Thread: I can't decide what engine to build....need advice

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Because of the lifter having a roller on the cam end vs. a flat surface, more aggresive rates can be used on the cam lift.... then there's the friction thing, a roller offers much less friction and wear on the cam lobe then does a flat tappet.... Richard can give you all the specifics on the difference in cam specs, I'm one of the "lightweights" on cam selection, and always defer to the experts at selection time!!!!!

I understand the difference between flat tappet and roller....I'm trying to understand the difference in dynamic compression between the two. These two cams look real similar. I used the dynamic compression calculator on Keith black's website and I came up with 8.095 with the xr282hr roller and 7.941 with the solid lift 282s. Techinspector1, are you getting the dynamic compression numbers from the DynoSim software? I'm not sure how accurate the calc. that I'm using is. I like the xr276hr too though....

Originally Posted by 35chevy

Can you help me understand the difference between the recommended 282 solid and the 282 roller? Duration is pretty close, the solid is 236/236 and the roller is 230/236. the intake valve closing point on the solid is 44 degrees and the roller is 41 degrees. wouldn't that make the roller have a higher dynamic compression since the intake valve closes earlier? What an I missing here?

Yeah, I must have used closing numbers from a different grind. Sorry. I went back to the post and changed it so that subsequent readers will be able to make sense of it, then added a dyno of the 12-432-8.

Originally Posted by 35chevy

I can't afford any of that right now.....I started a new job this year. Automotive Service Technology instructor at Elba High School. I'm at the bottom of the pay scale as this is my first year and I'm still working in my shop in the evenings to make ends meet. I would love to upgrade but I have no choice, the engine has to be replaced, and I have to stick with the old stuff at this time. I'm only looking for 375-450 hp with a little driveability, on the ragged edge of course, and using parts I already have and my access to machine shop equiptment. I should be able to keep it under $1500 for the whole build or I can buy a $1500 block??? I can see that in my future with a pair of turbos tucked under the front fenders but that's dreaming at this point. 383 or 400? I know the sportsman II's are old technology but I traded a $100 running 305 for them.......they fit my budget.

Great to hear we have another teacher on here. You guys deserve way more pay and way more credit for educating tomorrows leaders! I used to teach in the private sector, loved teaching, hated the hours, pay and some of the parents!

Great to hear we have another teacher on here. You guys deserve way more pay and way more credit for educating tomorrows leaders! I used to teach in the private sector, loved teaching, hated the hours, pay and some of the parents!

Thanks, Benifits are good, we put in way more hours than most people believe, a lot of preparation time, and the mental stress of dealing with day to day problems with teens is "WOW" to say the least. On the bright side...some of the things I've seen have taught me how to be a parent. My little girl is 4, maybe some of the things I'm exposed to will help me steer her in a different direction. Some days I want to beat a kid...every day I want to beat a parent. I can't believe how fast society is changing. These kids are parents....and these parents are kids!

Let's try one step lower first, 12-423-8

I think I might stick with this one..there's not a lot of horsepower difference and torque is down a little on the 12-432-8. I think playing this one conservatively might be in my benifit. After looking at the torque figures at 2000 rpm I'm thinking I might need to tighten up my converter a little. It slips up to around 2800 behind my 350. I don't know what affect lowering the rear gears has on that though. What do you think? My block cleaned up on .040 and it's going in the caustic soda tomorrow. Some of my parts have come in and I'm expecting a truck load tomorrow, well maybe not a truck load. I can't wat to get it done.

"I think playing this one conservatively might be in my benifit."

Personally, I wouldn't trade 14 ft/lbs @ 2000 for 12 hp @ 5000. The motor will be seeing 2000 way more often than it will 5000.

"What do you think?"

Proof of the pudding is in the taste. I'd wait and drive the car some before changing the converter.

Personally, I wouldn't trade 14 ft/lbs @ 2000 for 12 hp @ 5000. The motor will be seeing 2000 way more often than it will 5000.

That's the same page I was on, Later.............

Just for kicks I emailed comp cams for a camshaft recommendation. They recommended the xr288hr-10. I tried the camquest software and this cam is one of the ones recommended. I'm pretty settled on a smaller cam. I'm just wondering how they come up with thier recommendation? What software do they use?

Tech are you sure that picture is appropriate for this site?
Oh those are cams, sorry about that.
Reminded me of something else.
HE! HE! HE! Kurt