Ok. I just got off the phone with Summit and they suggested a Comp Cam 08-500-8 cam for my car. I have asked and have gotten alot of answers to this question. What is the max lift you can go on the stock 305 LO3 engine with factory roller and pushrods installing heavier springs???? I have heard .485 is max. Let me know. Don't need to trash my engine. Trying to get a mild cam. The sum 8800 is out of stock and the salesman suggested this comp cam. So, can I get some suggestions here, and some limits on what I can do with a stock 305 without going crazy. Just a cam and springs is all I want to do for now. Thanks

 

That's a suitable cam, a decent recommendation.

You WILL need new valve springs. WILL WILL WILL WILL WILL. Not "may", not "might", not "if you want", not "it would be better": you WILL need new valve springs.

Probably the best option is LS6 ones such as these https://www.texas-speed.com/p-9573-g...laced-ls6.aspx with the Comp "adapter" retainers https://www.summitracing.com/parts/cca-787-16 and their associated hardware. Pretty much dodges the whole "max lift" issue. All that will "work" with stock rockers and push rods but there's no guarantee you won't run into problems; however the motor will CERTAINLY run better if you replace those over-boiled spaghetti-noodle push rods and stamped sheet rubber rockers with something that translates the cam lobe profile all the way to the valve.

Be aware also, the L03 heads are CRAP for performance. They were designed to give good low-RPM torque and gas mileage. They sacrificed any hint of high-RPM flow or free breathing to get that. (after all, TANSTAAFL) Don't expect miracles. But that cam should greatly improve the car's performance.

A moderate torque converter upgrade (2500 - 2800 RPM would work wonders) and some gear (3.23, or 3.42 at the most) will also help.

The L03 didn't come in the 83 Z28. What car is this in?

 

I guess I need to update my info. my old car was an 83. I'm working on a 92 RS. I also have a 86 I Roc that will get some love much later in life. I want to get this 92 on its feet and see how the changes impact this car then maybe do some minor changes to the 86 vs what I've done to the 92. There are so many different ways to go. Everybody thinks that their way is the best and only way. Hell....I started a pretty good fight just asking about deleting smog pumps and egr valves. It was comical to read these two guys rip each other on the logistics of why emissions are so important......anyway. Thanks for that info. So. .500 is ok on lift on the valves?? I've been trying to find some spec on it and I get nowhere. Didn't know if there was a spec book on what you can and cannot install for cams.

 

The valves don't care about the lift. What cares is, the retainers smashing into the top of the guides; and the springs going into coil bind.

Yeah it's always amusing to watch the arguments people get into. Even about something as basic and well-known and all that as upgrading the L03, where there's been ABSOLUTELY NOTHING new appear in the last 20 years or so (kinda like a Frod flathead V8: "new", by its very definition, has moved on and left it behind), people still get all wound up about ... something.

IMO there is no benefit whatsoever, functionally, to eliminating the EGR, the AIR, or the cat, on that motor. That isn't what's making it a disappointment.

The way to make a car faster IS NOT to buy lots of big shiny krome gewgaws that all sit up top where all the 8-yr-old kids can ooooh and aaaah over it in a parking lot. What it IS is, to find the ONE thing that is MOST keeping the car slow; and attack THAT THING, in a manner consistent with goals and budget, and compatible with whatever is already there, to eliminate The Bottleneck.

Imagine your engine as being like a string of pieces of garden hose you have all hooked up one after the other to fill a bucket out in the far corner of your back 40. You've got 100' of ¾, 25' of ¼, 50' of ½, and 50' of 1". Your bucket fills up REAL SLOW and you want to speed it up but can't change the water source. Now THIMK: how much faster is your bucket gonna fill up if you replace that 1" with 1½"? How about with 3"? How about if you find a way to shorten the ½" from 50' to 25'? to 0'? RIGHT. None of that will make ANY DIFFERENCE AT ALL. None whatsoever. As long as that piece of ¼" is in there, the bucket will NEVER fill up any faster. Same deal with your motor: if something is choking it (say, the coffee-stirrer-sized L03 Y-pipe, and the swirlie ramps in the intake ports of the heads) then if you put a single-plane "racing" intake on it and a 1000 CFM Dominator, is the car gonna make ANY more power? Not no, HELL NO. Same deal here. Find The Bottleneck, and address THAT; not just buy fancy romantic-looking highly visible shiny parts and slap em on there "because all the fast cars have that". Doesn't work that way.

In the case of the L03, The Bottleneck is the exhaust system: every piece, from the heads to the rear bumper. It ALL needs to go in the trash. EVERY piece. Replace it with a set of good-quality headers (few things in life SUCK worse than crappy headers) but NOT NOT NOT NOT NOT with anything that's for L03, because anything that "fits" L03 will preserve The Bottleneck: the one thing you DO NOT want to do. Get the matching Y-pipe, a new cat, and a good cat-back of your choice. I'd suggest looking up headers for something like 88 350 TPI; they'll bolt right up. I doubt that a modern cat will "lose" more than about 2 HP on a L03, and probably less than that; one of those doesn't cost materially more than a "test pipe" anyway; and of course, if you ever DO need to worry about emissions, you're already pre-covered. For headers, I HIGHLY recommend stainless steel, with ceramic coating. All it will take is watching your cheeeeep mild-steel headers dissolve into a pile of reddish-brown flakes after the first snowstorm to make you wish you had spent your money on stainless instead; and meanwhile, for every piece of rubber (hoses) and plastic (wires, connectors, etc.) you have to replace when it crumbles to dust, you'll wish you'd had them coated, so that the heat from them didn't destroy everything else under the hood. Independent of AIR and EGR.

The Next Bottleneck in the L03 is the heads. As long as those POSs are still there, NOTHING else you do will uncork the restriction in their intake port. Best replacement, as far as stock parts, is 081 casting; 87-up 305 4-bbl and TPI applications. Avoid any 350 castings, as those will lower compression dramatically.

The Next Bottleneck after the heads is the cam. The one you are asking about will cure that, but won't come anywhere close to realizing its full potential without those other 2 things being fixed too.

 

I agree with you on most points, except the cam is a far bigger bottle neck than the heads. 178/194 duration and .350/.385 lift. The heads flow close to 180 cfm which is enough to make more than 350 hp. The cam on the other hand is done making torque before 3,000 rpm. With a TBI compatible cam that works with a tight converter, a person would not see 10-15 hp swapping heads. I had a TBI 305 make 230 hp at the wheels with stock TBI heads.

 

So, everything you both said I totally agree with and understand. Budget is kinda key right now, I can't do it all. I'm at a point where I have the alt off the car getting fixed, pulled the air pump and all the hoses just to clean up and get some room for the engine bay, plus I have read too much on how it really doesn't accomplish much. that's besides the point. I have a spectre air plentum on the TBI with a 4" intake going to a TPI airbox pulling fresh air from the raditor scoops. I plan on installing some hooker 2460 mid pipes with the 3" y pipe and going 3" all the way back with maybe borla???? Not sure there yet but 3" all the way. I guess, the question is this....should I change the cam now and run the stock muffler and headers till I can afford to do the rest. I was planning on the cam first then do all the bolt on stuff later. will that hurt anything? thoughts?? Thanks for the help. Most people just tell you what the best product is out there with no explanation why. Nice to actually discuss what issues we all face in working with these cars and real life. Money, time, stress, and wants. Thanks man

 

Do the exhaust first, then the cam. It doesn't make sense to do it the other way around.

 

So, I would guess these are stock. They rollers for sure. I ran a camera down there and can see the retainer clips that hold them from spinning. Next and most important question. How much lift can I take these heads with new springs. I have this picked out for a mild cam. Let me know your thoughts on mechanical issues. I just want a street car that you can tell has been cammed a touch. Not looking to rip the tires off the thing. I just don't want to damage anything. Thanks guys.

COMP Cams 08-300-8 - COMP Cams Computer-Controlled Camshafts 262/264 with .450/.480 LSA 112 I have new springs 986-16 springs and retainers with new clips all from comp cams. Will this work in my car without any spring issues or hitting the retainers.

Camshaft, Hydraulic Roller Tappet, Advertised Duration 262/264, Lift .450/.480, Chevy, Small Block, Each

CCA-08-300-8

 

986 will require machine work to the heads.

187 heads are not the heads to do this to.

Get the springs and retainers I linked you to. NOT 986. Not because 986 are "bad" (I've run them myself many a time, on better heads), not because of anything else, other than, YOU HAVE TO SPEND MONEY on those crappy 187 castings, which, at the first possible opportunity, you will THROW IN THE TRASH. And guess what... ALL THAT MONEY you might have spent on that machine work, will GO IN THE TRASH right along with them.

That's part of the "art" side of this hobby. NOT ONLY, getting the most out of what you've already got; BUT ALSO, figuring out how, when what you've got isn't "enough" anymore, how to keep from throwing money you've already spent into the trash.

Do the exhaust work I described - HEADS TO THE STREET - as soon as possible if not sooner. The thing about exhaust is, NOTHING ELSE can do what it's supposed to do, if that doesn't support it FULLY. Think of it as being like your rectum: if it's stopped up, the eyes get dim; the brain gets foggy, the legs get weeeeek, the hands get shaky, ... WHO'S THE BOSS? (Brain, hands, feet, eyes, a$$hole, ???, old fax humor joke, maybe you're too young to remember it) That's EXACTLY the same function that exhaust serves, with respect to a motor. It's how it gets the consumed fuel (food) out of its digestive system.

DO NOT UNDER ANY CIRCUMSTANCES waste unrecoverable money on those heads. Which means, DO NOT do "performance" machine work to them. Which means, you CAN'T use 986 springs on them. Even though, in days gone by, they were the way to go. Butt that was before LSx motors even existed. I think the first motor I put those on, I built in the 70s. Over 40 years ago. I ran a set on one of my own motors well up into the 90s. Butt no more. Times have changed. Parts choices have moved on. New things are available. Hell I'm almost old enough to remember when people threw things at their food as it ran by to get it to slow down long enough that they could take a bite; does that mean a grocery store isn't "A Good Idea" NOW? Of course not. Same kinda deal here.

Use the LS6 springs and the "adapter" retainers. ABSOLUTELY NO MACHINE WORK WHASTOEVER required, just bolt em on. When you realize after whatever else you do and it doesn't have the effect you want, that those 187s are GARBAGE, and you THROW THEM IN THE TRASH where they belong, you can take all that stuff off and re-use it, on WHATEVER heads you get to replace them, and whatever CID short block you put them on. (*cough* 96-2000 L31 *cough*). VERY DIFFERENT from machine work to the castings.

The "300" grind is not a terrific choice for a TBI 305, but will "work". Not as good as the "500" but w/e. I'd recommend sending that "300" back and getting the "500".

 

Ok, 08-500-8, texas speed ls6 springs and comp 787 retainers with some new clips the comp 611-16 locks. That will not give me any issues?? other than the heads are crap. So. I was trying to discuss this with the misses. Is this really worth the work and money. I know it's not going to be a rocket ship by any means, but will there be a noticable difference?? This is my first engine I've ever cracked open and really worked on. I know it's not much, but it's what I have. Should I just give up on a cam and install headers and exhaust and be done? Again. Sorry for all the nubie questions and issues, just getting my feet wet. Matt

 

Matt, no apologies necessary. You are doing the right thing by asking questions! And you came to a great forum to do it....lots of great expertise here, and tons of years of experience with the SBC and 3rd gens.

Have you ever seen good photos or cutaway images of the 193 heads to understand the recommendations being made? There are some good photos in this old thread, as well as debate for and against. They are an interesting design. They do increase velocity and swirl, which boosts torque. But when you see the photos, you will quickly realize it's kind of like trying to run a marathon with one nostril plugged (as half of that intake port is).

https://www.thirdgen.org/forums/tbi/...tbi-heads.html

I personally don't have much grief with advice for or against them. While they appear to contradict each other, if you read both carefully, they don't. Fast355 and other supporting their use are saying you can build a good little street motor with these head, as long as your expectations do not exceed something in the neighborhood of 300h.p. Others like sofakingdom might say in the long run, you will want more than that (horsepower is very addictive) and thus spending money on heads that are a known limitation is not a good investment. Better heads have more headroom for potential future growth. There are other factors that play into that too.

What you won't get much argument about is that the L03 exhaust is highly restrictive, even by 305 and 3rd gen. F-body standards (that a pretty low bar). And the "peanut" cam is thus named for good reason. It's a low speed torque cam, prefect for getting your overloaded pickup truck full of pumpkins rolling away from a corner and off to market. But it runs out of breath quickly. So spending money in these two places is not crazy.

You will get sound arguments and good logic on both sides. You will have to decide for yourself which to listen to.



Asking here guys: "IF" the OP decides he needs to modify the heads for better springs / more lift, are there do-it-yourself cutting tools that will accomplish that, like there are for Vortec heads? Just asking in case he wants to keep/modify the heads but not spend machine shop money.

 

I hear you, Sometimes you really just get too much info. Trying to digest it all is overwhelming. I've decided to do the headers and y pipe with the full 3" to the tail. Drive it for a bit and then do the cam once I've got the car back on the road. I was just deep into the engine bay and it made sense to get all the engine work done. Either way I'm going to do it all, just sometime don't understand why people just keep going with a full fix. You have to draw the line sometimes on where to stop. I've got a long way to go. Getting the parts ordered today and hope to get into it next week. Thanks for your help guys!!!

 

Step 1: FULL exhaust. Period. The factory exhaust IS the single greatest bottleneck. You will not realize the benefits of any other changes until this is done.

Step 2: Camshaft and valvetrain. Sofa posted the exact part numbers to order. NO MACHINE WORK TO THE HEADS.

DynoDave43 - just the cost of purchasing the valve guide machining tool is more $$$ than his stock heads are worth. My .

 

Yes. Been around for years, not specific to Vortec heads at all, although they have added the specific tools to fit those heads' needs since they appeared. Not hard to use at all, although also only as precise as the user's setup. Also, as said, not cheeeep. And also as said, not necessary in the present instance. Good to know about for other projects though.

Arbor for 11/32" valves (uses the guide as the ... guide) https://www.summitracing.com/parts/cca-4732

Guide cutters .500" https://www.summitracing.com/parts/cca-4715
.530" https://www.summitracing.com/parts/cca-4726

Seals .500" https://www.summitracing.com/parts/cca-510-16
.530" https://www.summitracing.com/parts/cca-503-16

There are also spring seat cutters that go with that toolkit, but once you get into that, there are dozens of ways the whole deal can go sideways. Not least, many stock heads have a sort of bulged-out place in the water jacket beside many of the spring seats, which you will hit water if you try to cut the pockets for larger springs, and go anywhere near the full depth of the existing pocket. Not a good project for a n00b.

I agree 100%, exhaust is the 1st thing that should be done to that motor, as I stated above. Cam or heads is next. However the OP asked about cams so we started there. As said, the benefits of the cam will not be fully realized - not even close - with the stock exhaust still on there.

 

To the OP, I went Hooker 2055 shortie's to a magnaflow 3 inch cat to a stainless works 3 inch cat back. It has 2.5 from the headers to the merge and 3 inch from there the rest of the way back. It sounds great and should last a long time. It was pretty spendy though. My main point to you though is, my but dyno can tell no power difference of any kind which, is kind of depressing. I just thought you should know that those other restrictions are numerous enough to kill the desired effect early in the HP game. I have an L03 like you with a 700R4. Sorry for the bucket of cold water on this.

 

What is your fuel pressure under load and what is your timing set at? Low fuel pressure and retarded timing have made more of these a slug than anything else.

 

Agree with this and also are you running the stock air cleaner assembly? That’s pretty restrictive. A dual snorkel (if you can find one) or even an open element will make a difference.

 

Whatever he does, needs to ditch that stupid spacer ring as well. I replaced mine with a 1" open center TBI spacer. Just found a cheap 2 hole one and cut the center out on mine.

 

Definitely

 

I also used an injector pod spacer, helps the TBI breathe, especially if it has the ultimate TBI mods done to it.

 

No mods on my car at all. It had the exhaust seam weld leaking from a thousand spots on the exhaust pipe from the manifold to the rear bumper when I bought it, so I did an upgrade. I have flipped the air cleaner lid to have about a quarter inch space all the way around the circumference of the lid with no noticeable power (or sound) improvement either. I did check to see if it had distributor weights that I could change when I did the cap but it is apparently too high tech for that stuff. Anyway, sorry for the thread jack. I'll search TBI mods to see what I can do as it's pretty slow.

 

-HO manifolds or headers, 3” y-pipe and cat back
-Open element air filter
-Bump base timing to 6 BTDC, 93 octane fuel
-Change rear end gears to 3.42’s

Wont be a rocket, but it will wake it up and will be a lot more fun to drive.

 

Thanks, I'll try. Got the exhaust I'll give the rest a go.