In another thread, Russ posted that in heavy vehicles (5000 lb) you need to advance the cam 4 degrees. As my 4 year old niece would say "But whyyyyyy?"

I assume this is the same thing as degreeing the cam. Correct?

Does this rule apply regardless of what cam you plan on running? In other words is it based more on how heavy your vehicle is than how hot your cam is? I plan on running the Crane 941 in my 4300 lb F150 with a 390.

OK, this will really show how little I understand this ... does this relate to the key-way settings they talk about with the roller timing chain kits? If so, does the Edelbrock roller chain allow you to advance the cam 4 degrees or do I need a different brand (I think Russ said the one he got has 9 key way settings)?

Glad you guys are patient. I have nothing but questions to add to this forum.

 

Some camshafts are ground with an advance or retard in them. The camshaft spec sheet will give you this info. The extra keyways in a timing chain drive gear are used to adjust camshaft advance or retard. You can experiment or read the spec sheet and ask the timing set supplier which keyway to use. I have had good luck with Crane camshafts providing an accurate spec sheet and I use only Cloyes true roller timing chains. I use the center keyway and set it "straight up". Others here may have additional advice depending on your intended use for this engine.

 

I think that is the same thing I heard from the guys at the speed shop when I bought my headers. These two guys told me that in addition to installing a 4v intake and carb, my engine would benefit a lot from installing a roller chain and running it "dead up". I guess that means the middle key way. Right? That was with the stock cam. I have no idea what the stock cam timing would be on my 1976 390.

My biggest problem is I can't seem to figure out how this affects the engine. We are basically talking about the link between the crank and the cam. Right? Well, I can't figure out why all cams aren't just ground so that they all would run straight up. Why would you need to advance the cam 4 degrees on a heavier vehicle? I assume advancing the cam means the the valves are now opening and closing earlier. How does this change the performance of the engine and why would you not do this in a small car but you might with a heavy truck?

 

Typically degreeing a cam is simply checking to make sure that it is as advertised. That the keyway is ground in the right position, and that the lobes are where they are supposed to be.

Advancing or retarding the cam is to move it from its factory ground centerline, to some other position. This is usually not more than 4 or 5 degrees either way.

Moving your cam is the only adjustment, or fine tuning, that can be done once you have it. It works like this. Once you have carefully considered all aspects of your engine, and how you want it to perform, and you have purchased a camshaft that matches those criteria as closely as possible, you install it in your engine and degree it to verify its settings. This is done in the straight up position. After evreything is verified, most people will run it in that configuration to see how it feels. If you like it, you're done. If not you can make small adjustments to your powerband by advancing it to move your power lower in the band, or retarding it to move your power higher in the band. If it still doesn't suit you, then your initial cam choice was wrong and you get to buy a different cam.

Simple, eh?

-Scouder

 

OK. I am starting to get it. But what exactly do you mean by moving your power lower in the band or higher in the band? Would moving your power lower in the band mean more torque at low RPMs? Is that why Russ said you want to advance the cam 4 degrees in a heavy vehicle?

BTW, I didn't like the last part about needing to buy another cam. That would suck.

 

Yes, advancing the cam will move the torque curve down the RPM range, retarding it will move that torque UP the RPM range.

In my 390, I have a 292/292 adv, 230/230@.050 and .554/.554" lift. My machinst degreed it first, to make sure it was right, and THEN advanced the cam 4 degrees after we decided that would be a good idea.

Reason being, my F250 is a 4x4 and I did use it off-road a lot (or used to). With a Holley 750, CJ exhaust valves, long-tube 1 7/8" headers and an Edel Performer 390 intake, moving the power band down made a lot of sense, mostly because of the Performer intake, because it wouldn't get near 6000RPM

And I'll tell you, I have more low-end torque than a stock 360, and so much torque above 4000RPM it's unbelievable. However, I have nothing to compare it to, just my impression that it really worked out well for me. It also pulls to 6000RPM quite well, so advancing the cam 4 degrees didn't do much.

BE CAREFUL on piston-to-valve clearance (especially with the CJ exhaust valves) when advancing or retarding the cam, too.

Too bad I gotta get rid of it...

 

OK. I understand it now. Thanks to all of you guys for the 'great explanations' (wasn't that a book by Dickens?).

Still not sure if I want it straight up or advanced a little, but now I see why 9 keyway settings could be useful. Especially with a radical build and a radical cam.

Thanks again

 

Hey, krewat. Why are you getting rid of it? Please, don't tell us you are replacing it with a bowtie or you just gotta have a Hemi.

 

The Village is on my butt about it not being registered, and can't afford the $1K a year in liability insurance just to keep plates on it.

And no, no hemi's around here...

I've had my '01 F250 V10 for two years now, parts availability (especially aftermarket) is good, engine has plenty of torque, etc.

While it's no 390 4bbl for high-end power, the low-end grunt is just way too amazing ... and my SD is basically the same setup as the highboy - even down to the "Dana 50" front-end which is really a Dana 60 housing with 44 gears in it

And to top it all off, the mileage is about the same, 15-16 on the highway.

I passed up the 80's 90's pickups because they just didn't do it for me, especially with an independant front-end they had in the late 80's up to '97 or so. When they went solid front axle in the SD again, I had to have one especially with a motor that put out more torque than my FE.

Funny, my 390 by desktop dyno is MAYBE putting out 425ft/lbs GROSS. My V10 puts that out NET (with accessories) on regular gas (not 93 like the 390).

Not getting into a "modular" vs. "FE" argument here, but for me personally, it makes a lot of sense.

I'm very nostalgic about my '74 highboy, my brother bought it brand-new when I was 8 years old, and I've had it for almost 18 years now. I've been thinking about parting it out and cutting out the VIN number that is stamped into the frame on the passenger side and putting on the wall

 

Sheesh that's a lot for liability, mine is around $400.

What about registering it as non-operational?

Barry

 

Ain't no such thing in New York, no way to get plates without liability insurance.

I'm on Long Island too, where there are 5 of the 10 most dangerous roads in all of New York (or was it the US?) ...

I'm still toying with the idea of trailering it up to my brother-in-law's place in Upstate NY where they won't care - there are mid 70's pickup trucks stuck/dead all over the place and they never do a thing about THEM ...

 

I'm also in ****-york. In addition to needing insurance to get plates, if you let the insurance laps or cancel it, the insurance company notifies the DMV who then revokes the vehicle's registration and YOUR driver's liscence!! This state creates a major vacuum in sooooo many ways!

 

By the way, I've been thinking about this, and I recall advancing my cam 4 degrees was also to bleed off some of the compression because of the heavy vehicle.

 

Just the opposite. Advancing the cam opens the valves sooner and consequently closes them sooner. Retarding the cam leaves the intake valve open longer into the compression stroke, bleeding off compression.

-Scouder

 

Thanks for clearing that up, I thought about it more, and that didn't seem to make sense. Maybe it was that my machinist warned me that it was going to happen - it's only been 12 years since it was done