Purple Cams!

[maytag]

Hey all:
it's time to start a write-up on this. Hopefully others will find it useful. Let me say first that Daniel and I have been working through all of this new stuff together and I'm very confident we'll come to a great conclusion. It's not always easy when neither of us do this for a living, and we live several states away from each other. But as far as Daniel's knowledge of this motor and what he has proposed, I trust him and respect his research and conclusions. I also trust him ethically, and so far have been very happy with the value I've gotten for my dollar.

So, I took note several months ago when Daniel posted about a new (to me) idea on cams.
See the thread here:
http://www.fiatspider.com/f08/viewtopic ... 11&t=17073

Daniel and I PM'd back-n-forth a bit, and long story short, I've got a set of these custom cams. Through the back-n-forth on it, I also ended-up with a set of custom springs and retainers... but that's a longer story.

I'm starting this thread because i think the info will be useful to others trying something new, and hopefully it'll prove-out to be a great combination and Daniel will be able to promote it to others.

Some of you may recall that this project began when I decided to desmog the car. next thing I know, I've got the car torn-down to it's withers and I've spent too much money and WAAAAY too much time.
This project didn't start-out with a plan. it's been "project-creep" since day-one.

So here's what I've got:
I lightened the rods and matched them to new 4.5mm-dome pistons in stock bore-size. I honed the cylinders really well for these new pistons / rings. I had the entire assembly balanced and included a lightened flywheel from Millers' Mule.



Once I got the cams and hi-performance springs, I started to assemble, only to discover that the springs had a slight "beehive" to them, tapering at the top just enough that I was uncomfortable with the way the retainers sat in them. I also noticed at the time that the springs seemed far too compressed in their static-state, like they would be prone to coil-bind.


I talked to Daniel, who asked me to send them back to him. After his review, he sent me back the same springs, but with a set of machined-down retainers that fit nicely in the spring.


In the meantime, I discovered that I had a couple of bent valves. I had originally planned to just button the old head back onto the motor, as I was trying to resist further creep and delays. But once I realized I had bent valves, I ordered replacements from Autoricambi. Again, I was hoping to avoid machine-work. the valves arrived, but they accidentally sent me the performance-valves. they immediately sent me the correct ones. Daniel and I had discussed big-valves previously, and he suggested that the big-valves were a waste at this stage. But when I took the head in to the machinist to do a valve-job, he pointed-out that the stock-replacement valves are 2-pc valves, welded at the taper. This is a machinist I've used and trusted for 30 years: when he says he wouldn't put 'em in a motor past 7Krpm, I trust him. So we decided to put the performance valves in. He did a beautiful job of grinding new seats and blending the SSR in the bowl.




So today I went to assemble, again. Finally. Even took a day off work to get it done.
foiled-again.

so: I get the new springs & retainers installed. ok.
I get the cams into the camboxes: ok.
I install the camboxes on the head and the new adjustable pulleys from Millers' mule.



but here's where the problems start: the cams won't turn. COIL BIND. I was correct in my initial gut that they would be binding. For anyone reading this who is unfamiliar with the term: the spring is compressed as far as it goes, the coils are stacked right on top of each other, and the valve is still not open all the way. Coil Bind.

An additional problem: because these cams are a regrind from a factory cam, they have a reduced base-circle. So on the exhaust-side, the tappets / shims have a gap around .2mm; nothing I can't work with. But on the intake-side, it is SIGNIFICANTLY greater, at about 2.5mm or more!!!

SO:
I pulled the camboxes back off. under the springs are two pieces of hardware: a thin shim (bottom) and a centering-base (top).


I removed the centering-base. I don't know why this should be needed with a single-spring (compared to the double-spring from the factory), so maybe Daniel intended this to be removed. (it is sometimes difficult to get ahold of Daniel, as he's very busy with his day job. So frequently I find I'm working through stuff he could probably save me from, if we could speak more readily).
So I removed these on the intake-side and reassembled the springs onto the head / valves.

here it is installed with the base:


and here without the base:


The cams turn, the springs don't bind. I would love to have some information on the springs about what their installed height should be, so I could reassure myself that they won't be suspect to float.... I don't know if Daniel has information on this or not, as it hasn't been a question I've raised obviously.

So then I put the cambox back on. I discovered that the shim under the spring is almost exactly 1mm in thickness, and is the correct diameter to install into the bucket on the top of the tappet, under the valve-shim. installed this way, and with a 4.2mm shim installed, I've still got a clearance of .5mm. Yes, I can get shims big enough to make that work. But I look at the amount of weight I'm adding to the valve-train, and the concern I have over the shim popping-out of the bucket, and I must say I'm nervous.

How many of y'all have used regrind cams? IS this common shim / clearance-spacing? how do YOU fix it? I've debated having the cambox milled 1mm. is that a good idea? I'll be degreeing cams anyway, so what other problems do I face if I do that? (other than yet MORE project creep, and MORE delays).

appreciate any comments. even if they are "this is what happens when you don't have a plan when you start a project" sort of comments.

again, I'm hoping that as this comes together and Daniel and I work-out some of the details, it'll become easier for someone else to follow after.

[djape1977]

you should have cut off portion of the valve guides protruding into intake and exaust ports in the head.

[maytag]

you should have cut off portion of the valve guides protruding into intake and exaust ports in the head.

I thought the same thing, but everyone I discussed that idea with (including my machinist and Daniel) told me it was of no value on this head, and could actually hurt.

[124ADDHE]

Yeah, regrinds are kinda false economy, extra weight where you dont want it is the nasty result, but damn, new cams are pricy for this rig...Those G.C. cams are really probably worth every last bit of money

[engineerted]

What the hell are you doing? Unknown single spring, not good, save yourself the hassle and buy the isky springs the Csaba sells. No issues running 11mm lift cams at 8500 rpm.

Regrind cams? What are the specs? Key factors are LATDC as I see that you have not cut bigger reliefs in the piston valve pockets or even offset pockets on pistons 1&4. You need to verify the valve to piston clearances other wise you maybe stuck run 110-115 lobe centers.

Cam boxes, and shims with reduced base circle, no cam box gasket, just rtv, or make yourself very thin gaskets. The stock gasket is about 0.035". The other method is to cut the valve seats deeper in the head.

Have fun!

[124JOE]

thank you matag i did know some of the idea about cams and your thread has info to learn from
i wish you the best on it
GO PROJECT CREEP!!!

[Daniel]

Thanks Dan for Posting this build on the site and sharing your progress and I am sure a few people
will learn some tips out of your detailed photos and description as you go a long .

This is a General response / Reply Not Aimed at any one person and intended to help people understand
Cam timing .

Checking and adjusting the camshaft timing can be a little bit intimidating for most DIY guys or first-time
engine builders because it is a bit complex at first. But it is also vitally important because getting it wrong
can cost you serious power. Plus, the ability to modify your cam timing can help tailor your engine's power
curve to your needs.

Valve timing is crucial to the efficient operation of the 4-stroke Engine. The opening and closing
of the inlet and exhaust valves at the correct time in relation to piston position must be precisely controlled,
either at a fixed compromise position, or variable within finely controlled limits.
The valves are opened and closed by the camshafts which are driven by toothed belt from the crankshaft.
Finding piston TDC Timing your camshaft involves measuring total lobe lift, the lobe center lines for both the
intake and exhaust lobes, camshaft duration at 0.050-inch lift, and lobe separation. But before we can do
any of that, we first have to find the crankshaft location when the piston in the number-one cylinder is at
top dead center (TDC). But it should always be checked because any number of variables can throw off cam
timing. These factors include, but are not limited to, an improperly timing mark, errors when machining the
block, Flawed Timing Belts, assembly errors, or even an improperly ground camshafts ( regrinds or New even
A Billet Cam )

Let's Talk Cam Timing now

1) Cam timing - in simple terms this means when the intake and exhaust valves open via the cam lobes to
provide the engine with the most gains. The most important aspect of cam timing is the intake valve closing
event which determines how much cylinder pressure your engine will build. In other words if you close the
intake valve early the cylinder will build more pressure as the piston compresses the mixture past BDC ( Bottom
Dead Center ) toward TDC (Top Dead Center )and you'll have a bigger "bang" at lower revs. If you close it later
you'll have less pressure but the engine will maintain it higher up in the rev range as the engine does not have
to overcome "pumping losses" compressing the mixture. The exhaust cam works similarly but is not as important,
only changing the rpm at which the engine will "overscavenge" due to valve overlap. An engine with greater valve
overlap will run more poorly at low rpm than one with less overlap. All things being equal the first example may run
better at higher rpm but the second example will develop better midrange (better street engine).

2) Lobe centers - basically the point of the crankshaft rotation where the cams are at their highest lift. If you
were to decrease the lobe center # for the intake, say 105 that means that at 105 deg. past TDC (meaning the
crankshaft degrees) the intake valve will be at maximum lift. This also means that the intake cam will be
"advanced" by 2 deg. and the intake valve will close earlier, meaning more cylinder pressure and better midrange
with a slight loss of top end. Higher lobe center #'s for the intake mean the valve will close later and some
midrange will be lost with a gain in "overrev" due to the piston having to compress less mixture in the cylinder
as it rises toward TDC. Cam TDC is centerline on the top of the Lobe dont confuse this with Crank TDC these 2
timing marks/ events will never happen at the same time .

For the person with some of the proper tools, measuring lobe lift is extremely simple. All you need is a valid
indicator with an extension so you can reach the cam lobe at the lifter bore. I like to use a Steel plate
with a hole drilled at the end so i can use the valve cover bolt to attach the steel plate for the Dial Snap
Meter that has a magnet on the end . The shaft of the indicator should be in the same line that the lifter
would follow in order for the readings to be as accurate as possible . A Degree wheel can be printed on paper
for a one time use type or you can buy them at performance shops . Finding one that fits a Fiat Cam Pulley
maybe hard to come by .

Turn the crankshaft until the dial indicator is on the cam lobe's base circle. That is the area on the back side
of the lobe that provides zero lift. When you know the dial indicator is on the base circle, zero out your gauge.
Now, spin the crank and keep an eye on the indicator. As the lobe moves underneath the end of the dial
indicator, the needle will start moving. Watch until the needle stops and begins to move in the opposite
direction. This is CAM TDC maximum lobe lift.

.050 DURATION


TAPPET LIFT AT GROSS VALVE LIFT WITH MIN TOP DEAD CENTER ZERO LASH
General Suggested Cam Timing Settings
TAPPET LIFT TAPPET 104 - 106 Deg Intake
TAPPET LIFT TAPPET 114 - 116 Deg Exhaust

The Simple Way to Adjust the Cam Timing Would to use adjustable Cam Pulleys with Markings on them but
the Pulleys Dan purchased do not have timing marks on them . The simple way to solve this would be placing
proper timing marks then adjusting the cams to the desired timing degrees which I suggested to be .
3 to 4 Degrees Intake Advance
0 to 1 Degrees Exhaust Retard

Exhaust opens at the beginning of the exhaust stroke, and intake opens at end of exhaust stroke / beginning of
intake stroke. Overlap is the time when both are open at this time.
The lobe centerline is defined as where max valve lift occurs and is measured in terms of crankshaft degrees
from piston TDC. Lobe centerine is often-but not always-the halfway point of that lobe's duration. When this
happens, it is called an "asymmetrical lobe" usually depending on cam timing and lobe design Stock Fiat Cams
have a asymmetrical lobe design I'm not saying that the design is good just pointing out it's simple design.


Many Modern Performance Cam Shafts have an off asymmetrical lobe opening and/or closing lobe design, different
rates to maximize the engines flow and produce a good power band at the desired RPM Range for that engine.
On NA cars, there will be "scavenging" where intake air is pulled through into the exhaust due to properly designed
headers and the exhaust pulses from each cylinder hitting one another in a way where there's actually vacuum in
the exhaust manifold. So if you advance the intake cam, it opens sooner and increases overlap. If you retard the
exhaust, it closes later and increases overlap ...

I will add to this topic later i made A promise to post something in detail and tried my best to make this
easy for all to read and understand. It's focus is a bit much on the basics i know but I hope for others it's
going to be insight they might not of had before .

Good night

[Daniel]

What the hell are you doing? Unknown single spring, not good, save yourself the hassle and buy the isky springs the Csaba sells. No issues running 11mm lift cams at 8500 rpm

Ted these Springs weight less then standard 2 spring setups and generate less heat as well !
You bring up a good point that I over looked (but also tried to discourage Dan from using Larger
Valves in the first place) now the clearance maybe an issue on valve reliefs on the outer pistons i
would do a dry assembly to check this before cranking over . A Simple way to test this would be just
to install the valves for piston # 1 place the head on the block timed using some of that playdough
stuff forget the name of it alludes me at the moment .

[maytag]

Daniel:
thanks for posting this. I know it's tough to find this sort of time right now. As always, you've provided some insight into not only the "how", but also the "WHY". I always appreciate that, 'cuz I prefer to understand what I'm doing. If for no other reason than when Engineerted says "what the Hell are you doing?" I can respond intelligently.

So, it looks like we are all in near agreement then that the factory timed the stock cams at 110d ATDC for intake and 110d BTDC for the exhaust. I'm extrapolating a little, because you are suggesting that in my 3d (cam-degrees) advanced position I would be at FL at 104 (crank-degrees). And since that coincides with the 110d that Ted told me on the other thread about Cam Timing, I'll take the agreement between you two as gospel.

So my next plan of action on this:
I'm eliminating the gasket between cam-tower and head to reduce the shimming required. (I'm going to go get me some Yama-Bond, and I'll post pics. I'm telling ya: the stuff is awesome. you'll never go back to anything else! )

I will set my lash as close as possible with the shims I have available right now, using the method described above, with the spacer under the shim.

And then I'll "dry-assemble", with some plasticine to measure clearances. While I'm at it, I will plot out the clearances available in about a 10-degree range, so that when I'm adjusting cams I know how crazy I can get!

QUESTION: When I'm dry-assembling, can I torque the head-gasket, and then re-use it? or do I need another one? Or can I substitute something that'd represent the crushed-thickness? what IS the crushed thickness of a standard head-gasket? I got this set from IAP. Just a standard gasket set.

[Daniel]

the head gasket will be fine if your just going to assemble and take apart if it's one of the types with
rubber like sealing areas i would apply a small amount of oil just to be safe this is just a cautionary
measure .

[So Cal Mark]

You're not checking the spring pressure?

[maytag]

You're not checking the spring pressure?

Well... no....
These are the same springs Daniel is using in his motor, so I was just gonna go with it. I'm not building this motor for fun, ya know.

Daniel, any reason I should be checking pressure? (please tell me no. please tell me no. please tell me no)

[Daniel]

These springs have 5 more pounds of pressure at max lift over stock springs but i am sure no one else
checks spring pressures on what they use or at least i've never seen any data or facts they just trust the
manufacturers specs, these Springs are tested and are being used in a race car that is winning races this
was one of the reasons i decided to use them on my engine build .

[maytag]

While I'm at all this:
is there a simple way to check the valve-to-valve clearance? While I'm mapping clearance available for adjustment of cam-timing, this would be a good thing to know as well. GC has a fixture he built to do it with. that's waaaay too much project-creep... there must be an easier way.
anyone?

[djape1977]

you mentioned that you'll be using bog standard fiat twincam head gasket if i understood correctly? with 9mm dome pistons and 1800 head? are you sure it's the way to go?