What do I need to know about installing a more aggressive cam?

On the X you pretty much never need different springs on a hot street motor.
They just aren't required. If you go beyond 10.3 mm lift, supposedly you may encounter coil bind and you need different springs, but not necessarily stiffer.
All they do is increase wear and decrease engine power (because it takes more force to open them).
 
I think if you just do the best you can to verify that the existing springs are within spec, that would be fine for the application.

The shop manual has specs on p 10-54 for free height, an intermediate height (probably installed/closed) and a lowest height (probably installed/open). The free height spec can be easily checked with a caliper, and if you wanted to test for the compressed specs, and you do not have access to a valve spring tester, you would have to rig up some sort of jig and have some free weight barbells collecting dust in the basement :) to check the installed heights.

I'm guessing that a regrind cam is going to need shims that are either going to be on the high end of, or thicker than, the stock range of 3.70mm to 4.70. My machine shop buddy has three trays of valve clearance shims with a lot of the fatter ones, so let me know if you need any and I will check if he has the sizes you need.

I get the impression that you are going to be doing the cam change and the valve seals with the cyl head in-place, something that is very doable if you use an air chuck adapter to pressurize the cyl or if you use the "rope trick" to fill the cyl to support the valve head while removing the spring. I find that the really strong magnets that they sell at Lowes Depot are handy for keeping the tappets and the shims in place in the cambox while removing and later reinstalling the cambox onto the top of the cyl head.

Of course since you need to remove the cam belt for this job, best to replace the belt and the tensioner bearing, cam box-to-cam oil seals and the two gaskets.
 
In addition to the excellent two posts (above), I'll add that in my opinion the stock Fiat valve springs tend to be rather stiff already - at least compared to other vehicles I've worked on from that era with similar types of engines. Remember they were designed for the "Euro spec" cam which is very close to the one you are installing. So the springs will be pretty well matched to that cam.
 
Thanks for good info all.

Dan Sarandrea (Phila) said:
I think if you just do the best you can to verify that the existing springs are within spec, that would be fine for the application.

The shop manual has specs on p 10-54 for free height, an intermediate height (probably installed/closed) and a lowest height (probably installed/open). The free height spec can be easily checked with a caliper, and if you wanted to test for the compressed specs, and you do not have access to a valve spring tester, you would have to rig up some sort of jig and have some free weight barbells collecting dust in the basement :) to check the installed heights.

I'm guessing that a regrind cam is going to need shims that are either going to be on the high end of, or thicker than, the stock range of 3.70mm to 4.70. My machine shop buddy has three trays of valve clearance shims with a lot of the fatter ones, so let me know if you need any and I will check if he has the sizes you need.

I get the impression that you are going to be doing the cam change and the valve seals with the cyl head in-place, something that is very doable if you use an air chuck adapter to pressurize the cyl or if you use the "rope trick" to fill the cyl to support the valve head while removing the spring. I find that the really strong magnets that they sell at Lowes Depot are handy for keeping the tappets and the shims in place in the cambox while removing and later reinstalling the cambox onto the top of the cyl head.

Of course since you need to remove the cam belt for this job, best to replace the belt and the tensioner bearing, cam box-to-cam oil seals and the two gaskets.
Click to expand...

Yeah I was planning on using an air compressor to hold the valves up while I do the valve seals. Turns out the fittings I have for my compression tester fit on the end of my air line already. The magnets seem like a good idea. At the same time I'm also going to be changing the cam belt, tensioner, and all seals and gaskets I can get to so front crank seal, aux shaft seal, cam seal, both cambox gaskets, valve cover gasket, and anything else I can get to - I have a full gasket and seal kit for this engine.

When I was planning to do this on the other X I had I got that head resurfaced, lapped the valves, replaced all the seals/gaskets, and measured and bought the correct shims for that head/cambox combo with the new cam. So I do have an assortment of thicker shims, but I won't know if I have exactly what I need until I make some measurements. If I need some I'll let you know - thanks!

I was debating if I should just swap the heads. Personally I don't think it's worth it. The gain would be freshly lapped valves and maybe some time savings if I ended up not having the right shims for the existing head on the car. The cons are a lot of extra work, potentially extra cost, having to deal with retorquing the head bolts . . . maybe I'll borrow a boroscope to see if I can check for pitting on the valve seats, but the compression numbers don't suggest an issue.
 
aarpcard said:
I was debating if I should just swap the heads. Personally I don't think it's worth it. The gain would be freshly lapped valves and maybe some time savings if I ended up not having the right shims for the existing head on the car. The cons are a lot of extra work, potentially extra cost, having to deal with retorquing the head bolts . . . maybe I'll borrow a boroscope to see if I can check for pitting on the valve seats, but the compression numbers don't suggest an issue.
Click to expand...
There's one thing that might persuade this decision a little. When I removed the valve springs from my head, the retainers ("keepers") were REALLY stuck (on most of the valves). This was with the head off and using a heavy duty valve spring compressor designed for American V8's, so it has a rather long lever arm and multi-pivot articulation to give more mechanical advantage. Despite lots of 'strong-arm' pushing, several severe impacts with a mallet, penetrating lube and multiple attempts with every tool I could think of, they would not budge. After doing some research I learned that this is common. It seems to go one of two ways; either they come off easily without undue effort (as some of mine did), or they do not budge (as most of mine did). I finally set up a fixture to put the head in my hydraulic press to break the retainers free (with considerable force). So if your retainers are as stuck as mine were, then you may end up having to take the head off anyway. I can't imagine compressed air being able to hold that kind of pressure to keep the valves in place. But hopefully yours will fall into the other category and come off easily.

That being said, I'd be inclined to remove the head anyway. To either clean up the valves and chambers and inspect for warpage and/or cracks, or swap it with the rebuilt head. Fresh surfaces and a new head gasket (properly installed) is good peace of mind with these engines being somewhat prone to overheating and resulting head issues. Plus it seems a good idea to have fresh valve surfaces to go along with the performance cam.
 
I'm resurrecting this thread again. I'm finally finishing this project.

Got the head off of my current X, installed the new cam, used a combination of lash caps and thinner shims to get the correct clearances, replaced all gaskets, and valve seals and cam seal, cleaned everything, and am ready to mate the head back to the block.

I have a few questions about the correct way to torque the head bolts. My head is a 10 bolt FI head with 17mm head bolts.

I purchased these new head bolts from MWB to use: https://www.midwest-bayless.com/Fia...rtone-x19-1981-88-wfi-ritmo-uno-yugo-new.aspx
I am use a new head gasket that was supplied in this kit I also bought from MWB: https://www.midwest-bayless.com/Fia...e-x19-1980-late-85-strada-premium-wseals.aspx

I have seen on this forum that the recommended procedure for torquing the head bolts is to heat cycle the engine prior to doing the first 90 degree pass on the bolts, and then do the second 90 degree turn after having driven the car for 500 miles.
I'm confused about this for three reasons:
1) I can't seem to find anything in the shop manual dictating this heat cycling process.
2) Does the heat cycling process only apply to "torque to yield" bolts and not "straight-torque" bolts or vice versa or both? I am using "straight-torque" bolts.
3) If the heat cycling process is not dictated in the shop manual, how did FIAT build these engines in the factory? Did they heat cycle the engines when the heads were first installed and then torqued the bolts 90 degrees? Did the customer then have to bring their car back to the dealer after 500 miles and get their head bolts torqued again?
4) MWB states on their website (for the bolts I am using) to torque them in an alternate three steps.
"Requires an alternate torque process to that specified in the factory manual, in three steps: 20ft-lbs / 40ft-lbs / 58ft-lbs."
If I do need to heat cycle the engine, what sequence of steps should I use with these new torque values. They don't specify 90 degree twists. 20ft-lbs seems awfully low to then fire up the engine with. . .


Below is the procedure I found in the shop manual. . . I can't seem to find anywhere stating the engine should be heat cycled between 90 degree twists (doesn't mean it isn't there - I just can't find it). All advise is much appreciated!
torque steps.png
 
I would just follow the 3 stages provided by MWB. Heat cycling inbetween ANY of the first 3 stage torque process seems wacky to me...

Do the 3 stage, drive the car for the recommended interval, then retorque. I'd check with MWB on the retorque though, I don't recall what the spec'd procedure is, since the torque proceedure is different than OE.
 
I have never heard of or seen any reference to any method that requires the engine to be heat cycled between the first two 90 degree passes...

The only reference you may find is to heat cycle the car numerous times, after following the full TTY torque procedure on rebuild, and then after about 500 miles or so, add an additional 90 degrees (in two stages 30/60 from memory) to ensure the head gasket keeps sealing.

The gasket set you've purchased doesn't appear to contain a polymer composite head gasket anyway, and the bolts are specified to be regular torque method non stretch type ... so the whole TTY discussion does not apply...

so use the "regular" torque method... i.e. in several stages to a final value... heat cycle the car once and let it cool completely, re torque... then drive 500 miles and re torque again. You will need the special cranked spanner(s) for installation and re torque.

SteveC
 
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I hope you have access to the whack-a-doodle factory head bolt wrench setup, otherwise you are going to dread all that retorquing, which without the special wrench will require removing the cam box....
 
Thanks for all the replies. I'm still a bit confused about the necessity to retorque after heat cycling the motor. Is that common wisdom or is it actually called out somewhere? The procedure in the shop manual doesn't seem to mention that and I'm not sure how the factory would have handled that either logistically.

I don't have access to the special wrenches, however I do have a few tools on order that I might be able to make work.

I did look at the Lycoming aero wrenches and I'll end up buying one if I can't hobble something together with what I have.
 
re torque of regular composite type gaskets was handled at pre delivery service performed by the dealer. This was part of the reason Fiat (in conjunction with partners) developed the astadur type gasket (a polymer composite construction that doesn't compress / settle when heat cycled) and the whole TTY system to eliminate the dealer interaction... obviously some statistical analysis led the management to this decision given pockets of early head gasket related failures where the dealers had neglected this step in the PD procedure.

re torque after heat cycle is needed, so is the tool (without taking the cambox off), otherwise you'll do the job more than once.

SteveC
 
fiatfactory said:
re torque of regular composite type gaskets was handled at pre delivery service performed by the dealer. This was part of the reason Fiat (in conjunction with partners) developed the astadur type gasket (a polymer composite construction that doesn't compress / settle when heat cycled) and the whole TTY system to eliminate the dealer interaction... obviously some statistical analysis led the management to this decision given pockets of early head gasket related failures where the dealers had neglected this step in the PD procedure.

re torque after heat cycle is needed, so is the tool (without taking the cambox off), otherwise you'll do the job more than once.

SteveC
Click to expand...

That makes sense - I'm glad this forum is around and active, there aren't many online communities around that share the depth of knowledge available here.

I'm assuming for the initial heat cycle, getting the engine up to 190F for a few minutes and then letting it cool completely is adequate?
 
fiatfactory said:
re torque of regular composite type gaskets was handled at pre delivery service performed by the dealer. This was part of the reason Fiat (in conjunction with partners) developed the astadur type gasket (a polymer composite construction that doesn't compress / settle when heat cycled) and the whole TTY system to eliminate the dealer interaction... obviously some statistical analysis led the management to this decision given pockets of early head gasket related failures where the dealers had neglected this step in the PD procedure.

re torque after heat cycle is needed, so is the tool (without taking the cambox off), otherwise you'll do the job more than once.

SteveC
Click to expand...
That may explain the loose head bolt I found shortly after my car was delivered by the most incompetent dealer I ever bought a car from. They probably never read the pre-delivery instructions.
 
aarpcard said:
I'm assuming for the initial heat cycle, getting the engine up to 190F for a few minutes and then letting it cool completely is adequate?
Click to expand...

Yes, more than adequate to wait until the front fan cycles a couple of times on / off. It's usually a good time to do a system bleed etc anyway while the car does it's initial run, and then I usually let them cool off overnight. If you want to get picky I also like to do the retorque early mornings when ambient temps are coolest too...most texts wont say it but torques etc are usually factored around 20 degrees C. (std lab test conditions)

Depends on the car, but often I'll fill with distilled water only for the first run to check for leaks etc, easy enough to drop a few litres out by the drain points and top up with coolant concentrate once you know everything is OK. I do the first run with the system filled, and a 2 litre bottle filled with water inverted in the filler neck... as the engine runs you'll see the air bleeding out, and as the thermostat opens a lot of the 2 litre bottles contents will empty into the system. have the allen key in the radiator and the bleed cock already cracked off and nipped... ready to open / close easily while you walk around the car at first run.

EDIT.

might seem a little long, but have a read thru this cut/paste from my ultimate sohc thread... it explains a few of the do's and dont's.

IMO the SOHC engine is not a head gasket eater. IMO failures most likely happen due to confusion about
a) torquing / retorquing procedure with changes over the engines production life

b) the use of non genuine - non astadur gaskets with the TTY system, which will lead to fsailure.

c) the reuse of TTY bolts that have yielded.


Head gasket choice and correct installation procedure.

So many people have head gasket issues, which I find quite amazing as the SOHC Fiat is NOT a head gasket eater even at high power levels. IMO it comes down to two factors why people have problems, gasket choice and installation technique

Torqueing and re-torqueing... why's, hows, do's and don'ts.

Before installation make sure bolt holes and threads are clean. Oil and drain bolt threads. Apply a small dab of antisieze compound under the nut/bolt head between it and the thick flat washer, this reduces the friction involved to a minimum and helps achieve the maximum clamping force without taking the fastener into the 'plastic (deformation stage) and keeping things in the 'elastic' range where the fastener will return to it's original dimensions when load is released.

If the threads in the block are not clean or lubed this can give you a false torque reading. Chase out the threads well, you can buy specific tools for this rather than using a thread tap which can remove metal from the threads, which you don't want, something a bit like this,




The M12 bolt / stud combination is always a retorque style engine, and uses a retorque style head gasket. It absolutely needs a retorque after a heat cycle and again after several hundred Km. Failing to do so will lead to a head gasket failure.

First torque on assembly. multiple stages, the more the better so the head clamps down evenly, 15/30/45/60 or 20/40/60 and then finally 69 lb/ft. This is going thru all the bolts /nut one at a time in torque sequence to each value, then stepping up the wrench to the next value, and repeating for the other nine fasteners... it takes a little while, but certainly pays dividends by only having to do the head overhaul / gasket replacement once.

First re-torque after one heat cycle... run car, fan cycles on / off maybe three times, shut her down. Let it completely cool, overnight is best, retorque in the morning when the ambient temp is coolest. A second re-torque, I usually do after maybe 100 miles (160km) again completely stone cold.

For retorques the procedure I follow is...In torque sequence order, one bolt/nut at a time, loosen the bolt/nut around 1/4 to 1/2 a turn with a breaker bar, retighten back the same amount. (I use a paint marker on the bolt nut to get it back to pretty close to its original position) Then swap the breaker bar for the torque wrench and using steady slow and even pressure on the torque wrench, take it straight up to the final torque value (9.5kg/m) Then go on and do the other nine head fasteners in precisely the same sequence, loosen/nip up/retorque.

Engines with M10 head fastening hardware, things are a little different. There has been much discussion about the 'Torque and Angle' (TAA) system used by Fiat during later production, and also the use and reuse of the 'Torque to Yield' (TTY) style of bolts used. Many servicing and instruction manuals imply that following a TAA system will negate the need to re-torque after heat cycling. But, it must be remembered that the non retorque system relies on the use of a compatible head gasket.

Goetze in conjunction with Fiat developed a Polymer composite construction gasket, which rather than settling and compressing under heat cycling (like a regular composite gasket does) it contains a special polymer which is heat activated and actually hardens. This style of gasket is known as 'Astadur' and when used with the correct bolts and tightening system, is the ONLY system which will not require retorquing after assembly and heat cycling. It's not the type of bolts, not the tightening method used, not the gasket alone, but a complete system that all works together to provide this non-retorque ability.

With EVERY other type of gasket, even when following the TAA system of tightening, the head fastening hardware MUST be re-torqued to ensure that the gasket doesn't fail.

Fiat service letters and manufacturers torque instructions confirm this, as it's likely they were receiving warranty claims from people following a non-retorque method when using a NON-Astadur style head gasket. Below is the torque specifications supplied with Victor-Reinz gaskets which clearly shows the use of TAA system for initial tightening, and the need to retorque after 1000km. Also a picture showing the torque specifications supplied with Elring brand head bolts and gaskets.

View attachment 87 View attachment 88

If you wish to source the correct Astadur head gasket the correct Fiat part numbers are;

5951682 is the 1.65mm Astadur (polymer construction) gasket for the TEN bolt M10 engines (up to 10/85) supersedes to 7588550

7580221 is the 1.65mm Astadur (polymer construction) gasket for the 14 bolt M10 engines (11/85 on) which supersedes to 7637103

7604404 is the 1.65 Astadur (polymer construction) head gasket for the Tipo 14 bolt engine (supersedes to 7666858)

So with M10 fastening hardware you have a choice. If your using a straight torque system, then you need to torque on build, retorque after one heat cycle, and then retorque again after a couple of hundred Km's ... that's the right way to do it.

Torque should be 61.5lb/ft for straight torque, at least three stages on initial torque too, so 20/40/60/61.5 lb/ft. For a proper Retorque you should back each bolt off 1/2 a turn, one at a time in retorque order, and then retorque it straight to 61.5 lb/ft and then move onto the next fastener in the head torque sequence and follow the same steps until all ten are done.

If you use torque and angle system, then 40Nm, and two x 90 degrees, one bolt at a time in torque pattern order at the initial torque value (40Nm) and then one bolt at a time to 90 degrees, and then through the whole sequence again with another 90 degrees.

Unless your using a genuine Fiat (Goetze type) Astadur polymer composite construction gasket then this initial torque should be followed by an additional 90 degrees after several 100 km's and this retorque is done without first backing the bolt off, it's simply one bolt at a time in torque sequence a further 90 degrees, with most systems recommending doing this in two stages 60 degrees followed by 30 degrees for a total of an additional 90 degrees.

follow these steps and you will have success.

added thought... it also pays to check the manifold to head stud/nuts at the re-torque stages... and also the exhaut flange nuts (if your running a twin front pipe) as these will also come down another 1/8 of a turn usually. after 100 miles I usually check the cambox bolt tension too, and run a feeler gauge thru the gaps to confirm the lash hasn't altered beyond spec.

SteveC
 
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I used the M10 Elring TTY fasteners together with a custom head gasket on my build.
I used the instructions posted above.
When done, I used a torque wrench to estimate the torque applied to the bolts with the angle method.
It was about 120Nm (88.5 ft-lbs)!
This is obviously much more than the 58 ft-lbs used with the non-TTY M10 bolts.
So if you are after clamping force on a high performance build, I would recommend the TTY bolts.

I cannot imagine retorquing the bolts another 90° since they already felt like they are about to snap with the method above. :)

I have to admit that I do not fully understand the interaction between Astadur gasket and TTY bolts and don't know what shoudl happen when the TTY bolts are used with a regular gasket.
 
Shaving the cam box will not change the CR.

To fully wake up the motor, you will need more air and more fuel. Having a machine shop open up the intake manifold and port math to the head helps allot.

There are Bosch injectors that were used on late 80's Jag xj-6's that flow a slightly higher rate at the same fuel pressure, and that helps the increased fuel need to match the extra air getting in the motor.
 
aarpcard said:
I'm resurrecting this thread again. I'm finally finishing this project.

Got the head off of my current X, installed the new cam, used a combination of lash caps and thinner shims to get the correct clearances, replaced all gaskets, and valve seals and cam seal, cleaned everything, and am ready to mate the head back to the block.
Click to expand...

As a concept substituting a lash cap for shim thickness is a good idea, because you are saving valve train weight, which is pretty much always a good thing. But, generally speaking when using lash caps under the cam followers/buckets, one has to be mindful that the lash caps are not so thick that the corresponding reduction in shim thickness takes the height of the shim down into to the bucket to where there is a danger of the cam crashing into the rim of the bucket. Hopefully that has been factored in!

PS--some pix would be nice, ya know! :)
 
dllubin said:
That may explain the loose head bolt I found shortly after my car was delivered by the most incompetent dealer I ever bought a car from. They probably never read the pre-delivery instructions.
Click to expand...
I have to agree, requiring the dealers to re-torque the heads before delivery to the customer is asking for head gasket failures. Based on my countless years of experiences with dealerships in general (not just Fiat), their mechanics tend to be mediocre at best (absolutely no offense to anyone). Even worse is dealership management (again, no offense), who likely would not even ask the mechanics to do this in the first place. I can see why Fiat decided to go another route with the gaskets/bolts based on this alone. As I said this is not a Fiat comment, but a dealer issue in my opinion.
 
Somehow I missed the whole retorque after a few heat cycles routine :D I did the initial, then retorque after about 800 miles. It's been 4K miles since. I used TAA bolts and gasket from Obert on the post-detonation gasket failures.

Pg 10-51 from the manual

Screen-Shot-2019-05-23-at-9-26-16-PM.png

followed by this after 800 miles
X19_0214.jpg
 
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