427Hotrod

I just returned from driving my 540" pump gas all motor (no bottle-no boost) Vette 2000+ miles to Bowling Green KY from Houston for the Forum Cruise In. Last year I did the same thing, but I ran it with a .731 lift solid roller in it. It made it OK, but I was sweating it.

Last summer I stuck an old Crane flat tappet in it, mainly because we were staring at it sitting on the shelf for 10+ years (new in box along with lifters) and the topic had come up about just how much performance you might REALLY lose with a flat tappet vs a good roller. We were going through the annual lifter rebuild/replacement drill as well as considering as many street/highway/traffic miles I put on this dude, we were thinking of some way to have a less troublesome setup. So in it went, and actually "butt-o-meter" tests were pretty impressive. Yes it was down, but it still pulled 7000 rpm easily. Never really had an inclination to run it at track, because I've been on a 9 sec quest and knew I was giving up some power.

I stuck the roller back in it in the fall when racing gets fun and managed a best of a 10.04@139.96 at one track. Later, on another day after some jetting work, I hit some 140-141+ trap speeds. Still working on 60's, but this is a Hp discussion thread.

So for this trip, I was doing the lifter check again, and the solid flat tappet was calling to me again, so I stuck it in along with the correct springs.

While up there, we had a chance to make a couple of passes at Beech Bend Raceway (neat place). They were having a big event this weekend, so us Vette dudes were sorta in the way, but we did get to run a little.

Now remember, these runs were made just as I drove it up there. All the normal "race tweeks" were absent. We drove it to track, unloaded lawn chairs and suitcases and junk and raced. Didn't even check valves after the 1000+ mile trip.

That means:

No slicks, it has a set of half worn 275/60 BFG plain street radials. NOT drag radials.
215/65 front tires- instead of skinny's
American Torque Thrusts- instead of light stuff
No carb spacer
Closed full exhaust to bumper
Sway bars in place
Stock shocks
Carb de-jetted lean (hey trying to keep mileage in the double digits!)

It always runs with belt driven water pump and stock pulleys as well as a fixed seven blade stainless steel fan.

And of course the flat tappet cam.


Anyway, I managed an 11.50@ 130.87 mph. That's with a 2.11 60' and LOTS of fancy foot and steering work to keep it going straight. Pretty much spinning and foot on the floor action didn't happen until deep into 3rd gear. Everyone seemed to like the 3rd and 4th gear tire smoke puffs on gear changes!

Here's the breakdown:

60'- 2.112
330'- 5.241
660'- 7.695
MPH- 102.51
1000'-9.764
1/4- 11.501
MPH- 130.87


Normally, in similar weather conditions with roller cam and in "race mode" (see above list) car does:

60'- 1.41-1.50's
1/8th-6.41-.6.50
MPH- 110.5-112 mph
1/4- 10.0's-10.20
MPH-139-141

I wonder what it would run with slicks, skinny front tires, lighter wheels, headers open, spacers on, suspension set for launching, shocks in race mode, sway bar off and some more fuel?? I think I'm going to have to try it before I pull this sucker out!

Wonder what it would run if I stuck in a flat tappet that actually is a lot closer to what this motor would really like other than what was laying on the shelf?

Here's what we're talking about spec wise.

Flat tappet:

.600/.620 Gross lift (around .585/.605 at valve)
266/276@.050 (intake 170@.200)
LSA-110

Roller:

.731/.731 Gross
266/272@.050 (180@.200)
112 LSA

Anyway, I thought it was interesting that it MPH's above 130 still with all those things fighting against it. The really neat part is that twice we were caught in ridiculous traffic jams on interstate (accidents) with start stop driving for miles, we went on a 5 hour cruise through the Ky, countryside, I gave who knows how many "high speed checkout rides" to folks, drove it home to Tx straight through yesterday and the valves sound just like they did when I left. Not sure I would be as confident in the average solid roller .700+ solid roller setup with 650# springs!

Thanks,


JIM

Corvette Kid

I'd be curious to see what just slicks would have done. Obviously you were hurting big time there.

69 N.O.X. RATT

Very interesting. Get that thing in race mode with the flat tappet and take it to the track Jim.

427Hotrod

I think this helps prove money and time spent on good heads pays off even with "weenie cams"!!


JIM

69 N.O.X. RATT

Sure sounds like it

big632

That is good.You will knock off some et with full race mode but your mph might go down or stay the same,10 mph diff with the other cam is huge.Your lucky they let you run it at all with no safety equipment.Get a cage in that thing or at least a bar.You need to think about what would happen to you if you lost a tire or suspension component at those speeds.Be safe.

comp

neat info,,, what about MPG on the trip

427Hotrod

Hey we were excited that it stayed in the double digit range! Pretty much the same as last year.....11-12 overall.


JIM

Mr6spd

Have you considered running these, to avoid the roller lifter failure/ rebuild issues? :

Roller - X lifters

I don't have any first hand experiance with them, but they look like a great idea.

427Hotrod

I've looked at them, but seems like no one has any first hand experience with them. They would be worthwhile if they really worked.

The concept is neat...I just can't figure out why no one is using them either. Must be something that ain't as cool as it seems.....


JIM

CORKVETTE1

probally because the price tag is $1000 for the set

427Hotrod

There was a deal going here a while back where if we could get 3K worth of purchases together, we could get them for around $700-$750 or so. That's still a lot of money, but IF they worked, it would be OK. A good set of Red Zones is out on the $550 range. Annual rebuilds can eat up $175-$200..so it would only take 2 years to break even.

But at this point, ,annual replacements is still the best choice.


JIM

korvetkeith

Interesting. I liked their radius ceramic matrix lifters. I think they would be really popular if they could be a direct replacement for roller lifters.

Is there any weight advantage to the Endure Xs? I assume they would have discussed it if there was.

427Hotrod

Aren't they "roller X" or something like that? I'd hate to compare them to the Comp cams "Endure-Nots"!!!

I think the roller X's are a lot easier to convert to without going to 1" radius lifter bores.

JIM

korvetkeith

Woops, your right sorry. Are the $920 versions for motors that come with roller lifters?

427Hotrod

You know I have to do some checking...


Seems like the main one uses a 1" radius lifter..thats the solid deal with radiused lifter that looks like a roller deal. Looks promising..but block must be bored etc.

Then there is the one with just hydrodynamic wedge oil holding a captured roller wheel away from body on a film of oil. That one looks good too...but it usually requires block work too...but a little simpler.

I just don't hear folks raving about them and that bothers me...for stupid stuff like we do with this stuff,,,the price is almost in the area of thinking about it if it worked.....LOTS of hardcore guys would be using them...but I just don't know of any. THAT worries me!

JIM

korvetkeith

So not even the Roller Xs can be retrofitted without machine work?

427Hotrod

I think you have to drill and tap block for a retainer.

JIM

korvetkeith

Even on a roller block? Thats what I tried to ask a few posts earlier, sorry for the confusion.

427Hotrod

You got me there...but I would expect yes. The guide for the Schubecks is a much stouter piece...I would expect he would tell you to chunk the factory setup and use his holder/guide.


JIM