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

 

 

I would also be interested to see the results if you bolted up a cast iron intake with QJet!

Sorry, I'm just a little sensitive after hearing you call your new cam, a cam with more lift and about as much duration of my factory L88 cam, "a weenie cam"! I gues I have that typical male predilection called cam envy! Even though I carry a bigger stick now it still hurts.

Chuck

p.s. MountainMotor would be proud! He would also not be above shouting, "I told ya so!"

 

You have a great all around flat tappet cam there stick with it.

 

Chuck I've been preaching similar to this since day one here An I told you so of sorts . BTW , a guy I know was hired to develop a better L88 grind way back . It was a 304 258@.050 .615 single pattern with symmetrical lobes that made more power throughout the range and was the powerglide/L88 cam of choice back in the day's .

There are other positives to running a flat tappet solid vs an extreme roller as well to include the valve job will last longer and more .

Not to diss the solid cam Jim used but imagine another grind with a modern lobe profile to get the job done even better with the big ports while saving money and parts .

Thanks for the post


[Modified by mountainmotor, 6:22 AM 6/28/2004]

 

Thanks for sharing... very interesting. I need to find some buddies that have free cams just laying around!

 

It is interesting isn't it?While this isn't a serious A-B type test, it does point out that at least I didn't kill it even with a cam that different than before. The old cam was a high rpm screamer and this one has shifted the curve back down a little.....so maybe that helped too.

If I was to actually pick out a solid flat tappet, it would likely be slightly different than this one......but like I said....it was an experiment and I was very familiar with this cam's characteristics, just not in a big motor. Plus it was free! Just a little labor and some new springs. it didn't let me down.

The old ZL-1 cam worked well in some serious motors in the old days as wellas many others. I know Ultradyne/Crower did some pretty decent flat tappets as well as Isky. I really like Engle's appraoch to these things and would talk to them too. But these old Crane's are reliable and can turn in the number. The issue as with any cam is just how aggressive and funky you can get with a cam and still keep longevity and stability in place. I know some flat tappets that last less time than race type solid rollers. This one isn't crazy, but compares well to many of the fairly serious Comp cams and some others. As always there is a line you cross.

Chuck....I thought you were using the Comp street roller in that L-88 these days? Did you change it back to something else?

I'll be back with more testing on it and some real ET's ASAP. It will be fun to see how it does with open headers, slicks and race stuff tweeks!

JIM

 

Jim, fantastic post man. Chuck, not to worry, Jim called my cam a little weenie cam too. But oh do I love it.
Mountainmotor, would you be referring to that Clay Smith grind you picked out for me and my 502. Just so you know, I love it. Keep the posts coming on this one Jim.

 

Very cool real world test.
I also run a solid on the street.

Joe

 

That would be it . Weenie cam it's not . The better the exhaust the better it will go but would use step larger in that brand for larger motors and or higher compression depending on the goal all the while keeping the different LCA's available in mind for the job.

here's more on the cam you are using
http://forums.corvetteforum.com/zerothread?id=850050

From a former engine builders viewpoint and studying tribology and motor oil chemistry as a hobby I find it interesting the seemingly total lack of concern about oil type used when reliability and ultimate parts protection is spoke about here at Corvette forum .

All oils are not created equal . Most are just mere mortals

 

Since this thread has the ear of all the motorheads, I have a question for you guys (sorry for the hijack).

How often do you have to adjust the lash on solid cams? I always heard that lash has to be adjusted every month or so.

Brett

 

It depends on how radical the cam lobe profile is along with the quality of components to include the valves and springs , if the valve spring sets in seat cups to prevent walking around and more . Symmetrical or unsymmetrical lobes can come into play as well again depending on the profile along with rocker arm ratio , valve guide quality .

One could go a bit farther and add in the fact that a high exhaust lobe centerline will increase heat vs a lower one of say 108 vs 116 changing things a bit over the inlet side .

The engine in the link above with good parts gets em looked at once a year or around 6k miles depending .

Variables are many and each engine will be different ....... just like our children




[Modified by mountainmotor, 9:42 AM 6/29/2004]

 

That's not bad at all....best to adjust em with the engine hot and running? Or off and hot?

Brett

 

With iron heads I adust mine cold and through the firing order manually adding .002 for thermal expansion of the parts .

 

I like picking on folks for "weenie cams".

And of course those AFR heads you have flow well enough to make a "weenie cam" work well!

You should hear the comments I'm getting for trying this! Hey but you never know until you try it. Way too often this stuff gets kicked around and opinions are formed. I like to try and add some fact/knowledge into the equation. This test is a long way from providing real data, but it's interesting enough to keep me playing with it for awhile.

I've always felt a good solid flat tappet is a viable alternative to a killer solid roller on these street deals. The solid roller street cams can be a little better, but given the cost, not sure if you pick up as much as a well planned flat tappet can do. Now my solid rollers are more to the race side, but with them comes maintenance. I just thought it would be interesting to play around here with a motor that should really LOVE a monster cam. It does, but it's got parts that seem to love a smaller one too. Once again..good airflow with heads and intake allows you to get by with less cam.

Mountain....you're right on oil selections. You and I have traded info on that subject a while back, and I learned a lot. Got any more insight?


And I always set mine cold and allow for expansion also.


JIM

 

I run a Dart Stud Girdle, and after 2000 miles no adjustment needed.

 

Mountainmotor, I was a good student all around as I am using the Valvoline Race 20W-50 you recommended to protect those lobes. I am also curious, what is the next step up cam from the one I am running?

Jim, keep the info coming as this thread really has the potential to provide some great info and maybe dispel some myth as well.

 

For the time that is still a good choice of oil for that particular engine . It uses an ashless detergent/dispersant pack and has a relatively high starting TBN with plenty of ZDDP.

Next step is the 306 263@ .050 .630 . After that is a 310 270@.050 .640 which is a sweet one with twin carbs and compression . Works in a oval port 468 too ...... in a boat . All are available with differing LCA's depending on the needs then just advance the intake to the needs and let the exhaust help pull in the mixture at rpm .

Isky has a couple nice cams as does Crower for when a dual pattern is needed depending on intake and heads used. Comp has one , keyword there

Take care , this was my monthly visit :flag