OK, lets have ANOTHER 318 cam discussion

[YY1]

I realized I was in over my head on my last cam discussion here, so I went and educated myself.
I've known that was coming, since I really didn't understand all the "new" specs.

I've been doing LOTS of homework, and have lots of info- all in one place now.

Before we go too far down the flat tappet road, can anyone tell me for sure if my 86 5th Ave mill is a standard, or roller cam motor? I have confilcting sources that say 1987 was the first year, and others that say 85.

I suppose I could pull the intake, but I'd rather not do that until I'm ready to play with it. It's also across town.

Is there a way to tell from outside?

 

[YY1]

Here's some background on the motor and the intended use:


My target is a 1986 318 with about 80,000. it's going to be a temprary mill in my 66, while doing the rest of the work, and before I decide what to do about the big block (right now I'm thinking 444/451). It will eventually find a home in my 74 charger, so it's not disposeable by any means.

Right now it runs great, and will spin the tires in the 5th Ave, given the right circumstances.

My goal is to get as much "bang for the buck" effiecent power out of it, with the least ammount of effort.
I'd like to add as much power as I can, while keeping decent mileage. I also don't want to sacrifice low end torque, but want good power up as far as I can get it. I know it sounds like I want everything, but I think it can be done.

I also want to keep as much as I can buttoned up, IE, not pulling the heads to change the valve springs or head gaskets. (I'll do this eventually, and probably change the cam again and intake and maybe use my Magnum heads
, probably when It goes in the charger. I might even use the FI).

As an enticement to paricipation, here's a sample of some of the info I'v compiled:

NARROW LSA WIDE LSA

INTAKE OPENS EARLIER LATER
INTAKE CLOSES EARLIER LATER
EXHAUST OPENS LATER EARLIER
EXHAUST CLOSES LATER EARLIER
OVERLAPS MORE LESS
CYLINDER PRESSURE GAIN LOSE
IDLE QUALITY WORSE BETTER
IDLE VACUUM LESS MORE
TORQUE CURVE PEAKIER FLATTER
PEAK TORQUE MORE LESS
HIGH RPM DROPS OFF HANGS ON

Lets get started, shall we?

Here are the specs I found for the motor, and some other info for the car:

302 "fast burn" heads 1.78/1.50 valves 59cc
9 to 1 compression. Already have hardened seats.
Factory cam specs D- 240/248 L- 373/399 (same for roller?)

I've heard that the factory springs can accomodate either a 450, 495, or 500 lift. Anyone know for sure?
I figure using the 450 number is safer, but if it's actually 500, then that opens up some breathing room for say a 465 or 470 lift cam.

Last week I scored an Edelbrock performer intake ($60 with all the linkage brackets), and I already have a Holley 600 DP.
I know the DP will kill off some mileage, but it's what I have right now, and it's the right size.
I have a 3:23 SG for the rear. Let's say the car weighs 3500 pounds.

I'll be using the car occasionally, maybe some 50 mile away shows, and maybe go to the strip (1/8) once a month (and the 1/4 once a year).

 

[YY1]

After reading all the lit I could find, including the comp cams site, I decided to use the MP factory 340 profile as my baseline. if nothing else, I don't think this is a bad choice, and may prove to be the best.
Duration 268/276 Lift 429/444 .050- 228/235 LSA 110 (unclear on LSA or intake center).

I'd like to analyze the potential effect of what similar profiles would have, relative to this cam, and how and why the differences cause the change.

Here are some cam generalities I've come across:

Higher compression can tolerate higher duration.
Too much duration will decrease torque.

Higher lift needs higher flow.
Too much lift is lost on small flow condition.
(this also plays in with stock valve spring lift restriction).

Lobe separation creates "chop" sound. Lower is more choppy. Starts about 110-108.
Idle sound is fairly low on my list of wants, but I must admit, I LOVED the sound of my 383 with the 284/484 cam.

Sound right?

Here are some 318 and A/LA word of mouth pointers:

Mopar small blocks like early intake opening and a healthy .050 duration.
Dual profile with more exhaust helps compensate for small exhause valves.

Here is where I will try some assumptions...

My 9:1 motor will help me possibly use a longer duration cam.
I shouldn't lose torque to duration relative to the 340 (at least post 71), since they were 8.5:1, right?

My Eddy intake helps with flow, right? Has 318 size runners vs 360 size...and the 302 heads also flow faster than most. That should possibly even help me use more lift than a 340/360.

Comp site has two different lifters for most cams, one says stock springs cannot be used, one doesn't.
(different seat height) Both kits say this...

Did the factory use different lifters and/or springs between 318 and 340/360?

Here are some that I've narrowed my choices to:


Comp 20-220-3 XE250H D 250 260 L 432 444 800-4800 206/212 110 106 19 Stock springs Y
Very strong torque excellentmileage, smooth idle

Comp 20-221-3 XE256H D 256 268 L 447 455 1000-5200 212/218 110 106 22 Stock springs ?
Shows only 822-16 lifter (stock specs?) "Strong torque through low and mid" More lift, not as much duration

Comp 20-222-3 XE262H D 262 270 L 462 470 1300-5600 218/224 110 106 25 Stock springs ?N


Comp 20-417-3 265DEH D 265 276 L 442 462 1600-5750 211/227 110 106 27 Stock springs ?
Midrange Comp says stock exhaust? Same Duration, more lift Shows both lifters (822-16 and 967-16)

Mopar P4452782 Discontinued? D 268 276 L 429 444 Idle-5800 228/235 114? Stock springs Y
Benchmark Factory 73 340 profile? Good .050 lift duration CL?

Mopar P4452759 D 260 268 L 430 450 1200-5200 221/228 110? Stock springs ?Y
CL?

Mopar 68 manual 340 D 276 284 L 444 453 Stock springs ?
One step up in lift, two in duration 4 speed makes up for torque lost to added duration

Mopar P4452761 D 268 272 L 450 455 1500-5800 228/231 110? Stock springs ?
Notes say use 4120249 spring CL?

Comp 20-309-4 268AH10 D 268 276 L 464 464 1800-5800 222/226 110 106 28 Stock springs N?
Split duration only Shows [7] in part number- no stock springs? ..but lift is only .002 more than 265DEH.

Edelbrock Perf+ D 270 270 L 420 420 Idle-5500 204/204 Stock springs Y
Single profile

Summit K6901 D 276 286 L 441 441 1800-5500 218/228 Stock springs Y
Split duration only Specifically says stock springs

I looked at the Lunati site, but most had WAY too much exhaust lift.

OK, that's what I got up til now.

 

[YY1]

Sorry, lost some in reformatting...numbers after RPM range are duration @.050 lift in I/E format.


...and I'm not really interested in a converter change, although later I may consider a small one like 2000-2500.

 

[shopguy]

I just took an 84 5th ave 318 out of a 60K mile car. bores were perfect, some main bearing wear on #1. I cleaned the block and heads (inside and out). new std main and rod bearings. Cam bearing were nice as is (plus a pain to change). Put in a new MP oil pump, new CI rings. cleaned/blasted all the valves, lapped them in. new double roller timing chain. MP 6901 cam/lifter package. No intake yet, still looking. Probably a dual plane performer or the old CI 73 340 intake I have (heavy, but same performance I'm told).

my opinion? cost alone 6901 for me. I've run the 6900 before....great all around cam. I'm hoping the 6901 will give a little more lope on idle and higher rpm punch.
We'll see.

 

[Coronet 500]

My 87 318, 302 head, is a flat tappet with the cast in bosses for the roller spider. It does not have the boss cast in for the rear timing pick-up. Came out of a 2bbl truck, put into 92 truck, performer, 600 vacum sec, XE256H and headers. Lots of low end grunt and highway passing gear pull, idles like a kitten. I broke in the cam with the stock springs then changed them, those stock ones are puny. Take a clean length of vacum hose, feed it into the spark plug hole,piston down, leave some out for removal. Then raise piston on compression stroke, this will hold the valves up. Now use a two jaw valve spring compressing tool and cover all oil drain back holes and replace the springs. Your spot on with the port match to that manifold. I ran some cams on the camquest program with the 302's, 300-310 hp, 350 tq up to 260 duration. after that port velocity drops and the torque falls like a stone. I'd go with manufacturers RPM recommendations.

 

[YY1]

Coronet 500- what rear do you have? How much does that truck weigh? Thanks for info on XE 256 working with stock springs. It looked right on the line. That one caught my eye. The XE 250 actually looks like it makes more tourque and the HP curve is wider. Only 4 less max HP as well.

Shopguy- what are the specs on the MP 6900/6901? Are they the 340 grinds?
Anyone have HP and tourque graphs for them?

Camquest ROCKS! I've put about 12 hours in it the past few days.

Is there a similar low cost or freeware app that lets you put in your own specs?

I've heard about desktop dyno, I think. There was a DOS text based one quite a while ago.

 

[Coronet 500]

Truck has 3.91 gear and I'd guess 4500lbs. I've always liked more lift less duration cams. Don't forget many cam designs are geared toward 340 sized engines with 1.88 and up valves, this covers alot of years and makes for more sales. With your plans I'd have a hard time keeping my hands off that XE262H and if the heads came off I'd be popping in some 1.88's and maybe 1.60's too. Would still be fun with 1.75's.

 

[YY1]

XE262 has a tad too much lift if 450 is the max, that's one of the questions I was asking, since I can't get a definative number on the stock springs.

In Camquest, if I bump the exhaust to just 1.6 and increase comp to 9.5 (mill or thin gasket) the numbers with the bigger cams jump to 375-380 HP, and the smaller cams are limited to about 350-360.

The XE 250/256 and a single profile 260 are in the 300-315 HP range.

According to what I've read, the weak point of the 302 head is those small exhaust valves, but the strong points are exxcellent efficency, good intake flow and quench.

I'm guessing close to max exhaust lift for spring and more exhaust duration could help overcome the valve size.

In the CQ app,I'm using "dual plane- high flow" for the performer intake.
I fugure standard flow would be a factory 4 barrel piece and max flow would be like an air gap or something.

Anyone else run any of these cams in stock 302 heads, or use valve lift figures above .450?


Comp 20-220-3 XE250H D 250 260 L 432 444 800-4800 206/212 110 106 19 Stock springs Y

Comp 20-221-3 XE256H D 256 268 L 447 455 1000-5200 212/218 110 106 22 Stock springs ?

Mopar perf P4452782 D 268 276 L 429 444 Idle-5800 228/235 114? Stock springs Y


Comparing the stock 340 cam to the Comp XE 250/256, looks like the MP is close to the 250 on lift, but has WAY more duration than either, but it's got a lot more D@ .05L. Interestingly the LSA is a lot different.
I'd love to see that MP cam plugged into CQ. The Comp "replacement" 268 cams have 464 lift, which might be out of my spec. That XE 268 was the one I originally wanted, until the spring thing came up.

I just looked up that MP spring #4120249 and it says 500, but that's what MP says to use on their 455 lift cam. Coronet 500 is using a 455 lift with the stock 302 head spring. No bent pushrods yet, I assume?

 

[Coronet 500]

Narrowing down your choices, that's progress, glad to see your being so thorough not just jumping in on someones say so. That MP cam would not be my first choice for a heavier car. Be careful with overcoming valve size with duration, at lower RPM's you will lose cylinder pressure and overall performance. I think I've got a pair of 302's around here I'll take a few apart and measure them for you. I know I checked the ones on the engine, which were Ok, but I can't remember by how much and I can't find my notes. Give me the morning and I'll get back to sometime this afternoon. My wife is going out soon and she dosn't like to see cylinder heads on the kitchen table. How she puts up with me, I'll never know.

 

[Coronet 500]

Casting number 4323302 spring installed hieght 1.64", seal thickness on stem .140"
Springs removed, retainer touching valve guide, NO SEAL, measured with dial indicator.
Exhaust: .591" .602"
Intake: .646" .652" .643"
Coil bind, spring compressed on head with retainer in place measured with depth gauge.
Exhaust: .490" .480" .507"
Intake: .505" .550" .515"
Most referance material I have says retainer to guide clearance= .050", coil bind plus .100" for minimum compressed hiegth for HP engine useage. Remember these heads were designed for .370"-.390" lift. My mesurements were .005"-.030" different across the head so careful measuring of your head is warranted. There are retainers that can increase installed hieght although they will reduce valve closed pressure. I would find manufacturers coil bind dimension add .100" subtract from installed hieght and that should give maximum lift.

 

[YY1]

So, you're saying on your heads-.470 to .475 exhaust lift is theoretically possible but less than that is safer? ...and you're running .455.

Wow! Thanks for doing all that leg work.

I'm not convinced that XE256 is the better cam for me. It seems to be moving the power band up the RPM ladder and narrowing it. Maybe if I had 3:55 or 3:91, instead of my 3:23.

Looks like the 265DEH pushes it up even more. Interesting how there's no XE cam with a 265-ish exhaust lift. It goes right to 270.

With all that being said, I'm the type of guy that likes to be Just barely over the edge (IE one more level than what conventional wisdom says) I caught a lot of crap about putting a 284/484 in my 70 383 with the stock converter (and still do on this board), but it ran like a scalded dog!

This is exactly the kind of discussion I was hoping for. Thannks...of course more participants would be welcome!

It's been so long since I drove with 3:23's that I probably just need to put the car together and see what RPM range I'm happy in. I might be just fine with a cam that doesn't turn on until 1500 or so.

My Dak R/T has 3:91 until O/D and then it's like 2:something.

 

[Coronet 500]

Long time ago I had a 284/484 in a 318 stock converter. It was a mutt off the line but once it was rolling it would break the 8" wide tire loose on the 2-3 shift at 6500rpm. I ran that cam on camquest and was shocked it performend close to some of the custom split, high lsa, high priced turbo cams. This is what we plan on putting in a 318 single turbo engine we are going to build, looking for 500 and up horsepower.

 

[YY1]

Help me out on your spring check....Did I get it?


OK, I found a Lunati that doesn't have over .470 lift.

Look at this...

•Advertised Duration (Int/Exh): 284/284
•Duration @ .050 (Int/Exh): 218/218
•Gross Valve Lift (Int/Exh): .458/.458
•LSA/ICL: 110/106
•Valve Lash (Int/Exh): Hyd/Hyd
•RPM Range: 1500-5000


That's a lot of duration, and the application specifically says lots of low end torque and broad power.

It is an old school single profile, though.

Maybe the trade off is MPG?

I was gonna try Magnum exhaust manifolds, cause I LOVE the way my Dak sounds (with dynomax ctas and magnaflow muffs), but I do have set of cheap A body 1 5/8 headers in the shed.

 

[Coronet 500]

Those coil bind numbers are how far the valve moved open "lift" until it stopped and bound like you stuck it in a vice and it won't go anymore. Those numbers should have .100" subtracted to be safe "by the book". When I changed my springs I changed retainers had it at full lift and pryed it more open, with a tool I made, until it bound and it was more than .100". That was good enough for me, I didn't do installed hieghts. So be carefull. If we agree there is .490-.507" available minus .458" leaves only .032-.049" valve spring clearance before bind occurs.
When you get to those larger duration cams, look at the intake BTDC opening and exhaust ATDC closing numbers to calculate and compare overlaps. With what you know now you can see the importance of overlap and how it affects rpm recommendations from the manufacturers.

 

[Coronet 500]

Just for chits and giggles looked up comps 901-16 spring for the XE256H.
Their recommended coil bind clearance is .060"
Installed hieght 1.65"
Coil Bind 1.10"
-----
.550"
Clearance .060"
------
Safe Max Lift .490"

 

[YY1]

So, I would take your lowest figure, subtract the lift of a cam I'm considering, and make sure there's .1 left over?

I used to understand this (20 years ago), but I don't think I'm quite getting it now.

You took coil bind measurements of three exhaust valve springs out of four?

The lowest was .480

If you subtract the .455 lift of your XE256 cam, that only leaves .25

What am I missing?

 

[Coronet 500]

Your getting it, Comp says .060" not .100". Here is one of their tech articles, see the installation portion, it will help the discussion. http://www.compcams.com/Pages/415/truth-about-valve-springs.aspx

 

[YY1]

I have a new contender:

P4452757 248/256 dur .410"/.425" lift . 211/218 @ .050 1000-5000 RPM

It's on the borderline of being an "RV" cam, but .480 minus .425 is .055, which is a lot closer to the reccomended .060 figure.

It is a modern split profile and has good .050 figures.

Looks like it peaks out under 275 HP gross, but has to be better than stock.
Might get me 220 net. I'm pretty happy with my 250 net HP in the Dak, and I'm sure the 66 Coronet is lighter.

I did read almost all of the comp cams literature, but went back and re-read it last night.

I worked my butt off yesterday and will do so again today.
I'm off from my job this week, and I'm setting posts, building a wall, and installing two 10' wide roll up doors in my garage. I'm also driving across town in the evening and working on my front suspension. Blasted and painted the LCA and UCA Sunday, and want to get them back on with new ball joints, so I can start my disk swap before next weekend.

Thanks again for your help, 500, especially jarring my head back to cam math mode.

What year 500 do you have?

 

[YY1]

...and there was a pre-plumbed twin Garret SBM (small block Mopar) setup around here on craigslist for $2500. I almost bought it. That would have been a hoot in my charger, and might have cleared under the bulge hood.