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#31
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 05-14-2006 at 08:19 PM. |
#32
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Scott had better say he still has my exhaust cams -Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#33
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Trevor, the reason for the 7 degree pull on the cams has to do with how Delta Cams grinds theirs. They use profiles from camshafts they have already. In saying this, they used a nissan profile for us and did what they could to make it work with our cars. This is what I understand from what we had discussed when first looking to do these. If we use the SVX exhaust profile, I do not believe we will need to retard the profile since it is basically what we want from the get go
Tom |
#34
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I can not see how various valve timings can be discussed without BTDC and ATDC figures being quoted, rather than simply duration. It is vital that these figures are specified, being the essence of what is being considered here. The cam grinders claim of retarding the complete period by seven degrees, if this is what is meant, appears strange. It would mean changing the position of the cam lobe which would mean one hell of a lot of welding and grinding. When you First mentioned this 7* I presumed the cam shafts had been moved via the gears. You mentioned the possibility of a one tooth and 7.28* adjustment. Have the grinders possibly intended that you move things one tooth and if so why? In fact how and from where did this idea of retarding the overall duration come about ? If the lobes are in fact retarded by 7*, as I think I mentioned previously, you could advance the cam by one tooth by way of an experiment and I would be surprised if there were not an improvement. Have you actually taken measurements with the re ground cams in place ? Before making assumptions you should check on exactly what you have received and paid for. N.B. measure in relation to TDC. You are basing your future decisions on what you have tested. You MUST be certain of the actual figures and not simply accept the grinders word.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#35
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I have measured the new cams in comparison to the old. The do increase lift by 1mm. didn't measure the duration, i do not have the machinery to do so. i reiterate that the i believe th 7* retard was just us being about to use that profile and keep our peaks at the apropriate relation to TDC
Tom |
#36
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You can also work off off the cam gear, taking the ratio into account, but have to be able to directly associate TDC. Frankly, you are completely in the dark, unless you are sure of what you have by taking your own measurements. QUOTE :- "i reiterate that the i believe th 7* retard was just us being about to use that profile and keep our peaks at the apropriate relation to TDC". The very point. You seem just not sure and MUST find out. To me 7* retard means shifting the cam lobe position by 7* and therefore the complete inlet period. This in my opinion would be bad news. Cheers, Trevor
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 05-15-2006 at 10:13 PM. |
#37
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I have a spare motor to work with... doesn't have to be done inside the car. Also, like I said I believe the lobe center was moved from the profile's initial layout to be complacent with our application. I need to find my spec sheet from Delta cam. Hopefully Chike or (those who we do not speak of mods) still has their sheets. I will go look for it now
Tom |
#38
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At the risk of telling you how to suck eggs - you will have to take into account the hydraulic lifters unless you have replaced them. I would guess that you can accept that when the cam solidly comes against the lifter, you can regard this as the lift point and vis-a-vis. In any event provided you are consistant any error should be obvious, particular if you do the exhaust cams, by way of comparison with the standard figures. The results will be of real interest to me and I am sure many others. Best of luck with it, Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#39
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So delta is increasing the lift? Im more looking to reduce overlap while keeping lift alone. I think the high turbine inlet pressure leaves something to be desired, and im pretty sure im over the 2:1 rule of thumb but have not had the car on the dyno to check it out.
Also, increased tensile pressure on the stock springs is a concern, and thus my chance of float since im boosted. Are they flexible on what they will do, or do these have to be in orders? phil
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. Last edited by Phast SVX; 05-15-2006 at 11:42 PM. |
#40
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Edit P.S. You could also try moving the cam gear one tooth, so as to delay the inlet opening by approximately seven degrees. Check back in the thread so that you have the complete picture.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 05-16-2006 at 12:47 AM. |
#41
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Guess i should have read the entire thread before posting....
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. Last edited by Phast SVX; 05-16-2006 at 01:35 AM. |
#42
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Overlap.
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Valve timing :- 76-40-40-76. i.e. 80 degree overlap. (i.e.Intake 76* BTDC, and 40* ABDC) The standard model has :- 64-24-18-70
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#43
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maybe it would be best for someone that has a head off a motor to do the measurements. This way the lifter can be taken into account? What would Bill think about it measuring my old heads?? Bill??
Tom, |
#44
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#45
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I still have the DeltaCams spec sheet (in the box with the cams)...
I will have my spare engine (thanks Dave/Ben) on an engine stand this week (I hope!). I've still got Harvey's instruction for taking measurements, so I'll just have to install one of the DeltaCams in the engine and have at it. This might take me a couple of weeks, as things are getting very busy the rest of this month. -Bill
__________________
Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
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