CAM SPECS! CAM SPECS! CAM SPECS!
While picking up our 1965 Mustang vintage racer–or, maybe more appropriately, future vintage racer–from Cobra Automotive, we also purchased a used race engine. We did the math, and it just seemed like the better option.
So, what did we get?
This 500-horsepower race engine is centered around a Dart block topped with World Products cylinder heads. The engine was built about eight years ago to meet HSR Group 3 regulations.
These rules require an iron block and iron heads, with our Vintage A-Sedan class (S/2) class mandating either 289 or 302 cubic inches.
If you run a 289, the required dry weight of the car needs to be 2700 pounds. When running a 302, the rules require a dry weight of 2800 pounds.
While the hundred-pound weight advantage sounds enticing, the reality is that you’re just not likely to get an early Mustang down to 2700 pounds. We figured that we might as well go with the bigger engine.
An overbore is allowed, too, we should note. Generally, in vintage racing, an overbore of 0.030 is allowed, which turns a 289 into a 292 and pushes a 302 to about 306 cubic inches.
Our perfectly good 302 had been run less than 100 hours since a bottom-end rebuild and refreshing in 2012. Cobra Automotive pulled it from a customer’s race Cougar–that customer had decided to move up to Group 5, which would require a more expansive engine build.
We were offered the engine for a more than fair price of $7500, and purchasing it solved one of the major parts puzzles in putting our project car together.
The engine was also complete right down to the plug wires and plugs. Only the headers, alternator and carburetor were missing. Again, this completeness would save considerable time and money.
Here are the specs of that new engine:
Update: The hand-written engine spec sheet:
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CAM SPECS! CAM SPECS! CAM SPECS!
Those "Vintage" engines are putting out far more steam than the real deal back in the day.
While I love the sound of a 9k+ SBC or SBF, the vintage T/A cars running those are not much like the reality of the era as they ran 7500 or so back in '69. Valve spring tech has come a long way allowing not only the high rpm, but much faster ramps on the cams building a lot more power.
In reply to GCrites80s :
Let me see if I can get some for you.
Do the rules forbid a roller cam? Seems odd that such a high level engine has a flat tappet cam.
It's high comedy that the power levels for "competition" at this level cannot be met with proper "vintage" (read: actual OEM) engines. Most of us former 289/5.0-faithful know how a real SBF (non-351) will burst into pieces over around 450. Allowing for 351 blocks (427 stroker!) would seem more reasonable, given the optimistic concept of brand-faithful "vintage" racing. That said, Dart blocks are quite nice, and will do well over 500 hp for a nice lifespan (with expected yearly rebuilding). On that note, it seems that somebody might be paying a Cobra premium for a used engine. May the happiest of luck be with you.
100 hours. Doesn't sound like much - for a street car, maybe that's 4,000 miles. Considering that a typical vintage race weekend might consist of 2 to 3 half hour sessions a day, say 5 hours tops for a weekend, that could be 20 race weekends. That's a lot of hours when you are hitting redline eight times or so per 1:25 minute lap, using my local track, Summit Point, as an example. That could be 30,000 cycles to redline! Time to do a leakdown test, change the bearings, valve job, etc.
Admittedly British iron is not American iron, but my Triumph GT6 engine gets rebuilt every two seasons, probably ten weekends, and those coated trimetal rod bearings are ready to be replaced at that point. Gets all new bearings, seals, needs a valve job, gets new piston rings, new valve springs (they've lost some strength), maybe a few other things.
You could put this engine in, just to get started, but if it's really close to 100 hours, or even 50, it's going to need another refresh.
Just got a scan of the specs from the engine build, so they have been added to the update.
Thanks.
^Awesome. Lots of lift on the cam! I suppose that's what it takes to spin to 7200 RPM.
In reply to BigIron :
The big difference is in the revised, but still cast iron, head design.
Just spent a few day as a spectator at the SVRA race at COTA. When the American Iron is on the track, I could always pick out the small block Fords just from the sound. I love the "shake the ground thunder" of the BB Chevys, but the wail of the SBF's down the front straight is magic.
When I got home, the wife made me change clothes in the garage, the smell of race gas in my clothes made her eyes water.
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