Ok i finished installing new heads, a cam, fuel injectors and superam intake. The whole top end is new. I have a 1990 Iroc with a 383 L98 and have a few questions. How do i start the car? the motor turns but doesnt start. How do you tighten down the rockers arms?

 

Are you sure you put the distributer i the right way? It's very easy to put it in 180 degrees off.....Although if it was it'll backfire badly. Is it getting spark?


As far as the rockers go most people will say it's best to adjust 'em with the engine running but my way has worked for me for almost 25yrs with no problem(and alot less oil mess) The way I do 'em is to remove the valve covers(of course) then start with the #1 cylinder and tap the starter over 'till the rockers are on the base of the cam(no lift at all that is) then tighten each nut down while spinning the pushrod with your fingers 'till you feel resistance while spinning 'em, then tighten the nut another 1/2 turn (most manuals call for a full turn but if you're gonna race it at all 1/2 is better) when you get the first cylinder done just move to the next one and do the same thing with it and all the rest 'till you're done, then button her up and fire it up

 

i think i may have put the distributor in the wrong way. It does backfire when you try to start it. I know it is getting spark. Thanks for your tip on the rocker arms. gonna go and try it again.

 

i turned the ditributor around 180 and tried starting the car and it started! it was running really ruff. Then one of the rocker arm studs broke! Could it be the nut was on too tight??? I have no idea. So now i got to wait till tomorow. Please help!

 

Guys never start the car without at least doing a cold valve adjustment and always prelube a newly installed valvetrain. Could have saved you a bunch of headaches......before you start it again follow this proceedure for adjusting the valves......

If you are using a hydraulic cam turn the rocker arm adjusting nut 1/2 to 3/4 turn after zero lash to set the preload. Zero lash is found by moving the pushrod UP and DOWN in the lifter, when there is no more UP and DOWN movement that rocker is at zero lash. Do NOT spin the pushrod to find zero lash. Now set the preload. For mechanical cams, you must get the correct lash specification from the cam maker.

In either case you can use the following adjustment order. This is the easiest method.

To put the #1 piston at TDC on the compression stroke disable the ignition and remove the #1 spark plug. Stuff a tissue over the plug hole or have someone place their finger over it. Tap the starter till the tissue pops out or the person feels presure. Now BY HAND rotate the crank till the mark on the balancer lines up with the 0 degree mark on the timing tab.
Now adjust the exhaust rockers of cylinders 1, 3, 4, and 8, then the intake rockers of cylinders 1, 2, 5, and 7. You can tell the intake from the exhaust rockers by looking at the port they are above. If the rocker is directly over a header tube then its the exhaust rocker....duh...

Turn the crank 360 degrees (1 full turn) BY HAND. Now with #1 piston at TDC on the exhaust stroke, adjust the exhaust rockers of cylinders 2, 5, 6, and 7, then the intake rockers of cylinders 3, 4, 6, and 8.

Now turn the engine over by hand once more and verify that your rotor is pointing at the #1 terminal on the cap.

 

Who built your motor?

 

Larry's Performance, Montebello CA did the bottom end and i did the topend.

 

Is this a reputable shop? Also what did it cost? Please provide additional engine specs.

Thanks again...

 

And I guess I've been doing it wrong for 25 yrs then huh

You can find zero lash by spinning it...granted if they're not pumped up it's harder to find the zero lash point but it can be done...easily, as I've done more times then you think. Plus you can adjust both rockers as long as it's on the base of the cam. It doesn't have to be done "by the book" like you've quoted.

Jeez, some people always gotta try to show they know more than you


1990irocz28....sounds like you did have one too tight Hope you get her going soon, sounds like it's gonna be a runner

 

I didnt say it couldnt be done by spinning the pushrod...just not to do it that way. Its too easy to overtighten the rocker that way. Sure if you've got 25 years experience then you know what you are doing. However this post was meant for the guys who seems like hes just etting started. I dont wanna offend the old folk....old guys seem so touchy these days..

 

That's cool....I was also just trying to tell him an easy way to do it hence the intake/exhaust at the same time approach with 'em on the base of the cam instead of the "right way" (by the book) way you explained with doind different valves/cylinders then cranking the motor.....that just gets me too confused

By the way I'm "only" 38 although compared to most people here I guess it prolly is old and if you're thinking the 25/38 thing I did build my first engine (327) and drop it in a 65 caprice when I was the tender age of......13

 

Larrys Performance did decent work. I have no complaints. All they did is install a 383 kit. New scat crank, Keith Black pistons, new cam bearings, rings, rods,etc. block was cleaned magnafluxed, hot tanked, etc. Cost me 3K. compression is 9.5:1. The topend consists of Pro Topline Alum. cylinder heads 200cc/64cc, 2.08/1.56valves, SLP 51004 cam 495/502,218/224,114. 24lb ford fuel injectors, Superam plenumand runners, edelbrock hi flobase,stock fuel rail, stock throttle body, msd8366dist., and a custom cold air kit(first you use an 88-89 firebird intake hose, then you go out and buy a nice polished alum. 3"honda civic CAI from autozone for $30 and then slap on a 7X3 K&N cone air filter and your done. you dont even have to move the battery). Thanks for you help guys!

 

Larrys Performance did decent work. I have no complaints. All they did is install a 383 kit. New scat crank, Keith Black pistons, new cam bearings, rings, rods,etc. block was cleaned magnafluxed, hot tanked, etc. Cost me 3K. compression is 9.5:1. The topend consists of Pro Topline Alum. cylinder heads 200cc/64cc, 2.08/1.56valves, SLP 51004 cam 495/502,218/224,114. 24lb ford fuel injectors, Superam plenumand runners, edelbrock hi flobase,stock fuel rail, stock throttle body, msd8366dist., and a custom cold air kit(first you use an 88-89 firebird intake hose, then you go out and buy a nice polished alum. 3"honda civic CAI from autozone for $30 and then slap on a 7X3 K&N cone air filter and your done. you dont even have to move the battery). Thanks for your help guys!

 

ahhhhhhh!!!I started it again and blew off another rocker stud! and i followed the directions this time too. Could the studs just be weak?? theyre the ones that came with the heads(pro topline). Im tempted to just go out and buy some ARP studs and swap them all out. Any help/tips would be greatly appreciated. thanks.

 

If you're actually breaking rocker studs you have a VERY serious valve train interference problem that changing to ARP studs WON'T fix.

Studs don't just break.

You're valve train geometry is not right; probably the pushrod length is wrong or rocker slot not long enough..

If you're using stock ball and sled rockers, the slot in the rocker arm is probably binding against the stud causing it to break.

I suggest you have someone who knows valve train geometry take a look at it before you wipe the camshaft.

Jake

 

I think your right about the pushrods. I think theyre tooo long(they 100 over stock) the studs seem to be bent toward the valves. i took off all the rockers and studs and i m gonna go tomorow to the speed shop to figure this out. the place where i bought the heads told me to get those pushrods. Im using pro Topline heads 200cc/64cc , slp 51004 cam 495/502,218/224,114, stock rockers, can someone tell me what length pushrods to use w/pro toplines?

 

Don't know about the length but the shop where you bought the heads should know (you'd think)

My suggestion is like Jakejr said, Since you're running stock rockers maybe the slot isn't long enough and binding against the studs (during lift) thereby breaking them. Although the lift on your cam isn't that big it's worth a look see

 

according to SLP you should be able to use all the factory equipment with that cam. Has anybody had this kind of problem as far as the rocker arm slot not being long enough? To me it seems like the pushrods are tooo long, but i dont know. Im on my way to the shop to see if i can figure this out.

 

Rocker arm slot: Absolutely, it's a common problem when you install a camshaft with more valve lift. The stock rockers - the sled and ball type - do not have a long enough slot.

If you examine the studs you'll see grooves or notches in them where the rocker is digging into the stud.

To check for proper clearance, you'd need to be able to slide a straightened paper clip between the stud and rocker from the underside of the rocker. This clearance should be there for the ENTIRE rocker movement cycle - with the valve closed, then as it cycles to fully open, than all the way back to closed.

Pushrod length checkers are inexpensive. Mr. Gasket, Moroso, etc., sell them. You simply follow the directions that come with the checker and use feeler gauges to see what length pushrod you need.

Be sure to check the pushrods that you have installed now, there's a good chance that one or more of them is/are now bent.

Jake

 

the pushrods were 3/4" too long.i was using 7.9" when i was supposed to be using 7.25". Thanks for your help guys.

 

Now get that machine fired up and get back with us on how you like it now