Degreeing my cams - input please!

[olympic]

I have my engine out and on a stand so I thought I might as well check how the previous owner degreed the cams (Crower Stage 4 click for specs). Here are the results:

Lobe centerlines:

Right intake: 111
Right exhaust: 117

Left intake: 113
Left exhaust: 113

I ran the measurements 3 times to make sure I got it right. Anyways, the car makes tons of power but runs like crap below 2500 RPM and IAT2's spiral out of control when I drive in city traffic even with a Killer Chiller.

I'm looking for input on how I could degree the cams to increase driveability. I've done tons of reading on eschaider's posts on modfords and his info suggests to open the intake at TDC and close the exhaust 10 degrees BTDC for -10 overlap. It would look like this:

@MalcolmV8 has slightly less duration cams and degreed his cams like this: Similar exhaust timing but a more advances intake cam.

Any input is greatly appreciated on how I should proceed!

 

[03' White Snake]

I believe the IAT2 sensor is close to the exhaust port on the cobras, that's why pretty much all cam'd cars show a high temp on this sensor. The exhaust port is opening up early and the combustion is firing. That's what gives the car the cam'd sound. More over lab the harder it lopes.

My car was showing high IAT2's on the dyno too. Nature of cams. I have no low rpm issues though. My cam specs called for 110 Intake, 118 exhaust. I set my cams at 109.5/109 and 119/119.25. I figured that was close enough.

 

[ctgreddy]

cams should not effect iat2's, the sensor is in the top of the lower intake right behind the blower, nowhere near an exhaust port.

For specs on this, I'd look up Todd warren and nicely ask him for help on where to degree them too. He can tell you what to do to increase driveability, altho that could very well be in the tune as well.

 

[olympic]

Thanks for the input guys! I'm going to seek out some expert opinion on what I should do. Maybe I'm just wasting time trying to tune these cams and should go with some thing more street friendly.

 

[Quick Strike]

Smaller is better sometimes! With Less overlap and wider separation, you have better vacuum, less reversion and a broad (with less peak) power band.

 

[tt335ci03cobra]

That’s a mild cam for a stage 4 based on what I expected when I pulled up the cam specs from your link. It should drive fine on the street. The overlap is only 5° different. I have stage 3 grinds from mmr in a turbo, t56 low compression 5.3 with gt500 heads application that are really closer to a stage 2.5 imo and iirc it’s like 238/240 but on a 118 but it’s been 2 years so I’m likely wrong. I have some minor drivability discomforts at say cold temp, part throttle off idle driving. My iat’s are good though. Warmed up, I can put through a fast food drive thru no prob, or 5pm traffic, doesn’t heat up or lug. Might be a trans issue you have, or any number of things.

I will say mine pulls like a freight train from 4000-8000rpm though. I wish I had an extra 50wtq at 2000rpm but that’s about it. I think your tune might need revision if you did get the cams degreed well.

 

[tt335ci03cobra]

Op, what trans, clutch, flywheel, compression, displacement, power adder and system, fuel, computer, head, cam (exact specs), intake etc are you working with?

Did the drivability change after just a camswap or after an entire build?

I’ve seen cars drive like crap at the rpm you described for many reasons besides cam issues is why I ask

 

[olympic]

Thanks for the input! I bought the car with the cams already installed so it's always been this way for me. The tune it came with was terrible so I had it redone by VMP which made a big improvement but it still has a ways to go. I read an old post over on modularfords.com that said Crower cams are known for having excessive runout on the base circle which keeps the valves from fully seating and can cause high IAT's, low intake vacuum, etc so I'm ordering the necessary tools to check that. If the cams check out I'll degree them to Crowers specs (110/118) and then work with a tuner to solve the issues. If the cams are bad I'm putting something much more mild in it.

@tt335ci03cobra the specs are:

T56 Magnum, stock ratios. Shifts like a dream!
Mcleod RXT
Mcleod alumunum flywheel
9.1:1 compression
Teksid block bored 0.020"
2.3L gen 1 whipple @ 19psi. Upgrading to a 2.9L gen 3 this winter.
91 Octane w/ methanol injection and Boostane
stock computer, SCT tuner, tuned by VMP.
stock Cobra heads with upgraded valve springs.
BBK intake with SCT BA2600 MAF.
Killer Chiller
Stock coils with NGK TR7IX Iridium gapped to 0.026.

Cam specs: Ford Modular Camshafts - Camshafts

The high IAT's are the biggest concern/problem. When I drive in the city at low speeds (30mph and less) the IAT2 just keeps slowly climbing past 160f and the car begins to really run poorly and I have to take it out on the highway to cool off. Even crusing on the highway in cold weather barely above freezing, Killer Chiller running with 35f intercooler fluid I'll have 90f IAT2s so something just doesnt seem right.

The second biggest issue is stumbling/bogging when tipping into the throttle below 2500RPM. If I blip the gas pedal at idle in neutral the engine just stumbles. When I tip in to the throttle a little too much below 2500RPM it will stumble and bog. AFR's go to full lean during these events so it's likely caused by the blower bypass valve closing too soon or it's a tuning issue, maybe both.

 

[03' White Snake]

How much vacuum are you pulling? Most boost bypasses need 10-15 in Hg to fully open. (Unless you have a low vacuum version) I had a tear in my diaphragm and it wasn't opening, the car idled like crap and surged like crazy. Installed a new one and the car ran 100 times better. With my cams, I'm pulling 15-16 in Hg. That could also lead to high IAT2's.

 

[tt335ci03cobra]

Vacuum was my next question, parts combo seems great, trans and drivetrain should be a great match. Should be a very fun combo. If it’s oullinh strong after 2500, your low speed woahs must be very annoying. I’ll dig into the info you posted and see if I can offer anything useful.

 

[gt347mustang]

Sound like your tune is off or you have a mechanical issue. Stumbling below 2500 isn't normal, even with cams that size.

 

[olympic]

Idle vacuum is around 10". I have the low vacuum bypass actuator and it does open the valve but I'm guessing it closes or possibly flutters open/closed as soon as I touch the throttle. Once I have the car back on the road I'm going to rig up a sensor that shows me what the valve is doing.

 

[cj428mach]

Thats a lot of duration for such a small motor. Cubic inches eat camshaft and a 233/244 would be a healthy cam for even a 350+ cube motor.

 

[tt335ci03cobra]

@NASVT

Anyone know if Todd is still on the site?

 

[olympic]

I've talked with Todd Warren over on his facebook page. He says it's a combination of the cams being too big for my setup, bypass valve not opening/closing properly and tuning.

As I posted earlier, the first step is too check the cams for base circle runout. I've ordered a digital dial indicator and a roller contact point to do the job but they wont be here unitl late next week.

 

[tt335ci03cobra]

The more I read on cam specs, the more I am finding that that cam spec is not ideal for a street car.

It should make excellent power from 6000-8000rpm+ though

I’m running a 3.73 and 26” tire. I think if I had a 3.27 and a 28” tire, mine wouldn’t have enough low end grunt for daily driving. My stage 3 mmr grind feels like it loves 4500-7000. It makes good power after 7k and ok power below 3k. My sacrifice point is from idle to 2500. Car still has ~300wtq down there but it pales by 3k and up is when it goes 400-700wtq. Turbo car so spool etc. I have to brake boost at 2500 to get a lot of spool/torque if I want to to pull very hard from 3k. That creates metric tons of crank case pressure so obviously I don’t.

My cams are about 25-33% milder than what you have, and they were a bit of a bitch to degree for street driving but not horrible.

If you sold those heads and cams for a set of worked over 4v c heads with a strong stage 2 cam in them, or medium stage 3 blower cam, I think you would end up with a much happier street car.


Do you mainly drive in the city/freeway or is it a weekend racer?

 

[olympic]

The car is strictly a weekend cruiser so it's mostly city driving. If I decide to swap out the Crowers I'd likely go with something like the Comp Cams XE258BH-116 or possibly a custom grind from Todd Warren.

 

[Quick Strike]

My custom cams are very similar to the comp cams directly above in duration, but have more lift. They are very well mannered on the street and really pull from 4000 right through the top end. Click on the dyno sheet in my signature in my first post to you. It is running pump gas and Torco.

 

[cj428mach]

The car is strictly a weekend cruiser so it's mostly city driving. If I decide to swap out the Crowers I'd likely go with something like the Comp Cams XE258BH-116 or possibly a custom grind from Todd Warren.

I think that would be a very streetable setup.

 

[tt335ci03cobra]

The car is strictly a weekend cruiser so it's mostly city driving. If I decide to swap out the Crowers I'd likely go with something like the Comp Cams XE258BH-116 or possibly a custom grind from Todd Warren.

A great cam like that would be very street worthy. For that price range you can’t go wrong, but see how well they can tailor a cam, or go custom.

MMR took my combos minutia into account and it makes a nice difference. Cam theory is almost like picking stocks for a mutual fund, lots of variables or consider.

For bolt on cars, off the shelf cams are great, once you get into different compression, displacement and head flow, intake/blower and header setups, a custom cam with a few tweaks vs a shelf cam can be worth the cost of admission.

When people spec a custom cam and have a basically stock eaton with 4 bolt ons, I don’t laugh but it’s jusy not necessary. Each their own though.