Speedytec

iTrader: (3)

While talking about cams here; we have something strange going on between two similar LSJ engines:

#1; LSJ, ported head, Harrop 80mm and ZZP stage 2 cams. (Cam base circle checked!) Runs quite decent and idles @42KPa with ~7% TB. Run it with 60lb's and also with the stock tune/injectors to check idle and low load behaviour. No issues besides dialing in the tune with new injectors.

#2; LSJ, ported head, Harrop 80mm and ZZP stage 1 cams. Idle and low load is sh*t. Top power is OK though, but this one only idles @53KPa and 11-12%ETB... It should idle with more vacuum due to the milder cams, as stock LSJ cams idle @33KPa.
We quickly checked the cam install with the chain links (OK), but next step will be controlling exact "cam timing with a degree wheel and valve lift. And measure the base circles + lift.
This engine also seems to have an exhaust leak at the header, but that should not influence idle vacuum that much, right?

mrbelvedere

iTrader: (3)

The stg1 zzp cams have a lsa of 109 the stg2 is 112 that is probably the difference in manifold vacuum an exhaust leak pre upstream o2 can effect idle quality

Speedytec

iTrader: (3)

Yeah, LSA affects vacuum and so does duration. But should be the other way around. The milder Stage 1 cams should pull more vacuum than my stage 2's...
The stage 1's do 10KPa less vacuum on his engine and needs ~11%ETC to idle @875rpm. Weird..

mrbelvedere

iTrader: (3)

lsa has more effect on manifold vacuum

if you look at the spec cards it should say to install the cams at 110 or 112

Speedytec

iTrader: (3)

According to ZZP's site:
ZZP Stage 2's have 111 LSA => pulls 42KPa vacuum @idle in my engine
Stock LSJ cams have 107,5 LSA and those gave me a 33KPa vacuum

His Stage 1's have 109 LSA and that is right between those 2 , but it only pulls 53 KPa vacuum. Probably due to the 11%ETC opening that his engine needs to keep idling...
(And we checked some old logs of his engine with stock LSJ cams fitted; also ~33KPa. :-/)

Checking cam profile and timing coming days.

mrbelvedere

iTrader: (3)

my zzp stg2 cams pulled 16in my custom cams pull high 12in
but 9.7in of vacuum on stock cams tells me the stock cams were probably out of time it should pull 19in(65kpa)

SSfamilywagon

iTrader: (2)

Sub'd for info since I will be going custom specs

Speedytec

iTrader: (3)

I'm a metric European, so:
Stage 2 cam 16in (merc) vacuum will be 54KPa vacuum. => ~46KPa MAP reading. (Close to my measured 42KPa MAP)
Custom cam 12in = 41KPa => 59KPa MAP value

Stock cams 19-20in = 65KPa vac => 35KPa MAP; right what we measured on both stock engines. Think the LSJ cams and my Stage 2's were/are timed right...

mrbelvedere

iTrader: (3)

the other thing your missing about the stock cams is they are advanced 11deg

map and guage different post normal not metric

Speedytec

iTrader: (3)

Not relevant; both engines measured with stock cams ~33KPa MAP, 20in vac, so mechanically nothing wrong with the engines. This is about the odd vac/map difference we find between the Stage 1 and stage 2 cams, while both cams are timed in a similar method...

Staged07SS

iTrader: (25)

I see around 15 in with my S1 cams.

My car idles nice.

Sounds like something might be off with the TVS car with the S1 cams. Maybe a vac leak somewhere.

mrbelvedere

iTrader: (3)

camshaft advancement is relevant as it can change manifold vacuum

map sensor reads different then gague

Speedytec

iTrader: (3)

it has no vac leak, his the ETB is around 11-12% @idle. With a vac leak you would see the ecu closing the ETB more to lower rpm, and if that fails will lower spark to even negative if the actual idle rpm keeps higher tnan commanded idle. (we did have a leak before, as the ZZP dual pass plate interferes with the Harrop TVS...)

cams measure base circle 30mm, so ok. Now to check actual cam timing..

mrbelvedere

iTrader: (3)

I had no vac leaks but mine would idle in negative timing on the zzp stg2 cams it wound up being tune related

Speedytec

iTrader: (3)

That's why we're busy adjusting/comparing tunes and swapping injectors. Even back to stock injectors and GM settings to start fresh.
My engine idles & drives quite nice with stock GM injectors, his stage 1 cams not...

This weekend measuring cam lobe centers to rule that out.

Speedytec

iTrader: (3)

So we did some measurements of the ZZP Stage 1 cams in the car. We repeated a few times with different measurement set-ups, but results were the same:

Degree wheel on the pulley, zeroed on TDC position and a measuring gauge on the valves.
Measured the crank degrees from start lift (0.050" on the gauge) to end lift at the same 0.050". Divide by 2 to get the lobe centerline degrees.

EXH: open @151*, close @346* => Lobe center = 248.5* ATDC => 111.5* BTDC (ZZP specs = 115*)
INT: open @-1*, close @193* => Lobe center = 97* ATDC (ZZP specs = 102*)

Lobe sep. angle = (111.5* + 97*)/2 = 104.25* (ZZP specs Stage 1 = 109* LSA)

These 5* less LSA degrees will create more valve overlap and very likely the cause of our poor vacuum and the idle bahaviour. Shame, as we especially bought ZZP cams because they are said to be accurately degreed for the LSJ... :-/

mrbelvedere

iTrader: (3)

I was figuring that it was out

Zooomer

iTrader: (1)

Getting accurate cams from comp has been difficult at best. We're working with them on some new fixturing for their machines but it's in process. Add to that the base circle issues and misboxing and it's been a real struggle. If you were to buy an LSJ cam by part # from a random vendor who isn't checking them, the chance of it being accurate isn't very good.
We've had a lot that were close and we shipped them. This is the unfortunate reality of the state we're in.

Currently we've taken LSJ cams out of stock. we have piles of them if someone wants a deal and knows how to use them with adjustable gears. Brand new, boxes say the right things, cams aren't what they say tho.

JapEatr

iTrader: (9)

I need some adj gears

Spawne32

iTrader: (1)

Why not run comp XE264HR-13, at the very least those arent regrinds and you shouldnt have any issues with the lash adjusters.

113400 - Cast core version Hydraulic Roller Camshafts

Zooomer

iTrader: (1)

None of the ZZP LSJ cams from Comp are regrinds.
The above cams would not be as spec'd when you receive them.

mrbelvedere

iTrader: (3)

zoomer why don't you all offer better cam sets

Josh@ottp

iTrader: (4)

I would say 1 out of 4 have too large of a base circle. A real pain in the ass.
I don't think anyone sells regrinds for the LSJ anymore. You can get them done but why.

Spawne32

iTrader: (1)

What are you using to measure the cams that you say are out of spec directly from comp?

Spawne32

iTrader: (1)

Not sure what you mean "but why?". Regrinds are the only way car's that don't have a large aftermarket normally get into the aftermarket camshaft game, and typically when there are issues with running out of base circle for more aggressive profiles you can just hardweld the cam. I just had a set of LE5 cams reground to Kelford's EVO 9 272 cam design only in a single pattern setup, no issues there, just gotta know your lift limits more than anything. I stopped at .425/.425. No reason to run any higher than that unless the head supports it.