205 lbs. compression?

[dan filipi]

It looks like what I thought was lean was actually rich so I let it run the bowls dry, maybe a piece of :sensored: got in between the needle and seat.
It's running very steady now.
I went and checked the pressure on this pump, looks good at about 2 lbs. so it should work.

It starts much better cold with these 1200 cams and I can hold an rpm easier.
It also idles smoother than it ever has.
These cams may be a keeper.

I also checked compression when warm.
155-160 on the left, 200-205 on the right. Why the left is down from 170 and right down from a solid 210 on both cylinders I don't know.

 

[dan filipi]

I just had a thought.
Could the lowered compression be caused by a different atmospheric pressure?
It was raining when I had the high pressure, it's clear and sunny now.

 

[slabghost]

Atmospheric pressure and humidity would both affect compression results. Are you certain you have valves set the same on both sides? It seems curious one side is so much higher. Congratulations on getting her this far.

 

[dan filipi]

I'm going to check everything in the next couple days getting it ready for a test ride.
valve clearances are on the list.

 

[joedrum]

:hi: :thank_you: :rocks: :music: :yes: :ahem: lets get it zip up and go for a ride :builder: im hoping this makes a big difference in the low end power ...ive got a feeling that this will be low end pit bull with bigger flow 1100 heads and carbs cant wait for the ride report... :mrgreen:

 

[dan filipi]

This difference in compression is very odd.
Something is different in timing between the 1100 and 1200.

The Haynes manual doesnt list cam degrees and overlap but I think Clymer does.
Does anyone have access to a 1200 Clymer manual?

 

[joedrum]

im not sure whats going on here but it makes no sense that things would be different from one side to the other on honda part ....theres just somting going on with your motor probably valves on that head thats weak ....an air test is the only way to maybe figure out whats going on ...whats leaking and whats holding air cylinder by clylinder ....i mean the head are not even a matching set ....one could have way more miles or abuse than the other ....with your motor anything is possible ....idont know how it would sync as far as carbs go but i read where you said the carbs were in sync....i dont know dan ...i have no clues ...but icant wait for the ride report that will say alot maybe it just needs to run awle to even out ....it boggles my mind that its ran all this time with two different cams in it already and that the compression was equal then ......air test is the only thing i can think of to try and figure this out :mrgreen:

 

[dan filipi]

It is strange.
I had tried different cams. With both 1000 and 1100 cams it's even side to side but with a 1200 cam it's high and only on the right side.
Weird.

Since compression is equal with the earlier cams that leads me to believe the valves must be in similar condition on both sides.

 

[joedrum]

yeah i know nothing realy making any sense .....im clueless here :mrgreen:

 

[mcgovern61]

It is strange.
I had tried different cams. With both 1000 and 1100 cams it's even side to side but with a 1200 cam it's high and only on the right side.
Weird.

Since compression is equal with the earlier cams that leads me to believe the valves must be in similar condition on both sides.

The only thing I can think of that will increase compression on a head that has had no other changes but the cam is the valves are staying closed longer allowing compression to build?

 

[AApple]

Dan...are you sure you didn't get a Mucus family that moved into that head while you were messin with it? That would raise the compression.... :smilie_happy: :mrgreen: :blush:

This has to be the strangest thing I have heard. NO other changes than the cam itself...head not off, cam swapped to other side with no change, and 1100/1000 cams have "normal" comp. on both sides.
It's time to call Maulder and Scully....the Truth IS out there! :headscratch: :rtfm: :help:

 

[slabghost]

Any test ride results?

 

[joedrum]

thats a good point gerry but it works the other way too .....when the valves open for a short time the motor can only such so much air to compress ....the spead of fuctulation is no where near this kind of spread were talking about ... in my opinion :headscratch: :mrgreen:

 

[mcgovern61]

thats a good point gerry but it works the other way too .....when the valves open for a short time the motor can only such so much air to compress ....the spead of fuctulation is no where near this kind of spread were talking about ... in my opinion :headscratch: :mrgreen:

I would be inclined to look at all of the lobes between a right side 1100 and right side 1200 and see if they are the same for timing. I am under the opinion (for what it is worth) that the right side 1200 cam is not opening or closing the valves at exactly the same time and there is a longer period in the compression stroke.

I guess I would like to know if the left side is also capable of 205 lbs of compression. Loosen the left side rockers all the way and test the compression? It is the only way I can think of to allow the compression to go up, keeping both valves closed longer.

 

[joedrum]

that sounds like a good plan gerry :headscratch: :mrgreen:

 

[dan filipi]

scdmarx had a theory earlier that made sense.

Looking at "stroke", the piston speed slows down near the end of it's travel. That being TDC & again at BDC. That makes the center area of the stroke the fastest place the piston will travel. That's were it will be able to create the most velosity for the incoming charge. (theoretically?) What if the 1200 cam is indexed to have the valve at it's most open point during that time of maximum velosity? *******

 

[slabghost]

Inquiring minds want to know. How does it run? Power band? Torque? Smooth? All compare to stock and 1000 cams. :beg:
please.

 

[slabghost]

Stewpid kweschun. If all the cam pulleys are the same. Why are 1000 and 1100 timing belts sold as interchangeable and 1200 belts sold seperately?

 

[joedrum]

the stoke is longer and the block is wider .....and the belt needs to be slightly longer ...about two thooths longer

 

[slabghost]

the stoke is longer and the block is wider .....and the belt needs to be slightly longer ...about two thooths longer

Might that explain the variation the varience in compression?