Projects 1964 PONTIAC 421 HO Engine Build

Great information and pictures. You solved my problem of how the lower dip stick tube fits. One question, how long is each of the 3 tubes and the dipstick? I am assembling a 64 389 (76X) engine that was in a GTO I owned in 1972.

 

I'll try to get some measurements for you when I can get a chance to dig out some of my '64 parts. I'll get back to you.

 

The 421 is now on the test stand and almost ready to fire up. We're trying to find a known working center carb for the initial run-in, if we can't I'll bring my restored 1964 Tri-Power center carb and use it for the break-in.

We are planning to meet up on Sunday the 25th to finally get it fired up.

I'm pretty excited.

 

very cool thread.

 

I know that motor

 

The big day has finally arrived.

Made the trip out to pick up the 421 and see it run on the test stand.

Earlier during the week my builder bolted down one of his own Tri-Power center carbs and did the cam break-in, running it for 20 to 30 minutes at 2000+ RPM. By the time I arrived the engine had about 1 hour of total run time on it, enough to burn up $15 worth of 91 octane premium.



We warmed up the engine and checked the oil pressure, once I was satisfied with how it was running we shut it down and proceeded to install my own restored 1964 GTO auto trans center carb. The engine ran perfectly with my carb, as expected.

Next it was my job to install the two restored outer carbs along with the new reproduction fuel lines and linkage.





No change in the idle, proving the two outer carbs were sealing up perfectly. We let it warm up a bit and then opened up all 3 carbs to check the throttle response, it made the transition nicely.

Now that we were satisfied with everything we let it cool down, drained the break-in oil and cooling water, then proceeded to pull it off the test stand to get it ready for transport.

Here Mick who did the build and his son Mark are working on getting the 421 off the test stand.





The 421 was bolted to a purpose-built Pontiac engine cradle for transport and storage until it's ready for use, it has 4 casters than can be easily removed in about one minute for truck transport.



Tucked in the front of the truck bed, almost ready to go home.



Everything is all secure and ready for the trip home. I also took the opportunity to pick up a clean 1970 Honda Trail 70 that my builder had at his shop, an impulse buy I simply couldn't resist.

I hope you all have enjoyed this build, I was lucky to have a retired friend who knows Pontiacs better than just about anyone I know take on this build for me.

Thank you Mick, you're the best.

 

Would you sell the 4bbl carb?

 

Great looking motor, nice job on the build. I like the detail you put into the build thread, thanks.
With the bottom end torque the big pontiacs have this thing should be a monster.

 

Sorry but there's no 4-barrel, only a trio of 2-barrels.

 

As a one time GTO owner I throughly enjoyed following along with this build.
Excellent detailed work,your friendMick knows his stuff. Thanks for sharing.

 

Nice.. I want to know what engine paint you used that is still on the heads after 1 hour of run time?
Most of that head design the paint burns off pretty fast.

 

PlastiKote # 208

Will probably end up looking just like every other Pontiac engine after it gets more hours on it.

A Pontiac V8 with the paint burned off of the exhaust ports is like a badge of honor, wear it proudly!

 

Loved this build and great photos all the way thru....thanks

 

On a run in stand engines do not make too much heat, but at full tilt the paint will be gone real quick

 

Adding it all up to see the total cost of this build. 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.

Happy Thanksgiving Everyone!

 

Nice build with several improvements made to OE design, why re-use stock bolts on main caps? is only question I have.

 

Why not reuse them would be my question.

They're a very high-quality fastener and have only seen one torquing sequence before this rebuild. I see no good reason not to reuse them, especially for a moderate 350 HP performance build. I'd have no problem with reusing the OEM main cap bolts in a 500 HP build either.

 

Yeah, I agree. I'd rather reuse original high quality main bolts rather than trust aftermarket bolts .....could be offshore crap, you don't know.

 

Here's the lucky recipient of the 421 HO, patiently waiting for a heart transplant.





I'm really liking the look of the thin whitewalls and dog-dish caps, tires are 215/70-14.







One of two GTO hoods I have for the car. The other one's even nicer than this one.











Fresh 421 HO waiting for its chance to motivate the Le Mans.

 

Only 350 hp on a factory rated 370 hp motor? Try like that thing is going to make 450 to 500 hp. Remember the factories under rated hp to get better advantages at the track and insurance rates. "401" hp SD Catalina's! Yeah Right!

 

Didn't read the whole thread, but if you still have press in rocker studs and you wing it, IT WILL PULL THE STUDS OUT! Yank the heads and have them drilled and tapped for BBC 7/16 studs use the locknuts and your good to go. Can get more R's. Old Royal Bobcat trick. Now you can adjust them like a chevy. Had '67 2plus2 ragtop wayback when Sherman, 434 4speed. Winged it to 7500. Ran 13.90's, street tires, 4200lbs with ALOT of shit missing, including girlfriend. Many more InJuns than that.

 

I'm fully aware of the numbers game being played with HP figures. However I'm quite realistic about the output my factory-rated 370 HP 421 is capable of. Lowered the compression from 10.75:1 (probably 10:1 actual, numbers game?) down to 8.8:1 so it will run on CA cat-pee 91 octane. I'll be running more restrictive log exhaust manifolds that fit my A-body Le Mans chassis rather than the free-flowing long-branch factory header-type B-body big Pontiac exhaust manifolds too. All that along with the mild factory 068 cam I think 350 HP seems realistic, been a Pontiac man since '89 so this isn't my first rodeo. I know that expecting 450+ HP is nothing but a pipedream for my combo, with all due respect.

I did spend the cash for both machine work and 7/16" screw-in studs with polylock adjusting nuts to address this issue.

 

Like I said, didn't read the whole thread. But I've seen to many "Pontiac experts" learned from many old guys. Arnie was one. Ray Bisek. Tom Kosiol. The Priest "Padre's Faith" ran Injun's on shoe strings. Run E85. Jump the compression to 13.

 

I'm going to use these log exhaust manifolds that I scavenged off of a 1964 326 Le Mans in the boneyard, they're the same ones used on the 389 GTO engines for 1964.

The 421 HO was originally installed in only B-body big Pontiacs and used a better flowing long-branch header-style exhaust manifold, but they won't fit my A-body chassis without mods to engine crossmember and frame rails. In the interest of economy and time I'll just have to be happy with these.

My engine builder was kind enough to run them through the bead blast cabinet for me. I'll clean them with hot soapy water and treat them with some Metal-Prep, then coat them with some POR-15 manifold grey using a paint brush.





They're a nice free-flowing design for a standard log manifold, especially the driver's side. Later designs lost some of the smooth curves and outlet length.





The passenger side manifold has a heat riser flap assembly that's still in perfect working order.

 

If you know somebody that does extrusion hone. Could hog them out with that and get a little better flow. I always ran Cats, the HO manifolds weren't a problem.

 

Thanks but I'll pass on the Extrude Honing, at the most a gain of a couple of horsepower for hundreds of dollars spent.

Instead I'll just open up the exhaust manifold outlets some to better match up with the pipe size that I'll be using. The driver's side manifold outlet starts out at about 1.850" as shown in the picture below, about the same I.D. as 2.00" exhaust tubing. Above that manifold is one I opened up to 2.150", about the same I.D. as 2-1/4" exhaust tubing.

The passenger side manifold already has a larger opening, measuring 2.050". It's bigger because it has to house the thermostatic flapper assembly.



Then I'll install a set of these head pipes, they're 2-1/2" mandrel-bent and neck down to 2-1/4" at the manifold attachment point. More than adequate for what I'm doing. The rest of the exhaust will be 2-1/2" mandrel bent pipes with an 'H' crossover and low-restriction 20" long Dynomax Super Turbo mufflers. Simply freeing up the exhaust after the stock manifolds will net some excellent power gains, but I'm not trying to build a race car here either.



I measured the inside diameter of the pipe at the flare and came up with 2.100".

 

Build all that engine and not let it breath. I don't get it. Put headers.

 

Stock ports, stock cam, stock engine.

I don't want nor do I need headers.

My car is just a cruiser with a big torque motor.

But thanks for your input.

 

Man, thats never gonna happen.

I wish you the best i do - and you've done an awesome job on this thread.

But you've castrated the engine here.
Compression is down 2 points , the exhaust manifolds are choking it, the pipes size will cause a drop in velocity - that and the cam is still up there for the 421ho build. I'll wager a guess you'll be down on power in the lower rpm ranges due to over cammed vs compression and in the upper range you'll be restricted on those tiny manifolds. I hope I'm wrong and I hope that you love it. I'm thinking its gonna run like grandmas Grandville not a 421 ho.

 

The cam I'm using is a very mild grind. It's quite well suited to just about any stockish Pontiac engine build.

It was used in everything from the 10.5:1 compression 350 HO to the 8.4:1 455 HO.

My last daily driver Pontiac was powered by a 455 bored +.030 (462 cubes), with low-compression #66 heads, sitting at 8.2:1 at best. It ran on 87 octane gas. This engine had a '66 Tri-Power and '67 GTO HO exhaust manifolds, the better-flowing HO manifolds afford you about an 8 HP increase at best on a stock engine.

I know a guy with a 455 that runs in the bottom 13s with the log exhaust manifolds in a fairly heavy '69 Le Mans convertible, they're not as bad as you think.

Anyways, I had this 455 engine in a '64 Tempest that weighed in at 3850 without my 200 pound ass in the seat. It easily ran in the 13.80s with a 2.56 open rear and TH400 trans, easing it out of the hole gently so I didn't blow the tire(s) off or bog the engine by cracking all 3 carbs open too quickly. I used only 1st and 2nd gear to run the 1/4 mile, trapping at 102 MPH.

Keep in mind that the 421 HO Pontiac big cars weighing only a few hundred pounds more at the most than my Le Mans or Tempest ran in the low-15s or high-14s at best, that was with a 3.42 gear and stick trans.

I have absolutely no doubt that this 8.8:1 421 (430) running on 91 octane will easily run just as well as that 455 I used to drive daily, if not better. Same 068 cam, same rear gear, same 13" converter and TH400 trans.

I know my Pontiacs and what they're capable of, but thanks for your concern.