Help me cam this 512

[Dartbloke]

Hi, I've been lurking around this site for a while and joined up today. I see there are a few guys with a lot more experience than I have of building fast engines, I could use a little help here. Would like some cam suggestions for my combo, needs to be solid lifter, no budget for a roller.
400 based 512 stroker, 11.5 static compression, 40 thou. quench.
BCR aluminium caps
Edelbrock rpm's worked by Indy, 2.19, 1.88, full port on stock window, supposed to flow 300@.600 lift.
Weiand tunnel ram, 660 centre squirters.
Want to make around 600hp, needs to run on pump gas as I drive to the track and use it on the street occasionally.
Assuming peak power with these heads will be under 6000rpm

Soooo, waddya think?

[Mick70RR]

Good to see you here Blue.

[Challenger340]

Hello, and a BIG WELCOME to the Board !

Some really smart moderators in here, with lots of experience, and I'm sure they'll chime in with some good opinions for your cam.

I'll "pm" you, some of my own Non-Engle, Flat Tappet Solid Cam opinions if you want  !

Lemme know.

Bob out.

[Dartbloke]

Love to see 'em Bob!

[Challenger340]

This may be a good thread to read completely, when ya got time.
See the dyno sheet at the end.

I'll pm some profiles we've had good success with.

http://www.dodgecharger.com/forum/index.php/topic,21828.msg237005.html#msg237005

[firefighter3931]

Want to make around 600hp, needs to run on pump gas as I drive to the track and use it on the street occasionally.
Assuming peak power with these heads will be under 6000rpm

Soooo, waddya think?

Welcome Dartbloke....that sounds like a nice build. The 600hp won't be a problem but the pump gas could be with 11.5:1 static compression. 

Why so much Compression if you wanted a pump gas build ?

Your assumption is correct on the peak power rpm...it will be all done by 6k or just over. 


How much stall and gear does the car have ? Weight ?



Ron


Ps. A cam for this type of combo won't be an "off the shelf" grind....something custom will work better. 

[Dartbloke]

Convertor is currently a 3800, rear gear is 4.10 with a 29" tyre. I realise a convertor and gear swap will probably be needed, car is a 2800lb Dart. The static compression is high because I figured the sort of cam profile I would need, would "bleed off" a lot of that, and I would end up with a dynamic ratio that would be pump gas friendly, or am I getting that wrong? Figured a custom grind would probably be needed, but I could use a bit of help as I've never tried to build an engine like this before.

[Dartbloke]

How about something like this?

http://www.hughesengines.com/partDetail.asp?partID=10292&eTypeID=14

[Challenger340]

Yeah, it's a real good Cam.
If you "drive to the track, and street drive occasionally", it should be more than adequate.

Be very careful on the break-in. Use a supplement in the Oil, and be sure to remove the inner springs.

Sometimes it is wise as well, to limit the Idle time, even well after the break-in period, like forever.

Don't mind me, I just get all spooked these days around the 155# seat pressure stuff for street guys, on todays Oils.
I know they match the spring rate, and still keep the max pressures "over the nose", but street drivin spooks me.
I'm OLD !

That stuff, IMO, has a limited shelf life no matter what, but it does make good power, that's the trade-off.

Bob out.

[firefighter3931]

How about something like this?

http://www.hughesengines.com/partDetail.asp?partID=10292&eTypeID=14

That cam is way too small for a 512.... inmho. I would be looking at something in the 270@.050 duration range especially if you want to bleed off some cylinder pressure and make it pump-gas friendly. 



Ron

[Challenger340]

yeah, you're right Ron, it'd probably only go to 5800 "max" on the 512, but it'd be a torqueeee S.O.B. 

I ain't a great street guy, those brain cells long gone !

OK, lets get serious here.

Whataya think about this for a "baseline", easy on parts/springs rates;

I'll start with some Comp. lobes

Intake # 6265, 264 @ .050 on .605" lift
Exhaust #6000, 272 @ .050 on .616" lift

or,

Intake #6304, 259 @ .050 on .587" lift
Exhaust # 6018, 265 @ .050 on .600" lift.

Dunno the head flow ratio, but lets "assume" and go 110 lsa, install @ 106, "forgiving" ?

How longs the rod on those 512 kits ? 
Thats a Small head on a 512, ported or not.

Bob out.

[Challenger340]

OOPs !
I just re-read your post, you got 3800 stall and 4.10's W/29" tires ?
And a light Car !

OK,  lets "kick it up a bit", this one works as good as ANYTHING out there, PERIOD.
It'll be within 5 hp of ANYTHING on a 500-520 inch deal W/eddy's.

Very similar to the OLD Ultradyne .613 "powerwise", but easier on parts.

Ya need more head. This is max for 300 cfm @ .600" with a tunnel, squirters or not.  IMHO

On 108 lsa
Intake # 7071, 268 @ .050, .600" W/1.5,  or  .640" W/1.6
Exhaust #7073, 272 @ .050, .608" W/1.5  or  .650" W/1.6

Install @ 106, shift @ 6200, and HOLD - ON.

Just my opinions

Bob out.

[firefighter3931]

OOPs !
I just re-read your post, you got 3800 stall and 4.10's W/29" tires ?
And a light Car !

OK,  lets "kick it up a bit", this one works as good as ANYTHING out there, PERIOD.
It'll be within 5 hp of ANYTHING on a 500-520 inch deal W/eddy's.

Very similar to the OLD Ultradyne .613 "powerwise", but easier on parts.

Ya need more head. This is max for 300 cfm @ .600" with a tunnel, squirters or not.  IMHO

On 108 lsa
Intake # 7071, 268 @ .050, .600" W/1.5,  or  .640" W/1.6
Exhaust #7073, 272 @ .050, .608" W/1.5  or  .650" W/1.6

Install @ 106, shift @ 6200, and HOLD - ON.

Just my opinions

Bob out.

That's the one i like Bob ! 

I was thinking that with the car being so light it wouldn't hurt to up the duration and bleed of some cylinder pressure at the same time. 

This engine combo will make more than enough power to run easy  9's at 2600 lbs 

Dartbloke is gonna need to do some major suspension tuning to get it to hook 



Ron

[Challenger340]

OOPs !
I just re-read your post, you got 3800 stall and 4.10's W/29" tires ?
And a light Car !

OK,  lets "kick it up a bit", this one works as good as ANYTHING out there, PERIOD.
It'll be within 5 hp of ANYTHING on a 500-520 inch deal W/eddy's.

Very similar to the OLD Ultradyne .613 "powerwise", but easier on parts.

Ya need more head. This is max for 300 cfm @ .600" with a tunnel, squirters or not.  IMHO

On 108 lsa
Intake # 7071, 268 @ .050, .600" W/1.5,  or  .640" W/1.6
Exhaust #7073, 272 @ .050, .608" W/1.5  or  .650" W/1.6

Install @ 106, shift @ 6200, and HOLD - ON.

Just my opinions

Bob out.

That's the one i like Bob ! 

I was thinking that with the car being so light it wouldn't hurt to up the duration and bleed of some cylinder pressure at the same time. 

This engine combo will make more than enough power to run easy  9's at 2600 lbs 

Dartbloke is gonna need to do some major suspension tuning to get it to hook 



Ron

Your so right about the pressure Ron, especially closer to sea level.
and,
IMO,
The last one will still start producing plenty of wind @ the 38-4000 mark with the big arm on the smaller heads(velocity).

Go DARTBLOKE !

[Dartbloke]

Good stuff, now we are getting somewhere! Ok, if I was going to go with the 7071 & 7073 lobes, how many degrees @0.50 would you be wanting to close the Inlet valve? That Hughes grind I mentioned closes @ 51 degrees ABC which really knocks some compression out of it, which I need to do. Yea, hooking this thing up might be a challenge, I'm on 29 x14.50 ET streets, I want to run deep in the 10's, any faster than that would be a bonus, but it has to run on pump gas and it has to have some sort of street manners if you know what I mean. I know the heads are small for a 512, but I was hoping to do it with torque rather high revs, which I have never tried before, I'm on a steep learning curve here....

[firefighter3931]

Good stuff, now we are getting somewhere! Ok, if I was going to go with the 7071 & 7073 lobes, how many degrees @0.50 would you be wanting to close the Inlet valve? That Hughes grind I mentioned closes @ 51 degrees ABC which really knocks some compression out of it, which I need to do. Yea, hooking this thing up might be a challenge, I'm on 29 x14.50 ET streets, I want to run deep in the 10's, any faster than that would be a bonus, but it has to run on pump gas and it has to have some sort of street manners if you know what I mean. I know the heads are small for a 512, but I was hoping to do it with torque rather high revs, which I have never tried before, I'm on a steep learning curve here....

You will want to close the intake valve as late as possible. Widening out the LSA will achieve that result....something on a 112* lobe seperation would be more appropriate most likely. That is a lot of cylinder volume to bleed off and the 11.5:1 static compression isn't helping things at all.


Have you purchased the stroker kit yet ? If i were doing this type of build a custom piston with an inverted dome (dish) would be part of the "plan" to make life easier. The pump gas requirement really skews the whole buildup and subsequent parts selection. The extra point of compression won't make that much more power but really complicates things. 



Ron

[Dartbloke]

Kit is already ordered, I guess if i come really unstuck I could always get a bit more dish machined into the piston. The reason I went for that compression in the first place, was so that I could use a big enough cam and still end up with good dynamic compression, I knew I would need a fair bit of duration to make the power so you need a high static compression to be able to do that. Do you have a better idea?

[firefighter3931]

Kit is already ordered, I guess if i come really unstuck I could always get a bit more dish machined into the piston. The reason I went for that compression in the first place, was so that I could use a big enough cam and still end up with good dynamic compression, I knew I would need a fair bit of duration to make the power so you need a high static compression to be able to do that. Do you have a better idea?

DB, i would go ahead and order that cam outlined above and have it cut on a 112* lsa. The reality is that the stroker is gonna make soo much torque no matter what you do to it so spreading the lobe centers out and extending the powerband is what you want. It may make a little less torque at the peak but it will make power over a broader power range. When using an undersized head (for the displacement) you have to go big on the cam profile. A little less torque at lower rpms isn't necessarily a bad thing when trying to drive on the street is it ? 


After you get it running then the tuning will take over....there's always the option of pulling some timing out of it for daily driving then mixing some race fuel in at the track....and bumping the timing back up. The car is so light that this might not even be necessary.   



Ron

[Dartbloke]

OK Ron, thanks for that! Would you mind listing exactly what information I need to give Comp Cams to get this ground right? That would be a big help! I'm getting really excited about this build, it should finally run to it's potential, it's been a long time coming. Don't mind using race fuel at the track but it has to be pump gas for the street, you would have heart failure if you knew what we pay for fuel over here, it's insane. We do have 97 octane super unleaded here, and although we rate our fuel differently, I still think it will be better quality than the stuff you have at the pump. The car is supposed to look as if it was built in '71, I am a big fan of the early pro stock cars, so a fair bit of the inspiration has come from that. After the motor is done, the next job is to finish the period paint with some lettering and decals from back then.

[firefighter3931]

DB, tell Comp you want a cutom grind cam with intake lobe #7071 and exhaust lobe #7073 cut on a 112* LSA. These are from the XX lobe family and are an agressive .875 lifter profile. The XX lobes work well in restricted head applications and make excellent power....while not being too hard on the valvetrain. That's a bonus if you want to street drive it because really agressive cams with high spring rates don't like to be idled at stop lights. 

On paper the cam will spec out as :

300*/304*@.020
268*/272*@.050
178*/182*@.200
.600/.609 lift@1.5:1 RR
112* LSA
*installed on a 108* intake centerline (4* advanced)

The Isky 8005 valvesprings will work fine if the springs you have now aren't up to the task. 

The new Howards EDM lifters are what i would use in this application. These are designed to pressure feed the cam lobe/lifter face as opposed to the traditional splash lube that flings oil off the rotating assembly to lube the cam. It's a much better design and definately worth purchasing. 

http://www.competitionproducts.com/prodinfo.asp?number=91718


Of course this cam should be degreed in and all the usual breakin cautions adhered to :

(1) removal of inner valve springs
(2) Moly lube paste on the lifter faces
(3) Comp Cams breakin additive with a good performance racing oil (non synthetic)



Ron

[Animal]

All good info as usual.

I realise when given the proposed build you can 'rough' out a cam grind , also get pretty near the mark as regards duration (displacement) , also LSA (overlap/vac) , am i right in thinking intake valve closure is a different story altogether , as this will be the determinating factor with regard to dynamic compression , which could break or make a build (detonation) , lookin @ this stroker build , bearing in mind the static compression ratio & the proposed duration/LSA , how do we know if this grind will bleed off the neccesary compression to keep detonation @ bay , or will it bled off too much & be a pig @ low RPM & how much D/C will it have @ high rpm?

Ron , most of what i've learnt has come from yourself (as you well know) & others , it is easy for you to pick a cam grind from the vast experiance you have , how is it done otherwise , this particular one maybe , also i realise the cam munufacturers help , but they must make mistakes when faced with trying to bleed off just the right ammount of C/R to avoid detonation when faced with builds running high compression on pumped gas , how many motors don't make the potential they should?

TIA.

[Dartbloke]

Thanks Ron, that's excellent! I'll get on to that in the new year. What is the problem with idling a cam like that? Wear issue? Lack of oiling?

[firefighter3931]

Thanks Ron, that's excellent! I'll get on to that in the new year. What is the problem with idling a cam like that? Wear issue? Lack of oiling?

DB, the main issue is with oiling at low engine speeds. So many guys like to idle the engine down for that cool rumpity sound but with agressive lobes and higher spring pressures required to keep the valvetrain out of float...this can be disasterous. The original engine design with splash lube wasn't really intended for the type of torture we put these motors through. A stock valvespring might have 250lbs over the nose with a slow, lazy lobe profile so it can live with less than adequate lubrication.

I really like the idea of prority lobe lubrication that these EDM lifters provide...it's a fantastic solution to an ongoing problem. The other thing i prefer is lots of oil pressure as you saw when i posted in the oil pump thread. Oil is the lifeblood of these engines and we need to protect our investment. There's absolutely nothing wrong with 50psi at hot idle....you might lose a few hp but who cares. I'd rather keep my engine happy and all in one piece. 


Ron

[firefighter3931]

All good info as usual.

I realise when given the proposed build you can 'rough' out a cam grind , also get pretty near the mark as regards duration (displacement) , also LSA (overlap/vac) , am i right in thinking intake valve closure is a different story altogether , as this will be the determinating factor with regard to dynamic compression , which could break or make a build (detonation) , lookin @ this stroker build , bearing in mind the static compression ratio & the proposed duration/LSA , how do we know if this grind will bleed off the neccesary compression to keep detonation @ bay , or will it bled off too much & be a pig @ low RPM & how much D/C will it have @ high rpm?

Ron , most of what i've learnt has come from yourself (as you well know) & others , it is easy for you to pick a cam grind from the vast experiance you have , how is it done otherwise , this particular one maybe , also i realise the cam munufacturers help , but they must make mistakes when faced with trying to bleed off just the right ammount of C/R to avoid detonation when faced with builds running high compression on pumped gas , how many motors don't make the potential they should?

TIA.

Adam, those are all good questions and i'll answer to the best of my knowledge ;

(1) Intake closing : this determines how much cylinder pressure the engine will make at lower engine speeds. By widening out the LSA and increasing duration you are effectively reducing cranking pressure. Tighter lobed profiles do the opposite by trapping more air in the cylinder and increasing bottom end power.

(2) How much is too much : It's a delicate balance when trying to sort out a cam but the combo in question will be quite forgiving. The 512 has such a long throw and makes so much torque that it's really hard to overcam it. The priority in this case is making it pump gas friendly which this cam should do. The brutal torque that this 512 will make might be a little less brutal than it would with a different cam....but any loss of torque won't be missed on a car this light. It might actually help the car hook up better (flatter/softer torque curve) and make it more streetable. Make no mistake....this will be one bad SOB and be a torque monster. DB will have his hands full trying to launch this animal ! 

(3) Cam Companies recommendations : by in large the cam companies are pretty good at getting it right. Sometimes when building something outside the box mistakes can be made. Smaller engines are more sensetive to cam profiles than bigger ones. So a wide lsa cam profile on say a 383 or 440 will have a more dramatic effect than it will on a 500 incher. By this i mean you can widen out the lobes without any major detriment to the whole power curve....hence the "more forgiving" comment in reference to the stroker build. "Cubic inches are your friend" was once told to me by an accomplished engine builder and friend....those are words to live by. 



Ron

[Animal]

Thanks Ron , maybe it is all voodo , it's knowing exactly when to close that IV , there's a rule of thumb somewhere , think it's between 35 & 60* ABDC , does'nt really give much away.

Was looking @ a couple of engine builds a guy did , one was a 350 Chebby , the other a 510 Ford , the Chebby made 750 HP @ 7500 RPM , the Ford made 1100 HP @ 7500 RPM , both used the same duration , & i always thought the larger the displacement the longerr the duration.