Been awhile....But here's another "What Cam" question!

[Propwash]

Alright Fella's.......I don't want to dishonor our Bi-Monthly "What Cam" question, so here we go.

Car: 1971 Dodge Dart
Weight: About 3,000lbs.
Transmission: 833 4 Speed
Rear: 8 3/4 w/3.55 Gears
Brakes: Manual
Motor: 340
-Bored .040
-Comp 10.47 Est.
-Zero Decked pistons/block
-Ported Eddy RPM Perf. AL 63CC Closed Chambered Heads (Quench!...040 Head Gasket), hand porting-not CNC program
-Port Matched DP Eddy Air Gap Intake
-Carb, Guessing 780 VS Quickfuel
-1 7/8 headers
-Hughes 1.5 Roller Rockers
-Dist...VA/MA?

So i'm stuck between a Roller Cam or a Flat Tappet, Either way I'm leaning towards a solid mechanical cam. Roller's are nice with their more aggressive ramps & quick action, but then comes better springs/hardware and heftier costs. Flat's are cheaper, but only come somewhat close in profiles, require more attention (setting valves a bit more/Zinc'd up oil/Lifespan). Costs between the two said and done.........$1000-1200 vs. $400-$600

Anyways.......I'm looking for around 450-475HP out of this engine. I don't mind a lopey idle, and like listed...it's manual brakes, so vacuum is not an issue. This car will be driven with a great majority on street, with maybe an occasional trip to the strip, just for fun. I run a Street/Strip 512 '69 Roadrunner, with Mechanical Advance Dist., Mechanical Secondary Carb and a solid Flat Tappet Comp Xtreme 244/[email protected], .520/.540Lift and 110LSA. The car perform's just fine on the street with an auto. That being said, trying to build/run a street-strip was bit like threading a needle and i'm looking for something that's going to be a little more accommodating.....like having a choke, vacuum advance & secondaries, bit smoother in ramping up and idle and doesn't require such drastic secondary systems in the fuel/oil/air/drivetrain department. Any idea's fella's?

 

[lewtot184]

i'm surprised there isn't all kinds of "recommendations" for you.

 

[Propwash]

i'm surprised there isn't all kinds of "recommendations" for you.

Hehehehe............Heck, I'd be happy with the whole 509 skit lew....something at least.

 

[383man]

Honestly your best bet is call a cam company or a good cam grinder that knows cams real good and let them spec a cam for the combo. I had "Dwayne Porter" spec a cam for my 493 as I wanted some good power with my 10.6 comp but I wanted to run 92 pump and I wanted some lump lump in the idle but I wanted to keep the idle clean. I could pick one as I know cams pretty good but I am not a pro who does it everyday for a living. I needed to have the intake vlave closing right to keep my cyl press in line for pump but still make power. So I called Dwayne Porter as he is definetly the best or one of the best out there in my opinion. And anyone who does cams should ask you alot of questions about the combo and the car to get it right.
But with that said I bet the MP .557 would work pretty good in that. Myself I would talk to Dwayne or some other good cam grinder and get one speced for the combo. And the cost from Dwayne was no more then any basic solid flat tappet cost. I have Dwayne Porter's info if you would want it. Ron

 

[lewtot184]

ok i'm in. I normally gringe at cam rec's. they're so subjective; what do you like, blondes, brunnettes, or redheads? ok, you have a xs282 that you seem to like in a 511" engine. obviously, that cam isn't going to drive or run as nice as the 511' engine in an engine that's 66% smaller. the 340 car does have an advantage of less weight and a 4spd. I think the 1 7/8" are too big for 340" driver, but that's what you have. if you look carefully at those xs profiles in the master lobe catalog you will see that the advertised duration is at .015" lobe lift but lash is .016" at the valve. .016" at the valve with 1.6 rocker .010" at the lobe. this means that the tappet is traveling an extra .005" on the opening and closing ramps. basically all this means that the seat timing at .016" lash is probably close to 10 degrees more than advertised. so your xs282 is probably 290/300 on the seat, too much for a small cube driver. If you like comp cams then i'd rec' a xs268s or maybe use the xs274s lobe on both intake and exhaust. a 282s magnum is actually 282 degrees .022" lash and .505 at the valve with a 1.6 rocker and .022" lash. going out on a limb a little here, but i'm not sure i'd use a split duration cam with the big exhaust. you may not need it.

 

[charger360]

to get that power with a stock stroke 340 you are going to need a fair bit of cam. I would go roller for sure because of the lift you will need I think it will live longer. that being said the rockers pushrods and springs and oiling system will have to be up to the challenge! It would be interesting to cost a stroker to achieve the same power level with a less aggresive cam and less revs. It may work out the same more cubes may cost less than a smaller higher revving stressed out small cube engine in the long run.

 

[Propwash]

Hey thanks fella's! Appreciate it. I heard/seen good things about the 268 in 340's, for a street combo. I'm not stuck with the 1 7/8" headers. They're just a $30 dollar Craigslist buy, that just needed a little welding of cracks by the flanges, so I'm open for spending a bit more for appropriate dia. pipes. I've heard a lot of good things about Dwayne porter in the past Ron. If you have Dwayne's info, i'd definitely like to get that from you. Never hurt's to talk to as many folks as possible.

Hey thanks again fella's. I appreciate you taking your time to post your input. Gives me some great ammo moving forward. Not a ton of action on this thread, but I suppose the window of folks on FBBO running 340's vs a big block are pretty small. I definitely need some advice/guidance. So use to big blocks over the years, I don't want to inadvertently build a small block like a big block and end up with a train-wreck of a motor.

 

[383man]

Hey thanks fella's! Appreciate it. I heard/seen good things about the 268 in 340's, for a street combo. I'm not stuck with the 1 7/8" headers. They're just a $30 dollar Craigslist buy, that just needed a little welding of cracks by the flanges, so I'm open for spending a bit more for appropriate dia. pipes. I've heard a lot of good things about Dwayne porter in the past Ron. If you have Dwayne's info, i'd definitely like to get that from you. Never hurt's to talk to as many folks as possible.

Hey thanks again fella's. I appreciate you taking your time to post your input. Gives me some great ammo moving forward. Not a ton of action on this thread, but I suppose the window of folks on FBBO running 340's vs a big block are pretty small. I definitely need some advice/guidance. So use to big blocks over the years, I don't want to inadvertently build a small block like a big block and end up with a train-wreck of a motor.

No problem as here is Dwayne Porters # 802-951-1955. Good luck , Ron