What cam to use with 402 big block engine? [Archive] - Nova Tech

: What cam to use with 402 big block engine?


69Nova355
Mar 13th, 06, 05:08 AM
I have a n/a 402 big block engine bored .030 with a set of 290 oval port heads fitted with stock sized 2.06/1.72 valves. The intake is a Performer RPM and the carb is a 750 Holley. The exaust is a set of 1 3/4 primaries that feed into dual 2 1/2 inch pipes.

The trans is a TH350 (may switch to a TH400 in the future) and the rear will be a 3.55-3.73.

The car is a '71 Malibu that will be a hot street car as well as make some 1/4 mile passes down the track.

I'm looking for a good hydraulic cam to make this car really move. Would like to have a little lope to it but yet still have ok street manners. Something that would perform well at the strip as well as on the street.

Thanx in advance.

NOVAJAYMES
Mar 15th, 06, 05:31 AM
You could use comp magnum 280 cam @480 lift would be as big as you proply want. but the th 350 won't last if your going run it at the track trust me. Go with th400 or 700r4 I have 454 with 292 comp magnum cam that ****used****(may be that is how I got my nickname lead foot laddy) to be backed with a 350 they can't handle the torque. 700r4 is also a good trans if build right though costly.

JohnnyO
Mar 18th, 06, 06:46 PM
I would go with something in the 220/224 @ .050, maybe low to mid .500 lifts., something on a 112 lobe center will give you a pretty good idle, and good vacuum, but it should still sound like there's something nasty there. If you want a lumpier idle, go a little tighter on the LSA, maybe 110 or even 108. Dont go big on the duration or you will have a dog on the street. Everyone recommends Comp Cams....I have nothing against them, but there are so many other good companys out there. Take the specs I recommended, and call a few cam co's, tell them what you have and see what they recommend. Try Crane as well, and Howard's Cams (I get all mine there) Isky, Lunati, etc...there are lots to look at. On the tranny, I dont race myself, but I have many friends that do, and lots of them use a TH350 behind a big block. If it's built right, it will hold up as good as any 700r4..TH400 is stronger, but dont go changing just because you THINK it might break.

1quik69
Mar 19th, 06, 12:59 AM
Take a look at the Edelbrock Performer RPM cam. I have the whole edelbrock package on my 468 and it runs very strong and has a decent lope to it. The package put out what Edelbrock advertises when we put it on the dyno. 540 hp with 9.5 compression.

Gloryhound
Mar 20th, 06, 10:01 PM
When it comes time to make a cam choice on my engine my plan was to call all the cam manufacturers I could find and get thier recommendation. You should get a limited range that puts you in your ball park. They are going to ask you for alot of info so be ready to answer. Document it all. If you plan on doing an occasional 1/4 mile get ready to become an addict. Alot of the guys I've met on the board that drag regularly started out saying they were just going to make an occasional pass, but once they get that time slip they all start looking at ways to tweak thier car to get a faster time slip. The next thing you know the upgrades start getting a little more radical, the street AT's are replaced with a set of slicks, the roll cage is getting installed, and thier winter project becomes building a bigger cube engine.

Motorhead62
Mar 23rd, 06, 09:30 PM
I would try the XE 274 by Comp Cams. That is a sweet cam in a big block. :thumbsup:

69Nova355
Sep 25th, 06, 04:28 AM
Thanx for the inputs, sorry I have not been on this board in 6 months atleast....

Right now I'm in the middle east fighting the war on terrorism, so I've got a little time to decide here.

I'm actually now considering going with a flat tappet solid as I want more power, especially after everyone has said solids make power in every aspect.

I'd be interested to know if the Voo Doo line of cams comes in a solid or not? And if so do they make a solid for big blocks?

Some more info on my combo: it's a 402 big block with a .030 bore to come out to 408 cubes. It has forged Speed pro pistons with a .180 dome, stock 402 rods, forged steel crank, ARP rod cap bolts, ARP main cap bolts, 290 oval port heads with 2.06/1.72 valves and stamped 1.7 rockers, Performer RPM intake with 750 vac. sec. 4150 carb, TH350 with a Hughes 3000 stall converter, 12 bolt rear axle with 4.10's in it (may change them to 3.73's in the future), 1.75 inch primary headers that feed into a dual 2.5 inch Flowmaster exaust. The Chevelle weighs 3620lbs w/o driver and I weigh about 185. Also my Chevelle has power brakes too.

My goal is to make the car run 11's if at all possible w/o the help of NOS and to still be streetable as I plan on making this a street/strip car. Since I have power brakes I'll need a cam with enough vacuum to operate the brakes.

Big Dave
Sep 25th, 06, 09:58 PM
Get 'em while they're hot! Actually that war for oil thing you are currently fighting has a caveat for solid cams that you may not be aware of. The oil refiners back here in the good ole US of A are reducing the zinc content in all motor oils because it interferes with the oxygen sensor on computer controlled cars (another way of saying any car built after '85).

Even though your Nova was probably built back in the days of high octane leaded gas, the cams in today's cars all have rollers and do not need the zinc (known as ZDDP) that is needed to make any flat tappet cam live. Every one knows that you have to build an engine using liberal amounts of GM's EOS (Engine Oil Supplement). And that to break in a flat tappet cam (especially one running high spring loads) you have to quickly bring the engine above 2500 RPM and keep it there for at least 20 minutes to break in the cam. (The high idle gets splash lubrication to the cam lobes, and the twenty minutes gives barely enough time to wear the hemispherical pattern into the bottom of the "flat tappet" to allow the tappet to rotate on the lobe to maximize cam life).

What people may not be aware of is that all synthetic oils and most mineral based oils do not have enough zinc content now in them to keep you from wiping the lobe off that new flat tappet aggressive grind cam you just installed. You must run a diesel engine oil like Shell's Rotella, or Havoline Truck CC CD rated oil, or a racing oil like Valvoline or Castrol GT with a SJ, SL, SM rating for the engine to survive. The problem with racing oils is they have no detergents to support street driving and they are not buffered to control crankcase acid build up.

Diesel oils will also be changed within the year as next year all diesel engines must also comply with EPA emission controls with means they will also get oxygen sensors.

The long term solution is to either run racing oil and change it every 500 miles, or to go with a roller cam.

By the way keep your head down, body armor chinched tight, and come home in one piece to enjoy your project car. :hurray:


Big Dave

69Nova355
Sep 26th, 06, 01:42 AM
Actually the war I'm supporting is for the falling of the world trade center towers, aka Operation Enduring Freedom. What you're probably thinking of is the other one, Operation Iraqi Freedom, which IMO is more about eliminating dictatorship in Iraq more than it is the oil.

Back on subject, the thought of a solid roller cam has crossed my mind. I've talked to a few who didn't seem to think going from a flat tappet to a roller cam did anything more than lighten their wallets. To me a roller cam is new school technology as a flat tappet is old school....sort of like comparing Vortecs to Camel Humps.

When we built my 402 we didn't use any of the oil additive and we broke the engine in with that Super Tech Wal Mart brand oil....probably not the best choice, but the guy that helped me with the engine is experienced and recommended to use the Wal Mart brand oil as well as lithium grease on the bearings and such when assembling the engine.

Immediatley after we broke in the cam the oil was changed and ran briefly and then changed again. I even went as far as adding a filtermag on my oil filter to help catch any of the glitter that may form. So far the engine maybe has 100 miles w/o any problems, and I have flogged on it a few times. The only problem so far as when we put in the pushrods we used stainless steel Elgins...one got bent at the tip when I put the engine under load and tached it up to 5k....turns out that pushrod was installed upside down....however I went ahead and replaced all the push rods with chromeoly 3/8 ones with an .080 thickness and have had no more problems since then.

But when I get the new cam I'm going to use the moly lube paste as I've heard this is the best for the engine. (The last time we used the Comp syrup that worked ok so far but I've heard afterwards that stuff is garbage) I'll probably even drain and refill the oil pan with Shell Rotella this time around just for added insurance.

Now as for a solid roller cam....I'm curious as to what kind of mods will need to be done to accept it? I know I'll need new valve springs which are in order. My heads have stock gudeplates. Someone told me to run poly locks which are also in order. But now will the heads or block themselves need any kind of machining to accept a roller cam?

Also I think I'm going to go with a cam that sees a max of around 6200-6400 rpm as I'm not a fan of winding my engines to the moon. It looks like a roller cam offer a bit more lift at a lower duration and less friction....which I will guess does it mean more power at a more friendly streetable level?

Also good vacuum is also in order as well for the power brakes. :)

Big Dave
Sep 26th, 06, 07:48 AM
Sorry about the war for oil comment, that was just a lead in to the oil issue, it was not meant as a political comment; though in retrospect that was stupid of me and my apologies, to you and all the troops.

Lithium grease isn't a good idea for assembling engines as it will clog the oil filter very quickly, and then the oil by pass opens up and you get no filtration what so ever. The cheap Wall Mart oil isn't a bad idea as any oil you install should be changed after thirty minutes of running. The glitter you refer to is the chrome plating ground from the bottom of the lifter and mostly the softer cast iron of the cam lobe as they seat during the cam break in.

Roller cams as a hot rod aid to performance have been around for decades. The original lifters in the first Otto cycle engine were roller tappets, so they are not new. They haven't been used before the introduction of the hydraulic roller because they cost more to manufacture than the flat tappet. The manufactures went to them only because the motor oils were changing to allow computer controls on the engine to meet emission standards.

Speaking of hydraulic rollers, if you are going to keep it below 6,800 (the max you can spin a hydraulic roller because of the lifter pumping up) why not use hydraulics? The hydraulic roller is even heavier than the solid roller and requires bigger springs (and more of them) to control it for that reason. If you have a late model block (one piece rear main seal) you can use the stock hydraulic lifter and the spider (a secondary spring to help keep the lifter in the bore) with an after market cam to accomplish the same thing as a solid roller.

Because every Chevy made since '86 has hydraulic rollers you can find them everywhere for peanuts. Unlike a flat tappet that must stay with the lobe on the cam once it is broken in, a roller can go from motor to motor. The lifters are the same on both the SBC and the BBC the only difference is the dog bone that keeps the lifter from rotating in the bore.

If you are using an older block then you would have to buy the retrofit hydraulic rollers that are the same in design as the solid roller. I would at that point opt for the solid roller as it is lighter, and will run to a higher RPM (not your idea of fun but should you sell it many love to twist them up).

Big Dave

69Nova355
Sep 26th, 06, 12:58 PM
Dave,

My block is a 1970 L34 396 block.

I've considered running a solid roller for max power and longetivity. I guess I could run a hydraulic roller too.

Here are three cams by Lunati I've considered:

60230

Solid Roller; Lopey idle, Good high performance street cam with good mid range torque and horsepower in smaller 396402 cubic inch engines. Needs 2500 RPM stall converter, headers, 9.1 compression ratio and 3.55 rear gears ratio.

Advertised Duration IN/EX: 261/267
Duration @ .050 IN/EX: 231/237
Gross Valve Lift IN/EX: .629"/.639"
LSA / ICL: 110/106
Valve Lash IN/EX: 018/018
RPM Range: 2500-6400

60231

Solid Roller; Rough idle, Good cam for high performance street or mild strip applications. Needs 25002800 RPM stall speed converter, headers, 9.5:1 compression ratio and 3.73 rear gears. Great cam for powertouring applications.
Advertised Duration IN/EX: 267/273
Duration @ .050 IN/EX: 237/243
Gross Valve Lift IN/EX: .639"/.655"
LSA / ICL: 110/106
Valve Lash IN/EX: 018/018
RPM Range: 2500-6600

60232

Solid Roller; Rough idle, Good cam for street/strip applications in 396427 cubic inch engines. Excellent mid range torque and horsepower. Needs 28003000 RPM stall speed converter, 10.1 compression ratio, headers and 3.90 rear gears


Advertised Duration IN/EX: 273/279
Duration @ .050 IN/EX: 243/249
Gross Valve Lift IN/EX: .655"/.663"
LSA / ICL: 110/106
Valve Lash IN/EX: 018/018
RPM Range: 2600-6800I'm thinking either the first or second cam would be the ticket, however I don't know what kind (if any) piston to valve clearance I'd run into.

dude67
Sep 29th, 06, 12:16 AM
I have almost the same setup in my Chevelle. Lunati VooDoo Cam 60203 check it out. This is what it sounds like in a 454.
http://s7.photobucket.com/albums/y260/keltieanne/?action=view&current=454short.flv