Dbilas camshaft

[digger]

something like that

if you widen the lobe separation and add duration you end up not changing overlap that much. it more affects the exhaust valve open and inlet valve close points.

at low rpm the early exhaust opening reduces the amount of power you extract from the burn as you release it down the exhaust as wasted heat and pressure instead of transferring to the crank. at higher rpm it becomes necessary to open the valve earlier anyway so you have enough time for exhaust gas to be removed. so early exhaust vale open is more beneficial at the topend less at the bottom end

at low rpm the late inlet valve closing late causes reversion as the piston pushes the inlet charge back up (it has worse trapping efficiency and dynamic compression). at higher rpm the additional air velocity counteracts the force of the piston and continues to keep filling despite the piston moving upwards, this is the ramming effect. So late closing inlet is also more beneficial at the topend less at the bottom.

[zaq123]

makes sense.

on the related but unrelated note:
once this engine is built and running on stock Motronic 1.3, I will be going to MS. Hopefully shortly after, ITBs.
Do I need slightly cooler plugs for my setup, something like bpr6es? Also what injectors would you recommend?

[apostate]

Do not want to spoil this fantastic conversation, but cams measurements should be taken at working conditions environment simulation, i.e. rocker to valve clearance 0.30 mm.
Of course, Digger will find a way around this, he is like Bear Grills. :)

[jeffnhiscars]

Of course, Digger......is like Bear Grills. :)

count me in :)

[digger]

Do not want to spoil this fantastic conversation, but cams measurements should be taken at working conditions environment simulation, i.e. rocker to valve clearance 0.30 mm.
Of course, Digger will find a way around this, he is like Bear Grills. :)

he measured his data with clearance set to 0.25 mm as per specs so what you see is what you get

[digger]

makes sense.

on the related but unrelated note:
once this engine is built and running on stock Motronic 1.3, I will be going to MS. Hopefully shortly after, ITBs.
Do I need slightly cooler plugs for my setup, something like bpr6es? Also what injectors would you recommend?

i would use a NGK BPR6ES which is one step colder.

normally id say that 24lb would be the go as thats probably what youd need with the ITB kit, not sure how that would work with M1.3 with stock manifold pending on what chip you had. i might be inclined to try 19lb on a stock chip

[zaq123]

Thank you

[zaq123]

Do not want to spoil this fantastic conversation, but cams measurements should be taken at working conditions environment simulation, i.e. rocker to valve clearance 0.30 mm.
Of course, Digger will find a way around this, he is like Bear Grills. :)

lash is a cam specific spec. OEM is 0.25mm, same as Dbilas spec for their 276 cam. I actually moved the lash down to 0.2mm as per Dbilas spec for their 284 cam just for the experiment. No, 0.05mm didn't change everything all that much.


Another interesting observation with this cam and HD rockers. I noticed that max lift is about 0.001" higher going counterclockwise on the crank. Makes me believe that cam lobes are not symmetrical at all. Kind of skeptical about 1mm lift measurements to figure out LSA since I have a suspicion that LCA is way off of LCL

[digger]

the cam is not symmetrical in that peak lift angle occurs at different point compared to middle of opening and closing points.

you should get same answer rotating both ways within the tolerance and accuracy of the method. note that any slop in the system could possibly change depending which way you rotate but my guess thing its just an accuracy repeatability error

[zaq123]

i would use a NGK BPR6ES which is one step colder.

normally id say that 24lb would be the go as thats probably what youd need with the ITB kit, not sure how that would work with M1.3 with stock manifold pending on what chip you had. i might be inclined to try 19lb on a stock chip

anyone has a part number for #19lb injectors? I searched and my head is spinning from all information....Bosch type III, type II, Ford, clip fits, clip doesn't fit, dremel something....
I'm overloaded with the info but still can't find what I need.. Thank you in advance

[digger]

0280155884
0280150556

are two that should work

[zaq123]

Just general cam question. Advertised duration... at what lift? I read somewhere that SAE standard is 0.006" (0.15mm). Is this the same for European makers? Looks like Catcams measure their duration at 0.1mm

[digger]

Schrick use the end of clearance ramp on opening to start of clearance ramp on closing according to them. On the cam I measured it Would be less than 0.1mm not much more than seat to seat once clearance is factored. I've only measured a 288. Different manufacturers use different standards so you can't directly compare. Aftermarket performance parts are often smoke and mirrors.

[zaq123]

the 288 schrick inlet lobe is -38 (38 BTDC), 250 (70 ABDC) = 288 @ 106 centreline.

I was looking at 288 Schtick cam...was the above numbers plotted? Schrick lists this cam as 110 LC and 34/74-74/34

I'm going to redo my plotting. I did a quick check for cylinder#4 lobes and I come up with ~110LCA for both IN and EX.
Where do you normally put the dial needle? I rested mine on the valve retainer (side of the eccentric bolt). I suspect that it maybe moves along the retainer profile when valve goes up/down and throwing off my readings (dial not precisely plumb??). Although unlikely since I checked both #1 and #6 and they came very close.....but this #4 is a little different for some reason....

[digger]

i put on face of valve as i normally do the head alone referencing the TDC for the cam. on the retainer is ok near the edge there is a flatish spot, i have a screw on tip attachment that makes it better as if there isnt a flat spot on the retainer as it will pickup on a convex surface if you square it up properly it works well

https://www.machineryhouse.com.au/Q2165

i checked and those are plotted for the schrick, the whole cam is advanced about 4 degrees

numbers are
inlet 38,70 =288 ICL 106
exh 78,30 = 288 ECL 114

so its advanced 4 degrees, a simple adjustment with cam gear and GTG, would work well a bit advanced anyway