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

 

 

Wow! To say that I am shocked you pulled the roller is an understatement!

I do agree from a reliability standpoint it is hard to beat a flat tappet. The duration figures on the flat tappet are pretty stout. Whose springs are you using and what are the opening and closing pressures?

Whose lifters are you using? I am gathering the parts for a 427 that I am going to put in my '69 Corvette restoration and have been looking at the Crower Cool Face lifters. They have that tiny hole on the face of the lifter that provides pressurized oil. Have you looked at them?

If I have any problems with the Crower rollers in my 632, I will go to the Schubeck system.

The ET and MPH are incredible. You have to be happy about that. Also, I am envious that you have places you can go that will allow for the kind of testing you do.

Steve

 

After a lot of consideration, I went with those (I heard nothing but good things about them), the Isky versions (#SO202H) for my BB replacement engine. I figured with the heavy springs it would be a good idea, I also Cryo'd the cam and lifters. Cam: Crane 134691 (580/600 256/266@50). Pump: Melling/GM LS-7. Oil: Valvoine Racing, 30 wt.

Jim: 11.3 @140, in street trim?...... VERY impressive



[Modified by 66427-450, 3:31 PM 6/28/2004]

 

66427-450: Not to get too far off the subject, but with those lifters did you still have to remove the inner springs to break in the cam?

Steve

 

While this wasn't truly an A-B test....it at least points to the fact I didn't completely kill it! The high MPH is of course due partly to using the G-tech and it's method of calculation, but even at the track the sucker usually only read 136-137 or so while track showed 132-133 or so. So to be up there at all is impressive to me!

Also MPH can be attributed to the fact the ET was so slow, I had a chance to get a good hard run at it!

I have Crane piddle valve type lifters in it. Only because my buddy handed them to me with the cam. If I was buying it all I would definitely use the one's with the oil hole.

I ended up with Comp springs. I figure they will do fine for this type of cam. I believe I ended up with 148 or so closed and 360 or so open. I'd have to go back and look at what I recorded. I added a little extra for them being new springs and for the 2.30 intake valves.

I have to go out in the country to find a place to play, and I only do it a couple of times so I don't get folks too upset.

I'll get some more quantifiable data soon...but this is a good start.


JIM

 

Interesting test Jim.

 

That .580/.600 Crane is also one of my absolute favorites. Runs killer, never breaks anything and sounds cool!

Good choice......

I think there are some valid choices out there in the "old cam" ranks.


JIM

 

Yes, it looks to be pretty much ideal for my application, torque peak at ~ 5000 RPM, and 610 HP at 6500 (again, thanks for the recommendation). Good all purpose HD engine. I just received a Tom's BOE rear end with 4.11's, and have a new Supercase Wide Range M22 (2.56 first) on the way.



[Modified by 66427-450, 11:39 AM 6/30/2004]

 

Yes, I used a set of light springs, just to be sure...... no big deal to change them. I used Crane cam lube, plenty of GM EOS, Valvoline 30W Racing oil, std 30 minute break-in run.

 

Wow....are you going to have some fun or what????

4.11's in a strong diff....wide ratio M-22....that's going to be cool! That's what we need...more old Vette guys out playing with them!! Folks just eat it up when you come out with a fast one.

Looking forward to seeing pics of it all done!


JIM

 

well, it'll be a little pale compared to some of you guys with the mountain motors, but I think I'll hold my own. that gearing combo will keep me right in the engines sweetspot when doing 0-140 MPH runs, and still give me decent top end. My goal was to keep a "stock look" (so I can hustle some of the local big block muscle cars... big mopar wedges/hemi's etc. he he he). it'll look pretty stock, orange engine/valve covers, all the correct engine hardware, winters snowflake intake and everything (but the intake is a 69 ZL-1/L-88, along with a new '69 ZL-1 855 DP, flowed to 875), the only real giveaway will be the big tube Stahl sidepipe headers, and 4" pipes under the covers (still working on that setup). Designing/Engineering a matching combo was fun, construction is slow (i'm one of those perfectionists). I'll send you some pics when it's all together.

Again, thanks for your tips/advice


[Modified by 66427-450, 8:54 AM 7/2/2004]