Technical 1242 16v engine with performance cam issues...

[JamesMK2]

Hi,

I currently have a 1242 16v FIRE engine and am looking towards installing some fast road cams. I have had a set of cams worked on by GSR and have trial fitted them. They have made the car extremely lumpy but this could just be down to mapping. I have since removed them because of this.

However my question is, will the hydrolic lifters adjust to take up the slack of the reground cams? How does the hydrolic lifter work? Will correct mapping will this remove the seriously lumpy idle? How can i measure what duration the cams are?

Unfortunatly I have been provided little technical support with regards to the nature of the cams and fitting. I have a feeling that this engine is something of a "grey" area when it comes to performance camshafts.

I look forward to your responses. Ideally I am looking towards fitting these cams again in the new year. Further to this I have also heard rumours that the 16v conrods are only good for around 130bhp, is this true? The last trip to the rolling road gave engine 119bhp & 115lbft.

James

 

[jug]

you fitted reprofiled cams without a matching set of valve springs and lifters (cam followers)? thats an odd thing to do. the lifters adjust the gap using oil pressure, but they are designed for a specific cam profile. using the stardard springs and lifters isnt always suitable. you're in a tricky position because you cant get any support on this. if it was me i'd probably try a set of springs and lifters from another cam kit (such as kent maybe?)

a lumpy idle is not uncommon after fitting a reprofiled cam. obviously it depends on the cam, a "fast road" cam is usually traffic friendly and allows the idle to be more or less stable. a "race" cam will almost always cause a lumpy idle, but thats the trade off of having more top end improvement, and not a problem on a track. its possible it will always be lumpy with this setup.

alternatively its possible that you didnt get the timing right. how did you set the cam timing? i've seen people get this wrong time and time again. did you use the full lift position method or the lift at TDC method? (or something else?) what degrees or mm did you use? where did you get the figures from?

i would think a remap will improve the situation, anything that changes the inlet and exhaust valve opening times and durations should benefit greatly from a custom remap.

usually i'd be inclined to think that timing was the issue, but on a pair of GSR cams its hard to say, i've never heard of GSR cams so i dont know what to expect, maybe they're lumpy cams and always will be

 

[DanGil]

If it run fines above 3-4k and its just lumpy below this then a remap will sort it out, if its lumpy all the way up the rev range you've got a problem.

 

[JamesMK2]

Thanks for your help guys.

I am still running on the stock springs and lifters. The only other firm I can think of who makes a kit for this engine is Colombo & Barini. I could try and find out if their kit comes with new springs and lifters?

With regards to timing, I timed it back to the fiat spec(ie using fiats timing tools). Could it be that I need to advance it on the timing belt? How can I calculate it the valves are going to hit the head? Or is it a case of moving the belt forward and turn the crange round to see?

I have been told the cam is a fast road but the supplier knew little about it at the time. On a whole GSR stuff is normally top notch.

It did really bog down when idling and if i lifted off in town it would easily stall. Can a map really sort this out? Or is this cam far more aggressive than I first thought?

 

[JamesMK2]

ok, i'm giving this some thought and I have a spare set of lifters. Could these be lengthened to fit the reprofile on the cam better?

I have had a look on the kent cams site too and may get in contact with them.

 

[JamesMK2]

ok, with regards to the timing on these engines, would the tdc method not be possible? As both cams are locked together by gears and only run off of one pulley?

 

[T.E.D. Jordan]

I cant see why you dont just email oldschool and ask him, seeing as hes the one who did them? He'll give you advise for free!

Jordan

 

[JamesMK2]

unfortunatly he has given me very little support on these. I have e-mailed and called him many times.

 

[jug]

With regards to timing, I timed it back to the fiat spec(ie using fiats timing tools). Could it be that I need to advance it on the timing belt? How can I calculate it the valves are going to hit the head? Or is it a case of moving the belt forward and turn the crange round to see?

if you used the fiat camshaft locking tools then i'm fairly certain your timing would have been out for those cams.

guy croft (the master of fiat twincams as you all probably know) wrote this about fitting cams to the fiat twincam engine. its well worth a read. http://forum.abarth-gmr.be/index.php?topic=786.msg1935;topicseen

his golden rule at the bottom is pretty much what i was going to say when i first read this thread.

whenever i've been involved with or witnessed the fitting of reprofiled cams the timing has always been set using either the full lift position method or the lift at TDC method. i prefer the lift at TDC method (only one i've used personally). you will need the TDC lift figure for the camshaft (which is why the lack of support may be a problem for you)

According to the Kent website this is how you do it.

1. Set your engine to TDC number 1 cylinder. it is important to ensure you are in the middle of the dwell which occurs a TDC.
2. Position a clock gauge on the inlet follower and turn the cam to achieve the specified lift (e.g. 2.72mm).
3. If your engine has separate inlet and exhaust cams then position clock gauge on the exhaust follower and set this to its specified
lift (e.g. 2.41mm).
With your cams set to their specific Top dead centre lifts it is now time to fit your cam belt or chain, inevitably there will be some
movement from the ideal TDC lift figure hence the necessity to check your figures a second time with the belt/chain installed and
tensioned.

this is exactly what i did when fitting a kent cam kit to a 1.1HCS fiesta, it was quick, easy, and it worked. you will only be able to do this if you can get the lift figures.

alternatively the full lift position method is as follows (requires degrees figures unfortunately)

For example take our Ford 2Ltr SOHC camshaft number RL30 which has a quoted figure of inlet timing @ full lift = 105 degrees. This means that the inlet valve should be set to be fully open at 105 degrees after top dead center. Therefore using a protractor or timing disc you can establish 105 degrees after TDC and it is at this point that your inlet valve should be at maximum lift. Minor adjustments from the standard timing point can be made with the aid of an adjustable timing gear.
1. Zero a timing disc on your crankshaft with the engine set at top dead centre (fig a)
2. Rotate crankshaft in direction of normal rotation (after TDC) to the specified Full lift position as quoted in the Kent Cams catalogue or web site. (fig d. 105 degrees).
3. Establish, with the aid of a clock gauge, that the inlet valve has achieved maximum lift and is in the middle of its dwell period.
4. Adjustments on the cam pulley can then be made to achieve this.
5. If your engine has a separate exhaust camshaft then return to top dead centre and rotate the
crankshaft to the quoted full lift position before top dead centre. It is at this point your exhaust valve should have reached maximum lift. Once again fine
adjustments can be made on the cam pulley

i've never used this method (seems more hassle to me) but it is easy enough if you had the degrees figures.

I'm sure people wouldn't go to all this bother if you could use the original fiat cam locking tools to get the timing correct.
if you can get the lift figures or degrees figures you can use one of these methods.
if you cant then you are a bit stuck.

you could email guy croft (very nice bloke) but i think he may tell you his golden rule, and thats not much help. its worth a try, he's the messiah of this stuff

 

[JamesMK2]

whats the golden rule?

Any way i can measure then cams?

 

[jug]

GOLDEN RULES!
1. GC SAYS - IF YOU BUY CAMS WITHOUT ASKING FOR DYNO PREDICTIONS AND SETTING-UP ASSISTANCE WITH THESE THINGS - DON'T COMPLAIN IF THE CAMS DON'T WORK!

If in doubt - e mail me on [email protected]

tell him the problem you have, maybe he can suggest an alternative method to find the required degrees or mm values.

sorry i cant be of more help

 

[ralphnz]

What is a remap?