Slant Six Forum :: Make Plans

Get a degree wheel onto the current engine and check some cam events, before taking everything apart. (that info. will help you with a new "go forward" plan)
DD

Yes... it looks like the wet cranking compression numbers are pretty high, for a street engine running pump gas.

A engine with decent static compression and a mild cam that is way far advanced would easily make those psi numbers.
If you get us a intake valve closing point, that would tell the story.
(I am guessing the IC is in the 20-30 ABDC range)

This type of set-up would likely detonate at higher RPM and that can hurt the rings and ring lands... causing poor oil control, bad mpg and lack-luster performance in general.
DD

... Will the intake valve closing point come from my degree wheel findings? Sounds like this will tell me straight up if my cam timing is out of whack...

Quote:

... Will the intake valve closing point come from my degree wheel findings? Sounds like this will tell me straight up if my cam timing is out of whack...

Yes & yes...
As I say: " The number don't lie..." The Intake Closing point (IC) is the most important number, when it comes to calculating the DCR.
Collect the "number" and ask questions, things will become clear before you know it.
DD

So in the mean time, study-up on how to degree a cam and on Dynamic Compression Ratio (DCR) calculation.

This process sounds complicated but it's really pretty simple, once you have the tools and have done it a few times.
Fact is, there are many internet calculators that make the DCR calculation process fast, once you have all the data.
DD

Author:	polara pat [ Wed Aug 08, 2012 12:23 pm ]
Post subject:	Make Plans
After I finish driving the hell out of our little Valiant this Summer I plan on pulling the motor for a refresh or possibly rebuild. I built this motor several years ago and it didn't quite go together as planned when it all came together. Things went horribly wrong during break-in and I may have my cam timing out one tooth. It runs but not awesome and the mileage is crap. (I know this could be any # of factors) Regardless, it's burning quite a bit of oil and my compression check (dry then wet) look like this. #1 155 190 #2 160 190 #3 160 225 #4 165 190 #5 170 210 #6 160 220 This was done with a warm engine with all of the plugs out but not with the choke and throttle wide open (forgot that one). I like the first #s but with 1-1/2 squirts of oil in each hole the huge leap seems to indicate worn rings. Correct? Here's what the motor is currently. Peanut head block and head converted to mechanical tappets; .100 cut from the block; super six with BBD; bone stock electronic distributor; stock exhaust. Any thoughts on this before I go in for the plunge?

Author:	Doc [ Wed Aug 08, 2012 12:26 pm ]
Post subject:
Get a degree wheel onto the current engine and check some cam events, before taking everything apart. (that info. will help you with a new "go forward" plan) DD

Author:	polara pat [ Wed Aug 08, 2012 12:30 pm ]
Post subject:
Quote: Get a degree wheel onto the current engine and check some cam events, before taking everything apart. (that info. will help you with a new "go forward" plan) DD I feel like I never left. The oil consumption was my biggest concern. Do those "wet measurements" mean much to you?

Author:	Doc [ Wed Aug 08, 2012 1:01 pm ]
Post subject:
Yes... it looks like the wet cranking compression numbers are pretty high, for a street engine running pump gas. A engine with decent static compression and a mild cam that is way far advanced would easily make those psi numbers. If you get us a intake valve closing point, that would tell the story. (I am guessing the IC is in the 20-30 ABDC range) This type of set-up would likely detonate at higher RPM and that can hurt the rings and ring lands... causing poor oil control, bad mpg and lack-luster performance in general. DD

Author:	polara pat [ Wed Aug 08, 2012 1:09 pm ]
Post subject:
Quote: Yes... it looks like the wet cranking compression numbers are pretty high, for a street engine running pump gas. A engine with decent static compression and a mild cam that is way far advanced would easily make those psi numbers. If you get us a intake valve closing point, that would tell the story. (I am guessing the IC is in the 20-30 ABDC range) This type of set-up would likely detonate at higher RPM and that can hurt the rings and ring lands... causing poor oil control, bad mpg and lack-luster performance in general. DD Thanks Doc, you may need to dumb it down a bit for me until I get back in the engine building mind set. Will the intake valve closing point come from my degree wheel findings? Sounds like this will tell me straight up if my cam timing is out of whack.

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Author:	Doc [ Wed Aug 08, 2012 2:24 pm ]
Post subject:
Quote: ... Will the intake valve closing point come from my degree wheel findings? Sounds like this will tell me straight up if my cam timing is out of whack... Yes & yes... As I say: " The number don't lie..." The Intake Closing point (IC) is the most important number, when it comes to calculating the DCR. Collect the "number" and ask questions, things will become clear before you know it. DD

Author:	polara pat [ Wed Aug 08, 2012 8:19 pm ]
Post subject:
Quote: Quote: ... Will the intake valve closing point come from my degree wheel findings? Sounds like this will tell me straight up if my cam timing is out of whack... Yes & yes... As I say: " The number don't lie..." The Intake Closing point (IC) is the most important number, when it comes to calculating the DCR. Collect the "number" and ask questions, things will become clear before you know it. DD Cool, I'm not planning on having any down time while our tiny window of cruising weather is here but as soon as it turns crappy this project is on the front burner. I would like to do as much info gathering as possible before diving into this project so I really appreciate all of your input for the diagnosis.

Author:	Doc [ Thu Aug 09, 2012 9:55 am ]
Post subject:
So in the mean time, study-up on how to degree a cam and on Dynamic Compression Ratio (DCR) calculation. This process sounds complicated but it's really pretty simple, once you have the tools and have done it a few times. Fact is, there are many internet calculators that make the DCR calculation process fast, once you have all the data. DD

Author:	polara pat [ Thu Aug 09, 2012 11:54 am ]
Post subject:
Quote: So in the mean time, study-up on how to degree a cam and on Dynamic Compression Ratio (DCR) calculation. This process sounds complicated but it's really pretty simple, once you have the tools and have done it a few times. Fact is, there are many internet calculators that make the DCR calculation process fast, once you have all the data. DD I have my marching orders then. I have actually degreed cams in before on our race cars but the majority of the operation is usually handled by our crew chief since he's the big brain around our camp. Stay tuned.

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