That is some good info! Thank you. I was planning on getting a Hughes cam because they said they are designed around the .904 lifter instead of "Chevy" lobes. Is this correct? I noticed their solid lifter profiles are very aggresive with lift compared to most other brands. Would this be destructive on the street and wipe lobes? Would 250 degrees @ .050 and .570 lift be too much cam? I will shift at 63-6500 rpm.
The lobes of a Hugesengines shaft are very aggressive but are not destructive to anything if set up properly with there springs and good machine work. The way to "Wipe out lobes" would be lack of oil or poor valve spring choice. When you break in a new cam, fresh oil, coat the cam with assembley lube and add break in additive since the new oil's of today lack the componets to protect the cam during break in. Huges also has this in bottles that should be purchased along with the cam, lifters and it's springs.
To much cam is dependent of alot of factors including what you can live with on the street. Mechanical factors are, limit of the heads total lift abilty, what it can handle, flow of the heads ports are another consideration, the cars weight, stall converter, rear gear axle ratio. Of course, the cars intended purpose.
I know fellas running around with duration @ .050 well over 260 and running lifts of .700+. Then again, these cars are not equiped with 2.76 gears and stock stall converters ethier. LOL
I have an older race 440 motor I have swapped into a hot street '74 Duster. The problem is the 440 has 11.5:1 pistons and angle milled iron heads. I guestimate the CR to be 12.5-13:1. It has a nasty Crane solid cam that specs out at 324 duration (forgot the @ .050 sorry!) and .620 lift, it is a single pattern. It idles at 1500. When I rev it it is like an on/off switch. I have a 4,000 stall JW converter behind it. Now for the questions. *** HOW *** do I get this thing to run on pump gas (93 octane)?
I just bought TRW forged flat tops with flycuts, LY rods, and a forged crank all balanced. I am thinking with the milled heads it will be 10.5:1. Is this an accurate guess? What solid cam should I run to keep cylinder pressure down or with the loose converter do I need to worry about it? Oh, I have 3.91 gears and the car weighs 3400lbs.
Thanks for ANY suggestions!
What you need to do right off the bat is figure out what the compression ratio is for sure and not guess it at all or assume. Most big cams/race cams are like light switchs. That is the nature of the beast.
A streetable compresion that still works with a sizeable cam is 10-1. A larger cam can go to 11-1 and still use 93 ocatne. I would not mill the curent heads since you stated they are allready angle milled. I would use a piston that will get to a zero deck clearance or dang close and go from there. Your really not worried about cam size and the pressure it builds at idle, but later in the RPM band when the "Ram - ing effect" comes into play. You can get around the pinging by limiting the advance in the distributor for this.
Not knowing how well the heads are ported or there flow abilty, cam recomandation is very hard. In example, heres a couple of Lunati split duration cams;
http://www.lunatipower.com/Product.aspx?id=2561&gid=317
or a smaller one;
http://www.lunatipower.com/Product.aspx?id=2560&gid=317
or;
http://www.lunatipower.com/Product.aspx?id=1574&gid=283
Once you know the heads cc's and there flow abilty's, the choices of cams can be narrowed down.
