ok plain and simple

1985 IROC Z28
1987 305 LB9 TPI
Hydrolic Flat Tappet Comp Cam

oh one question, since it was a roller motor, would the push rods from my original motor (85') be the right length?

and i basically just need a "how to" on valve adjusting being i just installed the cam and lifters and wana put the rockers on and adjust them and iv never done it before, always had somone else do it for me lol

 

I am almost sure that the push rods will be too short with the flat tappets(lifters). Why would you discard the roller cam for a flat tappet? The difference in price? Like the saying goes, you get what you pay for. Do you know how to break in a flat tappet cam? Did you lube the lobes generously with Comp's cam lube. It should have come with the cam. Did you prime the lifters with oil by either submersing them in oil, for a day or two or pumping them with a priming tool? If not, be prepared to have lifter knock for a while after start up.

As far as adjusting valves on a hydraulic valvetrain, there is a factory method where you put the engine at #1 TDC and can set half of the valves, then turn the crank 1 rotation and you can set the other half. On my performance builds, I prefer to set the #1 valves with #1 at TDC and then turn the crank 90 degrees and set #8 valves and continue this way through the firing order adjusting each cylinder at that cylinder's TDC. This is the most accurate method and when dealing with a large duration cam, I don't trust the factory method.

I set the valves at zero lash by turning the pushrod between my fingers until I feel resistance, then go in 1/4 turn. The factory spec is 1 full turn, some do 1/2 turn. It really depends on how high you intend to wind the motor. More negative lash will increase the incidence of valve float at higher revs.

Assuming that you did prep the cam properly with plenty of lube, and that you add ZDDP to the oil before startup. Once you have the engine running, take the rpms up to 2,800 as quickly as you can(making sure that the cooling system is working properly, that your fuel trims aren't too far off and that oil pressure is solid) and keep it there for 25 minutes to properly break in the cam. If you don't do this, you risk peeling off cam lobes. I've seen plenty of guys get away with variations on this method, but the risk is all yours. I don't use flat tappet cams anymore so I don't have that problem.

 

ok, this is all new to me, so this is what i did, YES i used all ove the lube that came with the cam, i DID submerge the lifters in oil for a week, what exactly is lash, i have books but i need guidance and some basic details,

as far as breaking it in, ya just made me nervous, reason why is this is a used motor i purchaced, ran before i pulled it from the donor car, had 89 k miles on it, but i have no idea how its gona react to the cam and headers in my car without a tune, should i be ok to break it in like that? i really do NOT want to hurt the motor, id freak if after all this time im putting into it i wipe out came lobes

 

as far as how high i intend to wind it, little more then stock limits because of the trans, its just a 305 with a cam headers stall converter shift kit in the trans and 3.73s, the trans shifts higher then factory tho, somewhere between 5500-6000 RPM (what it sounds by ear as my tach did not work 2 years ago last time the car ran, fixing that as well with the new motor)

 

one questions, say i take everyone heres advice and just get a roller cam like what the motor i have cam factory with, whats the break in and valve adjustment process? any differences?

and i bought the hyd flat tap cam because my 85 305 has one factory, if i had know my new motor (88') was a roller motor i would have gotten a roller cam. in experience can suck sometimes

 

I'm sorry if it sounded like I was beating you up. We all have to learn it somehow. First of all, the biggest issue facing you as to how this motor will run with your stock tune is cam specs. You didn't post a part number so I can't tell you what to expect there. Roller cam doesn't require the break in like flat tappet does. Honestly though, on OE springs, the cam break in is less of an issue. Be aware though that the OE springs more than anything else will be what determines your engine's rev ceiling. They will go into float at about 5,000-5,500. But, as I have said many times, you never know what you have until you fire it up and try it. All the expert advice in the world doesn't mean a thing until you run the motor. If you like how it runs, what I say isn't s**t.

Setting valves on a hydraulic valvetrain is the same for roller or flat tappet. Lash is valve clearance(the looseness or tightness between the cam lobe and the valve). On a solid lifter valve train, we would be talking about positive lash settings, like on a Honda or many other overhead cam engines. Negative lash is a term for the setting of hydraulic lifters where we actually tighten them beyond zero. Negative lash is compressing the hydraulic piston in the lifter so that the lifter's hydraulics maintain zero lash. As I said above, more negative lash(more of a turn past zero lash) will produce a quieter valve train but will also increase the tendency for valve float at higher revs.

Just for your edification, when installing a cam with higher duration and lift than stock, we generally want to install valve springs to fit the cam for coil bind, open and seat pressure. Setting this up generally involves the help of a cylinder head specialist who can help us with cutting or shimming spring seats and other adjustments that may need to be made to accomidate the increased lift and make the most of the cam's potential. This is done along with a good valve job to insure proper sealing and valve stem to guide clearance.

 

BY far the most accurate method to set the valves and know the cam lobe is on base circle is the exhaust opening/ intake opening method. Basically you work cylinder to cylinder. I can check valves in about 2 minutes using this method. dosnt matter where you start but on any particular cylinder, just as the exhaust valve starts to open, set you intake. And when the intake is 3/4 of the way closed set your exhaust. As far as preload, It varie's on valvetrain weight, lifter design etc... My 383 I went zero lash plus an 1/8 turn preload. (my valvetrain is very light) You can Find zero lash by spinning the pushrod until you feel it drag while tightening the adjusting nut.

 

heres the cam i have, http://www.summitracing.com/parts/cc...-size/5-0l-305


from what you guys are telling me this cam i bought a year ago and am trying to make work is more of a hassle then its worth...

that being said, i have an lt1 cam, which is roller obviously, the specs i think are lift is 447/459 and duration is 205/207 measured at .050, my comp cam is .444/.444 and lift is 260/268 measured at .000 so correct me if im wrong but isnt that basicaly the SAME specs? in a nutshell that is

would it just be smarter to use the LT1 cam with my stock roller lifters and push rods?

and by the way, im trying to avoid pulling the heads unless i have to, so if i can get away with NOT changing the springs that would be great, and iv heard of use compressed are and doing it that way but id still rather not touch them if i dont have to

 

ok and also let me make sure im right, you can tell ZERO lash by spinning the push rod in your fingers while u tighten the rocker nut, when it starts to resist turning thats zero lash right??? and after zero lash turn the nut 1/2 a turn? well if thats it then i got this lol

 

I do the exhaust opening/intake closing method as well but instead of spinning pushrod, i attempt to lift it up and down. 0 lash to me occurs when there is full contact on both ends of pushrod with the lifter cup and rocker arm. No more vertical movement/slack. Then i spin to feel how loose and give rocker nut a light snug by fingers. Pushrod is still very easy to spin at this point. Then do method described to set preload based on your lifters recommendation. Some like less preload which could be 1/4 turn past zero lash. Others like alot of preload, like a full turn

 

That's basically it. You will want to practice a little on the first one to get the feel. Be aware that the lifter will compress and as it does, the push rod will loosen up. So be sure that you are at true zero when you do the final 1/2 turn. As I said, 1/4 turn for higher revs, aggressive cam; 1/2 turn for general street performance, mild cam; 1 full turn for stock applications.

 

just a mild cam so im thinking a 1/2 turn will do fine, and ok the lifter may compress, or should compress, how can i tell if its true zero lash? just practice and feel and i should be able to tell? i know its hard to teach over a message board but im getting the idea thanks guys!

while we are at it any opinions on cam choice that i listed? just curious, iv been being shunned for buying a flatt tappet cam, lol

 

just a little back ground on myself, i am young only 21, but have been working in shops and a DIY'er since i had my first car at 14, i try to learn everything i can, i just get nervous with certain things, mostly when it comes to motor internals, anything else iv done myself with out a hitch

 

did you get the right length pushrods? roller cam is 7.200 inches, hyd flat tappet is 7.800 inches IIRC? big difference in lengths.

 

well, i have the push rods from the roller motor, which yea i noticed are shorter, and i have a what few push rods the old motor didnt eat i could use for reference...

but you guys now have me undecided if im even using the flatt tappet cam now since i have an LT1 cam also with basicaly the same grind

 

When doing your valve adjustment be sure your lifter is on the base circle of the cam. Your adjustment won't work if its partially on the lobe.

 

Just go buy feel. Its not super critical on this application. Slight resistance as you spin the pushrod will get you plenty close to true zero.

As you rotate motor around to do each valve the lifters will compress down since they have no oil and spring rate is stiff. So after you set one valve, and you come back to it, it may appear loose. Dont worry, oil will pump it back up. During cam break in listen for valvetrain noise to see if any remaining rockers/valves are loose. Can tighten them on running engine til they are quiet. Thats another method

Your flat tappet is alittle more aggressive in duration than lt1 but lt1 has more lift. Both will be close in performance but lt1 is smoother and more reliable and you could reuse stock roller lifters or buy ls7's from gm for 130

 

if i do use the comp cam i need push rods, if i use the LT1 or buy a roller then yes i already have lifters and push rods

 

Your call. Cam break in sucks and higher probability of failure with flats

 

alrite, well im not much of a risk taker, so im gona send the flat tappet comp cam back to summit

BUT from the specs iv provided, correct me if im wrong, but arent the LT1 cam and the comp cam specs i listed VERY VERY close? so i wouldnt see a difference on a dyno between them


ALSO open to sugesstions on other roller cams if you guys have any suggestions


I WANA HEAR IT RUN SOON! this is the ONLY thing keeping it from running right now

 

Do the push rod spin for set up, after the break in & the motor is at idle. Do the Run method & 1/2 turn. Always works.. Its nice to have a valve cover with the center cut out for adjusting, then you dont get oil every where.

 

Adjusting valves with motor running is messy and smokey. I've done this too many times using cardboard or the chintzy little clips that they used to sell that never really worked to stop oil from squirting everywhere. Plus, there is no way of really knowing what setting you end up with. This becomes more critical at higher rpms when a lifter that's lazy at idle pumps up. I'd rather have a little lifter noise on cold start up and know that my lifters are compressed just 1/4 turn and less likely to float on a 6,500rpm pull.

If you have the roller cam and components, my advice is use it. It will idle better and make more average torque with better drivability. Is the motor in the car? Third gen, in car, cam swap is a little tricky, worse if the car has AC, but I've done it a few times. If the engine is still on the stand then it's not a big deal.

BTW, since I'm on the subject of this engine's state of assembly, adjusting valves is easier before the intake is installed when you can see the lifters. This way you can watch as the lifter's piston begins to compress. This plus the feel of the push rod turning makes the job easier. Orr is right that once you've done the valves on a cylinder, and then roll the motor around, those valves will most likely seem loose. Don't get sucked into readjusting them. The original adjustment didn't change, the lifters have just been compressed.

 

no the motor is not in the car yet because of this issue we are debating, its on a stand, complete minus intake and accessories, and NO iv delete the AC heat and smog pump, only retaining the Alternator and power steering pump, as its a summer car, wont be driven unless the t tops can come off


and ok since they are such a close grind ill just use the LT1 cam, send the comp cam back to summit and buy other stuff i need like oil pan gasket and such

 

I forget the advertised durations of factory cams but they are very mild lobed for high mileage operation and softer springs. Lt1's typically are 202-207 deg at .050 depending which year and car you get the cam from. Your comp cam was 212/218 which is a step up. Slightly lower lift but more aggressive valve opening and closing. This may be worth few ponies over lazier cams of similar durations but lt1 has bit more lift which also maybe worth few hp more. Hard to say the differences between the 2 on a 305, i would be surprised if it was more than 5-10 hp apart.

 

so it wouldnt really make much of a difference you can feel on the street, got ya, and the advantages of having a roller cam out weight the 5hp loss anyway it seems, right?

 

if it matters the cam is from a 1996 Camaro Z28

 

It may be helpful to point out that since the LT1 was used in different applications with different power levels, there were several different "LT1 cams". It's good that you know what application your cam came from. That cam, according to LS1 tech, is 200/207 .447/.459 lift 117lsa. While roller lobes tend to have more area under the curve, meaning that they tend to provide more total valve open time than flat tappets, the LT1 cam you have is alot smaller than the Comp grind. Since it's a stock cam with less than great lobes versus the Comp being a performance cam with optimized lobes, it probably gives up alot to the Comp cam. Still, it's a big improvement over the stock 87 LB9 cam.

Best thing of all would be to purchase one of comps XFI roller grinds with duration numbers closer to that of the comp cam you have.

 

That is alittle smaller than i expected for an LT1 cam. I thought they were abit bigger in duration and lift. It will work ok but will be a tad less powerful than the comp but with better roller reliability.

You can try to find a older l98 or lb9 5 spd cam, 207/213 and run 1.6 rockers. Will be more powerful than the LT1's imo but again, close specs so fairly close in power.