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  #31  
Old 05-14-2006, 07:52 PM
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Originally Posted by TomsSVX
So my initial thoughts about using our exhaust profiles may have been dead on. I was thinking of just using the same profile as the exhaust on the intakes. Leaving us with exactly what you are recommending. I will call Scott this week at Delta and make sure he still has the exhaust profile fom the cams Bill sent him. I will also see what kind of price we are looking at as it seemed every time I called, the price went up

Tom
Please read all I have said and advise futher regarding the 7* advance. I am rather mixed up as to which, where and who involved here have forced induction. This is an important issue. The discussion must be confined to exact engine specifications and not SVX engines in general. In the case of forced induction, alterations to valve timing becomes less of an issue and not so worthwhile.
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Last edited by Trevor; 05-14-2006 at 08:19 PM.
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  #32  
Old 05-14-2006, 09:12 PM
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Quote:
Originally Posted by TomsSVX
So my initial thoughts about using our exhaust profiles may have been dead on. I was thinking of just using the same profile as the exhaust on the intakes. Leaving us with exactly what you are recommending. I will call Scott this week at Delta and make sure he still has the exhaust profile fom the cams Bill sent him. I will also see what kind of price we are looking at as it seemed every time I called, the price went up

Tom
Tom,
Scott had better say he still has my exhaust cams
-Bill
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  #33  
Old 05-15-2006, 10:03 AM
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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
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  #34  
Old 05-15-2006, 05:57 PM
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Originally Posted by TomsSVX
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
Tom, I have again read the complete thread in an effort to sort things out. I am now assuming that in all respects the discussion is confined to normally aspirated engines.

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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  #35  
Old 05-15-2006, 06:52 PM
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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
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  #36  
Old 05-15-2006, 10:10 PM
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Originally Posted by TomsSVX
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
Tom, machinery is not required. All I have used, like all those I know, is a home made protractor in the form of a large cardboard disk, attached to the crankshaft pulley and some kind of jerry rigged fixed pointer. Awkward to do on the SVX like everything else. (To be honest I don't know how you guys have the patience to work on the thing.) A mirror will help and you can make pencil marks, to be read after the protractor is removed. You will of course have to remove cam covers in order to view valve opening and closing and full lift points, which is another chore. A check on two valves should provide adequate confirmation.

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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Last edited by Trevor; 05-15-2006 at 10:13 PM.
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  #37  
Old 05-15-2006, 10:14 PM
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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
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  #38  
Old 05-15-2006, 11:18 PM
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Quote:
Originally Posted by TomsSVX
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
With a bench motor it will be a piece of cake and you should find it an interesting exercise.

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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  #39  
Old 05-15-2006, 11:40 PM
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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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Last edited by Phast SVX; 05-15-2006 at 11:42 PM.
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  #40  
Old 05-16-2006, 12:37 AM
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Originally Posted by Phast SVX
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
If you wish to reduce overlap, this can be achieved by simply grinding material off the cams and you will not be involved in any increased lift.

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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Last edited by Trevor; 05-16-2006 at 12:47 AM.
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  #41  
Old 05-16-2006, 01:32 AM
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Guess i should have read the entire thread before posting....

Quote:
Originally Posted by Trevor
...The overlap is therefore a very mild 11* ....
Wow 11*, that definetly counts me out of this conversation. definetly not high enough to cuase an excessivly fouled charge, as long as my turbine/AR is large enough. Guess ill just have to bite the bullet and go with a larger hot side to lower TIP. I had always thought that high overlap was part of the reason subaru had designed the intertia resonance system to regain some of the low end power. Learn something everyday
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  #42  
Old 05-16-2006, 03:11 AM
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Overlap.

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Originally Posted by Phast SVX
Guess i should have read the entire thread before posting....

Wow 11*, that definetly counts me out of this conversation. definetly not high enough to cuase an excessivly fouled charge, as long as my turbine/AR is large enough. Guess ill just have to bite the bullet and go with a larger hot side to lower TIP. I had always thought that high overlap was part of the reason subaru had designed the intertia resonance system to regain some of the low end power. Learn something everyday
As a matter of interest, I have an old 1971 Subaru FF1 sports sedan which I purchased new to drive in a production championship series of circuit races. It won hands down and I regard it as the best engineered car I have owned (there have been many) and therefore I still have it and drive it often. The engine is perfectly tractable and my wife ran the kids about in it for several years. Things start to happen at about 3,750 RPM and the valves bounce at 7,300 RPM. (Two valve push rod engine.)

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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  #43  
Old 05-16-2006, 06:50 AM
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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,
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  #44  
Old 05-16-2006, 07:56 AM
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Quote:
Originally Posted by TomsSVX
Hopefully Chike or (those who we do not speak of mods) still has their sheets. I will go look for it now
I never saw a spec sheet when Delta Cam returned my finished camshafts. If it was included, I may have thrown it out with the packaging...
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  #45  
Old 05-16-2006, 08:55 AM
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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
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