The mighty 318. Cams, cams, cams. What to do?

[CultClassik]

I'm running this low mile 318 that's probably a stock rebuild, runs decent, but..I've got a popping in the exhaust and a tapping sound that seems internal to the engine. I found another thread here that suggests this may be a sticking valve, or maybe a lifter? I really didn't want to get into this engine, but...hey let's face it, it's always fun to upgrade.

What I'm thinking is that I'll pull the heads and have them checked out, I have a wallowed out exhaust bolt hole that needs fixing anyway. While I'm at it, I'm going to throw a cam in there. Here's what I know about the engine -

I checked the casting number when I bought it, and it showed to be a 68+ 318 block. I'm guessing stock compression and probably matching heads. I'll check the head casting number when I get to the house in a bit. The guy said it had a mild cam...sounds more or less stock to me, so it can't be too exciting.

I was looking at the Whiplash 318 cam, given that it's supposed to be good for a stockish 318. However....if I were to go roller, I think it would keep me happier for a while longer, and I can always re-use the lifters on the next engine. Seems that there's decent prices on the Voodoo setups, and it seems easy if I grab the cam/lifters/timing chain/valve spring combo.

Question is, either way, will I need different pushrods? I do still have my 273 adjustable rockers if I need to use those...

The car (67 dart convertible) has a 7.25 3.21 SG, (I am replacing with a 8.25 3:55 SG that's sitting in the garage at some point) I rebuilt the 904 with red clutches etc, had the converter rebuilt and maxed out the stall on it (I think he said it should be around 2500 RPM if I remember correctly). Currently running an old Weiand that looks a lot like a LD4B with a rebuilt Carter 600.

So...if I went with a Voodoo, this is what I'm looking at, and it seems like a good match for my setup...

[SIZE=-1][SIZE=-1][FONT=Arial, Helvetica, sans-serif] [FONT=Arial, Helvetica, sans-serif]HYDRAULIC ROLLER: 3.23-3.91 gears, stock converter in 340 & 360, mild converter in 318, 9:1 compression, street machine.
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Well that copy and paste didn't turn out like I wanted....

So my questions are - do I need new pushrods?
Will the roller cam make this thing way more fun to drive? Worth the massive additional expense over something like a hyd flat Whiplash?
Any other cams that might be better for this combo?
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[67Dart273]

I'm not sure a roller on something that low budget would ever pay off. Frankly I don't see all the roller hype for a mild street engine. We've been running (way cheaper) flat tappet cams since when engines were invented. Nowadays, I realize oil is a problem. An off the shelf additive takes care of that.

 

[CultClassik]

I'm not really sure either. Then again, my first experience with rollers was the 5.0 Mustang, and that made a huge difference in those old design 302 engines, so it makes me think it must be some kind of good

Of course, I'd be more than happy to pay $200 for a new flat tappet than $900 for this roller kit...but if it's going to make a big difference in how the thing runs, I'm all in.

As for additives, the diesel oil seems to be doing the trick in this engine. Unless that noise I hear is something worse than what I think it is!

 

[skrews]

If it were mine I'd go with a 262*-268* range .904 lifter profile Hyd flat tappet, and put the $ saved vs the roller in to the heads. One piece stainless valves, some mild port work, and a nice valve job. You will get more out of your investment that way.

 

[CultClassik]

Thanks for the info! Mild port work may be done but no new valves. These heads aren't anything special, and won't be permanent for the car. Just looking to do easy stuff while it's apart - the only reason I'd consider roller is because I can re-use some of that stuff later.

I do have a pair of X heads already but I don't want to lose compression by using those, so I think very mild porting and new valve hardware if required by the new cam will be all I will do.

 

[This Bad Demon]

You know they make the Whiplash cam in the roller version too....

 

[273]

If it were mine I'd go with a 262*-268* range .904 lifter profile Hyd flat tappet, and put the $ saved vs the roller in to the heads. One piece stainless valves, some mild port work, and a nice valve job. You will get more out of your investment that way.

What he said.

 

[OldmanRick]

I would never consider a retro roller for that engine. The guys above are right......And i'd go as far as to recommend a Summit grind between 210/220 @.050 and save even more cash. Then make a plan for later and a different build with good heads for the future.

 

[CultClassik]

Good enough for me guys. I had looked at the summit 1789 Which is 216 @ .050 and .454 lift with 110 LSA. Seems like it should be a good match and have a little chop? $130 for cam and lifters seems cool...

Heads are 2843675 casting which should be 68-74 273/318. New valve springs needed?

Also assuming the pistons and heads are stock type, compression should be around 9:1? Not awesome but not too bad if so.

 

[racerdan80]

New springs would be recommended, 9:1 is what my 68 318 is listed at but other members who've rebuilt their 318's measured them to be 8.5 or lower. You mentioned that you have a pair of X heads, could change the pistons to counter the larger combustion chambers to keep your compression at least in the 9-9.5:1 range.

 

[YY1]

I've heard/read of folks keeping the stock springs with Summit cams in 318s.
I'd like to hear more personal experiences, though.

 

[CultClassik]

I called Summit today, they don't offer springs for that cam and say that stock springs should work just fine.

I'm going to go ahead with that, have the heads checked out, see if I can mill them a bit for some cheap compression, I figure if I can end up with between 9 and 9.5 then it'll be good.

I'll also see if I can get some inexpensive port cleanup done. All in all if I can get this done for $600 or less total I think it's a decent setup that will make the car more fun to drive while I've got that engine and of course get rid of whatever that noise is, lifter or valve. Not to mention the hosed up exhaust bolt hole. With no bolt in it, it hasn't leaked, but it would be nice to not worry about it.

 

[crackedback]

Put Comp 901 spring (or equivalent) and retainers on it if you are going to change springs.

Stock 340 springs will work too if you can find a set.

 

[YY1]

Is there anyone on here that has put this cam in with that being the only change?

I'd be interested in the differences versus the baseline.

What was the hp and tq gain, the et pickup if raced, and the mpg difference.

..also if anyone has those same baseline differences versus the typical swap combo of eddy perf and 600 carb in addition to that summit cam.

 

[CultClassik]

Man I wish this info were available as well. I'm guessing nobody would sit down and do baselines and back to back comparisons with this one since the dyno time would cost more than the cam.

I'm really hoping it has a little lope in the idle (who doesn't love a little chop in their sauce) but I think it's a really nice match for what I've got.

That said, the only other thing I'll be doing is a little head milling and very mild porting, so the intake, carb etc will remain unchanged. Then again, I'm not going to bother doing a baseline dyno either I'll throw it on the dyno after so we can tune the carb out. I'm guessing it will put out closer to 200 than 300 little horses!

 

[YY1]

I was also considering the Comp XE256.

That summit has a .454 lift and works with factory 318 everything else.

The Comp is a modern split profile and has a .455 lift.

Could the .001 max lift difference make a spring change necessary?

I'd love a comparison between those two cams as well.

Summit says 1500 rpm before power band.

Comps says idle and up.

Summit is on sale for $88 (basically free shipping).

Comp 256 is $135 from Summit (plus about $10 shipping)

 

[CultClassik]

I don't think you have spring issues until .500 or so lift, but I'm far from an expert. What I do know is that cams are usually a compromise and something that makes more power at off idle than another cam, will make less top end than that cam also. For me I think 1500 is livable, and with at least a 3.2x gear I don't think you'll spend much time below 1500.

 

[YY1]

Sorry, comp 256 is 1000-5200 RPM

1500 is my low cruise rpm with 2.7xs (Im assuming)

Still like to see a side by side.

Maybe I'll just buy both. I do have two 73 318s

 

[CultClassik]

Bahaha, nice. Since my setup is just stock-ISH... the higher stall and 3.21 gears anyway...hopefully at least 9:1 compression with the milling..but if you're cruising at that RPM I'd think you're good to go. Punch it and you're in the power band!

I'll be honest too....I'm still thinking about using the bigger Summit cam or even the Whiplash 318 still. I'm going to talk to the guy doing the heads since he's a Mopar dude and see what he thinks.

 

[bad440]

I'm not sure a roller on something that low budget would ever pay off. Frankly I don't see all the roller hype for a mild street engine. We've been running (way cheaper) flat tappet cams since when engines were invented. Nowadays, I realize oil is a problem. An off the shelf additive takes care of that.

lol love that quote,the flat tappet since engines were invented,still laughing. put in a small hydro flatty 268 somthing,and it'll sound good and still run good down low and be more fun in the midrange, ask saetun, he knows.unless it's a magnum or an all out build it's really not cost effective to change up all the things it would take to convert.

 

[CultClassik]

I actually just saw a set of fresh rebuilt heads, he says 1985 318, so I assume these are 302 castings, will get details.

Are these any better than the old heads I've got? All I know is the stock valve size is the same between the two...

For the price, if these will do me better I'll get them and sell mine off.

 

[CultClassik]

Ok I pussed out on being the test mule for the summit cam. Decided I'd like a little more cam and a better profile. I'll be sending back the summit cam and I ordered a Comp XE 268. Twice the price, but it also includes a double roller chain and 901 springs..however it does look like I may get to do a baseline dyno on this dog. I'm betting 170 HP. Place your bets gentleman!