402 BB rebuild

[72 Monte Carlo]

I bought a 70 Chevelle 402 330 HP engine and I'm in the process of rebuilding it. The only issue it had was a broken rocker arm on the #7 cylinder.

I just had the crankshaft turned and polished and it's now .010 on the mains and .010 on the rods. The crankshaft is the OEM stock crank.

I've always used Clevite 77 main and rod bearings in the past. I have heard good and bad about King bearings from other forums, but if I go with Clevite 77 bearings, should I go with the H or P series bearings?

I ran Clevite P bearings in a built 402 I had 30 years ago and never had an issue with them.

 

[Its Just Me]

Doug,

I'm running King bearings in a 400 hp 350 and can't say anything bad about them. The tolerances were within spec and they seem like a good product. I only have about 7500 miles on them, but no problems.

That being said, I just pulled my 427 apart. I built it in 1983 using Clevite 77P bearings.  That thing consistently saw 6500 rpm at the track and had probably 35,000 hard street miles on it. I took it apart because it was using oil and I figured the bearings were tired too. Suffice it to say, the bearings will be going back in because they have literally no signs of wear.

I think it comes down to proper clearances and regular oil changes. If you had good luck with the Clevite P's, I say stick with'em. 

Scott

 

[72 Monte Carlo]

What's everyone's go-to cast piston to run? Sealed Power, Federal Mogul, Silvolite, TRW?

 

I think Sealed Power, Federal Mogul, and TRW are all owned by the same company now.

 

Hypereutectic or regular cast for a street driven big block and no blower or nitrous added to it ever?

[Dtret]

3 hours ago, 72 Monte Carlo said:

What's everyone's go-to cast piston to run? Sealed Power, Federal Mogul, Silvolite, TRW?

 

I think Sealed Power, Federal Mogul, and TRW are all owned by the same company now.

 

Hypereutectic or regular cast for a street driven big block and no blower or nitrous added to it ever?

I believe the guy that built mine used Mahle 

[jft69z]

6 hours ago, 72 Monte Carlo said:

I think Sealed Power, Federal Mogul, and TRW are all owned by the same company now.

Many years ago a speed shop told me TRW was short for 'Tennessee Repackaging Warehouse', meaning they got parts from everywhere and just put them in their boxes. Made me laugh, but also made you wonder, lol

[Dtret]

2 hours ago, jft69z said:

Many years ago a speed shop told me TRW was short for 'Tennessee Repackaging Warehouse', meaning they got parts from everywhere and just put them in their boxes. Made me laugh, but also made you wonder, lol

That’s funny 😄 

[GatorDog72]

For stock-ish rebuilds I like Mahle. I also did a small block with summit brand pistons. They were super cheap. I think they were $85 for 8 pistons. Worked out nicely. I've used king bearings in my last two engines. Clevites work fine too, I have p series Clevite 77s on my big block. 

[MC1of80]

Sorry, street or not, if I'm building or having an engine built, it gets forged Pistons. Ya never know what you will add later. Ask me how I know. Lolol and never say never. Lolol

[72 Monte Carlo]

The machine shop just took it upon themselves to bore the block to their preferred choice of piston (Silv-O-Lite) without asking me first, so I'll be running those pistons along with a set of Total Seal gapless top ring set. A friend of mine for over 20 years is a professional mechanic with his own shop, and he runs TS gapless top rings in his OEM spec 327 in his 57 Chevy Bel-Air hardtop that will pull wheelies off the line (other friends have witnessed it first hand several times.

I should have the block back this week with it being hot tanked, new cam bearings, and new brass freeze plugs. I'm just waiting for the new pistons and rings to show up so I can have the new pistons pressed onto the connecting rods, then I should be able to start building the engine.

[72 Monte Carlo]

I've got my BB engine on the engine stand and have the crank and main bearings installed with the bearings to crank plasti-gaged. I ordered a ring filer tool and now I just need to gap my rings so I can get the pistons and rings and rod bearings installed, and new Melling high volume oil pump installed. 

My cylinder heads are the 290 castings which are semi closed chamber heads with 2.06 and 1.72 valves with 113cc chambers . With my Silvolite 1445-060 domed pistons and these heads, my comp ratio according to the machine shop will be 9.5:1. Is that too much compression for pump gas? The machine shop said that I'll have to run 91 octane and probably retard the timing a couple degrees for that comp ratio. If I find a set of open chamber heads like 781 or 049 heads that are 120 to 122cc chambers, it will reduce my comp ratio to 8.5:1. 

My brand new cam kit is the Lunati Voodoo 10703 kit - 268/276 LSA 110, 542"/554" lift, RPM 1,800-6,200, Dur @ .50" 227/233

It's been 30 years since I built my last big block and I need some input from you folks that have been in the big block realm more often than myself.

Should I find a set of open chamber heads or just get my 290 heads cleaned up and gone through?

Any idea of semi closed chamber head engine HP vs open chamber head HP?

Thanks,

Doug 

[MC1of80]

Sounds like you're off to a good start. I would rethink the high volume oil pump. They are known to pump the oil pan dry and spin bearings. Had a few big blocks that that happened to. 

Use a high pressure pump. I use one on my 496 and have had no issues so far. 

As far as open chamber vs semi closed, my understanding is that the bigger chamber unshrouds the valves better.  The 781 and 049 heads are the best flowing factory oval port heads. It may be a toss up between them and the 290s you have now. No matter which head you decide on, have bigger valves installed and blend in the short radius. You won't be sorry. 

[Michael Boyte]

Now that's speaking from experience !!!

And great advice !!

[72 Monte Carlo]

I'll have to look at the Melling oil pump that I bought to verify if it's a high volume or high pressure pump that I bought. It's still new in the box and can be returned if I bought the wrong one.

 

[420ponies]

My new to me 427BBC has my old "290" heads, milled dome forged pistons,new stainless valves, hardened exhaust seats installed ( unleaded 93 octane), has 9.7 to 1 compression. Has a nodular Steel crank(396), a 454 ,4 bolt block ,with all ARP bolts, Howard's hydraulic roller cam .... 567/578 lift, 276/282 duration . Has clevite P's in it. Weird, my heads are 96cc. I'd like to see you spend the extra money and get those hardened exhaust seats and stainless valves.cuts down on heat on seats.

 

[72 Monte Carlo]

My new oil pump is just a standard pressure/volume pump. Melling only makes High Volume but not High Pressure oil pumps for a big block Chevy.

I talked with my friend that runs his own machine shop locally and I've used him for getting my block ready, and said that the 3 angle valve job and deck the heads is $320, new valve guides installed is $100, and new hardened exhaust seats.

I've been told to enlarge the intake valves from the stock 2.06 to 2.19 and unshroud the valves/blend the bowls and install stainless steel valves. 

I've heard to leave the exhaust valves at 1.72 and I've heard to enlarge them to 1.88. I'm not sure which way to go on the exhaust valves yet?

[420ponies]

Doug, I have done both  size valves to my heads 37 yrs ago. The last blast on that motor broke the crankshaft in half, hence the rebuild and upgrade to hardened seats. These heads are a great with the upgrade to larger valves. Like they said "open the throat " on intake side and un-shroud  the exhaust side/blend bowls. really helps on flow. I was in the 290 com range on flow bench. I was going to go with aluminum heads , but the cost difference was over $1000 between my cast "290"s. Went with hydraulic roller cam instead. Sounds like your machine has you covered. Big Blocks Rock!

[72 Monte Carlo]

Which dual plane intake manifold seems to produce the best hp & torque?

Edelbrock RPM

Edelbrock Q JET RPM 

Edelbrock RPM Air Gap - I question this one for cold weather drivability issues? My buddy experiences it when the weather gets to 30's to freezing temps and has idle issues.

Weiand - Stealth

Holley - N/A in dual plane any longer

Offenhauser 360* dual plane

 

Also, which distributor system to use that will not fall off at 2500 rpm like a stock HEI and continue to work with camshaft rpm up to 6,200 rpm?

[MC1of80]

Rpm air gap, msd distributor and old  6al. 

[Dtret]

9 minutes ago, MC1of80 said:

Rpm air gap, msd distributor and old  6al. 

Old trusty and reliable. It’s a proven combination 

[72 Monte Carlo]

7 hours ago, MC1of80 said:

Rpm air gap, msd distributor and old  6al. 

What about idle issues when temps get down in the 30's and 40's?

My buddy has a RPM Air Gap on his 383 stroker in his 79 Z28, and he has idle issues when it gets down towards freezing temps.

[MC1of80]

Use a carburetor with a choke then. 

[72 Monte Carlo]

 

On 3/16/2022 at 2:40 PM, Dtret said:

Old trusty and reliable. It’s a proven combination 

Which MSD distributor - with or without vacuum advance? 

On 3/17/2022 at 5:27 AM, MC1of80 said:

Use a carburetor with a choke then. 

I have a brand new Speed Demon 750 cfm with electric choke. 

I called Edelbrock and the tech told me that the Air Gap intake will have issues atomizing fuel in the 20 to 30 degree temps, other than that it should be fine.

[MC1of80]

I use an msd distributor without vacuum advance. The "Covid" Montes small block uses the same. 

How often will you be driving in the cold weather? The temp under the hood once warmed up, won't be that cold. 

[72 Monte Carlo]

I'll drive my Monte once it's painted and put back together, probably at least down to the lower 40* temps.

I won't drive it at freezing temps just because it would be my luck that some dipstick would lose control and hit my car.

[714024SPEED]

I drive the "Covid" Monte all year long,rain ,snow cold and have not had any issues with the performer RPM.