Starving for air, thinking about Dual Quads

[davids2toys]

I presently have a single holley 850 dbl pumper, 428, in my Cobra. It went on a Dyno at a car show this weelkend and only made 288 to the rear wheels at 5300 rpm. I am thinking it is starving for air, it has a 9 inchx 2 3/4 inch air cleaner and the TURKEY pan. I called K+N and they said that filter was only flowing 470 cfm. the reason I am interested in a dual quad setup is two be able to run 2 air cleaners and double my cfm, also, if I have to get rid of the turkey pan which I love the look of, then the dual quads will also replace that WOW factor.
I was also told that the hood may also be contributing to a lack of air, I don't know if I agree with that though
Any help or advice would be appreciated...Thanks, Dave

[Aggressor]

I've always used dual carbs on my cars but I understand that a single is the performance setup for race/street. You can't beat duals for the wall-to-wall visual impact but they are a pain to setup. I dont think the hood is an air factor to worry about.

There are many owners very effectively running single carbs w/turkeypan and single air cleaners so I hope you gather some support information from them.

Question: Were your dyno pulls done with your odd timing?

- Geary

[davids2toys]

I've always used dual carbs on my cars but I understand that a single is the performance setup for race/street. You can't beat duals for the wall-to-wall visual impact but they are a pain to setup. I dont think the hood is an air factor to worry about.

There are many owners very effectively running single carbs w/turkeypan and single air cleaners so I hope you gather some support information from them.

Question: Were your dyno pulls done with your odd timing?

- Geary

Yes it was,
22 initial/ 18 mechanical...40 total
Still seems like the small air cleaner is not enough cfm for a big holley on a 428???

[eliminator]

I think you have other issues......not against dual quads but that is not going to solve the HP problem. There are single quad 750 cfms and Turkey Pans on 428's that will pull a 100 more HP at the rear wheel.

[JeepSnake]

Agreed - I think your primary problem lies elsewhere. Solve that timing first.

[davids2toys]

Yes, I would agree if other cars similarly set up are getting that much more. Are they running the standard restrictive sidepipe also?

[JeepSnake]

I don't know about similarly set up cars, but I'm with Rick on at least 100 hp being missing. My relatively mild (i.e. ported & valved factory heads) 351W dynoed 285 hp at the rear wheels through the factory sidepipes. So your 428 should be making plenty more...

[davids2toys]

I don't know about similarly set up cars, but I'm with Rick on at least 100 hp being missing. My relatively mild (i.e. ported & valved factory heads) 351W dynoed 285 hp at the rear wheels through the factory sidepipes. So your 428 should be making plenty more...

Agreed, what do you have for an air cleaner?

[JeepSnake]

I'm running a repro of the K-code 289 Hi-Po open element. Off the top of my head, I think the element dimensions are 14" outside diameter and 2 1/8" tall.

[Justin Upchurch]

A couple of years ago, one of the guys at our dyno day had the same air cleaner on his car with an FE. Pulling the air cleaner off only increased his output by 7HP, which put him right around 400 rwhp.
Did you check for WOT and if you are running 40 degrees total, this is too much.

Justin

[davids2toys]

I'm running a repro of the K-code 289 Hi-Po open element. Off the top of my head, I think the element dimensions are 14" outside diameter and 2 1/8" tall.

I went on Cobrarestorers and saw an long oval air cleaner set up,it said it was 2 3/4 high, I believe this would flow a whole bunch more than my 9 inch by 2 3/4 high round filter. Nobody was there when i called, i will have to try again. I hope it is a drop down so I will have clearance to the hood.
Anybody know?
I am also researching opening up the exhaust, I met another cobra in a show this weekend and he recommended LOBAK mufflers, the stock sidepipes are supposed to VERY restrictive.
I was actuaslly successful in tracking down the buisiness who built this motor in 93. He said my numbers were off, but not crazy off, Also said that I was losing a lot thru the stock sidepipes and the tiny air cleaner/ turkey pan setup.
My motor was not a radical build, a lot of midrange and very drivable, the previous owner want his wife to be able to drive it regularly!!!

Also, was not overly concerned with the timing, he said to just back off the total 2 deg at a time and see if I like it better. It was 40 total at about 3500 rpm

[RJacobsen]

The oval air cleaners were used with dual quads and 3- 2's on early T-birds, galaxies, fairlanes, and Ford and Shelby (Mustang) over the counter set ups. I have one on my 289 with dual quads and clearance is an issue for me, it just fits below the hood opening on the body and just clears the distributor cap on the engine. I don't think they were ever used on original Cobras for this reason. But it might be worth a try.

[Brent]

Everyone is dead on with their suggestions on timing etc.

I think you may be over-carbed as well. Your motor is basically stock other than a mild camshaft. Pistons being forged, heavy rods, stock heads, etc. It has good quality Ford factory parts that will last but not really a high performance minded build. I would get your timing in line then drop back off to a slightly smaller carb. Ricks motor has a lot more mods and parts than yours and only runs a 3310 750 Holley. My FE was 12.5-1, stage 3 aluminum heads, 651 lift solid camshaft, all MSD, billet rockers, etc. and it only required a 750 Mighty Demon.
Just a thought. 90% of street cars are over carbed. I am sure someone has one you could try before you buy one. Take it with you to the dyno and try both.

As the pic shows, I had the same turkeypan and filter as you do

Have fun,

[davids2toys]

Everyone is dead on with their suggestions on timing etc.

I think you may be over-carbed as well. Your motor is basically stock other than a mild camshaft. Pistons being forged, heavy rods, stock heads, etc. It has good quality Ford factory parts that will last but not really a high performance minded build. I would get your timing in line then drop back off to a slightly smaller carb. Ricks motor has a lot more mods and parts than yours and only runs a 3310 750 Holley. My FE was 12.5-1, stage 3 aluminum heads, 651 lift solid camshaft, all MSD, billet rockers, etc. and it only required a 750 Mighty Demon.
Just a thought. 90% of street cars are over carbed. I am sure someone has one you could try before you buy one. Take it with you to the dyno and try both.

As the pic shows, I had the same turkeypan and filter as you do

Have fun,

I agree with you completely, I dont even know how I determined it was a souped up 850, I forgot, it was over a year ago. I remember I could not find numbers on this carb at all, a coulpe of carb savvy peaple made that determination on physical size comparison alone.
Your motor looks great, but I think it would be sake to say that you are starving for air also, that air clearner is mighty small, my 9 inch x 2 3/4 inch is only flowing 470 cfm, your looks the same or even a little smaller.
Are you running any kind of special high flow exhaust with your setup, I am looking into RPM LoBAKs at the moment!

[Brent]

Dave I'm sure a large, round, drop base, circle track style air cleaner like the Weavers run on their Ernie Elliott motor would have been an improvement. I actually have that air cleaner on my 408" Windsor that is going in the Mustang. But you know I doubt it would have made more than a 5-15hp difference. Not really a seat of the pants improvement.

I had the stock Unique headers with the free flowing side pipes.

If you want a picture of that air cleaner click the lower of the two cardomain links below and scroll down.

Good luck!

[davids2toys]

Dave I'm sure a large, round, drop base, circle track style air cleaner like the Weavers run on their Ernie Elliott motor would have been an improvement. I actually have that air cleaner on my 408" Windsor that is going in the Mustang. But you know I doubt it would have made more than a 5-15hp difference. Not really a seat of the pants improvement.

I had the stock Unique headers with the free flowing side pipes.

If you want a picture of that air cleaner click the lower of the two cardomain links below and scroll down.

Good luck!

I Don't see the link you are refering to, yeah I know 14 inch drop down would be a much needed improvement, but no WOW factor at all!
My carb is an 850 Holley DP with center annullar squirters.
Tried it with NO air cleaner tonight, no real improvement to speak of!
Next, I will back off timing a little bit at a time and see what happens.
When you say Unique free flowing exhaust, are you talking about a sidepipe with a louvered baffle running up the middle of the muffled section, I have heard from just about everyone that these are very restrictive, unless yours are different than mine.
I tried to attach some pics, but it won't let me upload because I have already posted them to other threads at another time, what is up with that??? It was a pic of my carb/ air cleaner setup and 2 shots of my sidepipes.
I measured my primary tubes, real close to 2 inches. I have been told that is good because it is a light car

[davids2toys]

changed the name on the pics, see if this works?
NOPE, same message
Here is a link for sidepipes
http://www.uniquecobra.com/forums/showthread.php?t=7336

Here is one for carb setup
http://www.uniquecobra.com/forums/showthread.php?t=7383

[JeepSnake]

You know, I've been looking at the numbers posted about carb flow and filter flow, but there's one MAJOR piece of info missing: pressure drop.

When Holley says their carb flows 850 cfm, at what pressure differential does that occur? 10 inches of vacuum across the carb? 18 inches?

Same with K&N?

Is there an SAE or other industry standard on differential pressure that flows for carbs/throttle bodies/filters are measured at???

[Brent]

Zach,

I think you already know the answer to this! i have read all of your posts and I am SURE this is a loaded question (-: with your knowledge.

The CFM is based on all 4 barrels with a depression of 1.5" of mercury. 3.0" on a 2 barrel carb. The X factor on carb size is the VE (volumetric efficiency) for the given engine. Most carb suggestion software is based on 100% VE. BUT, a stock motor is only around 80%, a slightly modded engine is around 90-92%, a comp motor with properely matched components and a proper tune is around 95-97% and a blower/turbo motor with forced induction could be 110-120%. The kicker is an engine with serious mods, but without a proper tune, could still only be around 80% VE. This means you could have two identical motors, the one with a proper tune may need 850 cfm and it's counter part with a bad tune only needs 680 cfm.