cam for 340 street car

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alfred340

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Hi, my name´s Alfred. I´m new to this forum.
I got a 340 in a ´68 Barracuda and want to give it a little more power.
The engine is stock right now, even the cam, except for a FBO e-ingnition.
I plan on removing the heads and doing a valve job and cleaning the ports, and replacing timing gear and camshaft. Wont´t remove the block this time.
The AVS and iron intake shall be replaced by a 750 Holley and Ede RPM intake (hope this will clear the hood). Already have these at home. I´d like to stick with the HP manifolds on the exhaust side.
Car has a TF 727 with stock converter and 3.23 SG rear.
Car is mainly driven in/around town, some stoplight action, little autobahn, "once a year" strip. At all less than 1000mls a year (so mpg and comfort is of less concern).
The engine winds to almost 6000 right now, but without any noticeable power gain over 5000. So after my winter labor, the engine should make power to 6k and gain some extra grunt throughout the rpm range.

As I´m on a budget, timing chain, camshaft and perhaps valve springs are the only things I want to buy (except gaskets...).
I had an eye on the CompCams XE268H with matching springs. Advertised duration like the 340 cam but much more lift.
XE274H would probably need the expensive Mopar chrome silicone springs, because I don´t want to machine the heads for duals. Also I´m not sure about stall and valve-piston clearance.
Bigger Mopar cams like the 280° have single pattern, which doesn´t contribute my intake/exhaust combo. At what size power brakes start to make problems?

Please tell me about your experiences and further recommendations!

Thanks, Alfred

p.s. excuse my English (more rusted than the fish)
 
Will you please state the casting number of the heads you intend to use and if bowl blending and milding porting will be done,and the valve sizes you intend to use.Driving the car will be done mostly where,and what type of driving?Do you want normal performance,all through the power band or bottom end,mid range or top end power.IS 6500rpm the max you wish to spin the motor,and do you want a hydraulic or solid cam or roller.Will this combo stay together for a couple of years before trying some thing new?Every thing revolves around your heads choise?,Mrmopartech
 
Engine has X-Heads with 2.02"/1.60" valves. I´ll do no porting, just smoothing out casting burrs and sharp edges.
Car is driven mainly in town at 40mph in D. But as it´s not a daily driver, it should make some serious stoplight performance (0-50mph) and should perform well when leaving town or accessing autobahn (40-100mph).
Now it makes no sense to shift above 5000rpm, but I´d like to extend the manual shift points to almost 6000rpm, so (with the 727 delay) the engine never revs more than 6500.
So I want to help mid range and top end without sacrificing the low.
I want to use a hydraulic cam and stock stamped rockers.
Combo should stay like this for at least 3 years/ 10k mls.

Thanks
 
I built a 360 for my 68 Barracuda, 10.6:1 compression, magnum heads, crosswind intake, 600 Holley (for now) and the XE268H cam. With a 4spd OD, 3.55 gears the car is kick *** from 1500 to 5500 rpm.
 
XE268 cam, lifters and springs would be a good upgrade for your application.
At least have the heads bowl hogged to get rid of all the casting material obstruction under the valve seat. Then blend to get rid of remaining humps and bumps. Gasket match intake ports of the heads to be equal too or slightly greater than the exit of the intake runner. Blend the port back into the runner 3/4" so you have a smooth, unobstructed flow from the intake runner of the intake manifold into the runner of the head. Grind some off the pushrod pinch point, as that is one of the major limiting factors in head flow on small blocks - the pinch point. This head work is not difficult and the benifits are tremendous.
If you have a 71 or older 340 with the so called 10.5 CR this should give you around 375hp and around 400 if you went to headers. either way, you will notice a difference in the seat of the pants.
 
Hi Alfred,
the original cam (if you already have) is good enough...
I just have 2 340s. One with a 272 Crane and one with OEM. Last one ist (my opinion) a bid wilder but even streetable enough...


Michael
 
Hi Buschi

The original cam seems to be worn out, so I´d have to change it anyway.
I measured at the pushrod with the rocker gear removed, and lift varied among lobes of the same kind.

Alfred
 
I have a Edy Air Gap intake on my 69 B'cuda and hood clearance is close. I had to go with a low aircleaner. I went with the Edelbrock cheapo foam one.
I like my Comp XE262 cam.
-Shupe
 
The pinch piont /or the push rod casting boss in the intake runner.you will see a area in the port where the push rod runs close to,it is cast into the port wall,by running ofset rockers and filling this area in with weld or by press fitting a tube into it,you can regrind the port to make it look like no pinch area was ever there at all.This area can be grinded down to about .080 thickness and no more and will be safe,and will increase the flow with big effects.Mrmopartech
 
Mrmopartech, two thumbs up on that. This is a great mod for anyone wishing to stay with the factory castings. Done correctly, it can yield W2 results on the intake side. Also, port volume can increase to the mid 180's (cc). This works really well on the larger (stroker) motors. And, .. engine will look 'stock' . Terry.
 
if your really on a budget the Summit mopar cam(the bigger one) works quite well and comes with everything(lifters etc) you need(except the gaskets) and is under $100. It replaced a MP 284/.484 cam that was just too much for a 340 thats not being raced or something.
 
ok i know my sugestion is not realy a cheap one but i would like more peole to look a litle closer at rollercams iam running one that is pretty big with 0.650 lift on both intake and exhaust and it does not feel so big the idle is a litle rough but it is still capable to idle at 800rpm and its realy explosive at high rpm so i think a small solid roller or even a hydralic one would make a lot of sense to someone who likes alot of torque combined with some nice high rpm power!
 
Mrmopartech said:
The pinch piont /or the push rod casting boss in the intake runner.you will see a area in the port where the push rod runs close to,it is cast into the port wall,by running ofset rockers and filling this area in with weld or by press fitting a tube into it,you can regrind the port to make it look like no pinch area was ever there at all.This area can be grinded down to about .080 thickness and no more and will be safe,and will increase the flow with big effects.Mrmopartech
Click to expand...
sounds good. Would come more clearly for me with a little pic. I kinda familar withe english but not that perfect.......... :(
 
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