know alot about cams?

[hurri10209]

ok so i'm building my 347 stroker, i'm being told the AFR 185's would be perfect, the 205's will work great, i'm lost, i already bought the 205's, but i'm willing to sell them if they are to big, the set up i'm planning on running is,

347 stroker
keith black piston hyper
scat crank
eagle rods
edelbrock jr. vic intake
holley 750
afr 205's

my question is, will this cam work, i was messing around with desktop dyno and punching in different numbers, i'm not sure how cams work to well, i understand they open the valves and all that, but still don't have a complete understanding, so if you know alot about a cam can you tell me if this will run.

lobe center 114
intake crank deg. 230
exhaust crank deg. 235
valve lift .600
and that is @ .050
i've just been playing around and i made these specs, and it shows good on the prog. 588hp@6500 516tq@5k
above 400 ft-lbs from 2000-7000, so if any one knows alot about cams, if you want to help me out it'd be great(and i know i won't be able to take the engine that high, i'm planning on 6200)

[Dave Engel]

I would sell the 205's and opt. for the 185's, I'm not a big fan of Keith black pistons, but if you already had the assy. balanced make sure you gap the rings correctly. even with new heads I'd take them to a good machine shop and make sure they have a clean bill of health, and have them flowed. find out what your static comp. ratio is and call several cam manufactures and tell them your expectations are. They should be able to help you out.

Dave

[hurri10209]

the pistons have to stay, i got the rotation assy. for a good deal, i was going back to the 185's there's somany different opinions on the 205's on a 347, and i'd be able to get $300 more for the 205's so that's more money i can put some where else. thanks

[trularin]

With that lift, I would do a complete and very serious detail of the recipricating mass. Piston to valve clearance would be a concern. Valve spring travel. Push rod travel and rocker clearance are other immediate concerns.

I do not know what your capabilities are, but I would have these concerns if you are just going to "assemble an engine".

Good luck. If you do not have the tools to do this, I think I would pay someone to do it.

Just my $0.02

[HighPlainsDrifter]

Hi,
The cam you have has a 114* LC, that is for a EFI engine. With the 600 lift is too big for the street, unless you are going to be a serious racer I'd change it for a Crane 224/230 , .550 lift roller. That should spin up nicely and give more driveability on the street.
Ditto with the 205's, too big for the street,185's will work better.A street engine needs intake velocity, I'd dump the victor also, go with a Edelbrock RPM intake.
Perry.

[GT4T]

If you already have the 205s , I wouldn't bother with going to 185s , I think they will work fine. I'm using them.

On the cam, if you are still playing with settings try narrowing the LCA to closer to 110º and see how that works. I think it will give you a little better engine for street/occasional track type use. HPD is being a bit conservative, but dont let the durations (@.050) get out of the 230s (what you show is virtually identical to the cam linked to below.) The numbers you have come up with sound pretty close, but I think your HP number is a little generous. With similar specs and a very sophisticated program (a auto engineering grad student has accsss to at school) showed closer to 500 HP but the rpm ranges look very similar. One thing you haven't mentioned is the kind of cam/lifters you want to use. Since you are talking about 7Krpm numbers, I am assuming a solid roller. Comp has an off the shelf, XR Street Roller with specs very close to what you are using that will save you some $$: 35-769-8 check it out.

BTW, What trularin said! Good advice any time you depart from stock. Better safe than sorry. Blueprint, blueprint, blueprint. every vendor out there has different ideas about tolerances and different ways of measuring them.

Lynn

[hurri10209]

i choose the 114 because i had read the higher the LCA the better idle, i know most cams were 110, but i'm still not sure how the whole cam thing works to well yet, i am goin to double and triple check all my clearance. i'm not sure so can some one help me out, i know the high lift maybe a prob. with the pistons, so i should get cam, measure my piston to valve clearances, if i have to get them fly cut have that done, then have the rotating assy. balanced.

i was planning on using hydraulic rollers, that's why i had said i would only be taking the engine up to 6200, unless i can use the solid roller lifters with the valve springs on that head. this is all the information they have AFR Roller Lifter Spring, 1.550”
but i also seen AFR 1.625 Solid Roller Spring
so i'm not sure if i can use the solid roller with out changing springs, if i can then yes solid roller.

[ItBites]

Keep the 114 LCA (or at least 112). This will reduce overlap and keep dynamic cylinder pressure high at lower RPMs. The big lift you are looking at will allow you to make high RPM power as well.

Check it on your program. If you go to 110 LCA, low RPM power will suffer at the benefit of extending the curcve in the higher RPM regions.

Also good advice above about duration at .050. I wouldn't go more than 235 in that little motor. maybe even 230.


Oh, just noticed you didn't give CR. You need at least 10.5:1. Better above 11:1.

Just one last thing: Throw the pistons away and get forged pistons. Hyper-eutectic are hit and miss; a real crap shoot in a performance motor.

Have a nice day.

[hurri10209]

i'll look on ebay for some forged, and i thought keeping the LCA higher would be better, i was trying to keep as much mid range as i could, and the 114 had good looking nubers. i'll mess around with some more numbers, and keep the duration under 235
took you advice and kept 112, and under 235
LCA112
225/230
600/650
intake center 114

400+ft-lbs 2k-7k peak 505@5k
peak hp 567@6500
my compression ratio should be 10.8, if i did all my math correct

[GT4T]

If you've got hydaulic in mind, then don't change to solid. You should have no problem getting the ratios you need to make it turn the kind of cruise rpm you want.

I had to change the springs in my AFR 205s for solid roller. You'd probably be good with the hydraulic cam. You may want to consider some spring cups/locators and to check your retainers. When we pulled mine to check them, I was NOT impressed with the way the valves were set up. They had way too much room to move around and would have eventually eaten up the head. Retainers and cups/locators are cheap. Current wisdom likes locators better, but either is better than none.

With no desire to turn over 6500 rpm, the thought about keeping the lca to 110º looses its validity. I need to turn upto ~7200 rpm with the Porsche transaxle in my GT40 and trying to change the ratios is VERY costly. Its easier and cheaper to build a motor to match the gears :-)

I still think the 347 is going to be OK with the AFR 205s. AFR185s may have given you a couple more FP of torque, but probably not worth the hassel of selling yours an buying others. Seems like I always loose out in that kind of deal. And with the 750 carb, I don't think you are going to get a bad velocity drop in heads runners, which can be an issue with a wet intake (fuel fallout.) Nor, should you get any softening of the throttle response.

I absolutely agree with ItBites on the pistons. If you want a good forged piston at a reasonable price, take a look at the Mahle pistons. Not only did I like the price, I also liked the lightness of them (again remember our different rpm targets.) They come in Porsches, have been in every Le Mans 24 Hours winner for years and years, F1 uses them in about 80% of the cars. I think they are in the new Ford GT. They just don't have a big name here, YET. They are forged and come with pins and rings for the price of an every day piston. I got them from the Mustang Depot (yes an ebay store, but, hey! they had the best price) at ~$450 for a +.060 set. (I am running a 336 ci w/ 3.25 stroke.)

Anyway, it should be sweet motor when you get done. And, you won't have to reset the lash on the rockers like you would with a solid roller :-).

Enjoy,
Lynn

[hurri10209]

you guy's have been great with all the help, i am going to call cam research up, and see what they recomend for a cam, and ask about my number, thanks for the info about the locators. i'll part with the pistons i have now and get some forged. maybe i'll run nitrious, that was the only thing stopping me. thanks