cam chains 16v

[wcrado 0]

my previous 16v (KR) never ran right, and always felt like it was out of time.(rolling roaded at 130bhp after flowed head, manifolds and 4-branch) after i replaced the engine due to a slight lack of oil hitch, i discovered the reason for this was that the chain that keeps the cams in time with each other was very slack, so hence it was running slightly out of time. is this a common occurance? it's just that i have a different 1.8 16v now, after a slight collision in my old one, and i'd hate to think that my new one mite be suffering the same thing, as this one too seems to be flat at low revs just like the old one.

The replacement engine that went in the old car pulled much, much better at low rpm, and that engine had only covered 80k.

Both my new valver and the old engine from the previous valver had covered around 140k

Is this worth checking out, and if i discover it is slack, what do i do then? replace it with a genuine-only part, or can i tighten it somehow?

[davidwort 0]

my previous 16v (KR) never ran right, and always felt like it was out of time.(rolling roaded at 130bhp after flowed head, manifolds and 4-branch) after i replaced the engine due to a slight lack of oil hitch, i discovered the reason for this was that the chain that keeps the cams in time with each other was very slack, so hence it was running slightly out of time. is this a common occurance? it's just that i have a different 1.8 16v now, after a slight collision in my old one, and i'd hate to think that my new one mite be suffering the same thing, as this one too seems to be flat at low revs just like the old one.

The replacement engine that went in the old car pulled much, much better at low rpm, and that engine had only covered 80k.

Both my new valver and the old engine from the previous valver had covered around 140k

Is this worth checking out, and if i discover it is slack, what do i do then? replace it with a genuine-only part, or can i tighten it somehow?

 

they're not expensive from GSF etc.. not massively prone to wear AFAIK, but worth changing for a tenner or so if you have the head apart for cams or a re-build, can't be tightened.

Timing and fuelling can be way out on these cars if they're been fiddled with, I reckon there's a fair proportion of 16v's running around on a tooth or two out on the cambelt, I've seen two friends cars like that.

I'd invest in a tune up with someone who knows the 16v and preferably has a rolling road, make sure you've checked all you can first though to save time wasting, e.g condition of plugs, leads, dizzy cap and rotor arm, compression, ignition and engine timing.

 

David.

[wcrado 0]

cheers. i do have to take the head apart anyway, so i think i will ring gsf and get them to send one out, just incase.

the car has been fiddled with, it has the exhaust cam mod, so it's entirely possible things aren't 100% on the timing side of things. once i've replaced the head and fitted the new chain, then i'll sort the ignition timing and the fuelling.

car does seem flat until 4.5k rpm, very unresponsive and uneager. once it winds up it's ok, but nothing until then. exhaust cam mod could be responsible, but i'm not sure.

currently have a fully flowed and matched 42mm inlet on the car, on my previous 16v i switched from 42mm to 50mm and noticed an improvement in power most noticibly between 2.5 and 3.5 rpm, which goes against what i've read on here, that 50mm's are only good for top-end power. whats your theories on this? have heard conflicting arguments. have a 50mm manifold sitting in the garage, so if thats going to improve the 'usable' power of the car then i'll bolt it on

even if it only gives top-end bhp, i'm still considering it seeing as car won't pick up til 4500rpm anyway

[davidwort 0]

cheers. i do have to take the head apart anyway, so i think i will ring gsf and get them to send one out, just incase.

the car has been fiddled with, it has the exhaust cam mod, so it's entirely possible things aren't 100% on the timing side of things. once i've replaced the head and fitted the new chain, then i'll sort the ignition timing and the fuelling.

car does seem flat until 4.5k rpm, very unresponsive and uneager. once it winds up it's ok, but nothing until then. exhaust cam mod could be responsible, but i'm not sure.

currently have a fully flowed and matched 42mm inlet on the car, on my previous 16v i switched from 42mm to 50mm and noticed an improvement in power most noticibly between 2.5 and 3.5 rpm, which goes against what i've read on here, that 50mm's are only good for top-end power. whats your theories on this? have heard conflicting arguments. have a 50mm manifold sitting in the garage, so if thats going to improve the 'usable' power of the car then i'll bolt it on

even if it only gives top-end bhp, i'm still considering it seeing as car won't pick up til 4500rpm anyway

 

I've never fitted a 50mm myself, but, a very similar specced engine to mine is in GVK's car, Club GTI forum, he only got worse results using a 50mm on a 2L with a modified head, the results may be different on a 1.8 with a stock head.

What I do know is that 180bhp is fairly easy to reach on a 2L with standard 1.8 cams with an lower 42mm inlet port matched and polished.

I'm fairly convinced that 50mm is only required if you go with very wild cams on a high revving motor, e.g. a track day car and want to reach the magic 200 brake.

A road car seems to benefit from the 42mm every time and I've not really seen any cars/evidence to contradict this. I'm certainly very happy with the torque and power from my 42mm. My engine knowledge would suggest that a wider inlet = lower gas speeds = lower bottom end torque. But some results will I guess be down to odd combinations of cam specs and capacities etc.. which may complicate things.

It's interesting to note though that all the later Passats and corrados and golf 2's on the K/KE-jet system used 42mm inlets and only the earlier lighter golfs had the 50mm(generally), I've always thought that was VW trying to gain some low end torque for the heavier cars???

 

http://www.clubgti.com/forum/forum_post ... 5261&KW=50 mm

David.

[wcrado 0]

yeah i thought that too. But it doesn't change the fact that on my previous 16v, the upgrade to a 50mm inlet produced the most increase in low-down power. on the 42mm, the power increased nicely from 3k-ish upwards, and let fly at 4k-ish. once the 50mm was on, it had a small 'power band' from 2.5k to 3.5k, then it went flat, and picked up again at 4.5k. a bit irritating to drive, it meant dropping gears all the time, but it was nice to have some pull down there in the low revs. when on the redline however, it was hard to notice any real difference. i might just try it for now, and see how it goes, although first i have a ported/polished head to go on, which will mean i can fit the new cam chain and set the timing properly, so i'll wait til i've done all that and if i'm still not happy i'll throw on the 50mm and see if it improves or not.

 

whats your theories behind the exhaust cam mod? could this be causing the car to run flat at low revs? i thought so initially, and was tempted to put the standard cams back in, but other people on here that have carried out this mod seemed to think the car pulled nicely right through.

 

considering i'm going to be using a ported/ polished head, with a 4 branch and system, WUR mod, etc, what do you think the best set up is in terms of cams and inlet manifold?

[davidwort 0]

The exhaust cam as an inlet just gives you more valve lift, some say they like the effect on a 1.8 and others say it's OK on a 2L too. I haven't seen back to back plots to compare the power bands but I can't see a higher lift inlet cam giving you more torque low down on a 1.8???

 

With a flowed head you should benefit more from using a higher lift cam as the head will then cope with the cam profile better, i.e. one isn't restricting the other.

 

Lots of people swear by the exhaust cam mod, but it may just be that the whole power band is shifted and it makes the progression through the revs feel different, personally I like the standard KR inlet cam and I've run that on 3 different spec engines, standard 1.8, 1.8 with flowed head and a 2L with flowed head, all using the same KR K-jet fuel system.

Power was IRO 145, 155-160 and 170 bhp respectively.

Also, some people swear by a four branch, but a ported and polished standard manifold a downpipe has still let me get close to 180brake on standard cams.

 

David.

[flusted 0]

I always swear by the 2 zorst cams and ive done it to 3 cars now!It defo gives a bit better low down,but sort of kicks at 4k bigtime,then kicks again at 5 and a hlaf k all the way through!

 

I only had the 2 zorst cams and 4 branch and got 162bhp

[wcrado 0]

what about the inlet though? i know that its said the 42mm is better for torque, but considering i'm gonna be using a rev happy 1.8 with the flowed head and exhaust cam shouldn't i whack on a 50mm?

[davidwort 0]

I always swear by the 2 zorst cams and ive done it to 3 cars now!It defo gives a bit better low down,but sort of kicks at 4k bigtime,then kicks again at 5 and a hlaf k all the way through!

 

I only had the 2 zorst cams and 4 branch and got 162bhp

 

Flusted, do you have any torque or power graphs to compare the shape? The KR inlet cam gives a very distinctive power/torque plot on any capacity block it would be interesting to compare the shapes even if you ignore the actual figures, I've got both 1.8 and 2L plots with KR and 9A inlet cams, I just can't get my head around how a higher lift cam can give better torque low down.

 

wcrado, there is a bit more to it than just the mm bore, the 50mm has a different 'plenum' or whatever it's called, after the throttle and before the four branches, the 42mm is much larger.

 

David.