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Old 01-31-2005, 11:30 AM
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Cams, bigger isn't always better!?

I'm building a 327 small journal engine bored .03 over. It has a twist forged steel crank, stock steel rods, arp bolts/studs, clevite 77 h bearings, moly rings with trw flat top pistions, I'm planning on using world products sportsman 2 heads (2.02 intake, 1.6 exhaust, 64 cc combustion chambers, 200 cc intake runners), holly pro series 4150 650 cfm carb, not sure about the intake yet but it will be something to match the carb and heads. with the crank assembly I plan on shifting at 7000 rpm. I think the crank assembly will have no problem with that. anyways, the question is, the cam I bought is a solid hydrolic, has a lobe lift of .510" (intake), .533" (exhaust), duration at .05' is 244 deg (intake), 254 deg (exhaust). Is this to big?? or should I of gone bigger!!?? How many horses do you guys think this assembly can make??

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Old 01-31-2005, 12:31 PM
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First off.....what's a solid hydraulic?

It's either a solid lifter cam or a hydraulic lifter cam.....it can't be both.


I think 510 lift is more than you need on a 327.
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Old 01-31-2005, 12:44 PM
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Sounds like a flat tappet hydraulic for 350+ cube oval track cam.. Runs out of steam at 6500. Those stock small journal rods won't like 7000 rpm anyway..
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Old 01-31-2005, 12:55 PM
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What is the application? Seems a little large IMO.
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Old 01-31-2005, 01:07 PM
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I agree that we need to clarify the type of cam.

That said, it does seem a bit large for a 327. Remember, the same cam in a 350 vs. a 327 are going to act differently. The larger the cubes, the smaller the cam is going to act.

That is a fairly high duration spec for a cam even in a 350. For the 327, that is going to start your powerband probably higher than you'll want it, thus causing it to dog off the line.

But it all depends on what type of engine/car you are going for. Where is this engine going to live (RPM wise)? Whats its purpose?
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Old 01-31-2005, 02:31 PM
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Low torque engines with long cam end up two cycling on ya making the car harder to drive on the throttle. Peaky power output. Without knowing what the application is it's really hard to say what's right. Sounds short track cam to me though!
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Old 01-31-2005, 02:49 PM
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My appologies for not reading what I wrote before I posted it. I did mean flat tappet hydraulic. The connecting rods are used, they have about 25 passes at the drag strip. they were in a 327 reving about 8000 rpm so I'm not worried about them breaking. a 327 traditionally (in my opinion) is made for high rpms because of the light weight on the crank. a 327 is basically a 350 with a short stroke (3.25" compared to 3.48"). Lets also remember that a short stroke engine has relatively high specific power curve through a wide engine speed range. A rod length of 5.9" would be optimum but I'm on a budget and the 5.7" rods will have to do for now (the disadvantage being the piston compresion height is very tall). Like I mentioned, I plan on shiffting at 7000 rpm and dumping the clutch at 3000. The car will be a street strip car, not a regular driver. I want a drag car that I can still take a little cruise on the street with. I was expecting a power band of 3000 to 7200, but I guess I need to do more research. This particular cam was recomended to me by summit, I thought myself it was big.
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Old 01-31-2005, 03:00 PM
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But let's not forget once you start adding stuff and changing from OEM you don't have a detroit 327 anymore. Stock internals won't live long at 8000. Crank gonna break on ya someday.


Why not have a custom cam ground for you?
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Old 01-31-2005, 03:27 PM
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I should of had a custom cam made. But I went with the advice of the gentleman at summit, and now I have this particular cam. I'm hopping it will work. As for the crank breaking, it's a twist forged steel crank. It should be more than strong enough. and the rods are steel aswell. Nothing cast.
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Old 01-31-2005, 05:12 PM
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Is the cam you have an 1108 Summit grind? If so, I don't think it's too far off from what you are looking for. It's ground with a 114* LSA that should help out with the low speed launch issues the others have mentioned. 244 @ .050 would be too much if the cam had a 106* or so LSA. The wide LSA won't allow the cam to RPM as high as a tight LSA would due to the reduced overlap. I would install it at 110* intake c/l which should be +4. Your compression should also be at least 10.5-1. Dan
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Old 01-31-2005, 05:29 PM
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Thank you very much Dan! Your bang right on, it is a summit 1108. Do you know anything more about these cams? are they any good? The Summit guy said they were, but he's a sales man!! I also got the lifter kit. They look vary different from what I am used to. Are these lifters worth using?? Do you know what the factory c/l is, and by +4 do you mean advanced 4 deg?? I will be running about 10.5-1 compresion. How many horses do you think this engine will make??

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Old 01-31-2005, 06:14 PM
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LSA is Lobe Separation Angle. It is the distance between the exhaust and intake lobes at peak lift.

As far as I know, the cams hold up just as well as any other brand. Their lobe profiles are getting a bit dated now. Some of the current cam companies high end offerings would no doubt out power it.

What looks different about the lifters? You should be using a heavy duty anti pump up style lifter. Dan

Yes 4 deg advance. If you instal the cam straight up, it would be on a 114* c/l. 4 deg advance would put it at 110 c/l. Dan
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Old 01-31-2005, 06:25 PM
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The part # on the lifters is SUM-HT817. they look almost like two pieces. kind of like a plate is pressesd onto the bottom, or a line is just cut into it along the outside 3/8" from the bottom. their is a oil hole on the side. How can I tell if it's a heavy duty anti pump up style lifter.

Last edited by bwery; 01-31-2005 at 08:58 PM.
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Old 01-31-2005, 06:38 PM
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A quick trip to the Summit web sight says you need a set of lifters.

http://store.summitracing.com/defaul...T817&x=11&y=11

Says they are only good to 6000.


You can verify this by looking at the plunger retaining clip. If it's made from wire..........They're going to pump up....................Anti pump up lifters use a flat steel retainer and are set at zero lash.

From your description, you have a set of heavy duty lifters. They have a piece of hard, heat treated steel welded to the bottoms. I think that is the line you are seeing. The base will also be discolored from the heat treat.

The lifters pictured in the above link are standard lifters. Dan
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Old 01-31-2005, 06:57 PM
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Thanks for the information. I think I'm going to call summit tomorrow. The cam advertises the power band from 3500 - 7000 and on the phone I believe I was told 3000 - 7200 for my aplication. Why would the include lifters that are only good to 6000 rpm?? Or maby they are good to 7200 rpm but the quality all goes to hell!!! The web site did day "precision" oil control to 6000 rpm, but after that ......!! Thanks for the help. The lifters do have a wire retainer and look the same as the picture, with the exception of the plate thing at the bottom. It doesn't look discolored but has some polish type markings on the bottom.
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