[Troy Boswell]

All-righty then! I've got all my parts together and its time to put the old 460 back together. If I choose to advance the cam to the +4* position, what would I gain? The torque would come in sooner and power would fall off quicker yes? Just wondering if I really want to do that or not. Since it's in my car I doubt I install it advanced. If the motor never saw the high side of 4000 why wouldn't a person advance the cam? I would think a "truck" type motor would really benefit from it.
I believe I've already answered my question, but I'm just curious to get other's points of view and experiences. Thanks.
Bozz

 

[Mach1Morgan]

What cam are you using and what's the rest of your combination? Depending on your combination sometimes advancing a cam will you more power everywhere in the powerband, even on top end. This is especially the case if you're using a big single pattern cam on an engine that has heads with poor exhaust flow tendencies but has good intake ports.... the thing most big block Fords suffer from. A few years back I was running a big Crower hydraulic cam on a 429CJ. I picked up 70 ft/lbs of torque at 3000 RPM and 4 horsepower at 6600 RPM just by advancing the cam 8 degrees. Needless to say it was like an intirely different engine after that change.

<font size=-1>[ This Message was edited by: mach1morgan on 1/24/02 6:23am ]</font>

 

[hamiltt]

You need to play with a pc dyno program to see what you can change by advancing or retarding.

 

[1970galaxie]

Troy, when I advanced the cam in my Galaxie it noticeably helped a "Flat" spot off idle. It didn't seem to hurt the engine wanting to rev either. Every big car I have had has been advanced + 4. Just go and try it. It doesn't make a huge difference, but makes my boats seem stronger!

 

[Troy Boswell]

Here's "the combo": 460 bored 060 over = 472 CID, 780VS Holley, Performer intake, CC grind # 34-231-4(I think). It the smallest extreme 4x4 grind at 210/218 duration, .515" lift. I'm running PI exh. manifolds into 2" duals. I know, I know, that's killing me. I'm going to 2.5" duals with x crossover and Afterburner muffs as soon as I get the motor up and running again. All of this in a 1976 Elite(4800 lbs), 2.75 gears and C6.
My best 1/4 mile time was like 16.2 at 92 mph. She's a neck snapper huh?!

The cam specs list a 4* advance already ground into it. That plus the 4* crank advance would make 8*. That starts to getting into big changes when you jack with valve timing at 8* increments. The desk top dyno idea is a good one. Anybody want to help me out?

I'm putting the 460 back together this weekend. If I don't have any strong evidence that's pro-advance, I'll probably just intall it at the 0 mark on the crank gear.
Troy

 

[RANDY]

PALE RIDER,just remember when advancing and retarding a camshaft results in valve clearance!! I believe when advancing a cam you get the valve closer to the piston and retarding results in further away!!SOMEONE please correct me if I have it backwards!!Just check again your VPC!!!

 

[ausTOM]

Your cam should be dialed in to the specs set out on the cam fact sheet. This does not necessarily mean straight up ( 0 mark . Yours being a specific purpose cam (4x4) would have been tested by the manufacturer and deemed best at that dialed in position.

 

[Mach1Morgan]

On 2002-01-24 11:02, Pale Rider wrote:
Here's "the combo": 460 bored 060 over = 472 CID, 780VS Holley, Performer intake, CC grind # 34-231-4(I think). It the smallest extreme 4x4 grind at 210/218 duration, .515" lift. I'm running PI exh. manifolds into 2" duals. I know, I know, that's killing me. I'm going to 2.5" duals with x crossover and Afterburner muffs as soon as I get the motor up and running again. All of this in a 1976 Elite(4800 lbs), 2.75 gears and C6.
My best 1/4 mile time was like 16.2 at 92 mph. She's a neck snapper huh?!

The cam specs list a 4* advance already ground into it. That plus the 4* crank advance would make 8*. That starts to getting into big changes when you jack with valve timing at 8* increments. The desk top dyno idea is a good one. Anybody want to help me out?

I'm putting the 460 back together this weekend. If I don't have any strong evidence that's pro-advance, I'll probably just intall it at the 0 mark on the crank gear.
Troy

I ran your combo through my Engine Analyser. That cam seems to perform best installed at 0 and just going with the factory 4 degrees of advance. Your engine is severly exhaust flow limited. What you really should have is a cam with much wider lobe seperation angles. I played around for a few minutes with lobe centerline angles on your combo. Leaving the intake lobe where it is and advancing the exhaust lobe 6 degrees, which is widening the lobe seperation angle to 114 degrees, lost you no HP on top end but picked up 18 ft/lbs on the bottom. Installing a cam with your specs but with 114 degrees of l/s and at the same 4 degrees advanced, picked up 13 ft/lbs on the bottom, 5 ft/lbs at the peak and 8 HP on top end. Going even further and using a 116 l/s angle and 4 degrees of cam advance netted a total of 10 HP on top and 19 ft/lbs on the bottom with the same 5 ft/lbs of increase a the peak torque RPM. Narrow lobe centerlines and restrictive exhausts don't mix well. Any less than ideal exhaust systems should always be mated with cams ground with wide lobe seperation angles.

<font size=-1>[ This Message was edited by: mach1morgan on 1/25/02 10:59am ]</font>

 

[Hottarod]

Every cam should have a custom amount of degrees of cam timing depending on the complete rest of the setup and where you want its power band to be. The typical 4 degrees advance ground in is just the cam vendors shot in the dark with regard to where the cam should be timed. My buddies that dirt track race run all kinds of different cam timing depending on which cam they have in the motor and sometimes depending on whether they are running a shorter or longer straight away race track.

The really hot ticket is variable cam timing or VCT. It was experimented with in the 60's and abandoned for the time being but its back now in a few new factory motors. With VCT you can start out with more cam timing which gets you into the power band quicker. As the rpms come up you can back the cam timing down some to give the motor more top end. I want VCT for my drag car but I can't find anything for an old motor with a conventional timing chain. Another great application for VCT would be in multi-purpose vehicles like pickup's and SUV's that sometimes run out on the highway back and forth and other times pull trailers and boats around. I also suspect that VCT would help super and turbo charged motors or motors that are raced with NOS sometimes and sometimes without it. I sent an email to a few of the timing chain vendors about VCT for but got no responses.

 

[Troy Boswell]

M1M, Thank you for checking! That type of info is why this site rocks! You rock!! Everyone else's input has been great as well. I've printed this out and will keep it in my little recipe book at home. Anyone want to take a stab at the what kind of increase 2.5" exhaust will give me hpr/tq wise?

Straight up it is. Thanks again!