roller 302 and cam selection

steel1212 · Jun 16, 2005

Yeah, when I get around to the next motor, that 274 looks pretty good.

D.Hearne · Jun 16, 2005

washMO66 said:
I have no complaints with the XE274HR and the manners are fine on the street. I has a real nice lope to it as well. It will make power up to 6200RPM which is ideal for the street.

I have the AFR185's as well and it is a damn good head. I have some work done to mine (port polish) which helps, but I hear they are good right out of the box.

Only thing here is you're using the 185's on a 347 with that cam. There's gonna be a huge difference in where the powerband is with the same heads and cam on a 302 shortblock. He should at least consider using the 165 heads with that cam ( or a step or two smaller grind ) on a 302 shortblock. Also makes a difference in street manners with his choice of intakes. He hasn't specified what intake he's got or wants to use. Just me, but I've tried a Vic Jr and at least 3 types of dual plane intakes (stock, RPM, Ford A321 and my current six-pack), and I'll take a dual plane anyday for a street motor over the Vic anyday.

washMO66 · Jun 16, 2005

D.Hearne said:
Only thing here is you're using the 185's on a 347 with that cam. There's gonna be a huge difference in where the powerband is with the same heads and cam on a 302 shortblock. He should at least consider using the 165 heads with that cam ( or a step or two smaller grind ) on a 302 shortblock. Also makes a difference in street manners with his choice of intakes. He hasn't specified what intake he's got or wants to use. Just me, but I've tried a Vic Jr and at least 3 types of dual plane intakes (stock, RPM, Ford A321 and my current six-pack), and I'll take a dual plane anyday for a street motor over the Vic anyday.

Agree with everything except the single plane / dual plane comment. That one could be debated until the end of time with both sides sounding off and I don't want to hijack the thread..... maybe a little,

For me the high RPM improvement on my car going from the performer RPM to the VIC Jr was incredible. What? You say the low end grunt would be affected? On the street it will still roast the tires even starting in first or second (auto) at the track short times improved from a 1.67 best to 1.59 AND 1/4 mile times picked up by more than 3 tenths.

Idles at 800RPM, 2500 stall, drive in traffic all day long. Not sure where the bad manners are?????

D.Hearne · Jun 16, 2005

I ran my Vic Jr on a 302 S/B with the B303 in my 89 Ranger. It didn't "turn on" till 3 grand and pulled to 7500. Ended up cracking a cylinder. Now in my 331, with the bigger Z303 cam, but with the 3x2 dual plane and three Holley 250's, it "turns on" at 1500 and pulls to 6500. I don't miss that extra 1000 rpms on top AT ALL. My block, I'm sure, is a lot happier too. Sure the 30 extra cubes would have worked to bring down the power band some with the Vic, but I figured not much considering I've got a larger cam now.

steel1212 · Jun 16, 2005

sorry guys rpm airgap is what I'm useing now and will be transferring to the roller when I do it.

Hearne you think I should use the 165s over 185s? Faster velocity?

D.Hearne · Jun 16, 2005

I think they'd work better than the 185's with the few cubes of a 302. They'll work better at lower rpms than 185's will. You've got to remember that bigger heads and cams all work to increase the hp output, but they do this at higher and higher rpm ranges. Put a shortblock with more cubic inches under those heads and that pulls the range downward. 90% of your driving isn't going to occur at those upper rpms anyway. If you want all out power, then yea go for it, but if all you want is an engine that gives you some of both, then you need to pick more conservative parts. My Canfields are the equivalent of the 165's and I couldn't be happier with the results, they work even better on the 331 with the combo I have than what I had em on before with the 302. Those 7500 rpm blasts were fun till it cracked the block.

MitchGT · Jun 19, 2005

I say go with the X274 cam and a big set of heads( like the AFR 185's).The only other thing I would say is put them in a stroker.Building a decent stroker isn't much more expensive than a stocker, and the extra ten percent more cubes help to tame a larger cam, heads, manifold,etc. The top end power would be similer to the over-revving 302, but the bottom end torque would be much stronger.With the extra torque you could go with a little less rear gear and get back some of the mpg that you lost with the larger engine. I have the X262 on my 331 (with a single plane manifold) and it idles smoothly and pulls decently from idle. It would be a good cam for a 302 and a dual plane manifold if you insist with staying smaller.

steel1212 · Jun 19, 2005

I could not find a x262 on comp cams sight. I already have the magnum 280h in my pretty much stock 302, with 351 d00e heads, rpm air gap, and pullies, with magnum roller tip rockers. I love this cam and everybody is giving me smaller duration roller cams for my roller build and I really don't understand it? I know the roller cam will have more lift do to design but why are you trying to get me to buy a smaller duration cam? I mean the xe274 has less duration at intake and only slightly more on exhaust. It is a .555/.565 lift where as the 280h is a 512/512 though.

So whats up? I love the cam that is in my car now. You stomp it, it goes period.

D.Hearne · Jun 20, 2005

Rollers have more effective duration than a similar degree flat tappet cam, due to the lobe design and the ability of the roller tappet to follow a faster ramp. The lift specs are the same for either. You've mis-understood someone's advice here. I'm not sure what the difference in numbers in terms of degrees duration is but a roller cam with smaller duration will equal a larger degree flat tappet cam in actual performance.

steel1212 · Jun 20, 2005

Hearne, thanks thats all I need to know . Everybody was saying go with this or that but not really why I should.

D.Hearne · Jun 21, 2005

Glad you understand it now, maybe I should have been a little more detailed before, but sometimes I'm in a rush and don't have time for details ( I type too slow too )

roller 302 and cam selection

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