[slowbird]

That sounds like a very good plan!! Tear it down find where the oil is coming from and who knows what else you might find (sounds like there are quite a few issues!). Also letting Curtis Boggs check you heads is a great idea, you might also consider letting him look at your intake.
My cranking compression was mid 150 if I remember correctly. You have a smaller cam than I did with about the same compression so I am curious as to why your cranking compression is so much lower than mine (I know there are many factors that play into it but I wouldn't think there would be a 20psi difference, I could be wrong though).

[slowbird]

FYI I ran you numbers through the program I use and it showed 165psi with your cam straight up and 176 with it 8 degrees advanced. Something is wrong and I wouldn't be surprised if your rings aren't seated at all based on the oiling issues you are having. Or you might find that your compression is way low.

[p4msi1]

I can't thank you guys enough for all the willing help. This has been a 2 1/2 year ride and I'm ready to get off of it.

[cfmcnc]

Originally Posted by mike leech

Well here goes best as i can. There could be many things that are hurting you. 1st indicator that something is really wrong is the hp per cfm on the heads. At 440 cfm with the area of the tiger head making 2 hp per cfm should not be an extraordinary feat. 880 is what i would be looking for as an acceptable number. The fact that it requires 39 deg timing is also an indicator. I've helped a couple guys sort out situations like this and heres how it goes...one of 2 directions productive or basically not. The guys who never find it are the same ones that will not actually check everything, they say things like "i know thats not it" or have too much pride to have a pro look at something. Not sayin this is you....but this is were most people are. They will live with a wrong converter or cam because they picked it or its too much work to change in the racing season. Not tooting my horn at all but i sent my converter back 5 times to get it right just this last year. So the moral is its gonna take some work to find it.
Heres what i recommend for a productive plan to find the issue...
1. verify actual static compression ratio. If you are at 13.2/1 you should most likely be beating the bearings out of that thing on pump gas. This is also where i find the most deviation from the specs i'm given at the start. really look at the deck hight and pour the combustion chamber and piston top. You need to KNOW what you have.
2. I would contact a reputable cam guy and have them design a custom cam around your combination. Keep in mind that any cam manufacturer or arm chair quater back is going to have an opinion and try to sell you something. They all think they are experts...most are salesmen trying to sell you something. I use scott at http://www.buyracingparts.com/ Most times he does what i think i would have ordered....sometimes not but the results have been consistently really good. The cam you have is not what i would have picked for your engine and goals btw.
3. Take your heads to a REALLY reputable head guy with a reputation for getting results and have him look at them. there more to it than just the flow bench number.
4. See if you can borrow a tiger or bop intake for testing from someone. Your sheet looks good but there is a lot to consider when designing one. I personally posses the fab skills to make one but would never attempt it because i care about results more than i want to prove i could do it. That said yours may be close....or it just might be 100hp off. It wouldn't be the first time.
5.ensure that all the machine work was done correctly. A bad hone/ valve job etc can kill hp.
6. after all this is done schedule a dyno session with a good operator. If the dyno is stingy even better. But you really want a good operator with a lot of experience that can shed some light if you are having issues while there. Chassis dynos are notoriously off for a lot fo reasons. A bad converter can show a miserable performance loss. They are really good at helping you find things in the car though. If it improves it was an actual improvement in other words.

I hope this helps...

Ditto,Plus dyno with wideband o2 in each cylinder.Bill C.

[p4msi1]

Bill, that is also a good idea to have individual exhaust readings. Would really help out on manifold efficiency data. Dynojet sells the add on stack for that feature but I bet its somewhere aroud $1000.00- $2000.00 for the hardware. Right now all I have is the single wideband sensor that sniffs the tail pipe.

[cfmcnc]

WE have the individual cylinder wideband o2 on our dyno,helps a bunch with manifold development and firing orders.WE have built the 535 Tiger head pump gas engine at 892HP,alsc a 572 BBC at 10.8cr made 878HP,and a 565 BBC at 10.3 cr made 895HP All with single carb cast manifold.Also use a blowby meter on your chassis dyno ,good tool.Bill C.

[p4msi1]

Bill, never heard of a blowby meter! How does that work?

Steve

[p4msi1]

Bill, also as I add up all the cc's I think I am closer to 9.8 cr. as its built right now. I will change that soon enough.

[slowbird]

Your combustion chamber looks pretty large do you know what it cc's at?

[mike leech]

Originally Posted by p4msi1

Bill, also as I add up all the cc's I think I am closer to 9.8 cr. as its built right now. I will change that soon enough.

theres 50 hp right there with that cam you had...maybe more

[cfmcnc]

WE have a blowby meter on our dyno,it measures blow by in CFMs,It has a 10 cfm scale worst engine an aluminun block Mopar almost blew the ball right out the top ,good engines are under 5 cfm.Bill C.

[p4msi1]

Slowbird, I think they told me the chamber cc's are about 75cc. Pistons have a 30cc dish and also deep valve notches so I don't know for sure. I also don't know if or how much the pistons are down the hole.

Mike, the cam has always been 264-270 @ .050 & .800 lift 110 LSA. Do you think a longer duration can will make a big difference? The program I use doesn't show a big difference big going bigger on duration, maybe 15 HP, but the torque lost down lower don't look like a good tradoff.

Steve

[Dragncar]

I was going to tell you to get in touch with M Leech. I have talked to him and his cam guy and right off the bat you can tell he knows what he is talking about. He is going to cam my next engine and if I gets what he tells me I can get he will be the only guy who cams my engines. His cams are bigger than most would recommend but if you want to play you have to put a stick in it.
There are no free lunches.

[p4msi1]

Dragncar, I think you're right a new cam may be in my future. It sure seems when you move from a high 10 car to a mid/high 9 car, a whole lot has to change.

[p4msi1]

Dragncar, infact it looks like I'm changing pistons, cam and intake!

[gtofreek]

Had a long talk with Harold Brookshire about dynamic compression ratios. He doesn't believe in this approach and here's why.

Lets look at 2 cams. A hydraulic flat tappet and a solid roller cam. Lets say that both cams close the intake valve at the same point. Let's say at 55° ABDC. The roller cam is going to allow much more air/fuel into the cylinder and trap it there when the valve closes. If the roller cam lets in a lot more air and closes the valve at the same point, are both cams really going to have the same dynamic compression ratio? No, they will not. That's why cam manufacturers never base their compression ratio recommendations on dynamic numbers. Always static.

[johnta1]

What would the LSA be on them?

[gtofreek]

Originally Posted by johnta1

What would the LSA be on them?

If your asking me this, it is a hypothetical response pertaining to dynamic compression. LSA doesn't matter when you are talking only about the intake closing event.

The point was that a roller cam has a lot more area under the curve than a flat tappet cam so it can fill the cylinder a lot more. If your trapping a lot more a/f in the cylinder and compressing it for the same amount of degrees, you will have more dynamic compression.

Therefore, dynamic compression of 9:1 with a flat tappet cam, may be more like 11:1 with a roller. Even though the dynamic compression ratio calculators show the same dynamic compression between either type of cam, Harold's belief is that the roller cam will have more dynamic compression than the flat tappet cam simply because it is compressing more a/f. This is something that the calculators do not take into account, therefore, they cannot be deemed 100% accurate.

They are OK for generalizing things if you are comparing between two cams of the same type, but that's about it.

[BruceWilkie]

Originally Posted by johnta1

What would the LSA be on them?

Intake closing point determines start of compression or conversely amount of time in compression.

LSA and ICL are mere coincidences of chosen timing events. Best used for cam installation and inspection purposes.

To further follow Paul and Harolds statements. TRUE VALVE SEAT time is when full static compression starts. And here even a solid flat is usually far different than a hydraulic.

I recall Harold saying a solid flat can have as short if not shorter seat duration vs .050 than a roller.

Not so with a hydraulic as there is no clearance ramp.

.050 cam lift numbers are also best used for installation/inspection and secondly comparison purposes. Certainly shouldnt use .050" cam lift to guesstimate dynamic compression. Rocker ratio is part of reason why not. How fast and how many degrees sooner/later the intake shuts off is affected with rocker ratio.

Some of the biggest differences in cams from one brand to the other with seemingly similar/equal "specs" is in the numbers not advertised. That 1st .004"-.006" of lobe lift plays big roles in both valvetrain stability and staging of events. Sure not much is going to "flow" past a valve at .006-.009 lift but important pressure exchanges begin and end there.

One other point to consider.... as speed increases and ve improves... pumping losses decrease, plus any "boost" from exhaust "purge"/"scavenge" during overlap as well and you are going to trap more volume when the intake closes... Sooo...
In other words, dynamic cylinder pressures rise with VE and eventually VE (and torque/power fall off) drops and dynamic compression drops. Did you know compression also affects VE?

Dont crutch excess compression for the fuel being used...instead get the most out of the fuel being used by having the right compression and ignition timing for it. Yes cam timing does play a role but follow cam manufacturers compression suggestions. There is a reason!

[johnta1]

are both cams really going to have the same dynamic compression ratio? No, they will not.

Yes they will.



Now designing a cam for an engine just for the dcr, I probably wouldn't either.



Think of the piston motion/position of when the cam intake is closing.

If it's open longer, it's not building up pressure as much as if it closes sooner.