Question for our engine specialists.

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DonCichocki
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Question for our engine specialists.

#1 Post by DonCichocki »

I'm trying to find the offset between the lifter bore and the cam lobe centerline on our 356 engines. My engine is in the car so no way to measure it.
Thanks!
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DC

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Martin Benade
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Re: Question for our engine specialists.

#2 Post by Martin Benade »

What high tech plans are you making?
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Jacques Lefriant
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Re: Question for our engine specialists.

#3 Post by Jacques Lefriant »

hi Martin
i think he wants the offset that allows the cam to rotate. In the US the cam grinders normally put taper on the lobe. it is best to have a corresponding radius on the lifter so they rock when offered to each other. stock there is no taper or conical/radius lifters so the offset does the rotating.
j
 

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Ron LaDow
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Re: Question for our engine specialists.

#4 Post by Ron LaDow »

Don, the C/L delta really isn't the issue in rotating the lifter; it's the amount of lifter which overhangs the lobe.
If a flat lifter is contacted full-width by a non-tapered lobe, it won't rotate no matter where the C/Ls are located.
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Greg Bryan
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Re: Question for our engine specialists.

#5 Post by Greg Bryan »

Don - I was looking at a case today and measured the offset and it appears that the lifter center line is about 0.5mm closer to the crank than the cam center line.
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Martin Benade
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Re: Question for our engine specialists.

#6 Post by Martin Benade »

Don, did you want Greg's dimension. or measured perpendicular to that?
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Greg Bryan
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Re: Question for our engine specialists.

#7 Post by Greg Bryan »

Ah - maybe I misunderstood the request. That would be harder to measure .... at least for me. =8^)
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Ron LaDow
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Re: Question for our engine specialists.

#8 Post by Ron LaDow »

Martin Benade wrote:Don, did you want Greg's dimension. or measured perpendicular to that?
Yep.
I assumed the question referred to a 'plan' C/L delta. I've always assumed the 'elevation' C/Ls were equal.
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Vic Skirmants
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Re: Question for our engine specialists.

#9 Post by Vic Skirmants »

Greg; I have never checked the vertical offset of lifter bore-to-cam bore. With each cam lobe operating an opposing lifter, I'm not sure how that would work. The 2-piece case engines used special lifters to address that issue. I will have to look at a case today when I get out to the shop.

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DonCichocki
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Re: Question for our engine specialists.

#10 Post by DonCichocki »

Martin, I was just curious as to the amount of offset.
Greg, that's the number I was looking for. For some reason I thought it was larger, thanks!
Ron, I'm now running a wide lobe cam with no taper and flat tappets, wonder how much rotation is going on?
The engine will come apart this winter for a cam change that has taper and radius faced lifters. Will be interesting to see any wear patterns.

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Re: Question for our engine specialists.

#11 Post by Dick Weiss »

Don,

The C/line offsets of the tappet to the standard/regular camlobe is no more than 1,0mm; I didn't have a widelobe cam available.

Dick

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Vic Skirmants
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Re: Question for our engine specialists.

#12 Post by Vic Skirmants »

Ron LaDow wrote:
Martin Benade wrote:Don, did you want Greg's dimension. or measured perpendicular to that?
Yep.
I assumed the question referred to a 'plan' C/L delta. I've always assumed the 'elevation' C/Ls were equal.
Ron; do you have a good way to measure the vertical difference? I checked a case this morning and did see a difference in the vertical view. Admittedly, my technique was a little crude, you probably have a better way.

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Ron LaDow
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Re: Question for our engine specialists.

#13 Post by Ron LaDow »

Vic Skirmants wrote: Ron; do you have a good way to measure the vertical difference? I checked a case this morning and did see a difference in the vertical view. Admittedly, my technique was a little crude, you probably have a better way.
Just an eye-ball says they are awfully close, but I think a cam-bore slug with a cone end and a lifter-bore slug with a cone end, both dropped in place, should tell us. No time this evening, but it won't take long tomorrow on the lathe. I've got a case half on the bench.
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Ron LaDow
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Re: Question for our engine specialists.

#14 Post by Ron LaDow »

BTW, how close a measurement do we need? No use getting one within .04" if you need .02".
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Vic Skirmants
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Re: Question for our engine specialists.

#15 Post by Vic Skirmants »

We might be talking about the .5mm Greg mentioned.

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