Well, after the trip to Bowling Green for the Cruise In, the subject kept coming up about what is streetable and what isn't. Now of course mine might be a little out there as far as valvetrain and 2000 mile trips go, but it did make it and nothing died. I pulled intake and lifters out to check recently and everything is OK. I did feel one roller's needles felt a "little" rough or at least it seemed, but I'm paranoid about this stuff.

So while talking to some buddies we kicked around the old issue about how much performance would be lost on something as radical as this engine if I dropped it back to a flat tappet. I mean if ANY engine will respond to a big roller cam, this one is it. Naturally aspirated, big ports, intake and carb with no power adders.

So the decision was made to slip in a solid flat tappet for several reasons. One was, that it's early in the summer and good race weather isn't going to be here in TX for awhile to get that elusive 9.99 ET. Lots of cruising to do between now and good weather and it's possible I could lose a lifter or cam before it cools off. Plus there was a free flat tappet laying on a buddys shelf!

This particular cam is one of my old favorites in a radical 427 setup or a 454+ motor. It doesn't look super radical on paper, but it has always turned in great results for me in the past. So I figured what the heck...let's try it.

It's a Crane 266/276@.050 on 110 LSA with .600/.620 lift. Way low on lift for what my race ported heads need, but hey it was free! I pulled out my Engle solid roller with 272/278@.050 on 110 LSA with .731/.731 lift. The Engle is not really a wild cam and is easy in parts (obviously!). I stuck the flat tappet in on a 105 I/C. I checked the .050 and .200 duration numbers to make sure all was well. As usual, Crane makes good stuff. Just for reference, the .200 duration on the intake lobe was 170* vs 185* on the roller.

I changed valvesprings which was one of the trickier things to come up with. It took lots of digging to find a set that would fit my titanium retainers, clear my valve seals, fit my spring locators and have correct pressure open and closed. I installed cam with only outer springs and ran it for break in. Then I installed inner springs and dampeners. PITA, but the only way to break in a cam like this.

Initial impressions are it lost some of the cool radical sound of the roller, but it still sounds pretty tough. Idles at similar speeds (1100 rpm or so..but I keep just about everything idling about there on this hot rod stuff). It will idle lower, I just like it there. Driveability is of course better with less duration and overlap. It lugs down low a little better, but it was OK before really. Not quite as "choppy" while driving around, so maybe all the guys won't complain about riding around behind me and sucking up raw gas fumes like they did on the trip to BG.

I've put maybe 150 miles on it so far. I made a few hard runs with it the other day to see how it pulled and it would easily go into the 7000+ rpm range still.

So today I took it out to play with the G-tech on some back roads. I've had great luck with the G-tech coming very close on ET. I've actually used it at the track and compared it to the ET slips and it always comes up within .02-.03. That's about one quarter of a tenth..pretty close for something you plug in the cigarette lighter! The MPH read high by design since it reads the actual end of a qtr. mile instead of the average in the 66' traps like the track does. For example, if you turn around 105 mph at the track, you are probably actually going 109-111 mph at the actual finish line.

I made two runs in pure street trim. Capped headers, BFG plain 'ole street radials, air pressure correct in front tires, sway bars in place, air filter on, no carb spacer etc etc. No tricks at all. I was on a black top road after a bunch of rain in the area, so you can imagine traction was not good and I did lots of feathering to get it moving. I shifted around 6500 rpm and just let it pull.

First run was an 11.42@137+mph. Figuring something must have goofed up, I tried it again. This time it was 11.31@139.8 mph! To say I was impressed is an understatement!

So I have confidence that with practice there might even be a 10.99 run in pure drive around street trim. I can only imagine what slicks, removal of sway bar, setting up drag shocks, pumping up front tires, installing carb spacer, uncapping headers might bring??? Not that 9.99 ET..but for sure deep in the 10's still!

I'll get back to everyone with more results as I play with it some. But at this point, the smaller weenie cam is holding it's own well. I believe the race ported heads and intake are allowing it to perform well, even if it is relatively small for this size engine.

Anyone else have any back to back impressions of something like this?

JIM

 

Very interesting - looking forward to part 2!