Projects 1964 PONTIAC 421 HO Engine Build

Nothing really new to report on the 421, the heads are being finished up and we're still waiting on the custom Ross 26cc dished pistons that I ordered almost 3 weeks ago.

To keep moving on the drivetrain I dug out my old 13" Continental converter that has been sitting under my workbench for over a decade, so I could send it in to be checked out and have any updates that might be needed done to it.

The TH400 that I had been previously running with this converter had some issues. It had developed a noticeable vibration while accelerating in second gear. I removed the transmission pan and there was about 1/4" of fine gray debris covering the entire bottom of the pan, friction material I presume.

So rather than reuse this converter with my new TH400 I figured it would be wise to send it back to Continental so they could cut it open, clean it, check it out, refurbish it and send it back with a clean bill of health.

I had been running this 13" converter behind an 8.2:1 455 (462 cubes) with the 068 cam/1.65 rockers, 1966 Tri-Power and 1967 GTO repro HO/Ram Air exhaust manifolds, backed up by a 2.56 open rear and 25.3" tall 235/45-17 tires.

The new 9:1 421 (429.7 cubes), 068 cam/1.5 rockers, 1964 Tri-Power and standard log exhaust manifolds backed by another 2.56 open rear and 25.8" tall 215/70-14 tires should work quite well with this same converter build.

 

Wow, that convertor box and convertor looks familiar; I think I have seen some of them around here.
Tom

 

The new Ross 4.135" bore 26cc dished pistons have arrived at the machine shop. They took a little over 5 weeks from the day they were ordered to arrive, not bad at all for a custom order.

Now this project can get rolling again.

 

Waiting patiently to hear it roar.

 

Everything is finally back from the machine shop so now the actual engine build can begin.

The block prep began with some deburring of the lifter gallery and just generally removing any sharp edges inside of the block. The outside surfaces of the block will not be touched with the grinder, these nicely cast 421 blocks looks great just the way Pontiac left them.





The original style front oil gallery soft plugs will not be used on this build, the openings have been tapped for 3/8 NPT pipe plugs as part of the block prep.



Our machine shop did their best to bore the block the absolute minimum amount possible for bore clean up. You can see what's left of the ridge reamer fiasco that caused me to buy new pistons, those nasty chatter marks are all above the ring travel so they are of no consequence.

 

Things are moving along quickly now in spite of the 100+ degree heat we've been experiencing during the past week. I have to give huge props to my builder for continuing to forge ahead on this 421 project.

The block prep and cleaning was finished to the point where the painting could be done.



Brass core plugs installed.



Front oil gallery plugs installed. Note the grinder work done to help improve oil drainback to the pan from the lifter valley.



Brass oil gallery plug drilled with a .030" bit to positively lube the distributor drive gear, this drilled plug came in the H-O Racing oil gallery plug kit.



Heads came back looking great, we used readily available 1.96" and 1.66" stainless valves with .100" longer stems, with the heads cut down to 1.93" and 1.645" respectively to eliminate any possible valve head to valve head interference. The original valve sizes were 1.923" and 1.663" according to factory specs. There's simply no room to enlarge the valve sizes, they're just too close together.



The original trouble-prone press-in rocker studs were pulled out and the rocker stud bosses were milled down by .250" to make room for the bottom hex portion of the screw-in studs we're going to install.



Close-up shot of one of the rocker stud bosses showing one of the 7/16-14 Heli-Coils that were installed.



One final check of all of the combustion chamber volumes was performed so we'd know exactly where we stand compression-wise. It turns out we gained a couple of ccs during the final head work. This was likely a combination of the valve seats getting cut deeper during the valve job and the added volume of the small depression in the center of the new stainless valve heads as compared to the flat original valve heads.

All of the chambers checked out between 76.4 and 76.6 ccs with the exception of one stubborn chamber that came in at 75ccs. After some touch up that one ended up at 76.4 ccs. We originally carefully guestimated the heads would end up in the 74+ cc range with the final compression ratio at 9.05:1 before buying the 26cc dished Ross pistons. Now we're looking at 8.87:1 and that's fine with me, it gives me some breathing room on hot summer days running 91 octane in this A/C equipped auto trans car with tall 2.56 gears.



Now that they've met our standards the heads are getting masked and ready for paint.

 

Just a small update as we keep moving along. The heads have a nice coat of Pontiac Light Blue paint now, and the pistons have had the dish volume checked.

We found that the 26cc dished Ross pistons are actually 27.2 ccs after checking two of them. This puts our compression ratio down just a bit lower again, calculating out to 8.79:1 if our projected deck height works out. We will do our final calculation after the bearings arrive and we can check the deck height.

Still just fine at let's call it 8.8:1 compression. This gives me confidence that I'll never get into detonation in hot weather while running the A/C and the engine can likely tolerate a tank of 87 octane if the need ever arises, such as if I can't find premium out on the road somewhere.

 

We are now ready to begin assembly of the 421 short block.

First order of the day was to install the cam bearings. Since we have the proper tooling at hand here to install them and to insure they're installed with the correct oiling hole orientation we didn't have the machine shop do the work, plus it helps us to save a little on outside labor costs. Anything we can do ourselves will be done here at home not only to save on labor but to help insure the best possible quality control.



The next very important step is to test fit the cam, this is something you absolutely must do before installing the rotating assembly. While test fitting the cam it went smoothly into the first 4 bearings and became tight when entering the last one. To remedy this issue a cam bearing reaming tool was used to shave off a little babbit from the offending bearings. Having to ream the cam bearings is not unusual at all, most Pontiac blocks have some misalignment of the cam bearing bores.



Here is the tool that was used to ream the cam bearings. This tool was made from an old cam with all of the lobes ground off to prevent damage to the bearings, each bearing journal was modified to form a cutter.



BOP Engineering viton one-piece main seal. This seal is the latest technology in Pontiac rear main seals.



After checking the main seal fit in the block with the rear main cap tightened it was determined that it fit the machined receiver groove in the block perfectly with just the right amount of compression.



Main bearings in place ready for the crankshaft install. All main bearing clearances were checked with the proper measuring tools. After shuffling around some of the bearing halves all the clearances ended up between .0023" and .0024" so we're looking good there.



Here is the 4.00" stroke Armasteel 421 crankshaft after balancing, heat treating and being ground first undersize to .010"/.010". All of the oil passages were thoroughly scrubbed out with rifle brushes and it is now clean and ready to install.



No helpers were present to help install the heavy 80+ pound crankshaft and BOP one-piece main seal at the same time, so an engine hoist was employed to help accomplish this important and somewhat delicate task.



Crankshaft now installed, main caps have all been torqued to spec using the original factory hardware.



Checking fit of the original cast aluminum rear divider plate to the water pump impeller.



Closeup of impeller to plate clearance.



After years of running the thermostat bypass hole in the aluminum timing cover tends to grow in size due to corrosion, they usually start out at about 3/8" diameter. This one had grown to nearly 1/2", so it was about the perfect size to accept a 3/8-NPT pipe tap. The stainless steel pipe plug was drilled out with a 1/4" bit to allow enough bypass water for proper functioning and also to limit the amount of water than can bypass the radiator.



Water pump and timing cover assembly completed.

 

I am trying to understand the installation of the one piece rear seal, it looks like quite a trick. Can you give me an overview?

Big fan of Wade from BOP, by the way.

-Abone.

 

X2 on the one piece rear seal installation.

 

The seal installation procedure calls for the installer to slice it in one place with a sharp new razor blade, this enables you to work it onto the sealing area of the crankshaft. So you're still working with a one piece seal that has only one seam to seal up and not a 2-piece unit that has 2 seams.

Other than that I really can't say. I'm over 100 miles away from the action, my job in this build is to provide the funds and whatever technical input is deemed necessary to get everything done to my liking.

 

Should be a runner!

 

Thanks for the follow up on the one piece rear main seal. I couldn't fathom how to get it past the rear flange; cutting the seal makes sense.

This has got to be a major improvement over the factory rope leaker (can't really call it a seal!)

 

While we're waiting for the connecting rods to come back from being reworked due to a bushing installation issue we caught up on some of the engine detailing work.

When you get bored from sitting around waiting for the 'meat' of the project to get under way again, you find the time to get some small things cleaned up and painted.

A bead blasting cabinet is pretty much indispensable for us folks in the old car hobby for getting things cleaned up in a timely manner. These are the intake manifold bolts, note how much thicker the hex heads are on these 1964 bolts as compared to 1965 and later Pontiac intake bolts.



Oil filter adapter, head bolts and timing cover hardware. Everything you'll see on the outside of this engine will be OEM hardware. Just about the only hardware on this 421 that won't be 50+ year old factory issue will be the bolts in the Crower rods and the ARP rocker studs.



PCV nipples, hot air choke tubes and throttle cable bracket. Later on I might have the throttle cable bracket plated in the correct finish.



New aftermarket harmonic balancer and factory A/C pulley set, all painted the correct Pontiac Light Blue.



The flex plate has been neutral balanced along with the rotating assembly. Should I ever decide to use a stick shift trans in this car I can easily swap on a neutral balanced flywheel.



A check of the crankshaft end play shows that we have .006", right in the middle of the factory spec of .003" to .009". Very happy to see this.

 

Moving right along now that the connecting rod bushing issue has been taken care of.

The rods were rebuilt at Crower and arrived looking like new. New bronze bushings for our floating pins were installed but the big ends didn't need any work. They were carefully checked out at our machine shop before being shipped to us.



Crower spec sheet supplied with the newly refurbished rods.



Piston ring end gaps were checked and they were a bit tight at .014", our rings were supposed to be a non file-fit set. The ring ends were ground to achieve a .019" top and .021" second ring gap. Check everything, leave nothing to chance.

Pistons have been assembled to the rods and are now ready for installation.



All piston/rod assemblies are now installed. Piston deck height worked out to be .007" to .008" above the deck, giving us a nice tight quench distance of .037" to .038" with our .045" thick head gaskets. We were shooting for .005" above the deck with the new pistons, plenty close enough.

Our final compression ratio calculation now ends up at 8.82:1 using pistons .007" above the deck as our number.



The NOS 068 cam was to be installed at the factory 113 degree intake centerline. Using our Cloyes timing set we ended up at 112.8 degrees using the straight-up marks on the timing sprockets, you're not going to get any closer to hitting the mark than this.



Our Melling Select oil pump was a little sticky, upon disassembly some debris were found along with some dried up preservative that was causing the sticking. After a thorough cleaning all is well.



Pickup height was set while the pump was apart and then tack welded to secure it. Bottom plate was torqued down with some blue Loctite on the bolts and it's ready to go.

 

A few more pictures of our progress so far.

Here's the oil pump mounting hardware kit from H-O Racing that I pulled from my collection of parts, purchased probably 20+ years ago.



The oil pump mounting studs were installed in the block using blue Loctite.



The finished oil pump assembly is now installed along with the pump driveshaft, never forget the driveshaft! Pickup to pan clearance was set at close to 5/16" and checked using wadded-up aluminum foil prior to tack welding the pickup in place.



Blue Loctite is your friend.



The camshaft lobes have been liberally lubed-up with the proper moly-based assembly lube for a safe break-in cycle.



My builder's choice of cam and lifter lube.



Cam sprocket and fuel pump eccentric are now installed and torqued down for the final time after the camshaft position checking. There's a little bearing lube in between the sliding faces of the pump eccentric just for insurance.



Clevite bearing assembly lube. It originally was marketed as Michigan Bearing Lube, but Clevite bought them out a few years ago. Still the same stuff, and it stays nicely in place.

 

I see all those stock knick nack brackets and doohickeys and all I can think of is how much of that stuff I have tossed in the scrap pile over the years.

Sorry.....

-Abone.

 

Kind of reminds of the old-time rodders who scrapped the big stock headlights from their '32 Fords along with the fenders while building their cars.

Only to find out later on they threw some valuable stuff in the trash.

Sad, we all live and learn.

 

The 421 is a very special Pontiac engine with a lot of racing and hot rod history.

If I could afford to build a 421 Super-Duty I'd do it in a heartbeat, but I had to go for the 421 HO instead to try to stay within a somewhat realistic budget.

 

Being a Pontiac fan from way back (455 in a G-body G/P in my street racing days) I`m really enjoying this thread. Looking forward to more.

 

How much closed seat pressure on those valve springs? You might want to consider cam break in with a set of used stock springs then changing to the new springs after break-in
Nice project.

 

According to the valve spring spec sheet we should have 124 pounds on the seat at our 1.560" installed height and less than 247 pounds over the nose at the factory lift spec of .407", that 247 pound spec is for .450" lift and we're not going that high.

I really don't think we'll have any issues during our cam and lifter break-in with the current springs. I think most of the cam break-in issues of late are caused by soft off-shore lifters, inferior cam cores and aggressive cam lobes on today's quick-acting aftermarket cam profiles that seem to be so popular.

The NOS Pontiac cam I'm using was likely produced over 40 years ago, so it is made of excellent quality materials. The lobe profile is fairly lazy-acting compared to more modern cam profiles and easy on the valvetrain, so it's really not likely to wipe a lobe during break-in. The Johnson Hylift lifters are also made of very high-quality materials and are USA made with exacting tolerances.

Part of the reason for using the factory cam was to avoid problems during both break-in and down the road. I also wanted to experience as much of the original 'feel' of the 421 HO as possible by running the OEM camshaft for the 370 HP version of this engine. It's really not a bad thing to take advantage of the all-around good manners offered by a factory performance cam, along with longer life from parts that were engineered to keep on going long past the warranty period.

 

Love it. Its looking really great. I also had a 455 in my gp and was very happy to tell the mustang guys after I let them catch up to me.

 

Knowing that I would feel more comfortable as well. I too have saved several BBC cams as well as GM lifters from the 70's.

 

Wow, all the stuff you only learn from someone that's don it. Got a box of parts on its way from Butlers to build up my 400 blower motor, subscribed !!!

 

Finishing off the small details on the bottom end assembly so we can get the oil pan and front cover installed and call that part done.

Stubby block dipstick tube used on 1964 and earlier engines, I'm not exactly sure how many years back this dipstick tube style goes in production but here it is pressed into place.



The bottom dipstick guide tube is held in place by inserting the upper end into the block tube and the lower end is retained by the windage tray. Interesting to note that this style of windage tray bowed out after the 1964 model year, but this same design was revived for a very special and super-rare Pontiac performance engine, the 400 RAV tunnel-port in 1969.



Oil pan and front cover assembly are now installed, sealing up the bottom end and finishing off that part of the engine assembly. The Butler head gaskets are shown here in place ready for the heads after spraying the metal side of these composition-type gaskets with copper coat.

I've used these gaskets on several previous street engine builds and they've been very reliable. However they're just not a good gasket choice for a race engine that comes apart on a regular basis, only because of the need to tediously scrape off the black composition material from the block deck surface when changing them out. For something that's going to see many years and tens of thousands of miles before any possible future head removal they're perfect.



The heads have now been torqued down to factory specs using the original 1964 head bolts. The upper dipstick tube has been attached to a studded head bolt, one of the 2 special longer head bolts used on factory A/C installations that retain the cast iron A/C compressor mounting bracket. Non-A/C upper dipstick tubes will attach to the valve cover bolt.



A/C bracket shown here.



Here the valve cover to rocker arm clearance is checked using some wadded-up aluminum foil. Using a standard 1/8" cover gasket shows we're too close, the covers will end up getting damaged if we snug them down. A set of 5/16" thick gaskets will do the trick here. I knew we would either need valve cover spacers or hopefully only thicker gaskets to clear the polylocks and rocker tips.



Using the standard 1/8" thick gasket the polylock was right at zero clearance and the tip of the rocker arm had .087" clearance to the valve cover. Shown here is a cross section of the clay at the tip where we got this measurement. We're being extra careful here because nice '64 GTO chrome valve covers are not easy to find in excellent original condition.



After doing a full mockup on the pushrod length and doing the math, we ended up at the length of a stock pushrod after all the effort. Stock pushrods out of my 421 engine are 8.672" according to my reference book and measured at 8.675" with calipers.

The Johnson lifters have 1.7 turns from zero lash to bottom which works out to about .085" distance. The pushrod length test was run with the lifter collapsed and then subtract the lifter travel less .025" (half turn) preload or in this case .085" - .025" = .060" to subtract. So the 8.732" test pushrod length minus .060" equals 8.672".

Here are the new Manton pushrods. They were ordered on a Wednesday morning over the phone at around 10AM and arrived via UPS on Thursday afternoon, now that's service. Manton is located a few hours north of us, so one day delivery is a snap. The length specified was 8.670" with a wall thickness of .118", made from chrome moly tubing with a hard melonite finish.



After installing one of the new pushrods we can see the rocker tips are tracking nicely as shown by the travel pattern on the red valve tip. The new ARP 7/16" straight screw-in rocker studs have all been torqued into place.



The new Crower Enduro stainless steel 1.5:1 roller rockers were given a nice long soaking in motor oil before installing them for the final time.



Rockers installed and adjusted, the top end is pretty much complete at the point. This valvetrain is overkill to the max, so reliability will not be an issue here. The ARP rocker studs, Crower rockers and super-stiff .118" wall pushrods won't flex with the mild spring pressures and low-lift I'm running. I see this as a very good thing to keep the pushrod guide slots in the heads from wearing out prematurely.

I won't be pulling over to the side of the road to replace a broken rocker or pushrod, or to pound any old press-in rocker studs back in that have started to back out of the head.



More evidence of machine work that's on-the-money. After setting the lifter preload the polylock heights are all the same after checking them with a straightedge, telling us that the rocker studs are all the same height and the valve seats were all cut to a uniform depth.



Pressurized the system and oil pump is right on the money at 60psi, surprised how quickly all the rockers got oil. We normally don't worry about that because things always work out, but this time every rocker had an oil bath without turning the crank.

 

You put that expensive engine on a three wheel engine stand?????
Nice build, of course I just finished a 400 (408), 092 heads, 068 cam, 2x Rochester 4jets. Rick

 

Rick, have no fear. My builder knows how to handle things, he's had almost 50 years of experience building Pontiac V8s and I trust him 100%.

Best of luck with your dual-quad Pontiac 408, should be a fine runner.

Bart

 

The engine assembly is now complete.

Here we're doing a tilt test to check for static rear main seal leakage with 5 quarts of oil in the pan. So far so good, we'll leave it tilted like this overnight just to be sure. Next it goes on the test stand for cam break-in.



Note the carb block off plates for the outer carbs, this way we only have to deal with the center carb during the initial run-in.

 

Can't wait for the fire up.