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all or nothing
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Did you count valve clearances into 1.0 mm lift?

You should should use exhaust 0.7 mm and intake 0.8 mm lift when normal clearances.
 

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Autobanmod
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Discussion Starter · #82 ·
Did you count valve clearances into 1.0 mm lift?

You should should use exhaust 0.7 mm and intake 0.8 mm lift when normal clearances.
I worked with valve lift, not cam lift. Measured the height of the tappet/bucket inside the head with a pre-compressed dial gauge with 30mm range.
Of course with warm engine these figuers will change a little bit.
The duration @1mm is 238° and this is not effected by valve clearance.
Am I doing something wrong?
 

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Autobanmod
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Discussion Starter · #83 ·
Yes, I was doing two things wrong:
1) kept the flexible tensioner assembly in place which created some offset

2) the bores for the sprocket bolts of intake cam and exhaust cam have different offsets from the centerline, the sprocket on the exhaust side needs to be remachined
 

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Autobanmod
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Discussion Starter · #85 ·
I did it all over again, taking valve lash into account and with manually tightened chain tensioner, here are my findings:

Front
Exhaust Cam, measured at 1mm camlift
opening 117° after TDC, closing 4° after TDC, 247° duration
lobe center 119°

Intake Cam, measured at 1mm camlift
opening 18,5° before TDC, closing 46° after BDC, 244° duration
Lobe center 104°

Rear
Exhaust Cam, measured at 1mm camlift
opening 134,5° after TDC, closing 19° after TDC, 244,5° duration
Lobe center 102°

Intake Cam, measured at 1mm camlift
opening 18° before TDC, closing 48,5° after BDC, 246,5° duration
Lobe center 105,5°

I double checked this, probably I mixed up 1130cc and 1250cc cams, that would explain the different durations and other variations. The accuracy is about +/- 1,5°
 

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all or nothing
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That's what I measured before timing.
I had 6deg difference between exhausts, You have 17deg to opposite direction.
A front exhaust lobe center we have the same.

When durations are near each others, there can't be markable measuring mistakes.


cam.............duration.......lobe cntr
Front exh....245 deg.......119 deg
Rear exh.....245 deg........125 deg
 

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Killer Service Inc.
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Jan,

How did you come up with the exhaust cam shims?

Do you remember what size you had when putting in?

Rod
 

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Autobanmod
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Discussion Starter · #89 ·
Rod,

I don't fully understand what you're asking. This are used ebay heads, I reconditioned them before I installed them. Did some porting, recut valve seats and put in fresh/reconditioned valves, new seals etc.
I think it's fair to say that the time between overhaul of OEM exhaust valve seats and exhaust valves is in the region of about 10.000 miles when running turbo and 15 psi boost, I run my engines hard and often enough on the Autobahn... EGT is sometimes 1100 °C / 2000 °F
The intake usually looks ok, not good but still ok.
 

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Killer Service Inc.
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When istalling intake cames on the exhaust side of the heads.

When you did your valve lash check, what size shim did you come up with to sit under the bucket?
 

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Autobanmod
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Discussion Starter · #91 ·
Ok I got it.
There is no answer because I recut the valve seats (on all heads I have I did this) which results in a considerable difference in height. After that I have the valve stems shortened (exhaust 0,3mm / intake 0,2mm) and only then do I start fiddling with shims.
The shims I used were in between 2,1mm and 2,4mm
 

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1130cc is enuff 4 me
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For what its worth, I was at the AETC in Orlando in 2006. One of the presentations was by HD jointly with Comp Cams. They stated that the destroyer valve train was stable to 15,000 rpm. Since the rest of the motor would never see that, they stopped there. I'd like to have more lift to run more boost ( & begin boost sooner ). I heard it suggested that the Trask configuration would support 250 rwhp , if everything else was in place.
It's not really that difficult to understand... You guys probably already know that in order to make loads of power with a turbo set up you'll need to have cams with a longer exhaust duration & lift coupled along with a shorter intake duration & lift. Get the exhaust out of the motor/cylinder quickly as possible & you'll haul ass. (A duration of 108* is typically associated with very choppy idle. While a duration of say, 112* is smooth as butter)
 

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Autobanmod
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Discussion Starter · #93 ·
I've meanwhile had a chance to measure exhaust gas temperature (EGT) while running the engine with 4x intake cams. lobecenter on intake side remains unchanged, lobecenter on the exhaust side about 110°:
at 0.5 bar boost with about 50% throttle at constant speed on the Autobahn, 6.5k RPM, AFR around 13.3, the EGT was not exceeding 975°, that's about 120°C less than before with OEM exhaust cams.
This is still rather high, those who want to build an engine for LSR / salt lake high speed racing should definitely consider water injection.
 

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Autobanmod
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Discussion Starter · #94 ·
Time has passed.
Are there new turbo or supercharger cam specs available?
For example Jones cams, what profile do they have?
 

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Autobanmod
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Discussion Starter · #96 ·
I'm preparing a set of heads with swapped intake / exhaust cams, three angle valve seat cut, beehive springs, minimal porting.
Intake camshaft on exhaust side, exhaust camshaft on intake side.
Pink and blue curves apply for that.

Testing not before summer 2018, has anyone done this already?
 

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I'm preparing a set of heads with swapped intake / exhaust cams, three angle valve seat cut, beehive springs, minimal porting.
Intake camshaft on exhaust side, exhaust camshaft on intake side.
Pink and blue curves apply for that.

Testing not before summer 2018, has anyone done this already?
I know this is a old post, but was there any update on using the Exhaust on the Intake and Intake on exhaust? Any test results compiled?
 

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In my previous 1130cc build I had stock intakes on exhaust and stg1 intake on intakes. It gave me 206hp/[email protected],93bar (GT2554R) boost with pump gas. It was pretty nice and relatively easy to tune overall compared to my current setup.

Not experience from swapping intake and exhaust but 4x intakes should be good for boosted applications. Have to knock wooden table here.
 

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Thanks for the reply. If you read my signature, I am running 4 intake cams. My question was about Jan-Dirk testing intake cams on the exhaust and EXHAUST CAMS ON THE INTAKE
 
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