Biggest cam with Twisted Wedge heads

norwmustang · Mar 8, 2006

On their pages i have seen that they don't recomend any larger than 0,540" lift on a relatively stock engine.Do anybody know how much safety margin they have put in?

Does anybody have a big cam with a stock bottom end,with these heads?

I have a Stock 289 bottom and would like to put in a Compcams Extreme energy XE284H With a 0,541 and 0,544 lift. Do you think it could be done without notching the pistons.

5.0ina66 · Mar 8, 2006

That probably has a lot to do with the factory intstalled springs. With different springs, you could probably run whatever cam you wanted. That said, the XE284H is way too big for a poor little 289. I think I'd limit myself to the XE268H or a custom unit.

norwmustang · Mar 8, 2006

Maybe i shoul just stick with the Magnum 280H that i have in it now.

D.Hearne · Mar 8, 2006

With those heads and either of those cams, you're building a motor whose power band is going to exceed the capabilities of the bottom end. If you change the rod bolts ( at a mimimum), it'll last a lot longer. Better rods would be the way to go. The crank will handle the rpm's.

steel1212 · Mar 8, 2006

Hearne, are you talking about the xe series cams or the magnum280H? I was going to say I have a magnum280H in my 311 and my power band is around 2k to 6k. I was looking at some roller cams with a lot bigger lift numbers and on my desktop dyno, which will be as you take it, and the band is still in the same range maybe to 6500. Is that because its a roller and can go with more lift but only has slightly more duration?

D.Hearne · Mar 8, 2006

steel1212 said:
Hearne, are you talking about the xe series cams or the magnum280H? I was going to say I have a magnum280H in my 311 and my power band is around 2k to 6k. I was looking at some roller cams with a lot bigger lift numbers and on my desktop dyno, which will be as you take it, and the band is still in the same range maybe to 6500. Is that because its a roller and can go with more lift but only has slightly more duration?

Both really. the 280H is a little big for a 289. With more cubes, it takes more cam to move the powerband up. His choice of both the XE284 and TFS heads sounded to me like he's bought into the "bigger is better" line of thought. With a roller, you can get away with more duration and still have the same powerband. In my 331, I had Canfield 1.94 valved heads, a For Z303 cam with 1.7 rockers and it's powerband started at 1500.(pulled to 6500) But this also had to do with my choice of intakes ( highrise dual plane 3x2) With the same heads on a 307 shortblock and a Vic Jr., B303 cam, 1.7 rockers the power came in at 3000 and pulled to 7500. I just was trying to make sure he understood what he was building. More cam, heads, bigger intakes= higher rpm range. Add in fewer cubic inches, this does the same thing.

D.Hearne · Mar 8, 2006

norwmustang said:
On their pages i have seen that they don't recomend any larger than 0,540" lift on a relatively stock engine.Do anybody know how much safety margin they have put in?

Does anybody have a big cam with a stock bottom end,with these heads?

I have a Stock 289 bottom and would like to put in a Compcams Extreme energy XE284H With a 0,541 and 0,544 lift. Do you think it could be done without notching the pistons.

You also need to understand that the lift figures are just one part of the equation in figuring piston to valve clearance. The other, more important part is the duration and timing. The point where the interference comes into play is on the exhaust stroke, where the piston is chasing the valve up the bore(so to speak), at TDC when both valves are open (overlap), and on the intake stroke, where the intake valve is chasing the piston down bore. Not only would the XE284 cam's lift come into play here, but also it's faster ramp rates. It's going to open and close the valves a lot faster, increasing the chances for the valves to kiss the pistons. Either keep the 280H,(if you want it loud and rowdy) or better yet, follow 5.0ina66's advice and go with a smaller cam. This will decrease the likelyhood of piston to valve contact and make it much more streetable.

rbohm · Mar 8, 2006

the first problem you have is the valve to piston clearance. a 289 doesnt have enough clearance to allow a .540 lift cam to clear the piston. .500 is about the limit. remember you need .080 minimum on the intake and .100 on the exhaust. less than that and you run the risk of sticking a valve head into the piston if the valve floats. second the larger valves of the tw heads means you are going to have even less clearance than with a smaller valve.

and i agree that you choice of head and cam is too large for a 289. better to build a 331 or 347 with that head/cam combo.

Edbert · Mar 8, 2006

Disregard everything to read and hear when deciding what will fit and what wont on a high-performance cam/head combo. If your cam is over 0.500 you are in danger of having contact and should measure. Assemble it and check your clearances, it is the only way to REALLY know.

There are all kinds of stories where one guy used a certain combo without issue and the other guy had clearance issues with the same parts. There is no subsitute for doing it the old fashioned way and actually checking for yourself.

Regarding cam choice the 278-280-282 are all a bit big for 302 or less cubes in my opinion. Stroke with to 331 and they work much better. Or just get a 351W and you'll never regret the extra expense (which is hardly more than a 347).

norwmustang · Mar 10, 2006

I contacted Crane cams yesterday with my combo and they recomended me their latest cam series. The Crane Z series. The cam they recomended was the Z-274 with 0,504 intake and 0,518 exhaust. Duration @ 050 was 274 int & 280 exh

They said that i would get a smooth idle, and it would act good on the street due to their new profiles.

I think i will try it out.Hopefully they know what they are talking about..

D.Hearne · Mar 10, 2006

norwmustang said:
I contacted Crane cams yesterday with my combo and they recomended me their latest cam series. The Crane Z series. The cam they recomended was the Z-274 with 0,504 intake and 0,518 exhaust. Duration @ 050 was 274 int & 280 exh

They said that i would get a smooth idle, and it would act good on the street due to their new profiles.

I think i will try it out.Hopefully they know what they are talking about..

Those are the @.005 duration specs, not .050. With that at .050, it would never idle.

norwmustang · Mar 10, 2006

Sorry for the typo
Has anybody tested these new cams?

Bullitt · Mar 10, 2006

as far as your original question goes though, that cam will be too big for the valve springs in the heads. i ran a lunati roller with .536 lift for about 25k miles (and to 7k RPM on occassion) and eventually broke a valve spring.

go with the Track Heat springs (or beehives are the best!) for more lift capability.

norwmustang · Mar 10, 2006

I'm thinking about uppgrading the springs also.

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