360 cam / valve train help / choices

-
360moparjunkie

360moparjunkie

Well-Known Member
Joined
Dec 24, 2009
Messages
252
Reaction score
34
Location
Ceres, CA
I have huge confusion surrounding camshaft choices and limitations!
My 360 has been punched .030
KB-107 pistons
rods resized
crank turned .010-.010
Currently being balanced
Plan to run a 904 tf
Use my variable rate already purchased rhoads lifters
72 J heads with the 1.88 valves w/ factor rocker shafts thus far.(heard they flow high 180's-190's, don't really know.) ?Head flow can / will be a limiting hp factor? 2xhead flow for max hp?
Assuming compression will be 10.5 +/- Dont know actual static until I mate my new parts
LD-340
Camshaft- Help.

Looking hard at some of the 60401-4 Lunati's, comp's 262/268's. Maybe even one of the ridiculed thumper lines.

? At what point do you need to run adjustable valve train?

What is the big concern here? Is it valve geometry?
Will the rocker arm interfere with the spring nocking off one of the valve keepers / retainers? Don't want that.

Please help straiten me out here. Studied about as far on my own before making this thread.

Thanks in advance.



 
solids and big hyd's need adjustable rockers.

head flow goes like this, for every 5cfm =10hp, so add it up.

Your heads with a good valve job could flow around 190 -200cfm
with a 2.02 intake valve would flow around 210'ish cfm.
 
Sounds like you've done your homework good but I'd like to point out that if you don't deck the block and mill the heads you most likely won't even come close to 10.5 to 1 compression you think you'll have. I built a 360 a couple yrs. back using KB107's and didn't deck the block so the pistons were down in the hole .020" and the stock X heads I had cc'd out at 71 cc's. After milling them the cc's are 66 cc's. That puts the compression at 9.9 to 1. Just thought I'd let you know for reference.

As far as the cam, with that much compression I wouldn't run a Lunati 60401 or 60402 cam because it'll have so much cylinder pressure you'll most likely have a hard time getting it to run right on 93 octane. I have the Lunati 60404 cam and can only run 36 degrees timing before it spark knocks. I keep it at 34 just in case I get some gas that isn't quite up to 93 snuff. I'd go with a 60403 minimum. The 60403 is a real nice cam and thumps pretty good yet is still real torquey. I run stock rocker arms on mine with the 60404 but I wouldn't go any bigger than it on stock valve train parts. In fact they need to be in real good shape to go even that big on the cam IMO. I had no problem with the rocker arms clearing the larger than stock valve springs and retainers. I think the big concern is stock rocker arms aren't super strong and if you go too big on the cam and springs they'll break. Lifter pre-load is also a concern when you get up into bigger cams. Can't say much about the Comp Thumper cams as I haven't ran any or know anybody that has but I know on paper they don't look all that great for power. Just look like their ground to do what their entitled which is "thump".

Oh yeah you may already know this but if you run the 60403 figure on a 2500-2800 stall and if you run the 60404 figure on a 3000 stall if your running an automatic.
 
fishy68 said:
Sounds like you've done your homework good but I'd like to point out that if you don't deck the block and mill the heads you most likely won't even come close to 10.5 to 1 compression you think you'll have. I built a 360 a couple yrs. back using KB107's and didn't deck the block so the pistons were down in the hole .020" and the stock X heads I had cc'd out at 71 cc's. After milling them the cc's are 66 cc's. That puts the compression at 9.9 to 1. Just thought I'd let you know for reference.

As far as the cam, with that much compression I wouldn't run a Lunati 60401 or 60402 cam because it'll have so much cylinder pressure you'll most likely have a hard time getting it to run right on 93 octane. I have the Lunati 60404 cam and can only run 36 degrees timing before it spark knocks. I keep it at 34 just in case I get some gas that isn't quite up to 93 snuff. I'd go with a 60403 minimum. The 60403 is a real nice cam and thumps pretty good yet is still real torquey. I run stock rocker arms on mine with the 60404 but I wouldn't go any bigger than it on stock valve train parts. In fact they need to be in real good shape to go even that big on the cam IMO. I had no problem with the rocker arms clearing the larger than stock valve springs and retainers. I think the big concern is stock rocker arms aren't super strong and if you go too big on the cam and springs they'll break. Lifter pre-load is also a concern when you get up into bigger cams. Can't say much about the Comp Thumper cams as I haven't ran any or know anybody that has but I know on paper they don't look all that great for power. Just look like their ground to do what their entitled which is "thump".

Oh yeah you may already know this but if you run the 60403 figure on a 2500-2800 stall and if you run the 60404 figure on a 3000 stall if your running an automatic.
Click to expand...

I do plan on milling the block whats needed to obtain my target comp. I've went this far, so after a mock up I'll dis-assemble the assy. & have the tops shaved. Thanks for the fyi.....heading that direction already.

?Can I just mock up the four corners to determine piston ht to top of block rather than doing all 8 pistons? Seems like stuffing the two center holes on both sides would be a waste of time. Never went this far on internals so I could be wrong.

Bear with me. You are using stock "stamped" non-adjustable rockers with your Lunati 60404?

What valve springs / retainers n such did you use?

What is your rpm range? / Would you use this same cam-spring combo again?

Lifter pre-load would be dictated by push rod length if non-adj. stamped rockers were used. Correct? A little ahead of the build talking pre-load; however what is the ideal lifter pre-load? As little as possible?

Thanks
 
According to the KB listings, a J head with 72 cc head chamber and there 5cc valve relief should clock in @ 9.8-1 with a .039 head gasket.

I have run this exact combo long block before and I'm setting up to do it again right now.

The pistons "ON MY BLOCK" came in at zero deck height.

Idealy, lifter preload should be half of the total lifter travel and set at .050

Your cam should be performing in concert with the trannys stall and rear end gears as well as cars weight and intedned performance sought.

They are???????????????
 
1wild&crazyguy said:
solids and big hyd's need adjustable rockers.

head flow goes like this, for every 5cfm =10hp, so add it up.

Your heads with a good valve job could flow around 190 -200cfm
with a 2.02 intake valve would flow around 210'ish cfm.
Click to expand...

1wcg,
OK, so where is the line in the sand? .450-.460-.470-.480-.490-.50-.510-.520-.530-.540-.550-.560-.570-.580...................Somewhere big hyd's need adjustable rockers. Totally agree...........
Where?......................Why?

Also, what are the conditions of catastrophic valve train failure as a result of non-adjustable rockers where there should be?

I'm doing my best to understand what is happening and why.

Does the base circle of the cam in relationship to the cam journals create the need for the adj. rockers on high lift hyd cams?
 
well..On a mopar the stamped arms are know for push rod spearing as the lift increases, so adjustable rockers are stronger and are a fix for this.
The other side is if the stamped rocker didn't fail, all you really need is the proper pre-load accomplished by the correct length push rods.
 
1wild&crazyguy said:
well..On a mopar the stamped arms are know for push rod spearing as the lift increases, so adjustable rockers are stronger and are a fix for this.
The other side is if the stamped rocker didn't fail, all you really need is the proper pre-load accomplished by the correct length push rods.
Click to expand...

Thanks for chiming back in,
Spearing the rocker, got it, adj. are stronger,

What I'm getting out of this is you do not need adj. rockers if the lifter pre-load is correct by using correct push rod length.
I assume proper push rod length would correct the angle of attack from rocker tip to top of valve stem....right?
And at some point valve travel distance would demand a roller tip........or would you be better off going to a 1.6 ratio to help keep the tip on the valve stem?
 
problem is as you use a larger hydraulic cam...stiffer springs are required..

stiffer springs will shove the pushrod thru the non adjustable rocker ,,,,,
 
70aarcuda said:
problem is as you use a larger hydraulic cam...stiffer springs are required..

stiffer springs will shove the pushrod thru the non adjustable rocker ,,,,,
Click to expand...

Thanks for the help.
I'll continue to look for my camshaft and springs.
If need be I could purchase the proform rocker assy. for 230.00 Hoping to not need them.
Are they any good? Cheapest I could find.
 
360moparjunkie said:
Thanks for the help.
I'll continue to look for my camshaft and springs.
If need be I could purchase the proform rocker assy. for 230.00 Hoping to not need them.
Are they any good? Cheapest I could find.
Click to expand...

Junkie, i know a friend that ran the Proform rockers on his BB, they did pretty good holding up, but it was a track car only, on the street, you either need a good quality aluminum (pricey), or a decent stainless, i think Procomp (not Proform) is makeing a stainless rocker & shafts for the SB & BB mopars, the whole kits like 350.00 for everything, i've had these rockers in my hands & i will say they are nice. You really should run an adj. valvetrain with any high/fast rate lift cam & higher spring pressures.

I ran those KB107s in a 360, as said, there around 9.8 with a stock CC head, unless you plan on running good fuel, i wouldn't start milling the heads & jacking with that stuff, even if you try & achieve say 10.2/10.3 comp., you'll just be better off staying with 9.8, there won't really be any power gain that you can feel, but you chance detination, my choice for a cam would be either the Lunati 60403 or the XE274H, maybe even the 275HL.
 
360moparjunkie said:
I do plan on milling the block whats needed to obtain my target comp. I've went this far, so after a mock up I'll dis-assemble the assy. & have the tops shaved. Thanks for the fyi.....heading that direction already.

?Can I just mock up the four corners to determine piston ht to top of block rather than doing all 8 pistons? Seems like stuffing the two center holes on both sides would be a waste of time. Never went this far on internals so I could be wrong.

I would think just doing the 4 corners would be fine if quality parts are used. I say that because stock parts can vary a few thous. and you may put in one piston and rod and it set .010 below the deck and another P&R combo will set .020 below.
Click to expand...

Bear with me. You are using stock "stamped" non-adjustable rockers with your Lunati 60404?

Yes, and I am pushing the limits using stock type rockers. They are the Mopar Perf. aftermarket ones but their basically stock type. They are possibly heavier gauge steel since their called Heavy Duty by Mopar but I don't know that for sure. Normally I don't push the limits but this engine was only for short term use as I planned on building a stroker to replace it, which I now have nearly finished.
Click to expand...

What valve springs / retainers n such did you use?

I am using the Comp cams 995-16 springs and matching retainers and locks. I already had them or I would have went with Lunati's. Their real close to the specs the cam recommends.
Click to expand...

What is your rpm range? / Would you use this same cam-spring combo again?

I have a 3k stall and it is right there pulling real hard as soon as I nail it and pulls hard to 6K. I'm not sure how it'd do under 3k since it has a loose converter I can't tell. It will pull to 6400-6500 but you can tell that it's not really making any usable power up there so I shift at 6k as that seems to do the best. I think if I did it again I'd use the springs Lunati recommends just because I'm a believer in using what the mfg. recommends. The springs I have on now are 5 lbs. shy on the seat and 10 lbs. shy over the nose. Probably not enough diff to make it pull much more rpm than it does
Click to expand...
.

Lifter pre-load would be dictated by push rod length if non-adj. stamped rockers were used. Correct? A little ahead of the build talking pre-load; however what is the ideal lifter pre-load? As little as possible?

Thanks
Click to expand...

Right. As Rumble stated most cams call for .050 pre-load but I personally use that as a max just because if the lifter pumps up it leaves the valve hanging open .050" and if you run a little less pre-load and the lifter pumps up their isn't as much chance of a valve smacking a piston. I shoot for .025"~.030" on the ones I do. Still plenty of pre-load IMO.
 
360moparjunkie said:
I assume proper push rod length would correct the angle of attack from rocker tip to top of valve stem....right?
And at some point valve travel distance would demand a roller tip........or would you be better off going to a 1.6 ratio to help keep the tip on the valve stem?
Click to expand...


No. Pushrod length does not affect rocker to valve tip geometry on a rocker shaft type design. The only thing that affects geometry is raising or lowering the rocker fulcrum (shaft mounting point). If the geometry is right there's really no need for a roller rocker tip because if all angles/heights are right it's sweep will be tight, but a roller tip does decrease valve stem side loading so it is beneficial. 1.6 rockers shouldn't change the geometry if their designed right as it's the back side (pushrod end) they modify to change the ratio. If the valve tip end is modified it can screw up geometry big time. I had a set of cheap rockers that did just that.
 
Fishy, I read you can go as low as .010 since the last .010 is a deadarea issue that's dangerous to use. IDK.
 
hi, .010 to .015 works with our stocker grinds. in fact , usually strive for zero preload. less chance for lifter pump up. this makes it almost a solid lifter. just fod for thought.
 
My $.02 on the block work...
The deck height on an engine should be set. The way you do that is to add 1/2 the stroke, the rod length, and the compression height of the piston. That gives you the deck height figure for zero deck. In your case, that's (3.58/2)+6.123+1.675=9.588. The normal factory as-machined deck height is around 9.63. In addition to the "tallness", there is also the fact that in production mode the decks were rarely cut perpendicular to the crank centerline. Menaing the deck surface will vary in distance both accross it, and along the length of it. If you are seriously interested in making good power the decks shoudl be "square decked". (not to be confused with "decked".) What that process does is indexes the deck surface off the crank centerline and cuts it to the desired height at the same time. It takes a special fixture to do this. Not all shops have it, but most will say they square deck anyway because as the consumer you don't know the difference and they can charge more for it. I have all my engines align honed to establish a straight round crank centerline and then I have them all square decked and I give them the deck height I need. I can have them .005 down in the bore, .010 above deck, or dead even. Then the only factors affecting actual deck height for each hole is the quality of the crank and rods. Some of the less expensive ones can be of as much as .005" in length which can really ruin your day...lol In any event, mock yours up if it's all machined but make sure you dont install the cam bearings or the oil plug over the #5 main cap so the block can be cleaned properly after. Also note the end rails of the block will also have to be milled (I use the same amount as the deck cut) so the intake can be fitted properly. You will want to limit your static compression to no more than 9.8:1 unless your cam choices are larger than 230°@.050. If the cams get bigger, the static can go higher.
 
On my 360/904 combo I have the Comp 280H, lifters & springs and really like it. I use the HD Mopar stamped rockers and my final compression is 9.0 to 1. The rest of the combo is a PAW 360 short block, reworked 360 heads with 1.88/1.60 valves, Weiand Stealth dual plane hi-rise, 1407 750cfm Eddy carb and Hooker headers. Rebuilt tranny has a Hughes 2600 stall convertor. The 8-3/4 rear has 3.91 gears with a Powertrax Locker.

Duster runs very strong and lights the tires up at will. With slicks the car ran in 12.70-12.90 range. Street use only now.
 
fishy68 said:
Yeah I've read that too but am somewhat leery about going that little. I am going up to Hughes engines week after next so I might ask Dave what he thinks.
Click to expand...

Good, I'd like to know what he thinks. I myself wouldn't do a .010 preload.
 
If you are looking for a set of factory iron adjustable rockers, I have a set for sale. Figure $100 + shipping.

Put it together, measure for pushrods and you are ready.
 
crackedback said:
If you are looking for a set of factory iron adjustable rockers, I have a set for sale. Figure $100 + shipping.

Put it together, measure for pushrods and you are ready.
Click to expand...
crkbk,
I'll give it a think.
I am very on the fence concerning valve train at this moment. Moment of clarity will soon follow.
Weighing all options.....found a bare set of alum. racing heads today @ swap meet. Mopar #P5007904........checkin it out.
Have my hands full mocking up my new rotating components.

Huge thank you for the offer, maybe talking to you about it later.
 
rumblefish360 said:
According to the KB listings, a J head with 72 cc head chamber and there 5cc valve relief should clock in @ 9.8-1 with a .039 head gasket.

I have run this exact combo long block before and I'm setting up to do it again right now.

The pistons "ON MY BLOCK" came in at zero deck height.

Idealy, lifter preload should be half of the total lifter travel and set at .050

Your cam should be performing in concert with the trannys stall and rear end gears as well as cars weight and intedned performance sought.

They are???????????????
Click to expand...
r-fish, CC'ing my own heads proved 65-66cc's They've been milled at least once that I know of.
I'll be posting you back on what my deck ht. turns out to be. You have been one of those who helped steer me this direction. (remember the .1092 pistons?) I'm curious to find out the new piston-deck ht. myself.

Sure I understand that things work well "in concert"; however, this build is starting at the front and I am working my way back. I will build to suit as I move from trans. to rear end. I have flexability on tire size / gear ratio in the end. Furthermore, this will be no commuter car.

Cam choices are narrowing down.
 
moper said:
My $.02 on the block work...
The deck height on an engine should be set. The way you do that is to add 1/2 the stroke, the rod length, and the compression height of the piston. That gives you the deck height figure for zero deck. In your case, that's (3.58/2)+6.123+1.675=9.588. The normal factory as-machined deck height is around 9.63. In addition to the "tallness", there is also the fact that in production mode the decks were rarely cut perpendicular to the crank centerline. Menaing the deck surface will vary in distance both accross it, and along the length of it. If you are seriously interested in making good power the decks shoudl be "square decked". (not to be confused with "decked".) What that process does is indexes the deck surface off the crank centerline and cuts it to the desired height at the same time. It takes a special fixture to do this. Not all shops have it, but most will say they square deck anyway because as the consumer you don't know the difference and they can charge more for it. I have all my engines align honed to establish a straight round crank centerline and then I have them all square decked and I give them the deck height I need. I can have them .005 down in the bore, .010 above deck, or dead even. Then the only factors affecting actual deck height for each hole is the quality of the crank and rods. Some of the less expensive ones can be of as much as .005" in length which can really ruin your day...lol In any event, mock yours up if it's all machined but make sure you dont install the cam bearings or the oil plug over the #5 main cap so the block can be cleaned properly after. Also note the end rails of the block will also have to be milled (I use the same amount as the deck cut) so the intake can be fitted properly. You will want to limit your static compression to no more than 9.8:1 unless your cam choices are larger than 230°@.050. If the cams get bigger, the static can go higher.
Click to expand...
I'll be closer to choosing a cam once my static is confirmed. I'll know more once I've measured the piston to block ht.
Block does have a .002 "dip" in the middle. My local m. shop owner says it is nothing to worry about though.
 
You must log in or register to reply here.
-

Back
Top