crewguy

This engine is for my son's 86Z28. I started with a late-model Vortec 350 that did not need boring.

Scat 9000 3.48 crank
FM H345NP pistons+rings
PM rods w/ Arp bolts
Comp cams XR276HR roller cam
Factory roller lifters
Vortec 906 heads (unported but cleaned up)
SS 2.02/1.6 valves
Comp Cams double valve springs (includes retainers, locks, and seals from Comp Cams)
Narrow-body, full roller rockers.
Professional Products "croswind" air-gap intake
Edrlbrock 650 Carb.
Comp 9000 dist.
Headers

My machinist suggested that I did not need a high-volume oil pump. He said a stock M-55 would do the job.
What pump should I use?

Will I be able to use the stock valve covers with my cam and rocker combination?

How many horses will this engine put out?

ME Leigh

Don't use a high volume, they just waste power.

Mkos1980

iTrader: (8)

Correct. I use a stock melling 55 as well in my 383 with no problems. 20 PSI Hot at 700rpm idle and 50'ish on the highway HOT.

crewguy

What about using the stock valve covers? Will the rockers hit?
Thanks!

88IROC350TPI

You may need to gut out the inside of the valve covers but they'll fit. Whats going to be the compression ratio of this motor? I hope the car you're putting it into has some decent gears and if its auto dont even think about using the stock torque convertor.

Spectre

just out of curiosity, why dont you use the original rotating assembly since the block doesnt need to be overbored ?

the XE276HR stops making power at 5800 rpm if im right, and vortecs arnt proven performers over 6k ...

.. and from what ive heard, adding bigger valves doesnt help much with vortecs.

crewguy

I bought the bare block. The reason I went with 2.02/1.6 is to be sure I had 1 piece valves in the motor. My machinist didn't charge much to cut out the heads. I also went with screw-in studs for the same reason.

Stekman

Were the valve guides cut down to allow for more valve lift? Were the spring pockets cut to allow for larger diameter springs?

crewguy

I am using flat-tops, so the CP should be at least 10:1, right? Should I go with a thin gasket, or use the ones that comes with the gasket set? I don't understand the deal with quench. I bought a 2500 stall for the 700R4. After the install of the engine is complete, I am going to install a disk-rear with gears. What would you guys recommend for a gear ratio?

crewguy

Yes on both; at least they are going to be. I am taking the heads to the machinist this week (assuming the SS valves come in).

Spectre

whats the maximum lift you can get out of those heads ?

88IROC350TPI

I wouldnt be so sure of that. My block is 0-decked and I have 4-valve relief TRW pistons (-6.1cc) and my compression is around 10.3:1. If you have generic pistons in a factory block you might be quite low - maybe too low for that cam.

crewguy

Do you call FM H345NP pistons generic? Let me know so I can buy better ones. When you said your block was 0 decked, do you mean that the piston is flush with the block? These FM pistons specs are .025 in the hole. Which pistons should I use?

Stekman

H345NP slugs are just fine. I used them in my "kicker" engine about a year ago. Compression was just fine with 64cc heads, right around 9.5-10 IIRC with a factory deck.

rgarcia63

On a 350 the FM H345NP piston gives a CR of about 9.5:1 which is correct for a stock motor.
I have fast burn aluminum 64cc heads on my zero decked (actual .002 in the hole) 388 with SRP forged alum -16cc D-shaped dished piston which gives me a 10:1 CR.

Here's a good definition of quench:
Quench, or squish area is typically the flat area on the top of the piston that's almost level with the top of the block deck. It must have a corresponding flat area on the deck surface of the head to qualify as quench.
If you look at a combustion chamber, you will usually see these flat areas, and they will have the volume of the actual combustion chamber between them. When the piston is compressing the mixture, as the piston nears the head, the flat areas on the head and piston come together and force the mixture from those areas to "squish" into the chamber, where the spark plug and burning mixture reside, so you achieve a more complete burn.
The quench area also runs cooler than the rest of the chamber / piston. These lower temperatures are where the "quench" comes from.
When properly designed, the quench areas can have a tremendous effect on the quality of combustion, and allow higher compression ratios, and due to this they are considered "artificial octane" by scientific types.