I always degree the cam in right where the sheet says to. Without a dyno you are just shooting in the dark. I'd try to find out where it is in at & call the cam mfgr and see what they have to say about what was done.

 

I recurved the distributor my self and it did run different and the total advance came in a little earlier but not a lot sooner and it lost all hope for ever performing. I took the stocker out of my 429 and it ran a lot better with that one. The engine builder told me that this engine shouldn't ever float the valves because his superior enging building capabilities would allow him to perfectly match the valves, springs, cam, rockers, pushrods and lifters. It floats the valves at a lower rpm than a stocker I think!! As for the info you listed, that is nowhere to be found, but it might have gotten lost over the years along with my valve covers, my oil pan, and aboput 300 of my horsepower. I don't see how the engine will ever work right if the cam needs 5800rpm to make it's power band and this engine floats the valves at I think less than that. It is a good engine because I have been trying to blow it up since I got it and I think it has lost some low end power and maybe now makes some blowby, it still runs after 500 miles of over heating, floating the valves, and starting it cold and rodding the hell out of it, I was hoping it would blow up and I could take it back to the builder with a court order and say fix it or give me some money back. I don't seem to be that lucky though. if the rockers cost me some performance, then what kind of rockers do they make for a 460 that are good? Anything or nothing. They are comp rockers, and should be for a performance upgrade, not a downgrade.

 

The cam manufacturer won't say anything that is of any help. They said to put 35* total time on the engine before 3000rpm and that hurt what little power I have then they said the compression should be 180 psi. That seems outragious to me and the only other thing they said was that they couldn't give any advice on the engine because every engine is different. Some help they are, I'll not buy any more comp products with that kind of customer support.

 

Here's my SWAG....

1. Especially for a BB, that cam is pretty weak
2. With a power band of 5800, the oem valve springs shimmed by 1/16" can handle that rpm- so valve float, not even an issue
3. Comp is not a cam company that I would personally recommend for a variety of reasons- I suspect Comp uses Chinese cam billets and I suspect they do not Parkerize their cams (a chemical hardening process) and between these two items and the reduction of ZDDP, I suspect is a substantial cause of premature cam lobe failures.
4. The cam was either ground wrong, or mis-marked; or the cam/crank timing is incorrect as a result of lobe centers, etc.

With regards to the cam spec's,

I would start with the specific specs on the cam and verify it is all correct (opening/closing sequence, etc.) If it's not, pull it and see if you can get your $ back for the cam- I would recommend looking at Iskenderian & speaking with them by phone- they are still family owned and are the only cam company I know that still checks each valve spring before it leaves the shop- IIRR they also only use North American made cam billets!!!!!

With regards to the cam spec's; BB love a lot of lift- IMHO, because you want a relatively nice idle, need tq starting at 1500 or so rpm and you operate in high altitude, I would be looking in the 280-290 duration range with a lift pushing .600 if I could get that. Isky & Crower both are excellent cam grinders and pending lobe concentric center and valve timing requirements and existing valve spring spec's, I'll bet that they either have a cam that will work or will modify one for you (which both are very able & willing to do!) Especially with hydraulics, they are very forgiving with regards to idle quality andeven if it could become a potential issue, Rhodes & Crower both make "bleed-down hydraulic lifters"- basically you can run a very high (.600+ lift) cam and at low rpm the lifters bleeb oil through a bypass, reducing the actual lift, making for a "better idle" and increased vacume- then when you hit around 2000 rpm+ the bleeders close, you have full cam lift! Rhodes are a little noisey but Crowers are very quiet- FYI (though it has been a while since I have played with these so Rhodes might have modified their design!

 

You may be dancing all around a big cause of your lack of power and that is the timing curve. You mentioned that you started at 14 deg on the crank, but that has absolutely nothing to do with the curve. That is only for cranking. Also you said that when you advanced the crank timing until it was dragging, you picked up some power. That tells me that you are not getting enough low rpm power to start with.

Because of the cam and compression, I cant say what the curve just after cranking should be, but it should immediately go to ~30 deg, maybe more. Most folks dont understand that the curve must be taylored to the engine and be able to lose some timing (or not continue to advance) in the higher rpm ranges. I'm guessing on your combination, but the power timing curve under load probably should not go over ~35-38 degrees. The no load timing curve can be considerably more than that. What this means (my .02) is that the distributor should be custom tuned for your engine. If you are going to drive it on the street as a driver, then you will need to figure in the vacuum advance for for economy driving. All variable. Anyway, my .02 LOL

 

Warhorse,

To really figure out what the problem is, you need to pull the engine, pull the heads and degree the cam in. With the heads off, you can also confirm if the block was zero decked, where the top of the piston is level with the top of the block at top dead center. When you put the heads back on, check the pushrod length. You can calculate your compression ratio by the bore, stroke, volume of the dish in your pistons, the volume of the combustion chanber, the diameter & thickness of your head gasket.

460's make good torque and horsepower but it is under 6,000 rpm. The cam that you have in the engine is good to 5,800 per the specs on the Comp Cam site so it's going to be making less power at 6,000 rpm. I built a 545 stroker with a cam that has less duration & lift but the same power range, 10 to 1 compression, John Kasse super cobra jet head (basically same size valves), Edlebrock's RPM Air Gap dual plane intake with a Holley 750 double pumper. It dyno'd 500 hp at 5.000 rpm and had 600+ foot pounds of torque from 2,000 thru 4,500 rpm.

Plus that machinist doesn't know what he is talking about suggesting a 1,000 cfm carb. If you look at the formula for selecting carbs, a 750 is more than enough carb for a 460.

I know that once you figure out what the machinist screwed up, you will be happy with your engine.

 

I think it will be a pretty impressive engine if i get it built right. I have rode in 460 trucks that really impressed me, and that is why I built one. I will tear it down when i have time. I did some more jetting on the carburetor tonight and it picked up some more power and rpm, now that the engine has some miles on it. f350 strait, your build seems to be pretty good, that is about like something that I would want to do. I would rather use the 460 crank if possible, though. I don't have time now to fix this, so I will try to keep miles off of it till I can get it fixed. thanks for the help so far and I hope everyone had a good thanksgiving. Keep the advice coming I will start looking for parts soon.

 

Did you go larger or smaller?

I wonder if he machined the spring pockets to accept taller springs for taller valves and not set the proper installed-height. Did he install taller valves?

When you are able to check the engine parts, make sure you check the block height of each cylinder, there can be slanted cylinder block decks and slanted cylinder head decks which can also alter compression cylinder to cylinder. I agree with Beechkid, check out Isky for the valve train. Isky has quite a few articles on the website for some good reading.

The factory 460 crankshafts will handle your power output goal easily. Just minimize the oil coming in contact with the crankshaft during operation like any other engine. A windage tray will make you a little more happier while unlocking the power as you go

 

Maybe the cam wasn't degreed and you have the timing at 14 degrees advanced but the distributor is set for 0 degrees.
The cam could be set a tooth or two off also. That would really screw it up.

 

you will never make 500hp with a small cam like that plus you have a huge carb on it which requires a bigger camshaft. you might want to look into the 700cfm Holley carbs (preferably a 4160 series). If I remember correctly you said you had a 850cfm edelbrock?

 

Warhorse, I came across this thread while doing some research for a 460 build for my Bronco. I joined this site, just so I could post something that you may be overlooking. Ditch that POS edelbrock and beg borrow or steal a 750 holley DP mechanical secondary. I have ran around in circles trying to chase down the same kind of problem on a buddy's built 400 sbc. It had a basically new edelbrock 750 and ran like a dog. I have never had any luck at all with carter/edelbrock carbs. Worth a shot.
And BB429power your an idiot. Why would he change his gears just cause the cam catalog says 3.55-3.90. These are minimums, and a guideline. Tire size also comes into play, esp. on a truck.
HERE'S YOUR SIGN..........

 

The here's your sign thing was just a joke, and I was just trying to come up with anything to help. I've had a lot of experience with the wrong gear ratio and too big of carburetors. I know tire size changes it and that they are guidelines, but if I recall and I qoute, you said "minimums". I wasn't trying to be a dick like you are. I'm the nicest person you'll ever meet until you **** me off. Oh, and the reason your buddies 400 sbc ran like a dog is because its a crappy chevy. Doesn't even take an idiot to figure that out. Before I forget, nice criminal record by the way. telling someone to steal a carburetor. Pathetic.

 

It sounds like too many unknowns with your build. First of all, what do you want from this ~5K# truck? HP and moving this truck have very little to do with each other---except when you get the rpm up to where these ported, big valve heads work. No one here can tell you whats wrong except generally, because its not clear what you want or how this engine was built.

Plenty of knowledgeable people on here (not me, but I know some about 460's). Tell them what the deck ht is, what is the clearance volume, how was the cam installed (0-+4-+8 or minus---). The timing advance is important, but can vary, due to cam and compression. What you set on the initial (as I said previously) has nothing (maybe very little) to do with "timing" curve. Set the initial so that the engine does not drag the starter, set the rest of the curve up at the distributor. With this engine, 35deg may be a good loaded, power total, but is not the best for no-load cruising or driving. If you are going to be at 4K + rpm with your foot to the floor all day long, leave it there, otherwise, fix it, you are going to have to experiment. Problem with diagnosing someone elses build, is people dont know all the little details that are important----(you sure the dist was set in correctly ,on the right tooth, for example.)

Some new, one time poster is on here calling others "idiot", then he says go for a "double pumper", "mechanical secondary". He is right, there may be an "idiot" here somewhere! Not just no, but hell no on the DP w/mech secondary-----A vacuum secondary carb works very well for an all around heavy vehicle. You do have to be smart enough to set them up----or find someone who has. If you want a track only race truck, then thats O.K. but if you will have to drive it on the street, forget the big HP numbers----big TQ numbers are far more important.

I built a 429 CJ motor (big heads, valves) OEM 70 CJ cam and made a 10 to one 460 out of it---what a waste on the street. Same problem with the 4/2 bbl cleveland heads. Big is not always good for street. Heavy certainly isnt good either.

Anyway, best of luck I hope you can get this thing straightened out----.02

 

Unless he has larger than 35" tires on his rig, forget about gears. An of course I was being totally literal and condoning theft
As for the mech. secondary holley, I wasn't recommending it for your application. More as a tool to bolt on and see if you found your lost horsepower. Then you would know if you have a carburation issue, hence the "saying" beg, borrow, or steal one. The holley is just the easiest to throw on and will work, esp. at WOT. I too am trying to HELP, sorry if I came across as a dick, just as your Here's your sign joke. As for the Cheby being a POS, that is such a typical Henry F **** licker response. All manufacturers have bad designs and good one's too, inc FORD. Thanks. Truse?

 

I was just trying to get back at you. Plus I remembered that the higher gear ratio actually would have helped it. Truse