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stock cams vs. 107 vs. 104  Rating:  Rating
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 Posted: 06-10-2005 07:36 pm
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OverdriveGear
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I'm going to be doing a 2.0 rebuild with 9.5:1 pistons (and maybe dellortos) but I was considering getting aftermarket cams. I was just wondering how much better (in terms of hp or torque) the 107 cam is from the stock federal. I know the 107 cams don't require competition springs, but do they require different pullies?

And also how does the 107 stack up against the 104? How much of a gain is there between those? Since the 104's cost the same as the 107's it'd theoreticly make sense to get the hotter 104's. Opinions?

I'm not trying to make a racing motor or a really hot street motor for that matter; just wanted to put a little more pep in the step.

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 Posted: 06-10-2005 08:27 pm
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Esprit2
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The 107 cams don't make huge horsepower,  but they do make a pretty dramatic improvement in low end torque.   The car's top speed (horsepower) won't be significantly improved,  but it's acceleration and low speed driveability (torque) will be much better.   As a result,  the car will be easier to live with in traffic and will feel more powerful.
The 104 cams have the same duration as the OEM cams,  but they're re-timed to a 104 MOP giving them more overlap.   They also have a lot more lift which really helps the engine breath (requires special springs or deeper spring pockets).   The 104s will make more top end horsepower,  but at the expense of low end torque.   If you're a banzai boy racer and live at the top of the rev range all the time,  the 104s will be fine.   If you're looking for a general improvement in street driving and want a comfortable car in which to commute,  then 104s may not be the right choice.

A compromise to consider is to put a 104 on the intake and a 107 on the exhaust.   It will give you some of the high end improvement without hurting the low end torque very much.   The intake cam has more impact on the car's personality than the exhaust and will give some high end improvement.   But pairing the 104 intake with a 107 exhaust keeps the overlap in check so you don't have to live with the lumpy idle and weak low end that goes with large overlap.

There's more to cams than duration and lift,  and both the 107 and 104 cams are designed to run at different maximum opening points (MOP) than stock.   In other words,  they are timed differently compared to the OEM cams.   The cam's MOP is controlled by the location of the keyway that's cut into the pulley's bore.   So when you install either of these cams the matching MOP pulleys will also be required.

The best thing you can do to improve a 2.0 is to convert it to a 2.2.   Before investing in lots of add ons like cams and Dellortos,  check into the cost of a used 2.2 crankshaft.     If you really want a stronger street engine rather than  hotrod,  the longer stroke and larger displacement will pay bigger dividnends across the rev range than cams and carbs.

Tim  

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 Posted: 06-10-2005 08:33 pm
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Judson Manning
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We've discussed cams at length elsewhere on this board...you may want to do a search.  Also, Greg has done a lot of explaining in the JHPS store.

One of these days we're all going to get around to doing some dyno tests to show exactly what to expect from this kind of upgrade.  Until then, you'll have to rely on people who've done...all of which will tell you their's is the best solution!  lol

All cams use the same sprockets.

Not all cams can use stock springs and followers (i.e. 104 cams).

The 'flat-top' 9.5:1 piston is the single best upgrade anyone can do on a 907.  I cannot begin to tell you the huge difference between engines I rebuild 'stock' vs. stock w/ 9.5:1 pistons installed.  It's an easy 20% boost in torque across the board.

I would call the 107 cam a 'Phase I' upgrade.  It has less duration than the stock cam, but more lift resulting in a broader torque curve and better drivability.  Unless you are living above 5500rpm on a daily basis, the 107 is a fantastic cam.

Any other cam will require you to do some additional work...specifically, the cam breathing potential will exceed the JH head flow ability.  Using stock Strombergs and a less-than-optimum exhaust makes this problem worse.  Low end drivability typically suffers as well.

Boosting the engine performance by 10%-30% is easily done with stock Strombergs, Flat-top pistons and the 107 cams.  Getting more power out of the 907 requires A LOT more than just swapping cams.

 

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 Posted: 06-11-2005 12:31 am
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Ron Earp
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I hope to get some dyno numbers really soon on mine and maybe on Brian's in Apex NC which is a couple miles from me. Brian's is a Paco motor with Dellortos and is reported to make a lot of hp, it'll be interesting to see how it does with my budget IT build. As Judson mentions, the Strombergs are underrated and can definitely make power. 

I feel that on the 907 the best things would be a stroker motor, compression bump, a really good port job on the intake and head, along with a really good exhaust system that would basically not involve any of the OEM crap in any way, and good cams last. 

I was frankly amazed at restrictiveness of the stock exhaust and the design - there was little, if anything about it that I liked and I feel there are some serious gains to be had here for little money.  As for Strombergs, have them rebuilt, attention taken to the buterfly and flow of the units, and use them. They will flow plently for the 2 or 2.2L motors and I know it for a fact - we use exactly the same carbs on a 3.5L Rover V8 in our race TR8 and it is now up to 184 rear wheel hp with more to come.

I will basically have all of the above but the performance cams, I have to use stock. Maybe I can get some dyno results in 3-4 weeks.

Ron

Last edited on 06-11-2005 01:10 pm by Ron Earp

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