[Mental]

Ok heres the story.

Iv'e worked on motorbikes (hobby) for years .. so i know mechanics .. what I dont know is cars. With a bike engine, if a bit breaks, get a new one. With a car, if a bit breaks, theres options man! Options!

I know what a cam is, I know what a lifter is, I know what a pushrod is etc ..

What I dont know is .. Whats the difference between cam 'types' so to speak. I dont understand roller rockers, or 'anti-pump' lifters are, and I dont know why you need different lifters for roller cams Vs normal.

I ask this for 2 reasons.

If I may use your expertise, I wish to educate myself.
and 2, I own an XD 351c that underwent some luvin by a mechanic friend in Melbourne. He did all the hard work, I just bolted it in. The guy who did my heads put to much pre-tension (?? correct term?) on my valve springs and caused them to spring-bind (once again ?? correct term?) causing me to bend 2 pushrods in my first revolution (lucky she didnt fire really) anywho, so I replaced them and thought "What tha" got my mechanic friend over who diagnosed the fault straight away. He removed some spacers/washers from undernearth my valve springs. We got the beast running on a set of extractors and did a small run in around the country town it was at. changed the oil and I had a butload of filings. Thinking this was perhaps normal for my first oil change, i reloaded with oil and drove 170k's to home.

She sat in the shed for about 8 months while Life ran its usual course (long work hours) and I got her out this weekend. decided to check the vitals and found shavings all up my dip stick. Now I was worried. And after reading the forums .. I know exactly whats wrong. I've wiped the lobes of my cam.

After a small chat with another mechanic friend of mine, he totaly agrees ... :cursethis

Im gunna rip the manifold off and take a proper look, but I know what I'm going to find.

My current config:
Standard crank and rods, hypertechtic (no idea on spelling) pistons. All balanced and crack tested.
block is virgin, Torque bored and decked.
4V heads and chambers w/2V ports, so im assuming 4V valves as well. No remarkable work, just cleaned up. origional pushrods, and rockers.
Edelbrock Torquer with a 750dp Vac Secondrys.

I dont know what the lift/duration of the cam is, she had a mean idle (noticebly NOT normal) the cam cant have been to large, as im assuming the lifters woulda just packed it in, or i woulda shot a pushrod thru my rocker cover =p

So this is where I stand, in need of a new cam, lifters and pushrods. And quite frankly I dont know where to start. What cam would you guys recommend? Whats the difference in lifers? I dont spin past 6k. I also dont want to change my lifters if I can, I dont have all that much money to play with. And whats the chances of getting the cam out wihtout having to removed the engine .. I cant do that with what I have available.

thanks :hy:

 

[xcgxl]

You can just about rebuilt a Cleveland V8 for the same cost as rebuilding a single cylinder bike engine.

 

[russxr67]

If you have lost a lobe/s off the cam then to do the job PROPERLY the engine must come out and be pulled apart and cleaned thoroughly to remove ALL traces of iron.Cam,lifters,bearings ,oil pump ,rings and any other part that can harbour shards of iron will end up in the bin. Thats the way to do it properly. Lack of Zinc in most modern oils is usually to blame. Upon rebuild i would try to find some in the form of an additive and run the engine in with it mixed with the oil.

 

[Mental]

If you have lost a lobe/s off the cam then to do the job PROPERLY the engine must come out and be pulled apart and cleaned thoroughly to remove ALL traces of iron.Cam,lifters,bearings ,oil pump ,rings and any other part that can harbour shards of iron will end up in the bin. Thats the way to do it properly. Lack of Zinc in most modern oils is usually to blame. Upon rebuild i would try to find some in the form of an additive and run the engine in with it mixed with the oil.

Zinc additive. Added to memory banks..

Can I get a short explination of the difference between a standard cam and a roller cam (apart from its used with roller rockers). you use solid lifters with roller cams right? I also assume that roller rockers allow a larger stroke? Is pushrod length determined only by the deck height or cams as well?

Thanks all

 

[Mental]

You can just about rebuilt a Cleveland V8 for the same cost as rebuilding a single cylinder bike engine.

Ya reckon? =D depends on the bike i guess. but its probabley close.

I kinda regret selling the dirtbike .. im startin to expand at the waist hman:

Ya never realise just how fit you are .. until you arent!

 

[somebloke]

a roller cam is usually best used with roller lifters. roller lifters have a small wheel at the bottom of the lifter that sits on the cam lobe. roller rockers have a small wheel on the end of the rocker. roller cam/lifter/rocker combo is the best setup really cause theres bugger all friction. you can run a much more agressive cam profile without having a idling pig. a roller cam in my opinion if building a half decent motor is the best bolt on performance part you can buy. :driver:

 

[davis]

a roller cam in my opinion if building a half decent motor is the best bolt on performance part you can buy. :driver:

...and there are no break-in worries!


:davis:

 

[Mental]

I see. thanks! :hy:

Now for my next question, roller rockers come in different mounting methods, bolt down pedestal and something else. Whats does a clevo use standard? can they be both? what is the advantages of one or the other?

 

[gasxd]

A roller cam takes advantage of roller LIFTERS not rockers, it has a steeper slope that can open the valve quicker and hold it at a high lift longer. The steep slope will quickly destroy a flat tappet. With the roller you get more airflow without as much duration...

i hope these crap pictures help

---- flat tappet ----------- roller -------

 

[gasxd]

Clevelands use a pedistal rocker standard, the problem is the strength of the bolt that holds it. Upgradiing to larger studs solves the problem but you leave no room for the little notches that stop the rocker from turning (these get machined off anyway). To overcome this you use guide plates to hold the pushrods still and this keeps rockers still. Either method can use roller/non-roller rockers...

 

[Mental]

Ahh 'tis all makin sense now. I just assumed (with my limited knowledge) that roller rockers went with roller cams. But its just a method, not a rule.

All those bits and pieces that I have seen now are makin sense. For example, I knew 'of' guide plates, just not what they were for.

Well I certainly know alot more than I did to start with =p there's no doubt a mountain of information I dont know about cams, but atleast I have the ground rules setup. :hy:

thanks heaps everyone!