Hey there,
I've got a 1986 z28 that's got the 305 in it that I want to do a few upgrades to. I'm thinking about putting a new camshaft and lifter kit in it, and replacing the headers and exhaust as well.

My first question is what is a good camshaft to put in this engine? Keeping in mind that I'm not very experienced at this stuff as this car is a learning project for me as well. I have learned enough to know that since I have a 5 speed I dont have to worry about a stall converter. A local racing parts shop suggested one that was 214 duration @ 50. I'm not even sure exactly what it means but he said it would be a good performance boost. Advanced has one that didn't show the duration but was made by Lunati and said it was 900-5400rpm. They also have a similar Elderbrock.

The other thing I plan to do is replace the headers and exhaust. Again the racing parts guy told me he had the headers in stock for either 1.25 inc or 1.75 in. I had thought about going to a 2 inch exhaust system as I can't remember where but someone else told me that 2 in would be a good size. The guy at the racing parts store said 2 in pipes would be to big for my engine though. So what size header / pipes should I be looking to put on the engine?

Thanks for any advice on the subject!

 

The cam should be computer-friendly. It probably won't be a problem with the duration you've been recommended, but if you have the details on the Lunati cam, that would be helpful. Most likely the Edelbrock cam would not be a good choice.

Exhaust - pick parts for the '86-'90 TPI single cat application. I know, that isn't what you have, but that's what will work best and bolt in. The Hooker 2055HKR and Catco 9118 fit that bill, and whatever cat-back you want that is made for that application should be fine. As for sizes, there are different sizes for different locations. For the header primary tubes, you want at least 1-1/2" for a low RPM engine, and no more than 1-5/8" for a high winding 305 (the 2055HKR are 1-5/8"). The pipes coming off of the header collector should be 2-1/2", and the exhaust after the two sides come together should be 3" (which the 2055HKR Y-pipe is).

 

Dont buy an edelbrock cam. Buy a modern grind by Comp or Lunati etc. Like the xtreme energy or voodoo series. Stick to cams that have less than 220 @ 50 duration. The comp xe256 at I think 212/218 would probably be pretty nice. Just make sure you get one thats computer compatible.

Anyway if all else fails just come back here and give us the specs and the guys here will set you straight pretty quick.


I think you're stuck with a flat tappet cam since the roller blocks werent out in 86. So be aware of what it takes to break in a new flat tappet cam. 20 minutes at 2k-2.5k RPM. I like to vary it up a little as you go. Use break-in lubricant like Comp's Break in Additive and use their break-in lube too. Whatever brand you go with will likely have their own greases and oils to apply here and there to make sure the cam survives break in. After break in, change the oil, Then change the oil 500 miles later, and 1500 miles after that, then resume normal intervals. I am very paranoid with a fresh flat tappet cam, so I change the oil a lot and use break in lube every oil change. Some people get away with running no break in lube and changing the oil once, right after break in. But Im paranoid.

Anyway as long as you do it right it will go just fine.

 

carb or tpi?

 

Mine is a carb.

I called and got some more specifics on one at the local racing parts store.

It's a Engine Works, 214 @ 50 duration, 280 advertised duration, 443 lift. He said it has a dual center 107 and 117. It also comes with the lifter kit for $130 dollars. Seems rather cheap for a performance cam but figured I'd run it past you guys to see what you thought?

 

Thats around the right size but from what I gather about that brand they're more of a discount brand to help machine shops sell budget performance parts. I doubt that cam would make as much power or be as streetable as a good modern grind by one of the big cam companies.

Quick cam lesson:

The advertised duration (although every company measures it a little differently, but we can get a rough idea), the 280 number you threw out, that number is how long the valve is open during the rotation of the engine. This is what determines the street manners of a cam. It will affect idle quality and low end torque - for the worse. The bigger that number, the bigger the cam acts as far as practical drivability reasons are concerned.

The number at .050 (inches of valve lift) is how long the valve is open a significant amount (050 inches). Enough to actually matter for performance. Your valve is open at least .050 inches for 214 degrees, and open at least .001 (adv duration) for 280 degrees. 280-214 = 66 degrees.

The idea is to get the most power, and keep the car as practical as possible. The best way to do this is to open the valves real quick, so the drawbacks of having the valve open so long aren't as apparent because you get more duration at .050. Or you can go with a smaller cam and get a better idle, better vacuum, better streetability, and make the same power. You either get more practicality with the same power, or more power with the same practicality depending on which way you go with those duration vs duration at 50 numbers.

Anyway the idea is you want the valve to open quickly and close quickly. Your Engine Works cam has 66 degrees of rotation where it's in limbo zone destroying your idle quality and vacuum and not making any power.

Compare it to a modern grind like a Comp Cams xe256. It keeps the exhaust valve open longer because most smallblock chevy heads dont flow very well out the exhaust port, so the extra valve-open-time there helps with exhaust flow and power. The measurements are 212/218 (intake/exhaust) @ .050, and 256/268 degrees of adv duration. That gets you 256-212= 44 degrees and 268-218= 40 degrees. That's 2/3 of the engine works cam.

You'll have an engine that works better if you get a high tech modern cam. You'll get more power and more drivability that way. The xe256 kit with cam and lifters is, I think, $190 or so.

That engine works cam isnt really bad, it's just that you can do better.

http://www.summitracing.com/parts/CCA-CL12-256-4/

 

What do you mean as far as streetability and practicality? The Engine Works for example, is it going to idle rougher or drive rougher or something?

One of the main reasons I was considering that one was because it was in stock nearby and I had time to try and get this done this weekend. It's not a huge deal though, would be nice to do it this weekend but if I have to wait another week then I have to wait.

EDIT:
One other question, that cam you lifted says 1987 to 1998 engines. Mine is a 1986?

Also the computer compatible, what exactly is that for? I didn't think my computer really did anything with my engine beyond the carb for the choke and gas mixture.

 

The stock cam is the best one for just putting around town. It gets you from a to b and so forth. Bigger cams that make more horsepower shift the power curve higher into the RPM range (Remember horsepower = torque x RPM). You can get a giant cam and make all your power from 4000-8000 RPM and have a 600hp motor if the rest of your parts can handle it.

When you open the valves farther and longer, it shifts up the operating range of the motor for reasons that just arent really worth going into here. When you have a motor that's built to run well at 800-4000 RPMs, it will idle fine and pull good vacuum (important for things like brakes and HVAC vents and fuel injection systems, etc). If you have a motor with a big cam that runs well from 4000-8000 RPMs, the idle quality goes to hell, and the vacuum gets really bad.

If you've ever heard a NASCAR v8 idle, or a hopped up drag racing car idle, and you hear all those cracklings and pops and clanks in the exhaust, that's the engine misfiring and running like crap at low RPMs because the cam has pushed the engine's operating range so much farther up beyond the idle speed.

That cam I mentioned is pretty small. Just a notch bigger than stock for a decent stock cam, really. But you probably have the dawg of all dogs cam in that car, so it's a big improvement.

But yes, the idle quality will be worse and the power level will be the same or lower. With a newer high tech cam design like the one I listed, you'll get the same or more power, and better street manners. For cams that small it doesnt matter a WHOLE lot, but it would be noticable if you could try either back to back.

Cam swaps are a big deal and are probably the most important part of an engine build. They're a lot of time and work. I'd suggest reconsidering and getting a really good cam. The price difference isnt much. How many times do you want to go through the trouble to swap it? Might as well get the best one you can.


http://www.summitracing.com/parts/CCA-CL12-234-2/

I was mistakenly assuming you had fuel injection. If you have a carb then you can get the cheaper version that's not computer compatible. Your carb can probably adjust to it fairly easily, since it's such a mild setup. The 87+ thing is probably something to do with it being a computer compatible cam.

Remember what I said about vacuum levels being important for fuel injection? They use sensors that read vacuum to know how much fuel/spark to give to the engine. That's why they have "computer compatible" versions of all their cams. They tweak them to get a little better vacuum readings so the computers can work with them.


At the end of the day though.... since you wont be able to try both to see/hear/feel the difference, and the one that they recommended is of appropriate size for your situation. I doubt you'd regret just getting the local one. I'd be pushing a lot harder for it if you were trying to get a bigger cam than you are, but the one they're suggesting is so small that it means the differences between the cams are going to be smaller too. It might only be 5hp difference between the two cams in your situation, or a 100 RPM idle difference to get the same idle quality (you'd just leave it where it is from teh factory and be just fine probably)

 

Thanks for the feedback.

I ended up having some other things come up this weekend so not going to have time to work on it this weekend. So I think I'll just go ahead and order the 2nd one you linked from Summit Racing. Even if it's a small difference, I'd rather go ahead and get the better cam.

Just got to figure out what I'm going to do about the exhaust now. I was reading somewhere else that said if it's a stock cat on the car to replace that first. I know my cat has been replaced, but pretty sure it was replace with a OEM spec cat.

So for headers it seems the Hooker 2055 are one of the most recommended headers.

Any other opinions / recommendations for the cat besides the Catco 9118?

For the exhaust itself, I know everyone says to go with 3in diameter pipes, is this something I'll need to get a local muffler shop to do, or is there somewhere that I can order the pipes already bent properly where necessary?

Thanks again for all the help!

EDIT:
Wow, I just looked up the Hooker 2055HKR on summit, I'm surprised by the price of these: http://www.summitracing.com/parts/HOK-2055HKR/

What makes this item so special to be so expensive? I mean it's just exhaust pipes lol... figured the camshaft would be a lot more expensive than an exhaust pipe. The headers that I priced at the local racing parts shop were only 100 dollars. But I don't remember the specifics on them. Guessing they didn't come with a Y-Pipe either though.

Are these things really worth spending 470 dollars on? What kind of benefits can I expect to see going to these from stock?

EDIT2:
One other thing. The local mechanic that I have do some worth to my camaro at times when it's over my head or I don't have time (he works on nothing but camaros), told me while doing the camshaft and lifters I should replace the valve springs as well. Are there any special valve springs I should get, or just stock valve springs from advanced?

 

One more set of questions while I'm doing all this to my engine. I'm actually now considering pulling the engine and taking it to a machine shop to get everything remachined, rehoned and all.

Can I put a set of 350 heads on a 305 block? And if so will that change any of the other stuff I plan to put on there? What all would be involved in changing the heads?

Only reason I'm considering this is someone told me that I could put 350 heads on a 305 engine and basically turn it into a 350 for a little more performance, but I don't know how true that is.

 

It'll lower your compression ratio, not really worth the trouble. Most 350 heads are awful anyway. What heads do you already have? 416s?

If you're gonna end up doing machinework on a 305.... why not get a 350 block to start with? A new block is $100 bucks, and all that machinework can easily be $500+

 

I don't know how much of my stuff will transition over to a 350 block? No clue what heads are on it, whatever came on it from the factory.

If I get a 350 block even if I buy it used (I dont know where I can get one for 100, all the ones I've seen for sale have been at least 300 if not more). But then I don't know what all needs to change, I'm guessing I'd need different heads, new pistons are probably needed as well anyway. Would a new intake be needed as well? I mean at that point it's basically a new engine and I might as well buy one from CMEngines that already has all the work done. I was trying to avoid putting a new engine in it, I don't have to do the heads if they don't match well, but the engine is 26 years old with probably 200k or 300k on it (dunno since it only goes to 99.99k). I'm just figuring with as old as it is, if I get in it to replace the camshaft, I'm probably going to discover the cam bearings are bad or going bad.

 

I cant find any in your neck of the woods but this was one of the first results here:

http://macon.craigslist.org/pts/2550941627.html

I would recommend you find a roller block, though. That can be converted with a little work and cooperation form your machine shop, not too bad. But you should have a 1 pc rear main block... I think. And so the newer blocks will fit and MOST of them will have roller cam provisions, which is a big deal.

If you dont feel like looking for a 350 and going through the trouble then it's not a big deal.

But to properly upgrade the 305, you will spend a ton of money on new parts anyway. Boring and honing will require new pistons, new rings, new gaskets, machine shop bills, etc. It adds up real quickly.

Id just replace the cam, break in the new one, and call it good. No need to spend a lot of money freshening up a 305 block. People cant give away 305s, you can find another in good shape easy if yours has issues. It'd be cheaper than doing all that work to yours to just go find another 305. Seriously, I gave mine away for free. You could have popped your heads on it and bolted it up and been fine another 100k miles.

 

Well thanks for the info. The block aside for now, I'm still wondering about the cost of the headers. Are they really worth investing 470 dollars in a set of Hooker 2055 headers? 470 dollars for another 5 or 10 hp seems a bit much. Maybe if I had an engine built to max out hp and was looking for every tiny bit more I could get, but I'm not. I'm just looking for cost effective performance upgrades atm.

 

Those Hookers are really the best option for shorty headers you can get. The thing is if you EVER plan on doing an engine swap years on down the road or whatever, those headers will suddenly become a good investment. Otherwise you can buy cheap headers now and good headers later if you feel like your financial situation will be better 5 years on.

The other issue, and this is the one I have, is that non coated headers will rust out eventually. It may take a while, but $500 for headers that arent coated makes me nervous. $700 for coated ones is even more difficult but at least they'll last a long, long time and they're one of the best shorty headers on the market.

 

Yeah that is the other thing I was surprised about, the fact that they aren't ceramic coated at that price. I just can't see how they can be that much better than a set of 130 dollar headers. If the 130 dollar headers have the same diameters, that seems like what would make the biggest difference...

I don't know.

I'm torn atm between putting a crankshaft in my 305, and just buying a 350 long block with an estimated 340 hp from CMEngines.com that comes with a 1 year warranty for $1896. I can even buy a 3 year warranty on that one for an additional 175 dollars. And that engine already has a performance cam in it that gives it the lopey idle sound that I want, as well as everything in it is new or remachined and cleaned up.

Originally that is what I had planned to do, buy that engine. But then after thinking about it I was just going to do a cam and a few other performance upgrades to mine for now. And now I'm on the fence again because if I were to do mine right (having the heads remachined and all) then I'm spending nearly half as much as just getting the new block with a warranty and all the work already done.

The biggest problem with a new engine like that is I don't have anywhere to park the car in and spend the couple weeks I'd probably need figuring everything out and doing the swap lol. I only have a shop I can work on the car in for a couple days at a time and then have to be able to move it out.