OK, I'm finally getting an engine together- 4age bigport. I've got some one oversize 10.3:1 pistons on 40 mm rods, I'm cleaning up a head, I've got a light weight flywheel coming, and now I'm looking at cams. I've read the threads I can find here, some going back to '08, and I'm still not clear about what I'm doing. I've read about over bucket shims vs under bucket, and I think I get it that if the cam has too much lift or too steep a ramp one might experience the dreaded tiddlywink effect with the over bucket shims. I get it that somewhere around 264 to 272 degrees is OK for my purposes- street and back road twisties, but intake and exhaust the same? How much lift? I can get degree wheels for the cams I buy, but where to set the degrees? I've tried web searching various cams- Toda, Crower, HKS, and really don't find much help online. I work full time, I've got grandkids, my head is full of 66 years worth of useless crap- somebody explain in simple words what's a reasonable choice and how do I make it work.

On a second note, converting an fx auto to fx16 manual is not the jaunt around the park I'd hoped it would be.

There is a certain point where a big enough cam will cause problems with shim over bucket. One very often overlooked contributor is how tight the lifters sit in their bores. If the lifter to bore gap is too big or the liter and bore too tapered this can cause it to spit shims on a fairly small cam. With perfect lifters and perfect bores you can run a lot more cam than most people think you can.
Here is a little writeup on the subject and some pics where you can see just how worn lifters can get. This was just an ordinary street head.
http://www.matrixgarage.com/content/cam ... ketslifter


You say you have 10.3:1 pistons. Are these stock or aftermarket? Are they 20mm wristpins? If so are you using modified or aftermarket rods?

Intake and exhaust the same? That depends a lot on the situation and the grind. Kelford really likes staggered cams. On the other hand my cam grinder and many others very rarely stagger theirs. There can be times and reasons to run different staggers but generally speaking and on your average build I usually lean toward same grind on intake and exhaust. I wouldn't worry too much about that though.It's more about finding the grind that will work best for you.
Is the motor already together? 10.3 is a good bump for the stock cams but I would suggest more compression if you are looking to add much more cam.
As for what cam would be best for you that depends mostly on you.
How much lift? As much as you can.
Okay that might be oversimplifying things but in my opinion people tend to go way conservative on lift. I believe there are two primary reasons for this. The first is that the stock springs can only take about 8.4mm lift or a little more depending on how risky you want to play it so you will find a lot of mild cams below that so people don't have to upgrade springs to run their cams. The second reason is that there are a lot of race cams out there. TRD, Toda, TED, HKS, etc that are around 7.5 to 8.5mm lift. A lot of people think if these cams are good for race cars they must be good for their cars. Not realizing that these cams were made for classes that limited performance by limiting lift. The racers would have way preferred run 10.5mm lift. It was not allowed in their class. With that said 10.5mm lift isn't going to do much for an otherwise mostly stock motor though. More lift does also add some added stress and valve train wear so there are always some compromises. For a mostly stock head I lean towards the low to mid 9s.
It really does depend a lot on what the overall best cam would be for your application and for that we need to know as much as possible about your application.
1. How aggressive do you want your build? How much effort do you want to put into monitoring and fine tuning? Or do you just want something you can slap in and forget about?
2, Are you going to be running it on the stock ECU or aftermarket engine management?
3. Are you willing to change valve springs to run more lift?
How high of a priority is longevity? Are we talking about a motor that you want to go 200k miles, A play car that won't see 100k miles in it's life or a performance car that will get rebuilds more frequently?

oldae82 wrote:OK, I'm finally getting an engine together- 4age bigport. I've got some one oversize 10.3:1 pistons on 40 mm rods, I'm cleaning up a head, I've got a light weight flywheel coming, and now I'm looking at cams.

I've read the threads I can find here, some going back to '08, and I'm still not clear about what I'm doing. I've read about over bucket shims vs under bucket, and I think I get it that if the cam has too much lift or too steep a ramp one might experience the dreaded tiddlywink effect with the over bucket shims. I get it that somewhere around 264 to 272 degrees is OK for my purposes- street and back road twisties, but intake and exhaust the same? How much lift? I can get degree wheels for the cams I buy, but where to set the degrees? I've tried web searching various cams- Toda, Crower, HKS, and really don't find much help online.

I work full time, I've got grandkids, my head is full of 66 years worth of useless crap- somebody explain in simple words what's a reasonable choice and how do I make it work.

On a second note, converting an fx auto to fx16 manual is not the jaunt around the park I'd hoped it would be.

Know you are building your own... but I have a manual FX with a brand new reman engine.... makes great power for a "stock" rebuild......


For the most part.... yoshi and I agree... I tend to be a bit more conservative on lifts, getting big lifts and durations that are also emissions compliant are not easy - this is primarily why I recommend low 8 to mid 8, as it keeps durations more emissions friendly, while still providing a boost over an otherwise stock engine. If you don't have to worry about emissions, mid 8mm lifts to low 9mm lifts don't tend to be a problem, as lifts go further up (mid 9 to low 10) much more extensive head work is needed to get the most from the cams.

As to cam timing.... I'd be happy to walk you through it.... no big deal.

Ok to keep this simple....

1) if your head (bucket and bucket cylinders) shows as much wear as yoshi's page shows... you have a serious problem... get another head.

2) What engine management are you planning on running? This will determine what cams you want, as stock engine management has an rpm cut around 7500-7600. You don't need cams that make their peak power above 7600, as your management will not permit you to utilize all of the cam.

3) What valve spring do you want to run? The valve spring will be your limit on how much lift you will use. Stock spring can accommodate lifts to low 8mm (some stock springs more than others....). Aftermarket springs can usually accommodate more lift - some as high as 11mm (which you will not be needing)




assuming you keep the stock management -

Thank you both for your responses. I am: looking for something I can slap together and run; I've averaged 5k miles a year for the past 12 years on my current fx16; I won't be racing it, but I will be backroading it, and let me tell you SW Va. has some great twisties; I don't want to or intend to go into the engine again once it's together and right; the pistons are from a 91-93 smallport ae92 w/20mm wrist pins set on 40mm crank pin conn rods from 85-87 aw11. Or so I'm told. I'd like to have a good bottom to mid range power curve. I don't expect to be bumping redline much. The car itself is pretty scary at 100 mph and up. I have two heads in storage and two installed on engines. I don't feel I can drop a ton into the heads, although I know that's where most of the power comes from. I saw on ebay a purportedly ported and polished head purchased in Japan, possibly w/stronger springs, no cams. asking $750. I'm tempted, but there's a lot there to take on faith. In the 'for sale' on this site are two cam sets for sale, one HKS set 272/264, 8.1 lift w/cam gears and springs for $1300; a head by you, OST for $1150, but I'm not clear what exactly is included in the price. If it's a complete unit I'm VERY interested. There's another one somewhere but I can't find it now.

Oldseskewltoy: I saw your fx for sale before I got tore into this project. Now I'm committed to this path. If I bring one more car into the yard it had better be one I can sleep in. Plus getting it from there to here would be too high for me.

The stock 40mm rods have 18mm wristpins. Maybe you have already addressed this but the "Or so I'm told" makes it sound like you are a little unsure. So make sure this has been addressed. You can machine the rods to accept the bigger pins but personally I'd spend a little extra for some rods with bushed 20mm small ends. Of course I would just run the 42mm crank but that's just me.

If you are set on the pistons I would at least do what you could to get the compression up a little more. This is assuming you plan to run premium gas. At the very least run the thinnest possible headgasket. If it's not to late maybe even shave the head a little extra. Even for a no worries no hassle setup I'd aim for at least 10.8:1. That would be assuming 91 octane with a fairly modest cam. More octane and more cam can mean more compression.

Even on a no hassle setup I still recommend running a wideband. Your stock ECU shouldn't have any issues adapting to the setup we are proposing but your margin for error will be narrower and a wideband is a great tool for keeping an eye on the health of your system.
If you stay on the conservative side knock monitoring is much less important but I still suggest it because again the more you know about what's going on inside the motor the safer you are. This comes more down to budget and personal strategy. I would rather invest a few hundred more up front and have some great tools if it means it might catch something that could cost an engine down the road.
I highly recommend the wideband. The knock monitor is kind of more up to you. If you are running a largeport ECU remember that it doesn't have knock control so having something like a knock light is better than nothing.
This is the knock light I sell and run in my cars.
http://matrixgarage.com/products/knockl ... nock-light

We have a handful of our own cams. We can also get a number of cams made as semi custom if they would suit your build better.
Here you can see the ones we have listed.
http://www.matrixgarage.com/store/matrix-garage-cams-1

I think our 265 would probably suit you pretty well. You would want to replace the springs as well. If you really didn't want to upgrade springs you could run our 262 but I would go bigger. In fact I believe our 265 is a little on the small side but in your case it will be a little easier to get idling nice, it will be a little more mild and a little easier for the stock ECU to manage.

Be careful with used heads and with purportedly ported heads. A used head could be worn out and next to useless. If you are looking for heads or any used internals for that matter try to find one that has been inspected. A ported head could actually loose you performance if the person doing it didn't know what they were doing.

oldae82 wrote:a head by you, OST for $1150, but I'm not clear what exactly is included in the price. If it's a complete unit I'm VERY interested.

It is a complete head - no camshafts.

Let me try and be clearer... a completely rebuilt head: inspected guides, valves, seats, all still in usable condition. The valves and seats carry new valve jobs. There are new viton rubber valve seals. Used valve spring seats, retainers and keepers, with new valve springs. My port work, and all machine work. You also get 16 buckets, and 16 shims*.

* - If you send me the cams, I'll set the shims to your cams for an additional $80. If you don't send me cams, the shims will all be the most common (either 2.95mm, or 3.00mm)