Genesis 427 S/O- Should I be Pleased?

[Anthony]

[quote]Originally posted by CSX 4027

Originally posted by Anthony


[ I may not call it an all out racing cam, but it is more radical than probably anything ever offered by any the OEM's in the sixties, including the Ford 427's, hemi's, L88's.

Anthony,
The original 427 C3 AA Cobra Cam was in fact more duration than the Comp Cam in this thread. It was advertised at 306. The comp is advertised at 294. That's a difference right there and remember the Cobra's made about 480hp back then.

From what I remember, alot of the "factory" cams had a large advertised duration, but the duration @.050" was relatively short for the given advertised duration compared to afetrmarket cam specs, as the factory cams seemed to have a more gradual ramp. I'm curious, I'll have to see if I can find out the factory cam spec adv duration vs. duration @ .050" which, from my reading is a more reliable indicator of a how radical a cam is. So even though the comp cam is listed at only 294 duration, it wouldn't surprise me if the duration @.050" is actually larger.

[What'saCobra?]

Lots of good ideas and comments on this thread.

Perhaps the best advice above is to live with the engine for a while and see how you like it. It surely has lots of torque and must give a nice kick in the pants from that many cubies. Rick is likely correct that the car is quicker than you are, so a little on-the-job training might be in order anyway. Most guys lose it in the first 30 days, if they are going to do it and it is frequently at large throttle openings.

Unless you either have a minimum HP guarantee opportunity or a ready $4-5K, i would wait before making too much of those numbers. Drive it a while. There is a lot to be said about torque and keeping the parts together.

But, i would expect that the heads/manifold combo is the biggest oppportunity for improvement, along with the street muffler. Likely you don't have documented head flow numbers on your particular set of heads, because they would probably not look so good, unless the heads were seriously CNC'd, rather than just a clean-up. We all tend to under-report less than glowing numbers. There would have been no reason to flow test stock or near-stock heads. It takes time and money that is only of value if you are either developing something new or the builder is required by contract to verify head flow pre assembly. Otherwise, simple inspection and careful assembly will be sufficient for most builders for any known 'stock' combinations.

You might consider asking the builder what he would suggest. But, there is nothing really wrong with what you got for the money, since the street mufflers are good for 30 hp loss or so, pretty easily and 500hp isn't terrible at all.

i wouldn't jump all over the cam thing, unless i was satisfied that the heads/manifold combo was optimized for those cubes, which isn't particularly likely.

The open plenum/sinble plane manifold comment above is quite valid, but it will not be easy to get that 3310 to meter correctly at the low velocity rates of low rpm and large open throttle combinations with the bigger plenum. With that many cubes, low fuel flow from an old carb design with cause lots of carb spitting and even backfires. Very exciting and might necessitate fire protection under the hood.

Steve is correct that you might move up to an 850 pretty easily with all those cubes, but again, geting a larger 3310 to flow correctly will be harder than the 750.

i simply cannot overstress the excellence of new carb designs and their utility at wide-open-throttle and low rpms, particularly Holley's HP series. The old designs require huge accellerator pump systems to make up for lousy metering sensitivity at low airflow velocities. It is a drivability problem, not a horsepower problem. Once there is enough rpm, and enough flow velocity, the old systems work fine and dandy.

Stay away from 7000rpm like the bubonic plague, though. Short shift, particularly in the bottom two cogs, to avoid errors, particularly if your tranny is new and/or you are not currently high-seat-time qualified...

Break it in, not up.

And please don't put one of those puny small air cleaners in a turkey pan. Skip that pan expense and hp loss. Only turkeys belong in turkey pans, that's why they are so called. Screw style. Go for power.

Here is a suggested filter combo. It is 3" gasket to gasket and a minimum size for this 351. You should consider 4". Yes, there is a little fiddle (dremel tool cutting) necessary to clear the MSD distributor, which distributor i also consider nearly mandatory on anything decent. You could consider the K&N top filter cover, if you can't get 4" under your hood (i can't quite either), but it ain't cheap and only a dyno test would tell if it is worth the money on your engine.

In summary, bigger is much better. Look at the filter assembly under the hood of any NASCAR 358 incher. Huge and then some. OK, 8500 rpm is different than 6500 rpm, but you have 100 more inches to feed.

Anyway, good luck.

[cbmax]

Thanks for all the great advice.

I think I will look into the newer HP series carb and keep it at that for a while.

Dumb newbie question.....

The HP series 4150 Holley Carbs have no choke.

Can someone please explain if this is an issue for a street car not driven as a daily driver.

Thanks again.

PS will avoid the original air cleaner as well.

[DonC]

No chokes aren't a problem. I pump mine 4 times when starting cold and then just keep the rpm's at about 12-14 hundred for the first 3 or 4 minutes of idle. After that there may be a little stumbling down low until I start to show water temp but nothing extraordinary.
Just takes some minor getting used to.
DonC

[What'saCobra?]

PS:
i thought you might like to see how smooth the intake curves are on the Holley HP series. This is a dual pumper, mechanical secondaries piece that works and has worked perfect out of the box.

Note no choke, no vacuume secondaries, no vacuume on the distributor and it is just fine and dandy. OK, when i start it in cool weather, i use the accellerator pumps a bit, but it stabilizes within a minute or so.

[REDSC400]

CBmax:
Joe at DCE built the engine in my ERA back in 1992. It is a nice 428, does not leak oil, and is dependable as the day is long. It starts first time every time and is a wonderful mill that produces alot of torque in a linear manner. We have about 17,000 miles on the engine over 12 seasons of use.

During that long period of time, one thing is pretty much evident to me regarding HP ratings and such, especially with how I use the ERA.... pretty much cruising.

In the mode of cruising in the Northeast with our bendy roads, you will NOT be spending too much time above 4800 RPM in any gear for very long. So I would scrutinize your HP ratings and torque curves in the 2800 to 4800 range. That is where you will pretty much be living.

Those numbers sound like good numbers on your engine. Hopefully it will be a real torque monster with a near flat line torque curve.

BTW, your choice of carburetor, air filter and cold air box or turkey pan will change your HP at the rear wheels.

As an aside, this spring I switched my 12 year old Holly 850 Double Pumper with mechanical secondaries out for a new Barry Grant Mighty Demon 750 double pumper with mechanical secondaries. After 12 years the old Holly was getting old and needed a rebuild. The new Demon is just super and much more responsive.

[Anthony]

Originally posted by What'saCobra?



Perhaps the best advice above is to live with the engine for a while and see how you like it. It surely has lots of torque and must give a nice kick in the pants from that many cubies.

But, i would expect that the heads/manifold combo is the biggest oppportunity for improvement, along with the street muffler.

You might consider asking the builder what he would suggest.

i wouldn't jump all over the cam thing, unless i was satisfied that the heads/manifold combo was optimized for those cubes, which isn't particularly likely.

I agree with Whatsa. It's not the cam. It may be a combination of the intake/heads/exhaust to be the limiting factor, and possibly the builder has very conservative dyno numbers as well, which makes the hp seem low.

[Excaliber]

Thoughts on cam "profiling":
In the "Engine Masters" competition the motors are judged on h.p. and torque from the 2500 rpm to max rpm range. In other words, "real world" conditions. Andy Dunn, "The Butcher" made an interesting comment concerning camshaft design. He found that more significant than the typical "Lift" and "Duration" numbers was the accelleration ramp of the cam lobe. How FAST it could open the valve. A measurment rarely if ever reported.

It's note worthy that AFR has taken a similiar approach to their awesome heads, among the best available today. They design for "over all" performance, not getting hung up on "peak flow" numbers. Twisted Wedge heads, for instance, flow more peak cfm than AFR. But dyno results show a very modest gain in h.p. at high rpm over the AFR heads. AFR builds h.p. quicker and more evenly through out the rpm range.

I went with the 282S cam on my 427, my shift point is "down" from 6500 to 6000 with this more "mild" cam than my old roller solid. But the motor "feels" as strong or stronger, particularly more bottem end torque. Drag strip numbers are, surprisingly, very close to what I was running before! Gessford calculated I "gave up" about a 150 horse with the lower compression and smaller cam (was 667 horse). All I know is: The car FEELS like it's faster than ever!!

[REDSC400]

Originally posted by DonC


No chokes aren't a problem. I pump mine 4 times when starting cold and then just keep the rpm's at about 12-14 hundred for the first 3 or 4 minutes of idle. After that there may be a little stumbling down low until I start to show water temp but nothing extraordinary.
Just takes some minor getting used to.
DonC

I agree with Don. In my opinion, automatic chokes and big horsepower engines should not be under the same hood. You do not want excess fuel washing your cylinder walls when the engine is cold. This is especailly true with forged pistons. It's kind of fun using the footpedal to temper the whole she-bang.

[cbmax]

Okay I took a ride up to Danbury Competition Engines today.

I obtained some additional details.

Intake is actually a Blue Thunder Dual Plane. ERA likes this intake as it eliminates clearance issues with the air cleaner.

As for the Holley Carb, Joe strongly believes a vacum secondary is better for the street. I am going to stick with this for now and decide if I need to change after I have the car a while.

As for the Comp Cam, 33-246-4 is the part #.

Specs for cam installed @ 106.0 intake Center line

Intake Exhaust
Duration @ .050 248 248
Lobe Lift .3500 .3500
Lobe Separation 110.0

Motor made 460 ft lbs of torque and 470 HP at 5800 RPM's. Motor kept pulling up to 6200 RPMS at which point it was shut down.

I took photos, but it seems they are too large to post. I do not know how to compress them. Also triesd unsuccessfully to link them up to a website (snapfish).

Thanks again for everyones input!

CB

[What'saCobra?]

EX
Very interesting experiment you pulled. And i agree with what you found.

All the more evidence that this engine should be driven about a bit and 'felt' some before spending too much moolah.

[CSX 4027]

The vac sec carb is not terrible for the street if it is set right. The most common problem is in the weight of the coil spring that opens the back 2 barrels. Unless they are right, you can have a situation where the car gets scary when floored at cruise speed. Kind of like a turbo boost out of nowhere. I origianlly had one in 4027. I opted out.
The Blue thunder is a good piece.
The hp/tq is not terrible but, is just more typical of the standard cube 427.
You'll have fun and probably won't even use all there is anyway. Most don't and can't on the street unless you have a get out of jail free card.

[DuckRyder]

I am not a comp cams fan, and Id stick a Crower solid roller in it in a minute for more "area under the curve" so to speak, BUT:

I would not change a thing until I got it in the car and broke it in then the next money I spent would probably be for a day on the chassis dynamometer. If it churned out 470 HP on its first and only pull, it may very well have your 500HP in it with a bit of tuning.

I imagine 460ftlbs will really get your attention in a car as light as a Cobra too.

The Blue Thunder is an EXCELLENT piece; it is arguably the best manifold out there for a street FE. The 3310 is not as bad as it is being made out to be either, and you can convert it to a secondary metering block with replaceable jets if you find it helpful in the tuning.

JMHO

[DAVID GAGNARD]

CB;

I'm pretty sure it was Hal that "found" 30 to 40 hp on a chassis dyno with some tuning on his vac sec. carb,just changing out springs........ I have run a vac. sec. Holley for 7 or 8 years and once I got it "tuned" to my engine it ran great,then I was given an old (20+year old) holley double pumper,I rebuilt it myself and jetted it to my motor and love it,do not think I'll run another vac. sec. carb again...................BTW; it works great on the street and contrary to what I was told by many people,my gas mileage stayed the same,if I drove it the same,with your foot in it,the double pumper will burn more gas,but for cruising,gas mileage was NO different and I found the double pumper easier to tune...........Run what you got,but if you could borrow a 750 double pumper to try for a weekend,do it and compare,then decide what's best for your needs....................

David

[Excaliber]

eh eh,,, I was running Holley double pumpers and didn't like them that much. Switched to vacuum secondaries and like it much better! Smoother application of power for me. I just have a hard time controlling that right foot deep throttly application.

[rblong]

You guys are WAY PAST Me in motor experience, but as a close to one year driver of a cobra with about 50 less HP and torque I can tell you that any newbie better respect the shortnes of these cars. You just don't go rompin on one of these like a regular musle car. I will probably go for some more motor, maybe even another car with a hotter motor, but I am probably lucky I did not have it starting out.

As far as a choke - I put one on my speed demon and only had to use it this last winter - not to get the car to start, but I got tired of sitting in it and jacking with the throttle till it was warm.

[ToyCollector]

cbmax, my cam specs are not that far off from yours and I built the motor SPECIFICALLY for torque, not HP. You should be frightened with excitement keeping it on the road if all is well once it is installed.

[decooney]

CB,
Eh' get the Holley HP.

I ran the exact same 3310 carb and 282S cam; Same compression as you too on my last car. Good by not great. You will like the new HP carb with a little more CFM better on your FE the way its set up. I run the Holley 830cfm HP now. Works great with some moderate jetting and Power valve changes. Email me if you need help on what I ended up with. Get some break-in time as others have suggested and see what you think. Make sure you don't have one of those dinky stellings air cleaners on there. Odds are the HP carb and a good filter setup is your next purchase.

[Enginetime]

Hello,
We've talked before about your Genesis. I have the same engine block running a scat stroker (to 452 cu in), 10.8:1 comp., Diamond racing pistons, 750 cfm demon carb. 633 lift cam, Edlebrok Alum heads opened up to 80cc's. Dynos over 500hp. You should be able to get 500hp and have a streetable engine with a Genesis block with no problems. Joe is very good so perhaps you wanted a milder street version engine?
Mark

[flipper35]

Ernie, the lifter bore determines the ramp speed on a non-roller cam. Chevy has a .842" bore and Ford has a .875" bore. The larger the bore, the faster the rate of lift you can grind into the cam. Some cam companies will do a generic grind to the lowest common denominator (Chevy) and apply that grind to the whole line. Some now are grinding brand specific ramp speeds to take advantage of the differences. You also get a better idle for the same "duration".