Back at it - McCagh Special Cam in a �64

[Mark H.]

[Richard G.]

[Duke W.]

[Mark H.]

[Mark P.]

[Mark H.]

[Duke W.]

Hi Mark - did you do some porting work on the heads to benefit from that cam ?

Mark

Head massaging that typically yields an E/I flow ratio of about 0.8 compared to about 0.65 for OE machined heads is an absolute requirement for the McCagh Special camshaft. It's specifically designed for the 0.8 E/I flow ratio and is the reason the exhaust duration is shorter than the inlet duration. "The Tale of Two Camshafts" article is an easy Web search.

Duke

[Jeffrey S.]

[Michael J.]

[Duke W.]

[Michael J.]

[Gene M.]

Thanks Duke for the more complete explanation. I am annoyed at my '64 FI around my hilly terrain, due to lack of low end torque, but it also has a 3.08 rear end and the M20 tranny (only one available in '64) too. In considering another cam, I am also thinking about maybe putting a 4.11 or 4.56 rear end in it to help out, as I don't spend much time above 70 mph anyway and with 36 gallons I have plenty of range with lower gas mileage. I do love the 30-30 for lope and sound, and would hate to lose that.

There are plenty of modern computer grinds that will explode with bottom end and mid range. But as with most things in life ya need to give up something to gain something else. The 3.08 is not a good pairing with a long duration cam. Start there, but shouldn’t have to go as far as 4.11 or 4.56 unless your gonna drag race.

[Duke W.]

Thanks Duke for the more complete explanation. I am annoyed at my '64 FI around my hilly terrain, due to lack of low end torque, but it also has a 3.08 rear end and the M20 tranny (only one available in '64) too. In considering another cam, I am also thinking about maybe putting a 4.11 or 4.56 rear end in it to help out, as I don't spend much time above 70 mph anyway and with 36 gallons I have plenty of range with lower gas mileage. I do love the 30-30 for lope and sound, and would hate to lose that.

The LT-1 cam will provide more low end torque with about the same top end power and idle behavior, but the bottom like is that a big cam with a CR four-speed, 3.08 axle, and high altitude location is not a very good combination.

Another option is to install a Richmond Super T-10 four-speed with the 2.88, 1.91, 1.33, and 1.00:1 gear set. I think it's pretty much a "bolt-in", but you'll probably have to change the clutch disk and driveshaft yoke due to different spline counts, and I'm not sure about the OE linkage and backup light switch provision

My Excel gear chart program that I think is on the TDB and also the CF (search for threads started by me) is a good way to evaluate gearing combinations. Give it a try. The 2.88 first gear will increase first gear torque multiplication by about 31 percent. The biggest ratio spread is between 1-2, and they get progressively closer as you work you're way up the gears. It will be a much more responsive configuration.

Duke

[George J.]

Thanks Duke for the more complete explanation. I am annoyed at my '64 FI around my hilly terrain, due to lack of low end torque, but it also has a 3.08 rear end and the M20 tranny (only one available in '64) too. In considering another cam, I am also thinking about maybe putting a 4.11 or 4.56 rear end in it to help out, as I don't spend much time above 70 mph anyway and with 36 gallons I have plenty of range with lower gas mileage. I do love the 30-30 for lope and sound, and would hate to lose that.

Michael,
I have a 3:36 in my '65 FI car, and like it. You do need to slip the clutch a little more, but you can really cruise on the highway. You shouldn't need to go to a 4:11.

[Darryl D.]

Michael,
I have a 3:36 in my '65 FI car, and like it. You do need to slip the clutch a little more, but you can really cruise on the highway. You shouldn't need to go to a 4:11.

From the factory in 1965 with SHP engines the standard rear end ratio was a 3.70 and it came with a CR trans. Cars with a 300 h.p. came with a WR trans which has a lower first gear for better take off. If your car still has the CR trans I would think it would be sluggish on take off. The SHP engines really LIKE the 3.70 or 4.11 gears and really WAKE UP those engines.