Valve stem length, head thickness, deck height, lifter height, Head gasket thickness all play a part. If you want to be sure of valve train longevity, you need to measure. If you guess and its off, it will run, but could kill your valve guides pretty quick.

Its really easy to do...mock it up with an adjustable pushrod, and screw it up until the rocker rides on the valve at the right point. Then order pushrods of that length.


If you are not changing heads or head gaskets, just measure the difference between lifters, and order pushrods. It may not be perfect, but it will be close.

 

Roller rockers, lobe lift, cam core base circle are all variables that will change pushrod length. I would venture to say 80% of the people out there that have larger than stock cams have to short a pushrod based on proper rocker geometry. We all know you can't argue math.

 

As an example, my roller with milled heads and roller rockers are .7 shorter then stock.

Both intake and exhaust required it.

 

Ok, I think I get it.

Although it would be technically possible to devise a pushrod length calculator, it would involve a ton of variables and screwing up any one of them would get you a bad result.

It's simply easier to just measure and be done with it.


I was hoping that the head swap and cam swap was something that I could learn enough to do on my own, but the added complexity of a retrofit roller conversion AND honestly ensuring that I properly measure both the rod length and the cam play when installing the button just seems way too important of a thing to get right for me to try and handle it on my own. Setting the advance on the cam also is a bit intimidating. I don't have many tools so any of these things that cause me to have to buy a bunch of new tools essentially just adds to the cost of doing it myself.

I think I might just need to find a mechanic who'd be willing to let me observe and help out but not do the stuff that actually involves experience and skill...

The video was really good at helping me to understand it; thanks!


Adam

 

Dont be intimidated at all
Cam endplay p length can be very simple
Find one guy (say straub for instance) and listen to that one, too many sources yeah then youll be pulling your hair out/doing it the wrong way and not know it.

 

Well all I can say is after much looking and talking I decided on a COMP roller cam kit K12 422 - 8 for my 78 L-82. Pricey - yes but seems to be best choice for me. My engine L-82, 22,000 original miles, duals, headers, alum. heads 64cc/200, runs great but could use some more mid range kick.

 

Interesting..my 78 L-82 bored to 355 (.030) with new JE Forged Racing Pistons (9:1), AFR 180/64CC heads, howards roller cam (.525/.525, duration 219/225, LSA110 1,500-5,600 RPM) with 10.2:1 compression is a monster compared to the OEM L-82. I'm guessing that the lower lift of your cam (.495/.501) with 200 CC heads instead of the 180's (brand?) and a compression of around 9.5-.9.7 (factory compression was at best 8.9:1 usually less, all factor into the mid range torque issue. I built my L-82 355 with the howards roller cam and AFR heads to have very strong mid range torque and it does, pulling hard to 6,000 RPM.

 

If I remember correctly when you did the AFR heads and roller cam on your former L-82, you used AFR 195 and a lower lift roller cam (.510 or .501?) and Don you thought it lacked the mid range grunt that you were expecting with your auto trans? I suspect with the AFR's on a 350, one needs to use the 180 head for max mid range torque?

 

I thought the same thing... I searched for others running the same heads and ratio rockers as me and found .100 longer rods was what they seem to be using and went from there.. I then found a good video on yourtube which showed how to check for proper roller rocker geometry/tip travel against the tip of the valve stem and how to check it with a sharpe marker... I got lucky and everything fit perfect... I was also paranoid about wiping a cam lobe from all the stories I read here and found that many people dont cover all thier bases whether its matching the valve spring rates to the cam, using used lifters instead of new ones or running the correct zddp breakin lube.

I had no issues despite being a total noob at building an engine. prior to this the last engine I tore down was a briggs and stratton in my modified go cart/riding mower as a kid. I did however try to research every aspect of assembly as much as possible getting many opinions as possible and thats how I learned so people were speaking from very old experience were the cams and oils were very different than today. I believe this does more harm than good since we know cam profiles are more aggressive and the material is not as good (supposedly) the oil is now designed for emissions over lubrication properties as well.

What I did find was some people have built many many engines with flat tappets with no break in issues, others seemed to have problems and of course bad news travels farther faster.....
So was it the luck of the draw?

 

Adam,
If you have a basic set of tools, a torque wrench, and time you can handle the swap. Roller I feel is easier than a flat tappet as there is no break in period.

 

I won't touch on the pushrod length points, many folks above have covered the reasons. It's not that hard.

I did want to address your question on the Cloyes timing cover. I bought the unit for two reasons

*Structurally and cosmetically, it is a well built unit
*It comes with good documentation on how to get the cam button adjustment done easily and correctly. I was intimidated by this aspect of the conversion and felt I needed a more structured way of ensuring the adjustment was right since it was my first time, and potentially the only time I would be doing this.

Your comment on wanting to buy everything up front and then do the assembly. I would caution against that approach. Yep, it will take longer to do things serially, but that's not necessarily a bad thing. Having time between steps allows you to digest what you have done and think about it and the next steps. There were several a-ha moments for me as I went through my build(s).

I have completely rebuilt my motor by using the advice and writeups here on the forum. There's great information and very good people available. SO don't let that stop you.

Good Luck

 

I offered him mine with the bad fuel pump lobe and it is a perfect scenario as he is already running an electric fuel pump for EFI.

...and I agree the 200cc heads probably hurt you a bit. IMHO

 

The description of the cam set says right on it that it's not appropriate for computer-controlled engines (EFI); EFI doesn't like huge lumpy cams, right?


Adam

 

Where do you see that?

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=187&sb=2

It is very far from a huge rumpity cam. I'm sure others will chime in with opinions. You may be disappointed if you go too small thinking this is extreme.

 

They will be conservative wiht their footnotes on the "not comp. compatible" bit due to smog, or someone not getting everything rihgt, tuning then blaming the mfr.

Most cams need a little more than what they think to run hard.
I always plan in advance and overcam

 

Adam, what EFI system are you going to be running? If it is any of the aftermarker (MSD, Holley, FiTech, etc.) I think you are putting too much worry into the cam for what you'll be doing (as far as compatibility).

 

When I performed my retro-roller conversion in 2013, my out of pocket target was about $2,000. That included the complete retro-roller kit from Comp Cams (about $950), cylinder head refresh ($700), incidental parts and tools. My expenses landed in that ballpark... THEN, I proceeded to go over that by adding a really SOLID Milodon oil pan, canton timing cover and, my favorite extra bit: Comp Ultra Pro Magnum rocker arms.

I mistakenly bought the aluminum cloyes cover and found it would not clear the back of my OEM-style water pump without shimming and throwing off the pulley alignment. So, that aluminum cover, a fancy plastic distributor gear that I learned I did not need and few other items I sold on Craigslist.

Thankfully, I already had the DART heads with good valves and $700 freshening included the shop setting the heads up with shims, the spring, keepers, locks and seals that came in the K-Kit. I am VERY please with the results and I did the tear down and rebuild job myself. Bonus was I bought an engine lift that I now use as my 'garage crane' for lifting heavy items up on my workbench (avoids personal injury).

My cam kit: https://www.summitracing.com/parts/c...FYwlgQodmawAHw

The cam in the kit is compatible with the stock and most aftermarket distributors. That means the fancy bronze or plastic gears are not required. I think Comp uses the 'austempering' process to harden the cam and it will NOT destroy your cam gear. I clearanced the nylon cam button that came in the kit and having the thicker Canton cover was good idea. I did not install the new timing set only because my Cloyes true-roller timing set was like new. The lifters are link-bar type for the Gen 1 block. It includes the correct length pushrods. Total package that takes all guess-work out of the job. Only think I had to gradually adjust was the nylon cam button clearance. I slowly removed material and measured using 'wipe pattern' (I put some black cam grease on inside of the cover and once I was happy with the amount remaining on the cover/not transferred to the cam button, I buttoned it up and it works great). I would have liked one of those measuring tools that you can bolt to front of the engine that simulates the optimal distance of inside of timing cover to the nose of the button but could not find one. Ultimately, my solution worked but definitely a 'shade tree' solution.

I bought a few extra tools that I really didn't need but justified a bigger, better tool box so all is good!

My performance target included not having to change the base/total timing or the carb jetting. The engine has a Lars-rebuilt q-jet that has performed flawlessly since he set it up (plus E10 compatible) in 2000. In 2000, I also had a local speed shop/tuner lay down a great advance curve in the Accell Performance replacement HEI distributor. So, what I got was VERY snappy performance and more usable power through the entire rpm range (over my former single-pattern, hydraulic lifter Crane Energizer 272-H10 grind). Being an 1600-5400rpm cam kit, it is perfect for my 1800rpm stall in the 700R4 and the blueprinted 3.54 Spicer-geared Dana 44.

NOTE: I rebuilt the engine in 1999 with flat-top pistons and a bunch of other items added then and since. About the only original moving parts in the engine are the crank and rods.

 

From the Summit page for the kit:

"Computer-Controlled Compatible: No"


Also when I use the CompCams CamQuest software and select the EFI option, this cam disappears from the recommended list. I understand that CompCams recommendations may be overly conservative, but I'm a newb and this is an insanely complicated thing (CAM selection) so I'm being pretty conservative with it at this point.




Adam

 

Right, but you guys on here are pretty advanced and knowledgeable so you would appreciate the extra HP, realize what you're missing, and understand when you've gone too far; I don't know what I'm doing so going more conservative seems wise, especially given my goals.

Everything I keep reading says one of the, if not the most common mistake doing DIY engine building or top-end swaps that don't involve pre-packaged top end kits, is buying too big of a cam; my goals are to focus on TORQUE and still decent fuel economy AND EFI compatibility. -Given what little I know at this point, it seems the safe bet is to go slightly smaller and leave perf on the table that I probably wouldn't miss anyway.

I drive a base model 2012 Honda Civic and a 2.0T Mazda CX5; the biggest engine I've ever had in a car was a 3.6 Liter V6 in a Oldsmobile Intrigue (my first car was an 87 Monte Carlo SS with a 305 in it; that was fun, at least). I've got a bone stock (other than no cat true dual exhaust) 79 L82; 64cc Profiler Heads and an even mid-sized cam is probably going to rock my world and make me super happy either way. People keep saying I'm going to miss the HP I leave on the table if I go with a smaller CAM, but I think I'm going to have a huge grin on my face either way. (Again, I'm of two minds; I want to plan this "well" but I still want something inline with my goals that doesn't "waste" a lot of the capacity of the heads.)


Adam

 

The right cam will out run the wrong cam. Life is a give and take. If you give the engine a good flowing head you can take camshaft away. Bigger is not always better.