Hey all! I'm moving along with my early A-Body NASCAR tribute project 1962 Lancer 170ci 4 door 4 speed car with 3.73 gears 225/50 r15's 23.9 inches tall tires.

I need help selecting a cam. I want to rev this engine above 7000 and of course as much hp as possible. I want to run it on premium pump gas and drive it to the track. And that will be the only time it is on the street. I don't have the space for a trailer...

What else should I do to the motor?

Any recommendations for pistons?

Cheers,
Barnaby

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These ones go to eleven...

talk with Charrlie_S,, he runs and knows 170's

Sounds like fun!

I will try to work up a grind based on OCG lobes. Bob Dally in Seattle (Bonneville Barracuda) has a super stout 170 and his cam is around 240 @ 0.050 and 0.530" lift with something like a 108 lobe sep angle. I'll try to get exact specs and an installed centerline.

Spend lots of time (and/or $$) on the cylinder head!

Also, I will need to know compression ratio and valve sizes and if possible about how much head work/flow to give a good cam recommendation. I would think 10-10.5:1 for pump premium should work well, with a suitable cam and ign curve.

Probably 7000 RPM is OK with stock rods and pistons, but if you have the budget then forged pistons (~$600/set), followed by custom rods (~$700/set) would be more insurance.

Yep, Charlie and Doug Dutra should have some info on 170 cams. I have never built a 170, but have info from others and from concepts.

Best,
Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou!

I agree with you on the compression, that will affect the cam selection and vise versa right?

We are definitely going to town on the head, and using 1.78/1.45 valves.

Cheers!
B

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These ones go to eleven...

The 170 is best with a wider lobe separation than the 225. It has to do with the intake flow relative to the displacement. I worked this all out when I was building the 170 race engine. You don't want as much duration and overlap as a 225 either. The original hyper-pak cam was not far off the mark duration wise at 276/268° advertised, but it used old lobes so the lift isn't up to modern standards. I would fall back to a 268/260° advertised duration on a 114° lobe separation and install it around 106° intake centerline.

Comp Cams Extreme Energy solid lobes 6054/6053 would give you 268/262° advertised duration, 230/224° at .050" tappet rise and .489/.479" gross lift. The 6054 lobe is the same as Oregon Cam Grinding #791. Ask Oregon if they have the master for the Comp 6053 as well.

Shoot for 10:1 compression ratio.

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Joshua

Thank you Josh! This is very helpful.

Cheers,
Barnaby

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These ones go to eleven...

I'm going to go to OCG on Monday with my core and the numbers from Josh.

Any thoughts on aftermarket pistons? Bang for the buck? I'm certain we'll have do do a bit of notching.

Cheers,
Barnaby

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These ones go to eleven...

Hi Barnaby,

I did get cam specs from the Bob Dally Barracuda.

INT EXH @0.050" LSA LiftINT LiftEXH Overlap, and @0.050"
268 272 239 242 107 0.534 0.54 56 26.5

This is a 13:1 motor run on straight race fuel (112 octane, IIRC). I think it's a COMP cam, but the engine builder did not give Bob a part number or anything.

For your motor and application, Josh has some very nice specs laid out there. Personally, I would go a little bigger and I would use a different (smaller) LSA. The following is assuming that you want to run and make power up to 7000 RPM, you will have at least 10:1 comp, stick tranny (or high stall conv), and a good flowing head.

INT lobe - OCG 1475:
@0.050" DUR C'line lobe lift lift @1.5
236 282 106 330 495

EXH lobe - OCG
@0.050" DUR lobe lift lift @1.5
230 268 326 489

Use a LSA of 110 deg and an installed centerline of 106 deg.

This all depends on whether you are more of a conservative cam guy, or a big lumpy cam guy. If you are the former, I would go with Josh's recommendation, except 110 (a big more high end) or 112 deg (a bit more low end) LSA.

Yet another option would be cam #346 from OCG with the only change being 110 LSA and 106 installed c'line.

For the record, I have a 257/249 @ 0.050", 0.540" cam in my 225 64 Dart street car (10.8:1 comp, pump premium), so I am a bigger cam kinda guy. Works great for me.

Food for thought, anyway...

Happy building!

Lou

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Home of Slant6-powered fun machines since 1988

A wider lobe separation actually extends the RPM range higher as the intake closes later. Smaller engine/cylinders are easier to fill, need less overlap and a wider lobe separation and this really cuts the duration.

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Joshua

Mercedes did a study a few years ago where they concluded that a 1/2 liter per cylinder is about ideal for overall engine efficiency: economy, power etc. This view tends to produce more 1.5 liter 3 cylinders in the future, as a six the 170 would be close to ideal by this Mercedes rule.

Is the 1/2 liter for 2 valves or 4 valves?

My feeling is that 2 valvers need a bit more displacement (just a hunge, no way to back that up)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Thanks for your input, Josh. I agree with your statements completely, but I don't think I would change any of my recommendations above. The cam specs I gave are still way less overlap and earlier intake closing than for a 225. If Lobster wants a somewhat more docile motor, then he should go with your recommendations.

Best wishes,

Lou

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Home of Slant6-powered fun machines since 1988

I'm just going to say one more thing. David Vizard says that there is one optimal lobe separation for an engine and that it is determined by the cylinder size and intake flow. For a 170 with a 1.70" intake valve it's about 112° (not 114° as I mentioned earlier, sorry). Anything else compromises the torque curve and power suffers. Too narrow an angle is less detrimental to power than too wide. Find the lobe separation angle first, then the desired overlap and the duration is a given.

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Joshua