383 build. Heavy pics.
09-30-2016, 05:54 PM
#51
Re: 383 build. Heavy pics.
7.4 length. You can see I am getting closer to the intake but loosing my 90 to valve quickly.
Full lift.
Although I am getting closer to the center of the valve face, You can see my sweep is getting wider. Pretty much doubled.
.045
base... No lift.
Half lift.
Full lift.
Now mind you, this is the length PR I ordered for my first build, basing length solely off centering sweep on valve face. I did a good job but look at that sweep!! .070... more than 3x as much.
So based on my findings, I am going to look for a PR as close to 7.5, tip to tip, as I can.
What are your guys thoughts? Please feel free to comment.
Thanks
-D
Last edited by -=Z28=-; 09-30-2016 at 10:21 PM.
10-01-2016, 06:23 AM
#52
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Re: 383 build. Heavy pics.
First off, keep in mind that the MOST important aspect of valve train geometry to to be at 90 degrees to the valve stem at mid-lift. This is with a line drawn through the centre line axis' of the trunnion and roller tip.
Looks like that's the direction you're heading. Don't fall into the trap of compromising that target in an attempt to centre the contact patch.
Now, what I see is that you haven't taken any measurements.
Try this (if you will): And you can use the running springs for greater accuracy (maybe .040" in the difference here!) however you wont be able to do a sweep with your hydraulic lifter so just beware.
Anyway, with the lifter on the base circle, and I see that your retainer has a nice flat top side (or so it appears from your pictures), use a straight edge of some sort and extend the plane of the retainer top side surface so that it passes by the trunnion axis. Measure from this surface to the centre of the trunnion. Now do the same with the roller tip axis. Subtract the trunnion value from the axis value. The result should equal EXACTLY the half lift measurement. Remember that your half lift is the cam lobe lift times the 1.52 ratio of your rocker. Don't use the cam card spec as it may not use a 1.52 factor. Measuring is best.
It's good to see the nice narrow sweep of your contact patch as this is an indicator of good VGT.
I'd be interested to see if there are any differences between your method and the one I've described.
By the way, in your previous build with the 7.3" pushrod, did THAT build have the excessively wide sweep or was that just an experiment using that pushrod in this engine combo? Curious.
By the way, Comp has pushrods listed in .050" increments.
Looks like that's the direction you're heading. Don't fall into the trap of compromising that target in an attempt to centre the contact patch.
Now, what I see is that you haven't taken any measurements.
Try this (if you will): And you can use the running springs for greater accuracy (maybe .040" in the difference here!) however you wont be able to do a sweep with your hydraulic lifter so just beware.
Anyway, with the lifter on the base circle, and I see that your retainer has a nice flat top side (or so it appears from your pictures), use a straight edge of some sort and extend the plane of the retainer top side surface so that it passes by the trunnion axis. Measure from this surface to the centre of the trunnion. Now do the same with the roller tip axis. Subtract the trunnion value from the axis value. The result should equal EXACTLY the half lift measurement. Remember that your half lift is the cam lobe lift times the 1.52 ratio of your rocker. Don't use the cam card spec as it may not use a 1.52 factor. Measuring is best.
It's good to see the nice narrow sweep of your contact patch as this is an indicator of good VGT.
I'd be interested to see if there are any differences between your method and the one I've described.
By the way, in your previous build with the 7.3" pushrod, did THAT build have the excessively wide sweep or was that just an experiment using that pushrod in this engine combo? Curious.
By the way, Comp has pushrods listed in .050" increments.
10-01-2016, 01:25 PM
#53
Re: 383 build. Heavy pics.
I used a Mitutoyo dial indicator and a caliper to do all my measuring. I started off finding what length pr I would need to achieve 90* to the valve. This came out to be 7.6" long. That had my roller tip way out to the exhaust side. So from there I shortened my push rod in .100 increments to get roller tip towards the intake some, but with being 90* to valve at half lift my major focus. I worked this with 4 different length push rods, recording sweep, sweep location and my major focus, being 90* to valve at half lift. My findings told me that a 7.5" push rod gave the best results. Its a few degrees from being 90* to the valve, sweep is very narrow, and roller tip pushes on valve face in what I feel will be an ok place from reading and seeing MANY other set ups with achieving VTG.
The pictures above may seem confusing as there are several, with several different length push rods.
The pictures above may seem confusing as there are several, with several different length push rods.
10-01-2016, 10:15 PM
#55
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Re: 383 build. Heavy pics.
No confusion with the pictures. I can see your approach very well. What I was asking for is not the traditional method of dialling in the geometry but rather the approach from the paper I provided a link to.
What's unfortunate is that in a lot of cases, yours and mine included, is that we're forced to choose between optimum geometry and the contact sweep riding off the valve tip. You had to back off from being closer to 90 degrees by shortening the pushrod when the best case scenario would have been having the valve further away. That's the compromise with these aftermarket parts and why the big boys move on to a shaft mounted system. What I can't say definitively is how much we give up in terms of performance and longevity. You'll have to forgive me if I seem to be bordering on the excessive. I just hate replacing valve guides although admittedly, my most recent result was from inattention. The other time was my misguided thinking in getting the sweep centred although I've learned (as you indicate you have too) that's not the approach at all.
Some shops go so far as to mill off the rocker studs and relocate the mounting holes inboard so the VGT can be corrected.
That's also why I moved on to Crower's backset rockers.
I probably go back in this off season and revisit my own setup again.
What's unfortunate is that in a lot of cases, yours and mine included, is that we're forced to choose between optimum geometry and the contact sweep riding off the valve tip. You had to back off from being closer to 90 degrees by shortening the pushrod when the best case scenario would have been having the valve further away. That's the compromise with these aftermarket parts and why the big boys move on to a shaft mounted system. What I can't say definitively is how much we give up in terms of performance and longevity. You'll have to forgive me if I seem to be bordering on the excessive. I just hate replacing valve guides although admittedly, my most recent result was from inattention. The other time was my misguided thinking in getting the sweep centred although I've learned (as you indicate you have too) that's not the approach at all.
Some shops go so far as to mill off the rocker studs and relocate the mounting holes inboard so the VGT can be corrected.
That's also why I moved on to Crower's backset rockers.
I probably go back in this off season and revisit my own setup again.
Last edited by skinny z; 10-01-2016 at 10:23 PM.
10-04-2016, 06:42 PM
#56
Re: 383 build. Heavy pics.
Update-
Motor is together!! I sand blasted my intake, debated on shooting it with clear but decided not to. Next step is going through my carb and cleaning up valve covers. I cant believe what a nice set costs!!??!! I need to talk to dyno guy to see what all he wants me to put on. I'm guessing not much. So I hope to have carb, valve covers all done this weekend. Dyno maybe end of month. Need to save up some cash.
Pics soon.
-D
Motor is together!! I sand blasted my intake, debated on shooting it with clear but decided not to. Next step is going through my carb and cleaning up valve covers. I cant believe what a nice set costs!!??!! I need to talk to dyno guy to see what all he wants me to put on. I'm guessing not much. So I hope to have carb, valve covers all done this weekend. Dyno maybe end of month. Need to save up some cash.
Pics soon.
-D
10-15-2016, 07:54 PM
#58
Member
Re: 383 build. Heavy pics.
Tapping my foot, patiently waiting for dyno results.....................
10-17-2016, 01:46 PM
#60
Re: 383 build. Heavy pics.
I plan on having some numbers and video by the end of the month for you all. "fingers crossed"
-D
10-31-2016, 05:10 PM
#64
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