Lunati cam and Pro Comp head discussion

[rich weyand]

Run Mobil1 10W30 with one bottle of ZDPPPlus per oil change, every 3000 miles.

[nlauffer]

I really like Mobil 1, but I also like Royal Purple.  My current motor gets the cheap stuff, it eats it too fast.  Where do I get the ZDDP additive? 

My thought was that if all motor oils are changing "ingredients" and an additive is needed for break in, then wouldn't be beneficial to run it all the time.  I have read where others so there is no need to after break in.  But, why?

[rich weyand]

http://www.amazon.com/dp/B007X74HZW

Oil used to have more ZDPP (a.k.a. zinc).  Problem is, it is hard on catalytic converters.  So it was cut back in most oils.  Modern engines with roller cams (actually, the rollers are on the bottoms of the lifters) don't need it.  What the ZDPP does is form, under pressure, a protective coating on metal parts subjected to "wiping" motion, like cam lobes and lifter bottoms in older style flat-tappet engines.  Too much ZDPP, though, causes pitting.  Most oils now have about 800 ppm, pitting occurs above 2000 ppm.  Also, the ZDPP is used up, as, when it bonds it is chemically changed, then it is wiped off and replaced with more.  So that's why I say 3000 miles, so your ZDPP concentration doesn't fall too low for protection.

So, yeah, the short answer is that if it's a flat-tappet engine, use special oil or additive for more ZDPP all the time, if it's a roller engine, regular oil is fine.

[nlauffer]

So what would be a good oil to use?  Or do I just need to add ZDPP?

[rich weyand]

You just need to add ZDPP to current common motor oils to regain the same protection those oils once provided to flat-tappet engines.

I prefer synthetic oils, and know several people who have gotten upwards of 250,000 miles out of gasoline engines using full-synthetic oils, which is pretty remarkable. 

But for flat-tappet engines, even synthetic oils need higher levels of ZDPP than currently in the mix.

[nlauffer]

Engine is almost done as of a couple weeks ago he just needed to assemble it. He also said he would put new springs on the RHS heads. I stopped by today but it was too late and he was closed. I hope it is done and he just hasn't called me yet.

I spoke with a guy today who closed an engine build shop a couple years ago. He has some lunati voodoo 60101 cams which is the step below what I want and be has some Holley street dominator dual plane intakes. I think we might do some trading and I will get them almost free. I think free is good even if it is a smaller cam. It is the one the Lunati tech recommended

[nlauffer]

All in all I think going from a stockish 305 with 3.08 gears to a mild built 350 with 3.73 gears is going to be a huge change. I wouldn't be surprised if I double my horsepower and not sure about torque. Should be very fun and very street able. Serpentine belt setup is coming along a piece at a time. I am ripping into the truck right now replacing sheetmetal so the engine doesn't have to be ready right away. The rear end is gonna be fully removed to do the gear swap as I am lowering it 2.5/4 or so also. I have been tempted to remove the drivers side tank and go with a rear blazer tank. I don't want a bed floor fuel fill though. I would like to see a detailed taillight fuel filler or something in the bed side maybe.

[nlauffer]

Oh yeah, a stage 2 rebuilt quadrajet is the final decision on carb. M

My workshop is starting to look like a parts store. I need to start getting some of the work done.

[rich weyand]

Oh yeah, a stage 2 rebuilt quadrajet is the final decision on carb. M

My workshop is starting to look like a parts store. I need to start getting some of the work done.

Who's doing the carb?

[nlauffer]

Sean Murphy Induction.  SMIcarburetor.com. I have hear a lot of good things about them. I will send mine off and for $269 it'll get an amazing looking and performing build.

[rich weyand]

Sean Murphy Induction.  SMIcarburetor.com. I have hear a lot of good things about them. I will send mine off and for $269 it'll get an amazing looking and performing build.

Excellent.  I've talked to him, and am very impressed.  The Quadrajet needs to be tuned to the engine and the induction and exhaust setup; it's not plug and play.  And a lot of the tuning is drilling the proper size air bleeds in inserts in various passages and the like.  I think Sean has basically set up Qjets for just about any situation over the years, with vehicle and instrumentation in hand, and kept all his notes.  So he can get you to a proper tune on a Qjet for your vehicle pretty much no matter what it is and how it is set up.

Make sure he has the full scoop on how you are setting things up -- intake manifold, engine, heads, cam, exhaust -- and he can nail it.

[nlauffer]

I just rode in an 84 Chevy K1500 with 33x12.50 tires, Chance built TH350, stock bottom end 350 (with stock dished pistons), vortec heads, headers, Edelbrock RPM Airgap, Holley ???cfm carb, aftermarket HEI, and a Comp Cams xtreme 4x4 270H cam (# 12-243-3). 

The truck idles at 800 and sounds awesome.  Put it in gear (cold) and it idles at 600 and sounds just as awesome.  It has a cold stumble from the Holley, but you can tell it's got some power when you put your foot in it.  Oh, yeah 3.73 gears.  You can feel it in your stomach setting you back in the seat a little.  Now it's no race care, but makes a great pulling truck.  He uses it to pull his wrecker through the snow.

It's so close to the engine I am building, that I think I found my cam.

[rich weyand]

That cam won't have a lot of torque in the bottom, with 50* of overlap, but it's a high-lift, high-flow cam that will punch out hp once it starts breathing, no doubt about that.  Note rpm range of 1800-6000 and 2200+ rpm torque converter recommendation. 

Maybe 430 lb-ft at 4000 and 380 hp at 5000 with headers, 390 lb-ft and 345 hp at the same rpms with a manifold.

[rich weyand]

Comp 12-235-2 will give you 430 lb-ft at 3500 and 350 hp at 4500.  You give up 30 hp on top, but the torque and hp peaks move 500 rpm down, and the torque comes on much earlier.

12-243-3 will give you 346 lb-ft at 1500, but 12-235-2 will give you 379 lb-ft at 1500.

I ran these for you just for grins.  Download them so I can take them down, if you would.

http://users.rcn.com/weyand/smalls/12-243-3nlauffer.jpg
http://users.rcn.com/weyand/smalls/12-235-2nlauffer.jpg

[nlauffer]

Downloaded.  Thanks.