Bump and Whine

Another thing that happened last week:  I submitted a request to Comp Cams for a camshaft recommendation.  I filled out a bunch of information for the request, and I thought I'd get a pretty simple, almost automated reply.

Instead, I was contacted by an actual person, and after exchanging e-mails for a while, I was very happy with the result.  In the end I decided to get a hydraulic roller cam, although it will be pretty mild as far as roller cams go.  I told the guy that I am building the engine for driveability and low-end torque, and as we discussed things I eventually mentioned which cylinder heads I was planning to use.

I plan to get some Edelbrock heads, but they come assembled with springs intended for flat tappet cams.  I told the guy at Comp that I planned to just swap out the Edelbrock valve springs for the Comp springs, so that it would be OK for the roller cam.  (Roller cams tend to require heavier valve springs; I think this is due to a combination of roller lifters being heavier than flat tappet lifters, and also due to roller cams' generally more aggressive lobe profiles.)

Well, it's always a matter of asking the right question, and when I mentioned the Edelbrock heads, he looked up the Edelbrock springs and said that actually they would be fine for this cam, because it is such a mild grind for a roller cam.  But the roller lifters should give better wear characteristics and there should be less chance of wiping a lobe during break-in or anything like that.  It's probably overkill for this engine, but it gives me some peace of mind.

(I am reminded of a program I once saw about tanks; they declared the German Tiger tank from WWII the most dominant tank ever, realtive to its era.  They said its only real weakness was that it was so over-engineered.  As an example, they mentioned that its crank rode on all roller bearings.  The roller bearings had a service life of something like 40,000 hours.  By contrast, the Tiger tank itself had an average combat service life of about four hours.  So maybe this roller cam is just my inner German coming out.)

Anyway, eliminating valve springs, retainers, keepers and stem seals from the order saved me a couple hundred dollars, so I was glad for his help.

Today I had jury duty.  I never got called out of the waiting room, and they let us go home at about 2:30.  So, I decided to take advantage of being home during normal business hours and call up the place I wanted to get my transmission from.  This place sells 100% new Muncie transmissions with a few design improvements over the original factory units, and the guy on the phone here was also very helpful.

I told him that I wanted to get the Muncie M20 wide ratio trans.  Like I said about the Comp guy, it's always a matter of asking the right question, and fortunately the guy on the phone knew the right questions, because I certainly didn't.

He asked me about my project, and when I told him that I'm building a 1965 Impala with a little big block and 3.08 rear gears, he told me that the M20 was not a good fit.  With that rear gear, even with the M20's lower first gear ratio, he said the Impala would be a slug off the line.

In the end, we decided to go with his Muncie M22Z, which has an even steeper first gear than the M20.  The M22Z is based on the famous M22 "Rockcrusher."  The Rockcrusher's helical gears are cut at a shallower angle than the M20 and M21 gears.  This makes the transmission more efficient, but it also creates somewhat of a gear whine.

I think high-efficiency transmissions like this are the main reason why NASCAR stock cars have such a whine when you see the in-car camera views during caution flags, and I think it's also why the '55 gasser in "Two Lane Blacktop" had such a whine to it at lower speeds.  In other words ... gear whine and M22s are awesome, so I am delighted that this guy has one with ratios that will work for me.

Also when I got home, I had a package from Summit, which was my 1965 Bel Air Mark IV big block motor mounts.  I haven't tried a real test fit yet, but it looks to me like these are going to work.  They also delivered my bellhousing at the same time.

There was also a slip from FedEx saying they tried to deliver something that requires a signature.  I think this is probably my cam kit from Comp.  Glad I have lots of empty house to store all these parts in.  It's all (very, very slowly) coming together....