I would just use the 71+ cam, yes. You want low RPM, so that cam should work very well. I would just start with a locked dist (lean burn, or otherwise locked stock) and just set it to 20 deg advance. That will work pretty well over all ranges. Fortunately, the 225 is very tolerant to ign advance variations and it will start an idle just fine at 20-25.

Lou

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Home of Slant6-powered fun machines since 1988

I missed this thread with the initial questions. A Cam for both NA and boost doesn't exist. Way too much at odds.

If you've gone boost at this point your in unexplored territory as far as I"m concerned. I have a mix of stroke and long rod NA.

Not entirely sure what DI built. He does some good stuff, but he did a few things that I might have done differently based on my experience.

If your on boost at this point, I have nothing to offer you. NA is a different story.

PM if you are looking for NA experience.

CJ

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Part of Tyrde-Browne Racing

Interesting saga, lots of ideas here. I like the whole endeavor.

However, if I understand the situation here, this is a noted deadline endurance track car. Adding say up to a 50%? power increase out of the box, will change so many aspects of the on track experience, the engine will be way down the list of items needing attention IMO. Since everybody has limited time, I'd suggest the compromises needed to get the boosted engine in the car and on the track to start sorting all the new challenges a 50% power increase uncovers,, from driver skills, handling, balance, brakes, brake cooling, pads, brake fluid, brake balance, tires, higher cornering speeds with oil control, trans, u joints, DS, rear end, engine cooling, fuel slosh, etc, etc

The op has a full plate, I suggest KISS.

Yeah... that's why you should read the entire post...I just sold him a set of long rods, pistons, and rings...nothing else...

This thread is a winding chronicle of Frank trying to repower the Lemons Dart with a bunch of mismatched performance parts he got good deals on from various sources. As of halfway down the first page, we were all set to put together a long rod NA 225 with big valves, 9.6 SCR, and an OCG 346 cam regrind.

Then I saw Shawn Pohlman's turbo setup for sale at a very reasonable price. Our eventual plan was to add forced induction anyway (along with another big-valve head with lower SCR), and this removes most of the head-scratching and design work, so we decided to pull the trigger and skip the NA build. Luckily I already had a stock head fresh from the machine shop that I previously picked up from Wesola at a great price, so we'll use that head and not sweat the big valves for now. Should be more than enough power as-is.

Now I just have to assemble the engine, get it mounted in the car with the transmission that Bob is rebuilding, install all the turbo parts, and adapt the exhaust from Shawn's truck into an early A-body... and figure out where to fit the intercooler. I'm sure it'll be fine.

The rest of the car is pretty well sorted at this point. Our brakes will be taking more abuse, but it normally takes us 2-3 races to use a set of front pads. I already drive the wheels off this car in the corners, so I don't see our cornering speeds increasing all that much. Suspension is fairly tight with mostly FF parts, and it under-steers a bit in its current form. Already running a big 22-gallon FIA fuel cell. My biggest concern is how one of our less-mindful drivers is going to behave with another 60-70 HP at his disposal. I plan to put the fear of God into him before his stint, and call him on the radio every other lap to ask what the gauges are reading.

I expect there will be some teething issues, but that's all part of the fun with Lemons. I think if we spend more than half the race actually on track with this rig, we'll exceed the Judges' expectations.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Sounds great, Frank. The judges will really love this compendium of partz and you should score major points for "sculpting" the old iron.

Happy building,

Lou

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Home of Slant6-powered fun machines since 1988

One question I forgot to ask. How should I degree the stock '73 camshaft for a turbo application? Keeping in mind that the engine will be ~8.6 SCR, using a blow-through carb, and we want to avoid detonation at all costs.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

I would say shoot for 106-108. You would probably make more NA power at 102 or 104, but retarding a bit from that will protect against detonation.

Lou

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Home of Slant6-powered fun machines since 1988

I installed the cam straight up (or as close as I could get the two dots to straight up, which looks to be slightly on the retarded side). Then came an extended learning process wherein I fabricated a small bracket to hold a pushrod vertically on a lifter, made several adjustments to my janky dial indicator stand, and became very confused until I realized I was measuring #1 exhaust instead of #1 intake.

Taking measurements at 0.050" lift (on the lifter) on both sides, turning in the direction of engine rotation, I calculate an intake centerline of 107° ATDC. This could easily be a degree or two either way based on my newbie measuring skills and less than perfect equipment, but since I'm right in the middle of the range Lou recommended, I'm deciding not to worry about it.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

I always figure the real error for this centerline measurement is around +/- 1 deg, even if you are very careful. That much error will not affect how it runs, perceptibly.

Lou

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Home of Slant6-powered fun machines since 1988