I have my L98 pulled outta my 88 IROC, have the block stripped down, and ready to goto the machine shop, along with the heads. Gonna have the "normal" drill done, tank the block and heads, valve job, etc. Gonna keep it as stock as I can without having to get into the ECU. Don't really wanna open that can of worms. Queston is, what cam do I run, and with 130k on the clock, does it REALLY need to be replaced? How much HP will I get with 1.6 rockers, and if I go with roller (pivot and tip) rockers, do I have to go with bigger valve covers, and if so, will they clear everything else under the hood. (Emissions, A/C, etc.)?

What should the machine shop do to the block/heads? Is lineboring nessicary? Do I need the crank balanced (should only need polished), how bad would it be to put the original pistons back in? Engine was running strong before it popped an intake gasket. No main or rod bearing damage, no broke rings. Pistons came outta the top fairly easy, so the ring grove in the block is apparently minimal (to a rookies eye). So how much am I REAALLY gonna have to do to it?

 

Your question is going to get alot of perspectives and most are going to tell you to do the job right and replace, replace and replace. but I will just answer what I can.

1: cam( can of worms) the cams that came in your car are peanut cams and do not do the car justice. there is a thousand threads in here on what to buy so I wont get specific. but the knee bone is connected to the thigh bone and soforth. If you go stock of close there will be no problems if you go for HP then you will be looking a valve springs, Lifters and the like to take up the lift of the new cam you should go a little more on the cam but not radical if you don't want to change it all.

2: 1.6 rockers by them self will gain little if anything if you change springs and cam bigger valves then your talking... and yes they will clear the covers, mine did.

3: The shop is going to ask you what you are putting in the motor before they will know what to do to it. you need to know the specs of the cylinders and pistons to know if you can use them again. need to check for wear. if all is good then have them rehone the cylinders. jet wash the block and heads, check for worpage, clean up the valve seats, new frost and oil gallley plugs. and cam bearings

4:Using the old pistons is ok if your cylinders are ok. can't use them if you need to bore out cylinders. At the least if you do use old pistons u should get a re-ring kit and freshen up the motor a little. Taking the pistons out of the top my have damaged a ring or two and will you will do more damge than good. The machist will have to decide a lot whenit come to replacing things. He will be able to tell yo is the crank is good or needs to be ground.

Bottom line is there is a lot to think about when doing this. Not to scare you or anything but I just did and still doing a rebuild on my motor. I told my self if I spend over $1000 on it I am not happy. I am up to about $1600 and counting (need headers) but I am happy I have a motor that is stoaked and will be reliable. If I went the cheap way, I my be doing it again in 1000 miles wishing I had done it right in the first place. You have to go with what you can do and what your budget allows you pick. Most important ...getur done

 

Have the internals balanced for the longevity of the engine. If you plan to run a high lift you should have screw in studs vise the press in one that is currrently on the heads. Using 1.6 roller rockers did hit my valve covers on my 86Z.
Yes do replace your stock cam, do a search on LT-1 Cam and you will get a ton of info.

 

I changes my rockers to the 1.6. I have not started the engine yet ( next couple weeks I hope) I turned the motor over by hand to check the clearances and they did not hit. Is the lift going to be higher when the engine is running? if so I already have the tall covers what can i do about it granted my car is the 84Z carbed might be different altogether.

 

THANKS for the reply!! That is the worst of this whole rebuild, is deciding what to / not to do. You are probably right about the peanut cam. Makes sense. I had planned on the given.. new rings, rod, main and cam bearings. I will step up the springs a little, and of course, do the whole valve job routine.

The cheapest I have found the MASTER rebuild kit is at NAPA for around $650. Thats cam, roller lifters, pistons, the whole works. That by far is gonna be my biggest expense.... so far. I dont have a mic big enough for the pistons, but the crank checks out okay. No obvious stress on the rods, but I'll check on those too.

The 1.6 rockers, I was thinking would be better if I stayed stock. If I go with a bigger cam, I'll stick with the 1.5. Less confusion on my part, not to mention the whole valve cover issue. But, what about the full roller aluminum rockers? They are conciderably bigger, and really, that is what I want. For about $50 or so more, I feel like I'd be stupid not to, but not if those type are gonna hit the covers. I wouldnt worry about it, but I do have centerbolt covers, and they seem a bit more than the traditional style, and the adapters are like a hundred bucks to convert them over from centerbolt.

I guess my biggest concern, right now, is that really, I am a bit at the mercy of the machine shop. That makes be nervous. But, I gess thats part of it. Hopefully, I'll get lucky, and they will have mercy on me. Not alot of these cars on the road around here, even fewer of them being restored. There is alot to be said for someone who takes pride in their work, and really appreciates these cars as much as I do. If that person happens to have a machine shop, then he's the man to "GET ER DONE"!!!

 

I thought I went with the 1.6 but I just took out my paper work and have the 1.52. Summit sells the COMP cams magnum steal rollor tip rockers for a set $143.88 Part # CCA1412-16. They will not hit the valvel covers either. They were suggested by STEAKMAN. He is DA-MAn when in comes to head work. He realy knows his stuff. He should after what he did to his motor the last time Do not stay with your rockers you have now they are stamped steal and flex like crazy. they are good to melt down and use for boat anker.

Looks like you have a plan and that is half the battle. I bought everything from summit. they have a good tech support and can match all parts together. I prolly could have got them cheaper if I bought this from one and that from another but i did not want to go thru the hassel.

 

Is the stamped roller tip better than the needle bearing aluminum, or is that going too far, and wasting money? I just dunno about this stuff. I guess if those were recomended.... I thought about those, but thought the roller pivot and tip was what I wanted. But, it's not like I am gonna be turning over 6000 rpm or anything.

 

I can't tell you if they are better or worse. Steaman is the man to ask PM him and ask he will know off the top of his head. The only thing i have heard about the aluminum rockers is that they are good for the short time but fail in the long run.

 

Technically it's Stekman if you were to search for my name , but who's counting?

The main difference between Comp's steel (which aren't exaclty stamped) and a full trunion roller design with an aluminum body isn't the roller tip versus full roller design. It is the fact that Comp's Magnums have a far superior fatigue resistance strength. Rockers are subject to extreme pressure as they fly back and forth as the engine operates. Aluminum (at least the cheaper kinds like the $150 for a set of 16) in and amongst istelf simply does not have the restistance strength for this. I have seen several threads stating failure as early as 25-30,000 miles of use.

As far as rockers go, my recommendations will always lie as such: if you are on a budget or this is a mild street build, get the appropriate Magnum roller tipped rocker arms. If you want the best full trunion roller, get the Pro Magnums. The Magnums are about $150-190 for a set of 16, whereas the Pro Magnums are about $270-330 for a set of 16.

As for the benifits of the rockers themselves, they do make a difference, depending on the cam. The smaller the cam, the larger the difference will be. The slower the ramp rates (the slower the cam lobes open the valve), the better the gains. Basically, the overall advertised camshaft duration is ground into the cam and cannot be changed. However, .050" duration can be altered a bit, tricked, if you will. Under normal circumstances, with the factory setup, when the tappet is at .050" of valve lift, the valve is at roughly 1.5 times that (rubber rockers flex and give, so the exact number will vary). Increase the rocker arm ratio and you will transfer more of the tappet motion into valve lift. That means that the valve will reach .075" of lift sooner, which, in theory, increases the .050" duration. That, aside fromt he obvious that the valve will simply open further.

My advice would be to choose a cam, then select a rocker arm ratio. Get a lift "in the ballpark" and then dial it in more or less with the rocker arms. As far as what cam, I guess that really depends on just what you want out of the engine.

 

Dang, Stekman, 84 restore was right, you ARE the man!! THANK YOU for the reply! You just saved me alot of time and money that I can otherwise spend elsewere on the car!! Good info there...