Here’s what I spent building a 421 HO back in 2015. I built this engine to look like a stock 421 but with a few probably overkill upgrades on the inside. Link to 421 build thread:
https://forums.maxperformanceinc.com...d.php?t=774638
This listing might help give you at least some idea of what a typical competent machine shop charges and the number of new parts required to do the job right.
Of course parts prices and labor will vary depending on where you live and how many upgrades over stock you’re willing to pay for. New forged rods and pistons as well as stainless steel valves, new exhaust valve seats and valve springs are pretty much mandatory to do the job right in my opinion.
I don’t think spending between 6 and 7 grand on your 400 rebuild is unreasonable when you replace all the wear components and upgrade to better components than the engine left the factory with. Reusing the original cast rods, 2-piece valves, valve springs, pushrods and rockers would be out of the question and signs of a cheap budget rebuild.
Most of the parts prices listed are with tax and shipping included.
Parts purchased:
1964 421 Block, crank, heads, oil pan and timing cover - $1475.00
1964 Tri-Power Intake Manifold, Bare - Trade
1964 Water Pump, Rebuilt - $92.00
New Harmonic Balancer - $143.00
1964 GTO OEM Chrome Valve Covers & Repro Breather Cap - $90.00
Rebuild/replate Tri-Power carbs and misc. repro and genuine parts (throttle cable bracket, linkage, vacuum & PCV fittings, choke tubes, air cleaner set) to complete the setup, includes buying a 1964 GTO auto trans center carb outright - $967.67
Misc Tri-Power carb spacers, studs & nuts, base gaskets, restored plug wire looms, OEM 45 deg brass heater hose fitting - $161.50
1962 Pontiac Big Car Aircleaner, Excellent Unrestored Condition - $592.00
16 ea. Manton Pushrods - $230.73
16 ea. 73627-16 Crower 1.5:1 Enduro Stainless Steel Roller Rocker Arms - $478.90
8 ea. Custom 26cc Reverse Dome Ross Racing Pistons w/Pins & Spirolocks - $784.98
1 ea. Cloyes Tru-Roller Timing Set - $86.70
16 ea. H-O Racing VS-11 Valve Springs - Trade
8 ea. Crower Forged Connecting Rods, stock Pontiac dimensions - $900.00
1 ea. NOS Pontiac 9779068 camshaft - $200.00
16ea. Johnson 951R Hydraulic Lifters - $97.00
1 ea. Melling Select 60 psi Oil Pump & Driveshaft - $60.00
1 ea. Butler head gaskets & Misc Engine Gaskets - $75.00
1 ea. BOP Viton Rear Main Seal - $58.00
Misc. Gasket Sealers, Engine Paint, Spark Plugs, Break-In Oil & Gasoline - $110.88
Parts supplied by the machine shop:
8 ea. 6000SG S.I. Stainless Intake Valves - 1.960" x 4.970" - $128.00
8 ea. 6001SG S.I. Stainless Exhaust Valves - 1.660" x 4.970" - $128.00
16 ea. 6523 SBI Cast Valve Guides - $24.00
8 ea. 30677 Durabond Valve Seat - Exhaust - $48.00
2 ea. 30723 Durabond Valve Seat - Intake - $12.00
16 ea. OS810 Pioneer Viton Valve Stem Seals - $28.00
16 ea. 607-STA Isky Valve Spring Retainers - $92.00
16 ea. 101-7101 ARP Rocker Arm Stud Kit - $48.00
8 ea. 90922-1 Crower Custom Piston Pin Bushings - $100.00
16 ea. Helicoil Insert 7/16-14 - $16.00
2 ea. Helicoil Insert 3/8-16 - $1.50
4 ea. EPC18-B Brass Expansion Plug - $8.00
8 ea. 43M5529-010 Engine Pro Moly Piston Ring Set-4.125-010 - $120.00
1 ea. Clevite Main, rod and cam bearings - $287.40
$7644.26 Parts Total
Machine shop labor:
Cook/Clean & Blast Block - $67.00
Magnaflux - $34.00
Check Align Hone - $40.00
Cylinder Bore 2X & Hone W/Torque Plate, 4.120 Did Not Clean, Went To 4.135" - $369.00
Surface Block W/BHJ - 10.215" - $179.00
Block - Final Rinse After Machining - $39.00
Crankshaft Grind-H.P. Middle Spec - $129.00
Crankshaft Heat Treat - $195.00
Rod & Piston Work Bore For Pins Bushings -1.040" - $140.00
Balancing Job - Neutral - Make Flex Plate Neutral - $155.00
Complete Valve Job & Resurface - $309.00
Head Work Set Up Springs And Assemble Heads - $75.00
Clean & Mag Heads W/VJ - $45.00
Install seats - $67.50
Install False Guides - $80.00
Machine For Positive Seals - $36.00
Install Helicoils $20.00
Machine For Screw-In Studs, Helicoil For 7/16, Cut Bosses .250" - $179.00
Machine Valve Head Diameters - Intake 1.930"/Exhaust 1.645" - $96.00
Machine Shop Labor Total - $2254.45
Grand Total, Parts & Machine Shop Labor - $9898.76
As you can see, this rebuild/restoration of an antique Pontiac performance engine easily eclipsed the 10 thousand dollar mark.
I'm sure there are some things that I left out, I had been collecting parts for this 421 for about 5 years and some parts had been sitting in my garage waiting for a place to go for 10 to 20 years. I didn't include what I was charged for cleaning and assembling the engine, this cost is between my friend and myself.
There are a few pieces that I purchased that I really didn't need, but I wanted them so.....they added unnecessary cost. Just the initial price of the 421 block, crank and heads is about $1000 more than you'd pay for a common 400 or 455. The Crower forged rods were purchased way back in the early 1990s, so they probably cost now about 2/3rds of what I paid back then. The Crower roller rockers really weren't a necessity, but finding the correct stamped factory rockers would have cost about $150 anyway and I decided to substitute a top-quality part instead.