![]() |
|
|
|
||||
|
454 chevy, think i might have too much cam
Got an elgin cam for a 454 but think now it might be too much, the motor is .030 over, kb hyper pistons, 9:1 comp, 781 heads 2.19/1.88 valves, single plane intake, holley hp 830 carb, flowtech longtubes, the cam is hydraulic flat tappet,specs are Lift: .528/.552 Duration: 302/308 Duration @ .050": 224/234 Lobe Separation: 114 LC Lopey idle, wild street/strip.
Im feeling like it has way too much duration and wont come alive until somewhere in the 3000rpm range, need something that would come to life between 2000~2500, and will have to be another elgin so it can be exchanged. Is this one fine or should i get something else? |
|
||||||
|
That's a big cam especially for a street engine with cast pistons in it, the combo is a bit mismatched for durability and driveability...but that all depends on what your vehicle is...how much it weighs...how much gear and what kind of trans your going to run particularly if your going auto because your going to need a decent stall to get it out of the hole.
Lots of ifs in that paragraph...in other words more info needed...but for a big block that's going to be turning above 4K all the time just to stay above stall speed with an auto your going to need better reciprocating parts than just cast pistons at 9:1 to get durability. If your looking for a hp/cube you don't need that cam, 290@0.050 is plenty.
__________________
Outlawed tunes from outlawed pipes |
|
|||||
|
Quote:
this cam is 302/308 advertised duration, and 224/234 duration at .050 right, i know it can't be 302/308 @ .050 as that would be way too much. but i dont see how 224/234 @ .050 in a decent sized cube 454 would be too much for the street. i deal more with small blocks, not as good with big blocks but i certainly wouldnt think that duration is too much. now i dont like the advertised duration, but that is my opinion. the cam you have is E1070 advertised duration 302/308, 224/234 duration at .050, .528/.552" with a 114LSA. this is not a racing cam, more of a nice street cam. it looks like it is an old design but still a strong street cam. i didn't read the original post that well to notice the single plane intake, i think that you would be much better off with a dual plane intake. i still say that the cam you have is just fine. i'm not sure what 4 Jaw Chuck is talking about unless he mixed up his durations. i know he is knowlegeble as he is one of the forum moderators |
|
|||||
|
with your cam leaving the valves open longer { 300 deg duration} you loose a bit of vacuum and low rpm air speed torque, but by buying a dual plane intake like a rpm air gap or even the rpm dual plane manifold, this will help increase low rpm air speed which will make a crisper throttle and more torque at low rpms and help keep higher vacuum for any power accessories.. your cam and carb are fine, you just have the wrong intake... A single plane intake does not start making power until above 3500-4500 rpm depending on aplication, reason is a single plane manifold is more open and creates better air speed in the manifold at higher rpms because of it being more open , so a relative stock motor will be very sluggish at rpms below 3500 which in most cases is is cusing rpm.. Now if you buy a dual plane manifold and want a little bit more mid to top end, buy a one inch carb spacer and that will move the power band up a bit which in most cases is the choice that most will go to, but its a trail and error situation...
hope this helps Jon |
|
||||
|
Ordinarily, I don't post on big block questions. But, I personally think the duration is fine. The KBs at 9:1 are fine, if that's the calc'd ratio, not just what the piston catalog said. The LCA at 114, I think, is in your favor. I also think the carb will likely be okay. I do agree that the long advertised duration is a bit of an issue, but it indicates slow ramp rates, which should help to keep your cam alive a little longer in this world of "poor" motor oils. I also agree that the single plane intake will negatively impact your overall power curve. An RPM air gap would work better unless you'll be driving in a cold climate, in which case I'd use a regular RPM Performer type intake. Lastly. . . You cannot be too careful with the ring gaps. Follow the KB instructions TO THE LETTER, and you should be okay.
PatM |
|
|||||
|
what gear and stall?
intake is wrong. You need a dual plane. I would use a regular RPM intake, Not air gap (due to slow warm ups). Your cam would work best with a 3.40+ gear and some extra stall. I would run 20 degrees of timing at idle and 40 total with that cam, heads, pistons, and compression. Then get and adjustable vacuum advance canister and set it to add 10 degrees more and use manifold vacuum. So it will idle at 30 and go to 50 degrees under no load (high vacuum, and higher rpms). Idle it at 1000 rpms then set the idle a/f mixture screws for the highest idle which would also be the highest vacuum. I like the lazy lobe ramps on a 454, as BBC tend to eat cams and todays oils don't help flat cams live a long life. I think if you use the timing listed above, you will see a big difference. And it doesn't cost anything. Later, swap the intake. Finally, a cam like this will need headers. |
|
||||||
|
the way you listed the specs is hard to read
Duration @ .050": 224/234 is this correct? if so, I think you are ok it should be fine I would switch intake to an Eddy RPM the rest looks good to me |
|
|
| Recent Engine posts with photos |
| Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
| Thread Tools | |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| 153 tooth Chevy flywheel in an original '55 Chevy 3 speed stick. | Classic Chevy Dave | Engine | 2 | 09-17-2010 03:44 PM |
| newer chevy distributer in older chevy car,what are these four plugs? | gearjammer38 | Electrical | 11 | 08-09-2010 10:15 AM |
| Putting a 72' chevy 350 into 1995 chevy silverado that has a 4l80e trans | Willbee26 | Transmission - Rearend | 3 | 03-28-2010 10:40 PM |
| Can you use a 1933 or 1935 Chevy transmission in a 1934 Chevy? | mistermuscles | Transmission - Rearend | 0 | 07-18-2004 05:40 PM |
| 1986 305 chevy vs. 1987 305 chevy new style small block | mtinsley | Engine | 2 | 08-22-2003 11:55 AM |