205 lbs. compression?

[dan filipi]

I checked everything over again, even loosened the tappets for a loose gap but no change in compression.

Argh! So I pulled this right 1200 cam and compared against another loose right. Lift is very close to the same but enough different I had to try it.
Same, in fact I'm getting 210 lb's now.

Next I'm going to take a step backward and put an 1100 cam in and see what compression I get.
Maybe I'm doing something else wrong causing this high compression but I don't see what so my only choices are process of elimination.

 

[slabghost]

two questions.
1. Is there any difference in the timing pulleys from 1000,1100,and 1200?
2. Is it possible you have a mixed pair?

 

[dan filipi]

two questions.
1. Is there any difference in the timing pulleys from 1000,1100,and 1200?
No.

2. Is it possible you have a mixed pair?
As I was told by the seller they cam off the same engine which had less than 5k miles.
The lobes lift on both new to me 1200 cams measure very close to the same. Cam holders look very much alike like they came from the same engine.

 

[slabghost]

Perhaps I'm being unclear. I meant is there any possibility that there is a difference in the cam pulleys. Either in circumference or number of teeth. Just grasping straws here. I guess you can't swap pulleys as the timing marks would be 180degrees off. This is a tough thing to figger! :head bang: :head bang:

 

[dan filipi]

Perhaps I'm being unclear. I meant is there any possibility that there is a difference in the cam pulleys. Either in circumference or number of teeth. Just grasping straws here. I guess you can't swap pulleys as the timing marks would be 180degrees off. This is a tough thing to figger! :head bang: :head bang:

You were clear, the pulleys are exactly the same in diameter, number of teeth, keyway position, everything.

Good to know but I found the problem!

There is a difference in indexing between the 1200 and 1000/1100 cams.
I found it by chance.
When swapping cams I always back off the tappets all the way, well on the 1200 cam I could rotate the pulley to TDC mark without any resistance from the rocker pushing against the valve. Not so with an 1100 or 1000 right.
When looking down the center at the cam profiles with the 2 side by side I can see the difference.

So damn, I guess 1200 cams won't work in an 1100. Wah, I was looking forward to this working :crying:

 

[scdmarx]

Can you spell it out for me? Why won't it work? Are you just afraid of the compression? Or is there something gonna "hit"? I wouldn't think so, since you cranked it at full on cranking speed to check compression. Have you tried to start and run the engine? And....why does it work for the 1200? Is there more room in the 1200 head?

 

[dan filipi]

Can you spell it out for me? Why won't it work? Are you just afraid of the compression? Or is there something gonna "hit"? I wouldn't think so, since you cranked it at full on cranking speed to check compression. Have you tried to start and run the engine? And....why does it work for the 1200? Is there more room in the 1200 head?

I didn't want to start it without knowing the actual why for such high compression.
I don't quite understand why with a different index the compression is higher and I would rather not have to pull the head to replace bent valves or a blown head gasket. Maybe neither would happen but I want to be certain.

What doesn't make sense is why would Honda index the right cam differently from earlier years.

My question now is if the left 1200 cam is indexed differently than the right.
Since I have just one 1200 left (which is installed) I'll have to pull that side down to find out.

 

[joedrum]

all the cams have a different valve contact when the timing is set ....im not realy following you ...im just about at the opinion that when the 1000 cam was in there and the 1100 cam was on the other side your saying that the compression is 155 all around well thats no tequal comparison because the cams are different there but when you have like cams its way off....so its possible that there is a difference at the motor level ....

you could do an air test on the clylinders and see how equal they are by applying air to the cylinder and listening to the crankcase, exhasht and airbox for hissing ...its a way of checking cylinder by cylinder fror exhast or intake valve leaking and ring leaking it would either eliminate or include the motor as suspect cause maybe ...just a thought....

:mrgreen:

 

[scdmarx]

Here's is thought. I don't know any specs, but this is just some idle thought.

The 1200 is a larger volume to fill. Maybe due to larger diameter bore, maybe longer stroke, maybe a little of both.

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? *******

Somehow filling the 1100 cylinders more efficiently (even though we don't understand the why's and how's) seems to me like you just installed a super charger. But then, you gotta ask, at what RPM is the useable powerband? You don't even know there is one untill you go for a ride. (unless you have a dyno in your garage)*******

Are you aware that static compression readings are very much higher than running compression readings?
If you check compression on a motor when cranking and it builds up to, say 175psi, then release the pressure and start the motor, the psi will only build up to about 40psi. I do this sometimes when I suspect one cylinder is not quite keeping up with the others and I can't see any obvious reason why. If I find one significantly lower than the others, it will varify the need to start pulling covers to find the mechanical reason such as a cam lobe starting to go flat, or a hydraulic lifter not staying pumped, etc.*******

I hope this confuses you more. :good:

 

[joedrum]

yeah ron as far as i know this might be the first mod like this 1200 cam in an 1100 so the out come and effect is a huge unknown ...this just may be the supper mod .....if it is im not sure dans motor will take it... but it makes some sense about the stroke the bores are only .5mm different the stoke is 1/4 inch longer or 6mm i think it is .... :mrgreen:

 

[dan filipi]

Ron, that makes the most sense out of anything why the compression is higher with it's relative index point as compared to the earlier cams.
Taking another look at it (after having a nap), running it may not bump a valve because the valves are completely closed earlier in time than with the other cams.

What I mean is, #3 intake is the valve which causes the cam to move off TDC when the belt is removed with the stock cam. With the 1200 cam this valve is already closed at TDC, the cam has to be rotated a good 5 degrees before Top dead center for the rocker to contact the valve and cause that same resistance.
This "earlier" valve timing looks true in all the lobes.

To prove or disprove this theory I think I need to install this cam in the left side to see if compression increases.
If this is true and I've stumbled on some hot rod mod then I'll be looking for another right 1200 cam, after running it with this one first.

 

[scdmarx]

To prove or disprove this theory I think I need to install this cam in the left side to see if compression increases.
If this is true and I've stumbled on some hot rod mod then I'll be looking for another right 1200 cam, after running it with this one first.

Assuming you can even get it started with that compression! :salute:

 

[AApple]

You said you had 1200 cams in both sides, correct? So that, to me, is gonna eliminate that idea that just using the 1200 cam(s) is causing the higher compression. What if...just for grins....what if the cams you bought are some sort of aftermarket "Performance" cams? OR maybe even a hotter Honda "Hot" cam?
Gotta be some sort of deal like that, since you have a 1200 cam on the other side too....just not one of the ones you just bought(If I read everything correctly). :read:

 

[slabghost]

Since the 1200 cams use hydraulic lifters. You may need to set the valves a little tighter than with other cams. Have you tried that?

 

[joedrum]

good point vince theres an issue not mention yet ...im not sure it applies here but i cant come up with anything that applies ....good point vince ...something that for sure a difference to think on.... :mrgreen:

at this point i would like to see two 1100 cams installed and the compression check ....its seems the only real thing to do now to get some data that means somthing :mrgreen:

 

[dan filipi]

Since the 1200 cams use hydraulic lifters. You may need to set the valves a little tighter than with other cams. Have you tried that?

Well I have the left side adjusted tight and the compression is 155 cold.
If I adjust them how I usually adjust with a medium resistance in the feeler gauge then they clatter some around 3500 rpm but the compression is still 155.

I noticed with a tight adjustment I'll get an occasional "spit" in the intake, I'm guessing that's telling me an intake valve isn't closing completely. Come to think of it the 1200 I worked on did that also.
I think tight is the closest it should go.

 

[slabghost]

In thinking more on it. I think I'd set the valves way loose then adjust while running. Since hydraulic lifters can bleed down loose should be a none issue. Years ago I was taught that valves with clatter don't get burnt.

 

[dan filipi]

Unfortunatly there's no adjusting these while the engine is running because the amount of oil that gets pumped out with the valve cover off will empty the crankcase very fast and oil spray is EVERYWHERE.

 

[joedrum]

ahh a little christmas day winging going on ....im trying to get the 83 started ...but i seem to be out of power battery low and the charger has run off to the inlaws house .....so im kinda stuck where im at.....i cant get close enough with anything to jump it with..... :mrgreen:

 

[slabghost]

Unfortunatly there's no adjusting these while the engine is running because the amount of oil that gets pumped out with the valve cover off will empty the crankcase very fast and oil spray is EVERYWHERE.

A junk valve cover with appropriate cut outs will minimize oil loss. That is if you can find one.