With the 502A2LUN and 502A3LUN cams (630 lift and 660 lift), and a rev kit, Should I use the recommended springs? Lunati Recommends 210LB seat and 550LB open, but I have a set here with 185LB seat and 465LB open. The springs I have are for a .650 max lift, But won't an extra 10 thousandths be ok? Does anyone know what performance gains may be had my having the 502A3LUN cut on a 110 LSA? And last of all what do these cams sound like?

Use the right springs. No matter what. Too little spring is the recipe for disaster: coil bind, broken parts, wiped lobes and metal in the oil, broken springs and therefore dropped valves and holes in pistons, etc. etc. etc. If in doubt, get one step more spring than whatever the cam's minimum requirements are; not one step less.

If there's any one place in a motor not to cheap out, valve springs is it. Well, maybe rod bolts too... OK, 2 places.

UDHarold should be able to answer these questions and I hope he chimes in here because I had the similar questions about these cams.

I was also wondering what kind of HP / Tq difference there would be between these two cams.

Thanks for the input guys!I have been trying to call Lunati and ask these questions in person, But those guys must really be busy. I'll let you know what they say if I can get ahold of somebody before UDHarold reply's, 71454Chevelle.

Thanks Pony Hunter.

I was kicking around the idea of having the 276/284, .660/.660 (502A3LUN I think??) ground on a 108 lobe separation and installing. Should make killer mid-range power! graemlins/thumbsup.gif

Pony Hunter,
RB69 answered your question correctly.

In my opinion one of the worst thing you can do to a roller is not running enough spring on them.
It beats the crap out of the whole valve train & especially the rollers.
A rev kit is a good idea as it tends to keep the roller from "skidding" as bad on the cam instead of rolling.
The rev kit has very little to do with the amount of valve spring pressure you run as the weight of the parts on the lifter side of the valve train are relatively unimportant.
You NEVER want to sacrifice stiffness or rigidity for weight.
As an example an 18 deg engine we just flogged the crap out of on the dyno is using 7/16" .080 wall double taper pushrods,, definitely not light but very stiff ;)
This is a trans am engine & routinely goes 9200+ a lot of times during a race.

I have tried to call Lunati and talk to Steve a bunch of times, left messages and everything, but to no avail. I got the bigger springs already but still am having a hard time deciding on the cam, Got a set of 7/16 rods so i'm probably going with 502A2LUN. Sorry I couldn't find the answer to our questions 71454Chevelle.

Sorry about the phones at Lunati, but Steve and I have been over to Atlanta to NHRA's bash. I did a lot of talking, Pro Stock, Super Stock, Super Gas, Super Comp, Comp. Then I was out today, having to replace some plumbing in the house.....
I will be out of the office ALL next week, leaving Sunday, coming back Friday night.
However, we're talking with Tim, my right-hand man from UltraDyne, about coming on-board with Steve and Me. If he does, that will make 5 salesmen, including me, from UltraDyne and of course, Mike in charge of the grinding shop.
As far as the cams, the 502A2LUN is one of my old reliables. As a SBC, I had 2 of them each go over 2000 miles in 24 hours at LeMans. I have had reports of 10 years on the street or in off-shore boats.
As far as the 502A3LUN on a 108 LSA, well, I've never compared the 2 on a dyno. However, without a doubt, the 502A3 would have more bottom end, and the 502A2 would have more top end. It's hard to beat a 6 to 7 degree advantage at .200, and that's what the 502A2 has over the 502A3.
As far as springs, run the 210/550 spring. It has worked for 24 years on the street with .630 to .710 gross valve lift cams.

UDHarold

Harold,

How does the 502A1LUN and the 502A3LUN compare if ground on the same lobe sep and advanced the same as far as power?

What kind of realistic power would these cams make (110 deg lobe sep, 4-6 deg advanced) in a .030 over 454, 10:1 cr, big valved / bowl ported oval port heads, with say a RPM manifold and a 950HP?

Thanks in advance. smile.gif

Darren, please excuse my treading here....

For the 276/84 flat tappet, currently using a set of unknown springs that show 110-115 seat at 1.9 and around 345-350 over the nose. So far so good, but they're close on bind and they have 20-25K on them. Soon I'd like to replace the springs, retainers and locks.

Are you using the 73124 spring for that grind?

Looked at some Isky springs at 140/370 which seemed heavy for a street app. Yes?

Had a set of take out ZZ502 ( cheap) but were told they aren't any good.

Darren,

The 502A1 will be down about 10-15 BHP compared to the 502A3, however, they should have the same shape power band.
I would put the 502A1 at about 580-590 BHP, about 6200, because the 502A2 has consistenly made 610 BHP at 6400, in similar engines.

UDHarold

Crower has a 140/340 spring for that cam. The only one I've found. The rest are 140/355-360+ or 120/330-340.

It's not listed on their site, put if you type in the p/n from an old catalog, they still sell it.
68388 or 68101/202 I think. The # is on my desktop.

I ended up with isky 8305's at 1.98-99. May go SR later so needed more IHt.

Thanks Harold. smile.gif

And THNX Scott, and sorry to Pony for treading on your thread.

and sorry to Pony for treading on your thread. and me to man, sorry. smile.gif

No apologies guys! This is all killer info. Now you all have me wondering about using the A1 cam instead of the A2 or A3, on a 110 LSA.