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compression
Posted: Thu Jan 22, 2004 7:05 am
by greggholmes
On the subject of compression, the 76 2000 had a notice to remove the head gasket and replace it with a .060 base shim. what would be the effect of omitting the shim. good bad? would there be valve issues, deck hight issues?
Posted: Thu Jan 22, 2004 7:23 am
by MASSIVE TYPE IV
It would raise CR.... but thats not a bad thing unless done with the wrong cam (stock or too mild) is it going back in a bus?
Posted: Thu Jan 22, 2004 8:30 am
by greggholmes
all else stock. I want it to last awhile untill I can do a good rebuild.
I gather with a stock cam it wouldn't really be a good thing?
Posted: Thu Jan 22, 2004 8:56 am
by MASSIVE TYPE IV
Not good at all....recalculate your CR and keep it to no more than 7.5:1
Posted: Thu Jan 22, 2004 10:07 am
by greggholmes
I guess I'll just do what they say and remove the head gaskets and put in the base shims.
Posted: Thu Jan 22, 2004 12:13 pm
by smitty
MASSIVE TYPE IV wrote:Not good at all....recalculate your CR and keep it to no more than 7.5:1
Jake could you explain a bit more? What will happen useing the stock cam?Just trying to learn something.A while back I posted about my mutt engine stock 2000 that had droped seats,so I took a set of 1700 heads and had them cut for 94's.And also flycut them .005 deeper and removed the head gasket which were .025.So changeing to the 1700 heads with .030 removed the compression check changed from about 125lb's all around (before droped seats)with the 2000 heads to 180 lb's now.It hasn't seen any siting in traffic time or highway rideing because its in a woods rail. But it sure made this thing wakeup and is a blast to drive.I made the change about 4 or 5 months back and have been to the woods every weekend except one giveing it hell with no problems yet.So can I figure on this thing blowing apart soon or could it run awhile.I was thinking about takeing a set of 1800 heads I have and cutting them deeper and jacking it up some more to see what change that will make to this thing.
Posted: Thu Jan 22, 2004 12:39 pm
by MASSIVE TYPE IV
The stock cam is really lousy. It has a very low lift and duration and was used mostly by VW to speed up the rate at which the engine achieves operating temperature. Many more VWs were sold in countries that are much colder than the US. All VWs were outfitted with the same engine internals no matter where they were going to be sold (country- wise)
The stock cam like stock compression only.
The head gasket is only about .027, so removing it and adding a 30 thou cylinder shi should result in the same CR as you previously had.
Posted: Thu Jan 22, 2004 12:56 pm
by greggholmes
for the .060 I was going off of the Technical Bulletin from:
http://www.dolphinsci.com/techbull.html
#4 says replace with 1.6mm base shim or (.063)
Posted: Thu Jan 22, 2004 12:57 pm
by MASSIVE TYPE IV
That will drop the CR lower than it was with the head gasket...
Keep that deck!
Posted: Thu Jan 22, 2004 1:57 pm
by dstar5000
I'll BET it woke it up!
Your running around 9.8 CR now!
Don
Posted: Thu Jan 22, 2004 2:06 pm
by greggholmes
MASSIVE TYPE IV wrote:That will drop the CR lower than it was with the head gasket...
Keep that deck!
thirty thou it is..
Posted: Thu Jan 22, 2004 6:03 pm
by Trike Rider
So I can run without a head gasket? do I need to recut the head if I do?
I am going to assume that this gives extra compression by doing so.
By running a 1,200# trike can I get a little more compression without problems or should I stay with 7.9? I dont want to run special gas this thing will run every day.
Dennis