[Video] This dragster has a homemade 4 cammed, hemi-headed 360 on nitro (1 Viewer)


Nitro Member
I found this on youtube.



from the description:

Tom Dicktakes' homemade 4-cam hemi. Based on a Donovan 417 block, Tom has spent 40 years building the 4-cam heads out of his garage with a Bridgeport and an Atlas lathe. Here's a fire up on alky after Tom put the motor back together after it hurt the bottom end last year on a test run at Sacramento raceway.

My usual job is to start it and then check oil pressure and cylinder temps to makes sure there isn't any of them running too lean. We were down a guy today, so Tommy had me manning the fuel for the first time, hence my constant look of concern throughout the whole video. You can't see it, although you can see the red air tank on the bottom- but I'm standing by a pressurized fuel tank so after the motor is primed and started on gas (the squirt bottle) I bring in the alky with a regulated valve on top of the auxilary fuel tank.

While the motor is running I'm monitoring the amount of fuel by the RPM (an electronic tach is in the seat) and the misting at the pipes. You can hear the engine pick up as soon as I dial back the alky a bit. I'm also trying to get a look at the oil pressure at the top end of the motor. All my pointing is to show Tommy that we're down on pressure. We shut it down because the pump feeding the top end with oil didn't come up to full pressure.

You stop the motor in reverse- I reintroduce the gas in the primer bottle as I slowly close the fuel tank with the alky, so it runs on the bottle and I can shut it down with gas.

More work in the garage! Next time we should do another fire up to make sure the top of the motor is getting enough oil, then if it works, we'll be ready to take it out to the track again and run it on nitro.

Here is a tour of the engine:


A quick look at Tom's 4-cam hemi. Tommy made the heads, which are the aluminum plate pieces that all the stuff is mounted to. The heads are mounted to a Donovan 417 block, which is based on
the 392 Chrysler hemi - only Tommy wanted stronger sleeves, so it's down to 360 cubic inches. The good part is the valves are lighter than normal fueler valves and with the overhead cams doing away with the regular pushrod configuration he should be able to wind the motor tighter before the valves float. The cam drive is all helical gears at the front of the motor, and he's got it set up to be able to pull a pin during the run and retard both the cams and the mags.

OOF. It blew up :(


Registered member said:
Watch the guy in the fishing hat, at 1:54 he pulls the fuel shut off, the engine leans out as it begins to die , they changed their minds or whatever and the fishing hat guy turns the fuel back on and then BOOM!,.

Bummer. Gotta hand it to the guy, tho. Hopefully he gets it built again and has some fun racing.


Nitro Member
Just a question: I heard somewhere that NHRA banned OHC motors because they wouldn't be strong enough for nitro. Is this true?


Nitro Member
Just a question: I heard somewhere that NHRA banned OHC motors because they wouldn't be strong enough for nitro. Is this true?

Might want to check this old thread Sam...


The valvetrain was certainly more stable. There was a period where the hemi style motors were having catastrophic failures. To their credit some of those problems were corrected. A couple of respected crewchiefs came to us hoping that the 4-valve with no pushrods or rockers would eliminate the carnage and keep their drivers safer. Any performance gain would then be "icing on the cake". The block was also considerably stronger which was good and bad. The headbolt layout was a lot better and we seldom pushed out head gaskets. The only trouble was that if you broke a pinion or driveshaft and hydrauliced the motor you could push the crank out. On the 426 style motors, as ridiculous as it sounds, the headgaskets act like a secondary burst plate! Today the 4-valve engine would have more potential on 90% than it did in the unlimited nitro days.
Chris McGee.

We had come from a fairly successful background in oval track. After witnessing our first Top Fuel race we came away with the opinion that “these are the most awesome cars on the planet”
It was only natural, with a background racing overhead cam engines (our dad was the Meyer Drake “Offy” distributor in Australia), to ask the question why hasn’t someone done this before?

The first version of the engine was very much like an Offy with integral blocks and heads. Although powerful and strong it was very difficult to work on. In 1986 the motor was redesigned to a more conventional configuration and was actually faster to service than a Chrysler.

Obviously building a motor is just a small part of what is required to field a race team.Most of the “motor” problems had nothing to do with the motor. When you try to build more power you identify a lot of other weak links on the racecar. With the torque of the 4-valve engine we had a succession of catastrophic drive train failures and expended an enormous amount of time and energy making everything else on the car, better. As it started to run properly we started to burn it up and had to make bigger fuel pumps and barrel valves.In any combustion chamber when you have detonation it will damage the most vulnerable area of the chamber. On a two-valve motor a trough gets burnt between the exhaust valve and the plugs. With the 4-valve engine it would pick on the area between the exhaust valves. We made one piece dual valve seats that took care of that and we ran the last few years with a half dozen heads being rotated in service.

Finally we did start to run well. We bought a state-of-the-art chassis, hired a champion driver and assembled an experienced crew. We purchased the best clutches, superchargers and ignitions available and began to make respectable runs. At that point we began to qualify for most of the races, sometimes in the top half of the field, and occasionally won some rounds. We broke into the 4’s in 1992 with Gary Beck driving.

We went from being laughed at to being the subject of a lot of behind-the-scenes secret meetings with engine builders, auto companies, team owners and race officials. Long before the rules were written, in 1997, to outlaw overhead cam, multi valve engines, most of the teams had been scared off realizing that any advantage with the engine would be negated by added weight.

Today Phil and I are racing with our kids and having fun. Our dad, Hedley, was inducted into the Australian Speedway Hall of Fame in 2007. We still have some unfinished business in the world of fuel racing. We will be a part of fuel racing again. Visit Mcgee Cams Jr. Dragster Racing or Kaitlyn McGee Racing for more news. Chris McGee.
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Nitro Member
Wasn't there some talk of a multicam fuel engine making an appearance in Adrl next year at 50% Hmm Just thinking..


Nitro Member
I've seen this car self destruct on the stands in the pits. It is AWESOME. and scary as ****. I won't pit anywhere around him, and I'm not alone in my thoughts. "twin cam tommy" has been a staple of Sacramento Raceway for 40 years.

McGee had a 4 cam motor 'back in the day' too. not 100% sure why they were beat down by NHRA.
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