Building a Nitro-Blown Cadillac 390 V8 for a Vintage Dragster Inspired by Pancho González

*Update! In the time since this story was first published, the engine has been installed and is running. Scroll to the bottom of this article to see (and hear!) the video of its initial fire-up.

A little over a year ago, we told you the story of Pancho González, a tennis superstar and hotrodder who once helped set a World Gas ET record.

You can listen to our interview with Pancho’s family members Richard and Greg Gonzales in this episode of the OnAllCylinders podcast:

In that earlier article we alluded to the efforts of the Gonzales family to recreate one of Pancho’s former dragsters, and we’re happy to report that the car is coming along nicely. More importantly, we got into contact with the guy in charge of assembling the dragster’s iconic 390ci Cadillac OHV V8, master engine builder Hugh Reynolds of Reynolds Machine in Bakersfield, California.

Hugh Reynolds’ mentor was none other than famed SoCal engine builder and drag race legend Ernie Hashim.

Hugh has decades of experience building high-power motors for drag cars, and he generously supplied us with a trove of handwritten notes, data sheets, and photographs of the Cadillac motor’s evolution from bare block to a blown, race-ready dragster powerplant.

What follows is a compilation of his notes during the Cadillac engine project:

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Building a Nitro-Blown 390ci Cadillac V8 Drag Race Motor

By Hugh Reynolds of Reynolds Machine

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I was asked to build a 390 Cadillac engine to be used in a recreation of a Top Fuel dragster owned by Pancho González. I located a 1959 Cadillac 390 block with only 60,000 miles on it. It turned out to be all standard with very little wear.

To prepare the block, we cleaned and magnafluxed it.

Then we plugged all the bolt holts with bolts into the water jacket to prevent obstructing the threads. Then we filled the block with paver stone anchor cement. We then pre-honed the cylinders and surfaced the block 90 degrees with BHJ style plates.

Engine Bottom End

At this point, I did not feel that the upper main webbing up to the cylinder was adequate to support the thrust on the crank, from the nitro and supercharging.

So, I engineered and fabricated one inch thick, three inch tall splayed main caps from 4130 steel that would tie into the pan rail with 7/16 inch bolts at a 25 degree angle. I cut four pieces to the desired length, clamped two pieces together in a lathe with a four-jaw chuck and bored a semi-finished housing bore in the four caps. I machined the parting line flat in a Sunnen cap cutter.

I then clamped all four caps together upside down to machine all the caps with a step cut to fit into the block recess to the center caps. Next, I located and drilled all the center main bolt holes—at this point I also machined the 25 degree angle for the side bolts and drilled the bolt holes.

Before going further, I mocked up the caps and found I had to taper-cut the sides to clear the oil pan.

I mounted the caps by the center studs, laid out the bolt location, and mounted the block in the Bridgeport mill. I mounted the block mains-up to drill the block and tap the pan rail—all in the mill.

I then align bored the block to 0.003″ and finished the mains with the Sunnen line hone.

Rotating Assembly

Now we had to deal with the crank.

The one inch crank snout was too small for a blower and pump drive, so I had Marine Crankshaft out of Long Beach, California install a crank snout for a 350 Chevy for more strength.

There were no strong rods available for a vintage Cadillac 390 V8, so we used 6.535 inch Manley I-Beam Connecting Rods originally intended for a Big Block Chevy. I narrowed the big end to fit the 1.75 inch wide crank pin with 0.020 inch side clearance.

This also resulted in me narrowing the Clevite rod bearings, 0.060 inches each.

We stayed with a 0.990 wrist pin diameter and had custom JE Pistons made.

Once the parts were finished, we mocked up the engine—and we found that the rods had to be ground to clear the camshaft.

After the engine mockup and the rods were clearanced for the cam, I balanced the engine.

The new Manley rods were much heavier than stock, so it required four 1 x 1-1/2 inch Mallory metal weights to balance the crankshaft.

At this point, I modified the timing cover for a larger seal. I machined a 3/8 inch thick ring to center around the inside flange of the stock seal. This centered the adapter which I brazed onto the inside of the cover. That allowed me to center off the old seal area and cut it fit a larger Chevy seal—I used a Fel-Pro seal for a stock Chevy 350.

Short Block Assembly

Richard [Gonzales] and Ed Iskendarian were able to supply a Cadillac solid flat tappet camshaft ground for nitro, along with performance solid lifters with cam oiling holes.

We were able to use a Cloyes true roller timing chain and gear for a small block Chevy.

Now I was able to confirm all clearances, checking every rod and main for connect clearance. I also checked the end gaps on each ring: 0.024 and 0.026 inch, top and second, respectively.

At this point, I could finish the short block assembly, degree the cam, and install the front timing cover with the cam button retainer and thrust set to a 0.005 inch clearance.

I was able to order single studs, bolts, and washers from ARP for the mains. I used Clevite H-Series Rod Bearings (CLE-CB743HN) and Clevite Main Bearings (4119M).

Cylinder Heads

The Cadillac’s cylinder head work was done by David Mattox. He cleaned and magnufluxed the stock heads, and pressure tested them. He installed K-Line bronze valve guides, diamond-honed to size. The heads were surfaced and ground, with full port and polish work, and fitted with 1.625 inch Manley Severe Duty Series Stainless Steel Valves. The combustion chambers received an O-ring service and were fitted with 0.037 inch stainless wire rings.

When finished, the combustion chambers measured 71cc.

The rocker arm assembly was completely rebuilt, equipped Isky dual valve springs, cut for spring cups, and fitted with 10 degree retainers and locks.

We then port-matched the heads to the intake and picked up a set of Smith Brothers adjustable 3/8 inch pushrods.

As with the engine bottom end, we ordered individual hardware from ARP to make a custom cylinder head stud kit.

Fitting the Blower & Final Touches

Next, I cut a custom valley cover out of 3/8 inch aluminum plate and machined bolt holes for installation. At the rear of the plate, behind the bower, a hole was drilled for the oil fill tube.

On the final stretch, I installed the stainless O-rings into the heads and installed the gaskets I custom-ordered from SCE.

From there, I chased all of the thread holes in the block and installed the cylinder head studs and heads. Next, we put in the rocker assembly and pushrods and then set all the valves.

I shortened the rocker studs to mount the rocker arms, so we could retain the original Cadillac valve covers.

To top it all off, we painted the block, heads, and valve covers—yellow, per the Gonzales family request.

Finally, we reinstalled the valley cover, intake, and blower and sent the whole engine to Butch Bowers for him to drop onto the dragster chassis.

~Hugh Reynolds, Reynolds Machine

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Epilogue: The Caddy Engine is Reunited with the Chassis

Once Hugh finished the engine build, the motor was summarily shipped off to famed dragster restoration ace Butch Bowers in Washington State.

Butch took over for the previous leader of the González dragster recreation project, Wayne “The Peregrine” King, who passed away this winter at the age of 81. Wayne was one of the original members of the Smokers Car Club of Bakersfield, California and an influential figure in drag racing for decades. Godspeed, Mr. King.

Butch fitted the engine back onto the chassis, and installed the belts, fuel cell, and most of the other critical parts. Now he’s slowly taking things back apart for paint before final assembly.

We spoke with Butch to learn about the dragster’s progress and he’s optimistic that it will be ready to go for the Wally Parks NHRA Nostalgia Nationals this October at one of Pancho’s old stomping grounds, the iconic Famoso Dragstrip in Bakersfield, California.

Video Update: The Engine Lives, Hear it Roar!

After this story was initially published, we got an update from Hugh Reynolds and Greg Gonzales. Here’s the dragster in all its glory:

The engine is in the chassis and it’s running strong. And it’s wearing a paint scheme faithful to the original dragster.

The plan is to have the dragster ready to rock in time for the 2023 Wally Parks NHRA Nostalgia Nationals at the historic Famoso Dragstrip in Bakersfield, California this fall.

According to Hugh, the engine is running great with alcohol already and, with a few more tweaks, it’ll be ready for nitro. See the initial startup in the video below:

The Pancho González Cadillac 390ci Dragster Engine Quick Specs