69 alt and ps brackets will work on this engine? i know it has the 69 style pump, but this engine has a timing cover that seems alot larger and i think it's in the way of one of the ps brackets that mount on the water pump?

thanks!

[PARKERRS]

Not sure about the brackets, I used the late model serp. belt set-up from GM. The headers are a call you will have to make, bolt them up using white grease or some type of marking material and see if they are going to seal and by how much. If you're comfortable with the margin go for it. Personally I wanted more than 1/8 in. of sealing area because I thought that would make for gasket burn out rather quick and I hate changing header gaskets. One good thing is there are alot better gaskets available now than there were back in the late 70's and early 80's when I started hot rodding. Back then about the only thing that would last was the metal gaskets made for cast iron manifolds that came in engine rebuild kits, they were'nt meant for headers but they were 10 times better than the old paper header gaskets. Several makers offer a metal and material composition gasket for headers now that seems to take this old school trick to heart, just look in the summit or jegs catalog under header gaskets.Also the copper gaskets use a crush area to seal and if your contact margin is'nt wide enough to crush this ring then your header will leak.

[TheRoaringEagle]

cool thanks for the info. i'm going to try and use these headers for now, but i might be able to afford new ones. i still havent dropped the engine in yet. just trying to get around to installing all the little items before i do so.

[PARKERRS]

Hope the info helped. Stay away from the Edelbrock it has presented problems that I am still trying to cure.

[Shaker455]

Eagle,
I can build you a custom Holley to fit you needs at a good price.

what are you using for a tranny?

[MonzaRacer]

I would actually prefer to run a slightly larger carb on that engine. If its a street car I would prefer a vacuum secondary carb, and my preference would be to look for an older 780CFM 3310 with the dropped boosters. I set up a straight ethanol carb a few years back and we had to swap out the straight leg booster body for the dog leg and it faired better. We had already put in screw in air bleeds and swapped in different metering plates made for alcohol and new floats. It ran pretty good but could have used more air flow. The alcohol jets from holley are flow rated for methanol so it tunes slightly wierd in my opinion,,but it runs better and not having to dope the fuel to abate corrosion is cool.
Good luck
Lee Abel

[TheRoaringEagle]

yeesh, i want to work with something simple. and i also want to learn how to adjust a carb. so i bought a new 4160 with vacuum secondaries and manual choke. i'm used to starting the ol' 400 with the edelbrock by pumping the gas. but i noticed on my new 385 fastburn 350sb and holley 750, it just floods it. if i push the throttle it'll just dump a bunch of gas in that barrel. i'm running it out of the box with no adjustments.

it started twice so far and ran rough. i check the vacuum hoses and such. still waiting for the carb to dry out. any suggestions?

i'm also wondering if my 20-50 oil is making it harder to start my car up right.

parkerprint, what oil did you use?

[Shaker455]

TheRoaringEagle,
I would be happy to advise you as to adjust your Holley.

Send me a email or a PM

[PARKERRS]

I went with 10w30 mobil1 synthetic after 500 miles.Finally straightened out the carb and tuned it and the ignition curve on a chassis dyno.Man that 700R4 eats more HP than I thought it would.Engine dyno showed 416hp, 440 tq, the chassis dyno has me at 305hp, 315tq, at the rear wheels.Next time I'm going with a Tremec for sure.

Tommy