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hooker
Samba Member
Joined: October 07, 2004
Posts: 261
Location: Bend, Oregon
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 Posted: Thu Nov 13, 2014 5:11 pm Post subject: |
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| Max Welton wrote: |
Barrel spacers go between the case and the cylinders. This increases deck-height by raising the cylinder, lowering the compression ratio.
| hooker wrote: |
| Max Welton wrote: |
And a compression test won't tell you anything about the compression ratio.
Max |
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If you say so it must be true.  |
It seems like compression test results should reveal something about compression ratio, right?
Try this: My last compression test numbers were all between 100 and 110. What do you now know about my compression ratio?
How about if I tell you it's a 1776 running an Engle-100 cam at 7500'. Any help? No?
How about if I tell you it cranks at 250 rpms? Anything?
Problem is there are too many other things that affect the readings much more. Like the condition of the rings and valves.
Max |
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Using the info you have given me I would say you have a compression ratio of 7.5 to 1 if you were at sea level at 70* latitude. 70* F. on a standard day with 29.92 inches of mercury BP and using a stock or slightly modified VW camshaft. All providing the engine is in good tune/build.
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jz56oval
Samba Member
Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Thu Nov 13, 2014 5:19 pm Post subject: |
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| I have done the compression tests on all my cylinders and they were all good. I would have to look them up if needed. |
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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| Posted: Thu Nov 13, 2014 5:29 pm Post subject: |
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| hooker wrote: |
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Using the info you have given me I would say you have a compression ratio of 7.5 to 1 if you were at sea level at 70* latitude. 70* F. on a standard day with 29.92 inches of mercury BP and using a stock or slightly modified VW camshaft. All providing the engine is in good tune/build.
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Not bad. It's actually 7.2:1.
Max
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hooker
Samba Member
Joined: October 07, 2004
Posts: 261
Location: Bend, Oregon
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| Posted: Thu Nov 13, 2014 5:42 pm Post subject: |
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| Max Welton wrote: |
| hooker wrote: |
===========================================
Using the info you have given me I would say you have a compression ratio of 7.5 to 1 if you were at sea level at 70* latitude. 70* F. on a standard day with 29.92 inches of mercury BP and using a stock or slightly modified VW camshaft. All providing the engine is in good tune/build.
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Not bad. It's actually 7.2:1.
Max |
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Thank you. Depends a lot on your barometric pressure the day you did the compression test. Like you said, a lot of variables and they all work together.
If you have the Engle 100 cam in it it would show that low reading since it does have a little more overlap than stock.
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_________________
2007 NHRA Division 6 Finals Champion air cooled Rabbit P/U rear engine compact/import class, 13.32 sec 1/4 Woodburn, Oregon
Pauter Big Block VW 2610 cc turbo mid engine roadster 9.69 sec @ 147 mph 1/4 PIR Oregon
I spent most my money on women and VW race cars. The rest I wasted. |
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Dale M.
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Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Thu Nov 13, 2014 7:36 pm Post subject: |
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| MConstable wrote: |
| jz56oval wrote: |
| So I'm guessing that the shims are between the block side and not head side? |
Shims between the case and cylinders will tighten your deck # |
Aaaah...NO....
Dale
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burdpete
Samba Member
Joined: October 24, 2007
Posts: 544
Location: Nebraska
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| Posted: Thu Nov 13, 2014 7:51 pm Post subject: |
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| MConstable wrote: |
| jz56oval wrote: |
| So I'm guessing that the shims are between the block side and not head side? |
Shims between the case and cylinders will tighten your deck # |
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Max Welton
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Posts: 10697
Location: Black Forest, CO
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hooker
Samba Member
Joined: October 07, 2004
Posts: 261
Location: Bend, Oregon
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| Posted: Thu Nov 13, 2014 8:13 pm Post subject: compression |
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It's a long road for one just starting out. I'll watch.
_________________
2007 NHRA Division 6 Finals Champion air cooled Rabbit P/U rear engine compact/import class, 13.32 sec 1/4 Woodburn, Oregon
Pauter Big Block VW 2610 cc turbo mid engine roadster 9.69 sec @ 147 mph 1/4 PIR Oregon
I spent most my money on women and VW race cars. The rest I wasted. |
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MConstable
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Joined: May 04, 2004
Posts: 1822
Location: Saint Charles IL
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| Posted: Thu Nov 13, 2014 8:13 pm Post subject: |
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Now hold on, how will that not not lessen the deck ?
Freaking moron, got it backwards, ugh
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Kfeher2000
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Joined: November 03, 2014
Posts: 38
Location: Portland, OR
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burdpete
Samba Member
Joined: October 24, 2007
Posts: 544
Location: Nebraska
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| Posted: Thu Nov 13, 2014 8:22 pm Post subject: |
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| MConstable wrote: |
Now hold on, how will that not not lessen the deck ?
Freaking moron, got it backwards, ugh |
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Fri Nov 14, 2014 12:44 pm Post subject: |
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Back to the cam issue, Another idea if you don't want to split the case would be to use 1.0 to one rockers from a 40hp engine which would reduce the hammer effect along with using some good aluminum pushrods. This would reduce the lift to .429 and would help the valve train track the cam better.
Dan |
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GTV
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Joined: March 27, 2004
Posts: 2084
Location: Si'ahl
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| Posted: Fri Nov 14, 2014 4:19 pm Post subject: |
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| Dan Ruddock wrote: |
Back to the cam issue, Another idea if you don't want to split the case would be to use 1.0 to one rockers from a 40hp engine which would reduce the hammer effect along with using some good aluminum pushrods. This would reduce the lift to .429 and would help the valve train track the cam better.
Dan |
Won't help the lifter bores.
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Dan Ruddock
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Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Fri Nov 14, 2014 4:33 pm Post subject: |
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| GTV wrote: |
| Dan Ruddock wrote: |
Back to the cam issue, Another idea if you don't want to split the case would be to use 1.0 to one rockers from a 40hp engine which would reduce the hammer effect along with using some good aluminum pushrods. This would reduce the lift to .429 and would help the valve train track the cam better.
Dan |
Won't help the lifter bores. |
Sure it will.
Won't load the lifter as much because it is not opening the valve as fast and is not compressing the spring as much effectively reducing the spring tension load the lifters sees.
Dan |
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[email protected]
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Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Fri Nov 14, 2014 4:45 pm Post subject: |
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lifting .430" at the valve is barely in "performance cam" territory.
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Dan Ruddock
Samba Member
Joined: October 25, 2012
Posts: 3594
Location: Sarasota, in my adopted state of Florida
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| Posted: Fri Nov 14, 2014 5:00 pm Post subject: |
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| [email protected] wrote: |
| lifting .430" at the valve is barely in "performance cam" territory. |
I would agree but sometimes you have adapt to others mistakes.
I will always push big ratio (1.4+) rockers as the best way to get big lifts when the cam is designed for the ratio.
For a long lasting street cars I like to limit lift to .500
Dan |
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jz56oval
Samba Member
Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Sat Nov 15, 2014 3:01 pm Post subject: |
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All of you have been very helpful and informational
Thanks |
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jz56oval
Samba Member
Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Sun Nov 23, 2014 10:05 am Post subject: |
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| Was thinking, since I got the engine pulled out. Wondering if I should have the cam changed to a 120. Will I need anything else that would need to be installed or changed while I'm in the process? If it's too costly then I'm just gonna check and set DH, and Cc the heads. |
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jz56oval
Samba Member
Joined: September 03, 2007
Posts: 375
Location: bay area
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| Posted: Thu Nov 27, 2014 7:07 pm Post subject: |
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Hey all you guys. Happy turkey day.
I just got done pulling my engine heads off tonight and here are the #'s
The head cc's are 56
Deck height is. 126"
The DH seems really off. Any suggestions on what I do next? Also there is some black build up at the end of the pistons. Will this make a big difference on measurement on the DH? Do I need to mess around with my spacing or is there a calculation that will make it quicker?
Thanks again |
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Max Welton
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Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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