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cam timing advice needed

8K views 33 replies 14 participants last post by  MustangNicko 
#1 ·
ATTN Grunt 51 - cam timing advice needed

this is a continuation of my 'no power top end' thread i started ages ago. i finally found out how to check correct cam timing on my car, so this arvo i pulled off the rocker cover and checked it as per instructions. they state that the timing mark on the cam must be level with the head or no more than 3mm above it (more distance=more 'retarded' cam) i measured mine and it is about 4.5mm - is this enough 'retard' to cause my car to loose power and not want to rev past 4700rpm under load?

I want to get a DEV 3 package from Jim Mock, but i want my car to be making its correct amount of power before i get it, just in case the problem is major and i kill the engine from the extra herbs. if the cam timing is the problem then will a vernier cam gear from the DEV 3 fit the standard cam and will it cure it, or do i have to get a new timing chain (AAARRRGGGHHH - that will be a pain in the butt to fit!)

here is a pic of the cam timing:
 

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#2 ·
your best bet try a dyno,best bet get them to check spark,a/f mixtures,exhaust temperture,compare dyno figures plent in threads,had my coil and vct soiloind replaced by myself $260 big ones, still looking for the turbo i put in also (lol) best of luck.
 
#3 ·
It looks to me that the timing chain has warn some, the tensioner is on the left which would retard the cam alittle..Agree with above though you MAY not loose performance..
 
#4 ·
yes the cam is retarded (and so is my bloody car!!!) but im just wondering how much difference 4.5mm can make...ive heard that these motors are very sensitive to cam timing, im kinda hoping Grunt51 will give me some advice...how much is it for the vernier cam gear from the DEV 3? i was going to get the exhaust first, then leads cam cam gear etc later, but if my tax cheque is big enough it might stretch to exhaust and cam gear at the same time...

oh and i broke the passenger side engine mount the other night when i was being a rough bugger, does anybody in brisbane have a spare???
 
#5 ·
How many Klms the engine done? I'd fix chain before vernier gear..Possibly be done same time as D3 iff it replaces the cam..There is a kit with gasgets, chain, tensioner/guids, Pulley etc..Reasonably priced...

I guess a well plained head will do this too!
 
#6 ·
well it had 110,000k on it when i got it, has 119,000k now, the owner reckons the engine has never been apart when he had it and he bought it with about 30,000 i think.

i havent asked him if he ever noticed the lack of revs issue, i highly doubt it, he was not a rev head at all, and i havent spoken to him since i bought the car - the head might have been off it before, people never tell the truth when they are trying to sell you something...

the manual says if you can lift the cam chain more than 2mm off the top of the sprocket with your fingers then you should replace the chain, but mine is still tight, maybe the head has been machined before, but i dont think it would make this much difference...
 
#7 ·
A Mock cam will come with excellent easy to follow timing instructions (wich include photos). You'll need to fit the variable cam gear and get hold of a dial indicator to be able to do it tho. I never "dialled" a cam in before in my life and had absolutely no problems doing it.
 
#8 ·
Variable Cam gear is about $100 on its own from anywhere like autobarn etc, not sure on how much Mock charge for it.
Is it possible that when the chain was put on, it was placed a tooth out, in the retarded position?

If this is the case, you could easily fix it by loosening the tensioner, and carefully moving the chain over a tooth. If it sits a little advanced it should still be ok. You can always give the dizzy a lil turn to compensate a little.
If it were my car, that's what I would try anyhow.

I have had my head decked on the EA, and chain still sits fine. I put in new chain guides, and was going to put in a new chain, but the chain was still in good condition, so there was no point.

Anyhow, God Luck.
 
#9 ·
Bass Crazy said:
.....If this is the case, you could easily fix it by loosening the tensioner, and carefully moving the chain over a tooth. If it sits a little advanced it should still be ok. You can always give the dizzy a lil turn to compensate a little....
Sorry Bass but CAM timing and SPARK timing (moving the dizzy) are completely different things (OK, related but different). Retarding one to compensate for the other being too advanced isn't what I'd be doing.
 
#10 ·
I may be a bit off track here as I have no I6 knowledge.
Lets assume your cam was installed straight up. Zero advance.
Most increments will run with a gear tooth. To use a V8 top timing gear as an example.. 3* up or down is usually several teeth on a gear and I would assume it would be at LEAST ONE on you rtop gear. Now if you were to move your timing gear by ONE tooth you would "consume" that 4.5 mm without doubt. The timing mark would not be visible above the head any longer given that your crank must stay still.
Therefore the change between 3mm and 4.5 is irrelevent to your timing as far as a seat of the pant measurement goes. You may be talking the difference between 0* and 1* retard. That will have no seat of the pants feel. Only a dyno/strip can pick that up and then at 4500 plus rpm most likely too.

Make sense?? Doesnt help you with cam timing but I think your problem is elsewhere.
 
#11 ·
tonyk is spot on - first I would be repositioning the chain to take up the difference as Bass said - but no, don't retard your ignition timing to try matching it to the cam.

Retarding the cam will generally effect your low speed response not your high speed performance, because as revs increase the later the inlet valve closes the more complete filling of the combustion chamber occurs and hence it follows better power at high revs - this is a general statement and will hold for a small increment of values (up to 4 or 6 degrees) depending on the actual cam you have. Advancing a cam gives better low speed response at the cost of some high speed performance.

I also think your problem may be elsewhere - but first, adjust that chain to eliminate it from your mind as the cause.
 
#13 ·
Bass Crazy said:
Yes, you guys are right, I'll retract the statement I made about moving the dizzy.
It would be right if dist was driven off cam.But in this case it isn't..Have been caught myself..

I reckon it's one tooth out on the bottom/crank sprocket..{Looks like 1/2 tooth on the top one}
 
#14 ·
[
ebxr8240 said:


It would be right if dist was driven off cam.But in this case it isn't..Have been caught myself..
Not really, dizzy timing is related to the movment of the camshaft regardless of if it's run directly off the cam or not. And if you camshaft timing is out too far then you wont make good power anyway coz the piston will be in the wrong spot...
 
#15 ·
I reckon it's one tooth out on the bottom/crank sprocket..{Looks like 1/2 tooth on the top one}
yes, thats right, the teeth on the cam gear are about 9 to 10mm apart, if i advance the cam i tooth at the cam gear end then the timing mark will be about the same dist below the head ~4.5mm i am not to keen on doing that as it is a vary big change, however i have been breaking my brain thinking about the 'one tooth on the crank gear' statement...

the cam spins at half the speed of the engine, so if i move the crank 10mm then the cam will move 5mm, but if i move the chain one tooth on the crank then will it be the eqiuvalent of one tooth on the cam gear (teeth are same size top and bottom, just crank has less of them) or will it be half? :bang: :idk: :be: this is SOOOO confusing!!!

oh, by the way, dizzy timing is related to both crank and cam timing, you time the cam off the crank (top dead centre of a particular cylinder) but you time the dizzy off the crank and cam (spark has to be top dead centre of a particular cylinder, but also TDC of the compression stroke, not an exhaust one)

on the I6 the dizzy is run off a seperate gear, you can change the cam timing and it wont affect the dizzy and vice versa, this is not so on other engines that have the dizzy running off the cams directly.
 
#16 ·
Rollin said:

the cam spins at half the speed of the engine, so if i move the crank 10mm then the cam will move 5mm, but if i move the chain one tooth on the crank then will it be the eqiuvalent of one tooth on the cam gear (teeth are same size top and bottom, just crank has less of them) or will it be half? :bang: :idk: :be: this is SOOOO confusing!!!
One tooth is one tooth!!! You're right in what say though. For example if one tooth on the crank is equilavent to 10mm then the camshaft has twice as many teeth so each one has to equivalent to less, 5mm in this case.
 
#18 ·
The cam runs at half crank speed. I've previously counted the teeth on both the cam gear and the crank gear (sorry don't remember the numbers now) - and calculated that one tooth on the cam gear is actually a bit over 4 degrees of crank rotation.

I've also tried running a variety of cams (std, Crow 22825, EDXR6, EF std and EFXR6) at normal, plus 1 tooth and minus 1 tooth and discovered that the general theory of more retard improves top and more advance improves bottom holds quite true. BUT, the improvements are not as much as you'd think and in the case of advancing, more top end is lost in proportion to bottom end gain than the amount of bottom end that's lost in proportion to top end gain if you retard the cam one tooth. My preference ended up being in favour of a bit of retard.

As a matter of interest I found that one tooth advance resulted in a car that was very lively up to about 100kph (ie. round town) and yielded VERY significant improvement in fuel economy around town - but over 100 forget it (ie. engine was really dead above about 3000rpm). If I were to turbo an EA/EB/ED I'd leave a std cam in it and set the cam one tooth advanced.

That picture actually looks pretty normal - you'll find just about any I6 will look pretty similar (1.5mm is pretty small in relation to one tooth) so I agree with some of the other posts here that the problem is most likely something else.
 
#19 ·
DAMMIT! im fully sick (NOT FULLY SIK!!) of trying to figure out what is wrong with my car, im going to bloody burn it to the ground, get insurance money and buy another XR.

not really, im just going to keep fiddling and spending money on it, and getting the sh!ts at every set of lights because i have to change at 4500 or i lose heaps of acceleration, and im sure the car should be faster through the midrange as well, i cant even get the bloody thing sideways proper 'cause it wont rev out and it dont have the guts to begin with, when my old EB would have been begging for another gear and leaving black marks everywhere...

(i dont drive like this much, but when i do i want it to bloody run properly!)

does anyone have any suggestions? i have heard the coils on these cars stuff out a lot, is it a work/not work situation, or is there shades of gray (like my car...) also i have heard the distributors can have dramas, and someone (not from fordforums) even told me to replace the entire dizzy. i dont know how much that costs, and i would if i thought it would help, but i dont see how it would benifit me, though maybe if the PIP/SPOUT electrics are misbehaving it might cause a weak spark. if the spark is not strong enough it might cause my problem???

i have been trying to fix this since i bought the car, which was back in April, im fresh out of patience.
 
#21 ·
Another we have had on cars with 100k.Klms is some times the cat converter breaks up and restricts the sh!t out of the exhaust system.

On the timing marks look at the distance its retarded about 1/2 cam tooth which is one full crank tooth..[Going by the rivets]
Poor performance up top can be alot of things from air cleaner,exhaust, timing,fuel/ filter pressure,bad sensers including map senser..

Timing dist or spark is "usually" done to piston in relation to degress of crank rotation as its done at the harmonic balancer/pulley.
 
#22 ·
longjohn1 just sent me a link to a website about cats ( ;) thanks mate!) and they have a pic of a cat that looks ok from each end but is stuffed in the middle. i have previously checked my cat (visual inspection) but this website gives me new hope that i might have found the problem - i dont care how much it costs to fix i just wanna fix it!!!!

one of my mates has a EB I6 so i might swap cats with him on the weekend and see if it makes a difference. *crosses fingers and toes*

keep the replys coming fellas any idea might help, ive checked everything i can think of, so new ideas are very welcome!
 
#23 ·
Rollin,

I had another thought - a few months ago I saw an EB or ED MPEFI manifold on a bench at one of the local mechanic's workshops (I think it was part of an old engine they were pulling down for a sprint car project), and the thing that struck me was that the injector cutouts were all choked up with what looked like carbon - there was just small irregular gaps in each cutout where the fuel was still blasting thru but I wondered how healthy the car could have been running.

Maybe you should consider pulling your injection gear off and seeing if you have a similar problem - ie. disconnect fuel lines then unbolt and lift away the whole rail+injectors from the manifold (I'd get new O rings for the reinstallation too).
 
#24 ·
Ford and other manuals say 3mm is max but I guess it also depends on things like if the head has be shaved and how flat the top of the head is. I know when I rebuilt my NB engine I sweated over this a bit and it seemed a bit more than 3mm to me but it worked fine. The Ford manual also says the mark should be at 3 degrees above the horizontal axis of the top cog so get out a protractor and check - this will also be right regardless of any shaving of the head etc.
 
#25 ·
Rollin said:
oh and i broke the passenger side engine mount the other night when i was being a rough bugger, does anybody in brisbane have a spare???
I'm in Brisbane and I think I have a spare (used) one, but I would advise getting a new one if you work the car hard. I have found that the rubber goes a bit soft over time, and the engine moves around so much that the sump touches the K-frame.

WRT your cam timing issues, the easy way to check the timing is that when #1 is at TDC compression, the lift on the inlet and exhaust will be equal at neutral cam timing. You need two dial guages for this (which I don't have) and a bar to bolt to the head to mount them on (which I do have).

Given that your cam is retarded (which which will move the power band up in the rev range and rev more freely up high) I don't think that it is causing your problem
 
#26 ·
fitted new engine mount tuesday, at a cost of $23 for part (love that discount!) was easy to fit :)

the old one came out in two peices...clutch dumping is bad...no more for me!!!

im clinging to the hope that it is my cat that is stuffed, please please please i hope that is the problem, i cant wait to see how quick my car feels when it finally goes properly!!!
 
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