86VetteZ51

Hi All,

Long first post so pull up a chair, go to the bathroom or get a fresh beer first.

I've been lurking around here for years. There has always been a lot of good straight talking technical info and now its time for my question.

A bit of background:
I live in Canberra Australia, Federal Capital and home of the summer nats (I don't go).

In my younger days I owned a couple of local bodied darts and celicas all gutless as for most hi po cars back then.

Back in about 2013 I decided it was time to get some form of American V8. By which stage the old darts etc were too expensive cause all the Baby Boomers wanted them. I looked at C3 Corvette and couldn't afford one (not even rubber bumper). I started looking at C4's and realised they were a much better car and I could afford one (actually about the only thing I could). I also like the 3rd gens just as much.

I ended up locating a running driving fully loaded originally tuxedo black 86 Z51 for $1750 in southern desert California with a smoky engine and sun roached interior. Were currently mid way through a basic mechanical and interior restoration. Were looking really forward to finishing the car and enjoying it.

This brings me to my question about Cams, first some background.

I tore out the smoky 350 TPI to find at one stage the short motor had been replaced with a 638 truck one which had apparently spent some time underwater, crank bearing full of trash, worn bores with pitting etc...

Ironically the 624 heads had been fully rebuilt, they're for sale.

So its at the machine shop getting a 30 th torquplate hone, zero deck etc.
Other parts of the build I have bee scrounging over the years are:
1pc factory forged crank machined 20/20 with ACL bearings, being internally balanced by machinist;
6" Manley Sportsman rods - bought used from a dyno only or one summer engine;
416g Wiseco Pro Tru Street Flat Top Pistons and JE Plasma molly rings 10.2:1 compression (cheapest American made pistons I could get and really nice/good value)
Heads are actually some 190cc procomp castings I picked up in a round about way. I was going to turf them but got some good advice from Chad Speier so thought I'd give them a go. The machinist is putting a 5 angle on the intakes and a radius on the exhaust, then I will bowl blend them and do a little basic porting, best assume 200cc with about 250/180 cfm at 0.055 lift.
One thing to mention is we had to go to a 2.08 intake valve as the 'factory' pro comp bowl blend job merely consisted of taking out about 30 tho directly under the valve seat with a carbide bit.
Springs are 918's on +0.100 long stem valves for about 0.600 lift.
1.7 Scorpion RR's I got another deal on.
Pro Flo XT intake with stock LS1 throttle body
OBX SS Long tube headers
Full 2.5 twin system with H and tuned resonators through straight through muffler (LT5 OBX)
2100 - 2400 stall
3.07 'performance' rear gear I'd like to keep this for the time being, I have too many other little jobs as it is.

My big obstacle to getting on the road is passing a full tech inspection. Before I do of course I need the new motor in the car. They told me I need to be stock and after can do what ever I like.

I think I can squeak through with the long tubes as long as all emissions are connected. TPI will be on for inspection too before becoming garage art and being replaced by the Pro Flo XT.

CAM:
I cant have a cammy lopy engine idle, I think I can get through with a 'noticeable' strong/powerful idle and just explain it away with the long tubes/exhaust and 'yeah corvettes got bigger cams'

I definitely don't want to be sent home to pull out a cam to pass inspection.

But I want some POWER! Pulling to about 6k sounds about right.

Car use will be drives in the mountains, maybe some tarmac rallies and other pretty sedate 'gentleman' motor sports (guys who don't want to crash their classic car).

I know there is lots of golden oldy well proven and respected cams out there, but was hoping to use a more modern lobe for a short duration high lift cam with almost no lope (after tuning). A strong/powerful idle of course is desired.

I can go off the shelf or custom, no real difference in cost, just custom have to wait a couple weeks longer. As I will be using the Pro Flo, good heads and LT's, I have been wondering if something like a modern LTx LSx cam may be the hot ticket.

Off the shelf I'm looking at:
Lunati 20120720 Voodoo
262/270 at 0.006", 211/219 at 0.050", 112 LSA, 106 ICL, 575/580 lift with 1.7 RR's - probably about perfect. A 215@0.05 intake lobe and a 110 LSA pep things up a little?

Lunati 20080721 Voodoo
270/278 at 0.006", 219/227 at 0.050", 112 LSA, 106 ICL, 580/600 lift with 1.7 RR's - maybe a bit big?

I can order a custom cam from lunati for the same price and they have 215 and 223 @ 0.050 Voodoo lobes to throw in the mix.

Also remember the 1.7 RR's increase duration through the lift seen by the valve like a LS1.

86VetteZ51

Howards cams:
181145-10
272/278 at 0.006", 219/225 at 0.050", 110 LSA, ?ICL, 600/600 lift with 1.7 RR's - What I have read of this cam people like it but was with a carb and probably 1.5 or 1.6 RR's?

181145-12
272/278 at 0.006", 219/225 at 0.050", 112 LSA, ?ICL, 600/600 lift with 1.7 RR's - As above but with a 112 LSA, recommended for EFI?

I can also get a custom Howards cam too but their lobes don't have great lift until about the 272/219. I could do a 219/221 or 219/223 @ 0.05 which would allow a little less lift on the exhaust side (not really needed).

Has anyone run the above cams - or something similar (especially with 1.6 to 1.7 RR's) on a HSR?Pro Flo XT 355, LT1, LT4 or LSX?

How did it idle and run?

Any suggestions on tweaks to the listed cams?

86VetteZ51

Heres Hypothetical Lunati custom 1
Lunati Voodoo custom 1
266/270 at 0.006", 215/219 at 0.050", 110 LSA, 106 ICL, 580/583 lift with 1.7 RR's - 2 extra degrees @0.05 on intake and a 2 deg narrower LSA than 20120720.

Lunati Voodoo custom 2
266/270 at 0.006", 215/219 at 0.050", 112 LSA, 106 ICL, 580/583 lift with 1.7 RR's - 2 extra degrees @0.05 on intake and same LSA as 20120720. Smoother idle than #1.

Lunati Voodoo custom 3
270/274 at 0.006", 219/223 at 0.050", 110 LSA, 106 ICL, 583/590 lift with 1.7 RR's - 2 less degrees @0.05 on exhaust and a 2 deg narrower LSA than 20120721.

Lunati Voodoo custom 4
270/274 at 0.006", 219/223 at 0.050", 112 LSA, 106 ICL, 583/590 lift with 1.7 RR's - 2 less degrees @0.05 on exhaust and same LSA than 20120721. Milder option of #3 and 721.

Thats about the combos for a lunati custom cam unless I go for a single pattern or play with LSA and ICL some more.

86VetteZ51

Custom Howards cam 1:
272/274 at 0.006", 219/221 at 0.050", 110 LSA, 6ICL, 600/538 lift with 1.7 RR's 4 deg less and lower lift on the exhaust lobe 181145-10. Could do a 112 LSA too.

Custom Howards cam 2:
272/276 at 0.006", 219/223 at 0.050", 110 LSA, 6ICL, 600/538 lift with 1.7 RR's 2 deg less and lower lift on the exhaust lobe 181145-10. So 2 deg more duration on the exhaust than #1. Could do a 112 LSA too.

Both the above intake lobes could be lower in lift, Howard's have 5 different 272/219 lobes with lifts from 0.51 to 0.61 with 1.7 RR's.

So lifts could be like 580/538 int/exh.

86VetteZ51

Ok I think I'm done now.

Orr89RocZ

iTrader: (20)

I dont like the 1.7 rockers. They might not give you good geometry, and make aggressive lobes more aggressive so not sure your springs will work good

I like the 219/227 lunati on a 112. With good mufflers and fast idle speed it wont lope all that much and will go to 6000 rpm no problem. But the fast lobe with a 1.7 rocker makes me alittle uncomfortable

You absolutely dont need .600" lift. A 1.6 rocker would make things better imo

Orr89RocZ

iTrader: (20)

Howards custom 2 would work well on a 112 lsa and intake lift around .560-.570 be fine, exhaust can be .530-.550

86VetteZ51

Thanks Orr, I've read a lot of your posts over the years. Always good stuff.

I got the 1.7's as a deal when I thought the smoking problem was just worn guides of a 144kmile engine and it was just going to be a head swap with new rockers for a bit more lift on stock cam. Once I tore into it though...
In my defense it had perfect oil pressure and compression.

I also had the choice of 1.65's, which I immediately regretted not getting. Oh well well find out now, rockers arn't hard to change anyway.

What do you think of Lunati custom 1 and 2? A little smaller than the others.

86VetteZ51

I can do the Howard's custom 1 and 2 272/219 intake lobe at 0.555" or 0.580" with 1.7 ratio. 274/276 exhaust lobes only come in 0.538" at 1.7 ratio so this gets me near your recommendation of 0.560-0.570" intake and 0.530-0.550" exhaust.

Orr89RocZ

iTrader: (20)

Lunati 2 on the 112 might work good. Duration is abit smaller for 6000 rpm but has good lift. Its a more aggressive looking lobe than the howards lower lift option it looks like. I would tend to lean towards less aggressive with those 918 beehive springs. And that large 2.080" valve. You need to control this so it dont float.

86VetteZ51

Thanks Orr. I included the Voodoo lobes because the late UD Harold was so proud of his soft closing ramp, but agree 1.7 RR and 2.08 may be too much for a 918. Something to think about.

What do you think the 110 LSA would do for these cams?

86VetteZ51

Ok so Summit says it will take at least 3 to 4 weeks to 'get it out of them' for a custom cam from Lunati.

Erik Johnson from competition products answered my first email and says about 5 days for a custom Howards cam. I have bought from these guys a few times and theyre always great.

I don't fancy another FlynBye experience so it will be a Howards cam.

Orr89RocZ

iTrader: (20)

110 lsa would bring in the low mid range more but it will be more choppy at idle and not as much a sleeper. Plus if you have to pass emissions i wouldnt do that tight lsa

86VetteZ51

What springs are these

I just typed up a post but lost it going to advanced, so I'll keep it short. Whats prings are these?

Orr89RocZ

iTrader: (20)

Are they used? What were they on? I have heard some comp 918's had green stripes. But most had blue after the bad batch was corrected. Idk what they have now. I seen one guy say his blue stripe turned greenish in color after being used for a few thousand miles

86VetteZ51

They were 'white box' High-Tech brand from Competition Products. They seem to sell a lot of stuff which is production over-run, cancelled orders or whatever. My guess is they just came out of a big box destined for one of the name brands to repackage, like their valves etc. For example they're currently liquidating all the Scorpion lifters and valve springs.
I too did read about their failures but these were back in 2007. I bought these late 2015. I remember the specs were the same as 918's and the Howards equivalent.
I only found one reference to green stripe and that was on Gen 3 hemis. Maybe the blue did turn green after a few years laying around.
My concern is they're a dud batch which sat around and eventually ended up at Competition Products to clear out.
They are a nice looking product though.

86VetteZ51

Best I came up with is they are the 6.1 SRT Hemi exhaust spring the 5.7 Mopar guys use as a performance spring with new cams.

86VetteZ51

Back to the topic at hand.

Howards custom 3
270/274 217/221 560/540 112 LSA +6 advance 48* overlap. 1.7 RR's

Also the 1.7's make the cam appear bigger to the engine everywhere except seat.

This is with a 2100-2400 stall, TH700 and 3.07 gear.

How do you think this puppy would run? Idle, mid range etc.?

86VetteZ51

Just got this back from Competition Products who I got the springs from:
The 2406 springs are 120lbs @ 1.800 & 330lbs & 1.200 and coil bind at 1.125

Orr89RocZ

iTrader: (20)

I like it but i would run it no more than 4 deg advanced

Should sound mostly stock but definitely give good performance. Thats a slightly hotter version of the hotcam which always made good power and had good driving characteristics when tuned well. The howards should do even better as it will have less seat to seat duration

86VetteZ51

I didn't even think about its similarities to the Hot Cam, but your right, maybe a more 'modern version'.

When compared to the hot cam way less seat duration at 48* vs 59* (11* less). 6* less exhaust duration at 0.05 (better exhaust port). -5* overlap at 0.05 as compared to -1*. Should idle better.

I was originally thinking single pattern but with the 2.08 intake valve and 5 angle VJ with a 30* back-cut valve I added 4* to the exhaust lobe to help it out. I could go to 6* but at my RPM range do you think there would be any benefit (and possible a loss of low-mid range torque)?

Also I put the ICL on 106* to help with low speed torque (3.07 gears), the Lunati shelf cams above are on a 106 ICL for 6* advance but I see the two howards are both +4. What advantages/disadvantages to the 2* diff in ICL?

Orr89RocZ

iTrader: (20)

Honestly dont think you'll see much difference on 2 deg advance changes but that cam shouldnt have a low end torque problem.

I just figured i would favor top end side of things more so 4 deg advance seems fine to me.

Exhaust port seems weak on that head, esp if intake is opened up to 2.08 valve and picks up some cfm. 4-6 extra deg should work nicely. I'd lean 6

86VetteZ51

Thanks Orr, good advice - all of it.

If I get up early enough tomorrow morning I might make a call to Erik.

But its a maybe because tomorrow is Australia Day and my Birthday

One thing I want to definitely avoid is the sound of all the overcammed LS motors I hear out on the main road. Listening to those things struggling to come on cam

Theyre not all like that, some sound crisp and strong.