Which CAMSHAFT did you use and why....

Performance mods and Advanced Stroker discussion.
Black00Sahara
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OBD II

Post by Black00Sahara »

So, does anyone know of a cam that will work with the OBD II and a CR of 10.2 ?

I shipped the cam off and will have a custom grind made for it, so I am open to sugestions.

Is there a formula for something that will produce as close to stock AFM so the computer is happy?
604rail_king
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Re: Which CAMSHAFT did you use and why....

Post by 604rail_king »

pretty much any 4.0 performance cam can work with the stock obd 1 or 2 ecu however your cam choice will vary your compression. just like your piston choice, deck machining, cam adv/retard, and even elevation. all these are factors to consider when you play with the stroker calculator (link on top right)

if you plan to run stock valve springs, look for a cam or regrind with .450 or less lift. then with your other parts/factors decided, plug them into the stroker calculator to get your SCR, DCR, and quench. or take a look at the recipe page for combo's.

hope that helps your decision
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

604rail_king wrote:pretty much any 4.0 performance cam can work with the stock obd 1 or 2 ecu however your cam choice will vary your compression. just like your piston choice, deck machining, cam adv/retard, and even elevation. all these are factors to consider when you play with the stroker calculator (link on top right)

if you plan to run stock valve springs, look for a cam or regrind with .450 or less lift. then with your other parts/factors decided, plug them into the stroker calculator to get your SCR, DCR, and quench. or take a look at the recipe page for combo's.

hope that helps your decision

Ok thanks. Its already built and i am trying to get the engine to run since the shop that built it swears the stock cam that they installed will work in my build.... It doesn't. It detonates and is undrivable.

I have been looking at the websites but am having a hard time determining which one to select. I have had help and been directed (by forum members, thanks everyone) to look for a cam that has a long duration and a good overlap to bleed off the cylinder preassure. I also have an automatic trans (which I have been told plays a part).
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

604rail_king wrote:******* however your cam choice will vary your compression*********

I'm just trying to get it to run on pump gas. Regular 87 octane would be great, but I will run it on Premium if i have no other option.

Its a short rod stroker, 15.1 dish on piston, I guess I am at around sea level "ish" here in dallas... I get a 9.7 CR when I plug in the numbers in the calculator.
Retlaw01XJ
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Re: Which CAMSHAFT did you use and why....

Post by Retlaw01XJ »

Black00Sahara wrote:
604rail_king wrote:...the engine to run since the shop that built it swears the stock cam that they installed will work in my build.... It doesn't. It detonates and is undrivable.

I have been directed ... to look for a cam that has a long duration and a good overlap to bleed off the cylinder preassure. I also have an automatic trans (which I have been told plays a part).
Did you mention what cam you have? ... Need to where you are starting from.

To decrease the compression (DCR) you need a later closing intake.
You could take your stock cam duration specs, and increase the lobe separation to 114 degrees or so..... that would keep the computer happy (still has low overlap) and also close the intake later to bleed off DCR (compression).

From Dino's cam comparo page:
http://www.angelfire.com/my/fan/Jeep4.0Camshafts.htm
--Hesco has a few cams with late closing intakes:
H264-14B6 has 214/214 duration, 114 Lobe separation (LS) with intake close at 38 deg ( close to '87 to 95 cam)
H274 has 224/224 duration, 114 LS with intake close at 43 deg.
--505 Performance:
266/272-14H has 218/214 duration, 114 LS with intake close at 41 deg.

Increased valve overlap does NOT bleed off compression. I've seen that posted a few times and had to say something! :mrgreen:
Increased overlap will generally reduce vacuum and make the idle rougher.
Walt K
Eastern Pa
2001 Cherokee 4.6 stroker 90 day build
Buick GS's and Saab turbos for other days...
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

Retlaw01XJ wrote:
Black00Sahara wrote:
604rail_king wrote:...the engine to run since the shop that built it swears the stock cam that they installed will work in my build.... It doesn't. It detonates and is undrivable.

I have been directed ... to look for a cam that has a long duration and a good overlap to bleed off the cylinder preassure. I also have an automatic trans (which I have been told plays a part).
Did you mention what cam you have? ... Need to where you are starting from.

To decrease the compression (DCR) you need a later closing intake.
You could take your stock cam duration specs, and increase the lobe separation to 114 degrees or so..... that would keep the computer happy (still has low overlap) and also close the intake later to bleed off DCR (compression).

From Dino's cam comparo page:
http://www.angelfire.com/my/fan/Jeep4.0Camshafts.htm
--Hesco has a few cams with late closing intakes:
H264-14B6 has 214/214 duration, 114 Lobe separation (LS) with intake close at 38 deg ( close to '87 to 95 cam)
H274 has 224/224 duration, 114 LS with intake close at 43 deg.
--505 Performance:
266/272-14H has 218/214 duration, 114 LS with intake close at 41 deg.

Increased valve overlap does NOT bleed off compression. I've seen that posted a few times and had to say something! :mrgreen:
Increased overlap will generally reduce vacuum and make the idle rougher.

Thanks, thats good info. The cam that was installed is the stock 4.0 cam. The company I sent it to said they could grind in more duration but only regrind it to 111 lobe seperation and he really wanted/recommended 112 or 113. So, I may have to purchase a completely new one, which is ok if it works.
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

I just got off the phone with Crane and they said they don't make a cam that will work with my build. (this leads me to believe no one will)

They said one issue is that its an electronic fuel ignition engine and that doesn't play nice with the cam they have (753901) and the 9.7 CR. Their cam is only rated for 9.5 CR.

He also said that with 9.7 CR they don't have a cam that can produce enough vaccum and it causes all kinds of issues.

What do y'all think?? Where do I go from here?
Retlaw01XJ
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Re: Which CAMSHAFT did you use and why....

Post by Retlaw01XJ »

Look at cams from Hesco and 505 Performance....
Wide lobe spacing like 114 degrees will reduce overlap and give a good idle and vacuum.
More duration with later closing intake valve will reduce the Dynamic compression ratio.
That's my advise if you want to use your present hi compression pistons and head.....
A thicker head gasket would drop CR as well.
Anybody out there agree or disagree?
Walt K
Eastern Pa
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Buick GS's and Saab turbos for other days...
604rail_king
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Re: Which CAMSHAFT did you use and why....

Post by 604rail_king »

maybe post up all your build details here so other members could chime in on an aftermarket cam choice that will help. piston bore, dish, rods, hg, deck height machined to, head surface machined off, what year stock cam, ect, ect.

OR a way to help you use the stock cam if thats possible - using an adj timing set and degreeing the cam in proper to your setup. this option might be hard with the stock cam

you may have an SCR of 9.5-9.7 but your DCR may be too high to support pump gas on your motors current setup. again degreeing in your cam maybe an option. but maybe not.
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

I am using the H802CP with a 15.1 dish
Stock 4.2 crank
Stock connecting rods 5.875
.020 over on the cylinder bore = 3.895

Ok so I think the 10.2 cr calc was incorrect. SilverXJ did the calc on another post and its at "SCR of 9.72 and DCR of 8.41"
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

SilverXJ wrote:x2 on the smaller companies. After going through a Comp cam 68-231-4, some Crane, and a Hesco RVOB I went with a custom JCR cam. It is based on the 99+ cam core with wide lobes and the retaining plate. Seat duration is 260*/264*, .050" duration is 204*/208*, lift is .472"/.478". Out of Lunati, Comp, Crane and Isky, JCR was the only one interested in looking for the correct core.

What spring set up are you using? Am I correct in my thinking that the max lift the stock springs can tollerate is .450 ?
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

You all have made some great points and I have been listening, So I have been reading like mad and trying to find a cam that will work with my setup and found the following article http://www.mopar1.us/cambasics.html

This paragraph is in the article -

Overlap and Compression- A very common idea, although for the most part incorrect, is that overlap bleeds off compression. Overlap, by itself, does not bleed off compression. Overlap is the angle between the exhaust closing and intake opening and is used to tune the exhaust's ability draw in additional intake charge as well as tuning idle vacuum and controlling power band width. Cylinder pressure is generated during the compression cycle, after the intake valve has closed and before the exhaust opens. Within practical limits, an early intake closing and late exhaust opening will maintain the highest cylinder pressure. By narrowing the Lobe Seperation Angle 'LSA' for a given lobe duration, the overlap increases, but the cylinder pressure can be increased as well. Thus cylinder pressure/compression can actually increase in this scenario, by the earlier intake closing and later exhaust opening. By increasing duration for a given LSA, the overlap will increase, the intake closing will be delayed, and the exhaust opening will occur earlier. This will decrease cylinder pressure, but the decrease/bleed-off of compression is not due to the overlap, it is due to the intake closing and exhaust opening events.

So If i am reading (and listening to y'all) correctly the second to the last sentence is what I am looking for- ""By increasing duration for a given LSA, the overlap will increase, the intake closing will be delayed, and the exhaust opening will occur earlier""

So I need a late model cam (since mine is a 2000 model) with increased (more) lobe seperation angle duration. This will cause the intake to close later and the exhaust to open earlier.

Right?

I will call Hesco and 505 and a few others monday morning.
Black00Sahara
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Re: Which CAMSHAFT did you use and why....

Post by Black00Sahara »

I found the Crower 44915 that has the specs I need (i think) but it says its NOT computer controlled compatible....

Also the comp cam 68-231-4 ... not compatable

In fact, most say they are not computer compatible ... does this actually mean they won't work with any OBD 1 or OBD II engine?
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Re: Which CAMSHAFT did you use and why....

Post by Retlaw01XJ »

If you are using the stock springs, lift should be limited to 0.450" or so. That limits your cam choices.
Looking at Dino's cam spec page again:
http://www.angelfire.com/my/fan/Jeep4.0Camshafts.htm
The stock '96-'04 cam has intake close at 28 degrees (0.050" lift) and valve overlap of 41.6 degrees ( 'advertised'.... be careful here. Manufactures use different specs for 'advertised' specs, so they may not be directly comparable. They may use lifter rise between 0.002" and 0.006". I prefer to go by specs at 0.050" lifter rise, if given... then you're comparing apples to apples.)

Since your goal is to use stock springs, keep the computer happy (not too much overlap), and a late closing intake valve to lower the Dynamic compression ratio, there are only a few choices:

Isky 133125
202/202 duration (@0.050")
0.450" lift
Intake close at 33 deg (0.050")
112 lobe spacing
32 deg overlap (advertised)

505 Performance 263/265-14H
208/212 duration (@0.050")
0.0427"/ 0.438" lift
Intake close @ 38 deg (0.050")
114 deg lobe separation
36 deg overlap (advertised)

Erson E720112
208/214 duration (@0.050")
0.448"/0.0458" lift
Intake close @ 32 deg (0.050")
112 deg lobe separation
60 deg overlap (huh??, doesn't compute!)

I'm liking the 505 cam for you. Plug that into the compression calculator and see if it makes a difference for you.
Trying that cam in a dyno simulation program would be a good way to compare cams as well. If you can get more detailed info from 505 ( a cam card) we could give you a better comparison.

Another member here , TR1Hemi, posted some pics of his heads with opened up chambers, 68 cc. That might be an option for you to lower your compression.
Walt K
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Re: Which CAMSHAFT did you use and why....

Post by dwg86 »

What is your quench?

I ran a 112 lobe separation with 214 duration @ .050. and.501 lift installed 3 degrees advanced. I had no problem running this cam with a stock computer.

You are probably going to have to change your springs to run a cam big enough to bleed off cylinder pressure. You will be limited to spring selection with stock valves. You can use mopar performance springs and retainers. You can also check with hesco to see what springs they have.
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