89 formula TPI

I have been talking with another member back and forth and decided to go ahead and replace my valve seals to cure my blue smoke on start up issue. While I'm in there I wanted to take advantage so I figured I'd also replace the original valve springs since they were probably due. This is a '89 bone stock 305 TPI motor with 85k miles. Goal here is to keep it stock.

While I'm in there should I be looking at replacing anything else? ANY tips or suggestions? Thought about rods and rocker arms as well but I don't think they wear out the same way a spring does. Also, anyone have part number for original direct replacement springs?

Thanks

AlkyIROC

Valve springs do wear out over time and the spring rate decreases. If they're still original, it doesn't hurt to replace them. As for part numbers, ask your local auto parts supplier for some stock replacement springs. A specific part number will depend on the brand. Pioneer is a popular stock replacement but won't have the same part number as GM.

sofakingdom

iTrader: (1)

Stock rocker arms do indeed wear. Push rods, not so much. Hard to say whether you "need" them; won't be hard to figure out once you get em off though.

http://www.summitracing.com/parts/sum-174001/overview/ is a suitable direct replacement for stock springs, with new retainers and keepers also. Get some extra shims. http://www.summitracing.com/parts/cca-4753/overview/ Leave the "rotators" and splash shields off of the top of them. Add .090" of shim under the exh springs to whatever is already there, to take up the thickness of the "rotator". Use "positive" seals on the int; NOT "umbrella" type; don't bother with the O-rings. http://www.summitracing.com/parts/fel-ss72527/overview/ int & http://www.summitracing.com/parts/fel-ss72526/overview/ exh.

89 formula TPI

Thanks for responses and part numbers. Is there any issue with mixing fresh springs with older parts like rockers or push rods if I don't end up changing them? I think they say ur supposed to change lifters when u change cam or something like that. Want to make sure nothing else like that applies

cardo0

Well the self locking rocker arm nuts aren't really to be reused (though plenty do still work). My self I like the Comp Cams cast rockers w/roller tips but then again on a lo-po 305" just some good quality stamped rocker like a Crane 1.5 will be more accurate than the stock rockers. Yea your old p-rods r OK.

Your biggest worry should be adj the vlvs correctly. To much preload and u hold the vlvs open. To little preload and your engine starts to eat it's self. Learn what "zero lash" and "base circle" mean w/o any doubts or guessing.

Good luck.

AlkyIROC

Factory stamped steel rockers are highly inaccurate. Even an aftermarket replacement rocker will be much closer to a 1.5 ratio than any OEM rocker. Spending a little more for a roller tip rocker is a good investment. A full roller rocker is nice but isn't always required especially for a bone stock engine.

89 formula TPI

I am fairly familiar with lash adjustment but u raise a great point. I have the service manual procedure and have read quite a bit on it. Ill find out when I get in there I guess. I have not heard the term base circle before though. How does that come into play?

sofakingdom

iTrader: (1)

"Base circle" is the part of each cam lobe that has no lift. Specifically, the portion directly opposite (180° away from) the tip, of each lobe.

Contrary to the gloom-&-doom stuff posted above, valve adjustment is one of THE EEEEEEZIEST things to do right, IF you ... do it right. Which is eeeeeezy.

There are coupla simple ways to get it ABSOLUTELY PERFECT. Most accurate is, to take advantage of the 180° relationship as described above, and realize that cyls that are 4 positions apart (half the firing order) are 360° of crank rotation apart in all their operations & events. That in turn means, if you turn the engine to where let's say #1 intake is fully open, the int of the cyl 180° away (4 positions) in the firing order is on the base circle, and ready for adjustment. That would be, #6. Then when #6 int is adjusted, you can turn the engine exactly 90°, and adjust the next int valve in the firing order, which of course would be #5 (18436572). And so on, through all 8 intakes. You can watch #8 int as you approach your 90° turn and verify that it's at full open. Then repeat the same process for the exhaust.

The other eeeeezy and most accurate way to locate the proper adj point for each valve (aka base circle) is the "EOIC" method. It's not quite as "perfect" as the first method, but is PLENTY accurate enough. It's based on the operating cycle of an individual cyl: the int valve is fully open halfway through the int cycle, meaning it's on the base circle exactly 180° away from that point in that cyl's cycle, which of course would be, halfway through the power stroke, which is just immediately before the exh starts to open (it opens as the piston approaches the end of the power stroke), and likewise, the exh is full open halfway through the exh stroke, which is halfway through the compression stroke, which is right after the intake closes since the int closes just after the comp stroke begins. Look at a cyl and watch for the exhaust to just start opening (exh open, "EO") and at that point, adjust the intake; you can go through the rest of the intake valves every 90° same as above, since by definition a V8 operates 1 cyl every 90°; then find an int valve that's coming off its peak and closing, and just as it finishes closing (intake closing, "IC"), adjust that ones exh. Repeat every 90° through the firing order.

DO NOT try to use ANY method that says set the engine to one place and adjust any more than one valve!!!! They DO NOT WORK and will only lead to grief. Use one of the 2 methods above ONLY, and adjust ONLY one valve at any given engine rotation position.

The main and most frequent mistake n00bs make, which the n00b above failed to mention being quite the n00b himself, is not understanding what "zero lash" is. The Point of valve adjustment is to depress the plunger in the hydraulic lifter partway, usually about halfway, although consistency among all cyls is more important than the absolute amount. We call this "preload". Different "books", "specs", "methods", etc. call for different amounts of preload, for different reasons. All are based on the idea that preload goes away as the parts wear. The factory uses one full turn (glue the valve covers down and don't touch em again for 100,000 miles), Chilton's and the like call for ¾ turn (they figure anybody that's doing this isn't going to be too shy about having to do it every 5 years or so), "performance" cam mfrs usually call for ½ turn for street motors and ¼ turn for race-oriented motors (since a motor used for any significant amount of racing is going to have to be torn down or worked on more frequently anyway), and a "pure race" setup might even use as close to zero as possible like 1/16 turn, to avoid "pump up" which is what the lifter does when the valve "floats" (bounces off the seat when it's supposed to close) at very high RPMs. Using parts that don't wear as much as stock, roller rockers for example, also often would argue in favor of less preload. In a case like yours, I'd suggest ½ turn as being in the right range for your application, esp if you put better rockers on it.

The lifter has a little spring in it that works its plunger in conjunction with oil pressure. "Zero lash" is the adjustment point at which you JUST BARELY have taken up all the VERTICAL play in the push rod, between its seat in the plunger, and the rocker arm. You tighten the rocker nut just to that point, then however much "preload" more, which then pushes the plunger partway down into the lifter but leaves a cushion below it in the form of a "chamber" full of oil. DO NOT try to use the "twist the push rod" method!!!!! This DOES NOT WORK. Invariably it will lead to tightening the rockers WAY too far, to the point that some of them are unable to close fully (because the plunger in the lifter gets pushed all the way through its travel and bottomed out).

So its really quite simple: find the first convenient valve of each type starting from wherever your motor happens to be sitting as you start, go through all 8 of those tightening the rocker nut until the push rod just barely can't be jiggled UP AND DOWN any more and then tighten ½ turn more, then repeat for the other valve type all the way through the firing order.

89 formula TPI

Loads of good info, tyvm! Also glad u mentioned the jiggle vs twist pushrod test. I have not heard of that method before

TallTim

iTrader: (2)

In the car valve seals was a much harder job than I thought it would be. Once the spring was compressed the locks did not want to release from the retainers. This was on a stock 100K engine. Also you don't want to mess up the valve tips. Suggestions on separating the locks from retainers? Maybe a soak ahead of time with WD40?

sofakingdom

iTrader: (1)

Rotate the engine to where the cyl you are working on is at TDC. This will keep the valves from falling in. Then put a socket on top of the retainer (5/8" or so works great) and give it a good whap with your BFH. You don't even need the spring compressor at all to take them apart; only to reassemble.

ploegi

You ever have a problem launching valve springs with that method?

I just put the on-the-car valve spring compressor on there, tighten it down good, then tap it with a hammer. Usually one tap is all it takes.

having a magnetic stick to pick up the locks isn't a bad idea either.

sofakingdom

iTrader: (1)

Not really; launches em pretty good usually. I can launch EVERY ONE if I really want to.

None of that stuff that's on there in the situation at hand - retainers, keepers, springs, rotators, oil shields - is going to be re-used anyway. It's all trash. So there's no need in expending effort to collect it all carefully, might as well just sweep it all up off the garage floor afterwards. In other situations, where it's all still good and I DO want to keep it, I'm more gentle.