Not exactly an A-B-A test of a flat tappet vs solid roller, but still interesting..
05-31-2005, 01:06 AM
#1
Race Director
Thread Starter
Member Since: Jan 2000
Location: Corsicana, Tx
Posts: 12,603
Received 1,874 Likes
on
912 Posts
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Not exactly an A-B-A test of a flat tappet vs solid roller, but still interesting..
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
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
05-31-2005, 07:29 AM
#2
Le Mans Master
Member Since: Mar 2001
Location: Watkinsville, GA and Glen Cove, NY
Posts: 5,788
Received 854 Likes
on
625 Posts
Jim, truly excellent post. Congrats on making that trip again with no issues, very impressive. I really look forward to seeing the results of that cam in "race" trim. I change my mind daily on whether I will go the solid roller route. I am curious as to what you would consider to be an optimal flat tappet cam for your motor. With your good exhaust and heads I would assume it would be a single pattern. Would you consider going to a bigger flat tappet lifter size? How much lift can you get away with in a standard .842 tappet? How about in a bigger lifter diameter? Great stuff Jim.
Bill
Bill
05-31-2005, 07:39 AM
#3
Race Director
Member Since: Nov 2000
Location: Waterloo ontario Canada
Posts: 11,872
Likes: 0
Received 9 Likes
on
9 Posts
When I switched to a comp cam 288R roller I felt I lost power over my old flat tappet solid cam. The only reason I left the roller in is that I had spend about $1500 on the switch.
05-31-2005, 08:15 AM
#4
Team Owner
Jim, I have that 11.50 pass of yours on Video. Paul used my camera to film some runs... Let me know if you want it and I'll e-mail it to you!
I'm sure that you would've hit mid 10's with traction... Next year you gotta bring slicks and the solid roller
I'm sure that you would've hit mid 10's with traction... Next year you gotta bring slicks and the solid roller
05-31-2005, 11:28 AM
#7
Burning Brakes
Originally Posted by Les
Very impressive! I'd love to see that video too. Any chance one of you can post it here?
I would love to see the video.
05-31-2005, 03:10 PM
#9
Le Mans Master
Could the results have anything to do with the size of your engine? Do you think the results would be more dramatic if if were a small block? Do you run a stud girdle with your solid roller and if so do you notice much lash change with it in place?
Sounds like you had a great trip! Wish I was able to join in on the fun
Sounds like you had a great trip! Wish I was able to join in on the fun
05-31-2005, 09:59 PM
#11
Race Director
Thread Starter
Member Since: Jan 2000
Location: Corsicana, Tx
Posts: 12,603
Received 1,874 Likes
on
912 Posts
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Thanks guys...
I'd love to see the video Oliver. I'm no good at posting stuff like that, so if you can post it it would be great. Can you send it to me too?
Looks like you were making some power too, but I never got a chance to watch you..I was always behind you in line.
Years ago, there were a lot of "mushroom tappet" stuff out there. Not much around anymore, but I had considered using one of them once just for fun. I think you could get a very serious cam in there with good wear. But of course you have to machine block and it has to be all apart to get to bottom of lifter bores.
I think you could step out to a .875 or a .904 lifter or even go ahead to the Shubeck style 1.00" stuff. Of course to optimize it you would need to get a cam ground for them, but that's not a big deal really.
You have to be careful here. This particular cam is a relatively mild one really as far as ramp speed goes and is extremely easy on parts. It also requires pretty mild spring pressures. So that helps longevity a lot. There are some serious flat tappets out there, but getting one to live on the street can be pretty tricky too and that puts you right back where you started with the roller cam. There is just so far you can go and not have the lifter dig into the cam lobe. That's where rollers come in.
The street manners of this cam are not as nice as the last roller. But the roller was on a 112 LSA as compared to this one on a 110. I had a previous roller in it on a 110 LSA (though it was a slightly bigger cam) and the manners were similar to this one. When I say manners, I'm discussing how low I can lug it with my 3.07 gears in 5th gear and have it still not be jerky. This one will handle 2300-2400 rpm ok, but it's much happier around 2500-2700 rpm on the highway. But also remember I'm using huge heads, intake and carburetor. Smaller stuff would be much smoother I'm sure down there. Also anyone with "real gears" or a converter wouldn't have any issue.
I think cam with similar duration...maybe out to 268-270 max and maybe 272-274 exhaust would be good. I would use a 112 LSA just for nicer cruising, plus it would help top end. I don't need much more bottom end.
I would shoot for lift as high as I thought I could get away with. The lifter size and lobe aggressiveness would determine that. My heads would love anything over .700 lift, but that is tough to get away with. But I could see using a .640-.660 or so and maybe using some 1.8 rockers on intake side to kick lift up some.
Isn't this stuf fun? Some of you guys need to go over on the Hot Rod Magazine web site and help me out. I started a thread about getting the editor to do some testing like this on cams, heads and intake on a 540 (selfish huh?) He has expressed interest, but a little prodding could be good!
See ya,
JIM
I'd love to see the video Oliver. I'm no good at posting stuff like that, so if you can post it it would be great. Can you send it to me too?
Looks like you were making some power too, but I never got a chance to watch you..I was always behind you in line.
Years ago, there were a lot of "mushroom tappet" stuff out there. Not much around anymore, but I had considered using one of them once just for fun. I think you could get a very serious cam in there with good wear. But of course you have to machine block and it has to be all apart to get to bottom of lifter bores.
I think you could step out to a .875 or a .904 lifter or even go ahead to the Shubeck style 1.00" stuff. Of course to optimize it you would need to get a cam ground for them, but that's not a big deal really.
You have to be careful here. This particular cam is a relatively mild one really as far as ramp speed goes and is extremely easy on parts. It also requires pretty mild spring pressures. So that helps longevity a lot. There are some serious flat tappets out there, but getting one to live on the street can be pretty tricky too and that puts you right back where you started with the roller cam. There is just so far you can go and not have the lifter dig into the cam lobe. That's where rollers come in.
The street manners of this cam are not as nice as the last roller. But the roller was on a 112 LSA as compared to this one on a 110. I had a previous roller in it on a 110 LSA (though it was a slightly bigger cam) and the manners were similar to this one. When I say manners, I'm discussing how low I can lug it with my 3.07 gears in 5th gear and have it still not be jerky. This one will handle 2300-2400 rpm ok, but it's much happier around 2500-2700 rpm on the highway. But also remember I'm using huge heads, intake and carburetor. Smaller stuff would be much smoother I'm sure down there. Also anyone with "real gears" or a converter wouldn't have any issue.
I think cam with similar duration...maybe out to 268-270 max and maybe 272-274 exhaust would be good. I would use a 112 LSA just for nicer cruising, plus it would help top end. I don't need much more bottom end.
I would shoot for lift as high as I thought I could get away with. The lifter size and lobe aggressiveness would determine that. My heads would love anything over .700 lift, but that is tough to get away with. But I could see using a .640-.660 or so and maybe using some 1.8 rockers on intake side to kick lift up some.
Isn't this stuf fun? Some of you guys need to go over on the Hot Rod Magazine web site and help me out. I started a thread about getting the editor to do some testing like this on cams, heads and intake on a 540 (selfish huh?) He has expressed interest, but a little prodding could be good!
See ya,
JIM
05-31-2005, 10:37 PM
#12
Team Owner
posted the video in C3 General because it would've been moved if I would've posted it in Tech......
