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i have a 1980 camaro 305 4-speed and its all stock and im wanting to get more hp out of it with out killing the miliage or breaking my bank. the 305 puts out alot of torque but the power starts dying off in the higher rpm's and i was wondering how to get some more high end hp without killing my mpg it gets a good 19 mpg which i like very much but i would still like more power.
 

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I have an article that I kept from car craft that used a bone stock 307block factory installed rings pistons and bearings (bottom end). they installed heads,cam,intake, carb and headers and made over 300 hp. the article said that it would probably work well on the 305 as well. I will look for the magazine and give you the issue info. :D Brian
 

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rockandroller1991 said:
i have a 1980 camaro 305 4-speed and its all stock and im wanting to get more hp out of it with out killing the miliage or breaking my bank. the 305 puts out alot of torque but the power starts dying off in the higher rpm's and i was wondering how to get some more high end hp without killing my mpg it gets a good 19 mpg which i like very much but i would still like more power.
I had a new 1981 Z/28 with the 305, 4 speed and 3.42's. MPG's were right around 21, I swapped in an Engle RV-100H cam and removed the catalytic converter. Mleage stayed the same but perfromance improved greatly. It still was no race car but it was a lot more fun to drive. The stock cam in those was terrible, I'd start with the cam and there are even better cams available now, that was in 1981. While you're doing the cam swap install an Edelbrock Performer intake, headers and free flowing exhaust.
 

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You can actually get more power and better gas mileage if you select the right parts.

A better exhaust should help the most on your stock setup: small tube headers, 2-1/4 pipes, high flow cats, and Dynomax Super Turbo's. You should skip the headers if exhaust noise bothers you. But you will lose about 20 hp.

A small camshaft like a Edelbrock Performer Plus would not hurt mpg and would help power a lot. 204/214 duration, 0.420/0.442" lift. A compcam 252H would also be a good choice (206/206) if the heads you use flow well on the exhaust.

Use a Edelbrock Performer intake with a stock Q-jet carb.

The biggest improvement you can make is with the cylinder heads. But you need to know the stock compression ratio and what cc heads you have now so you can select a head that will maintain the same compression ratio or increase it a little. Check your head casting numbers and the stock engine specs then do the math to find what cc chamber you need.

A set of vortec heads would be the cheapest but would require a Vortec style intake, valve covers, and rocker arms. So they will end up costing the same as a set of 180cc darts that would just bolt on. 180cc darts come on 49, 64, and 72 cc chambers.

I bet you could almost double the power and increase the mpg if you install exhaust, cam, intake, and a set of modern style heads. A mild 305 build can easily make 280hp (using headers) with out hurting mpg. Should get your car into the 13's 1/4 mile.
 

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I think your biggest improvement per $$ will be the cam.

My cams of choice would be the extreme energy series CompCams XE250H or XE256H maximum. Get the valves open with little duration and lots of fast opening ramp. Buy the cam, lifters, gears/chain, springs as a set. Degree the cam. Break in cam with the old weak springs.

A second consideration would be 1.6 rocker arms for slightly more lift// only if I needed to buy new arms and $ were available.

Headers 1 1/2 inch preferred, maximum 1 5/8. Keep the collectors 2 1/2 with dividers and at least 16 inches of 2 1/2 and use maximum 2 1/4 inch mandrel pipe, Walker Super Turbo mufflers. Cats optional. H pipe or X pipe if you like its sound.

I'd do all the obvious things, tune up, ignition curve, etc, cold air intake.

Trouble is, your mileage will go down, because you are romping on it so much more because it feels soo much better. :thumbup:
 

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On the cam break in I would also suggest removing the inner valve spring just for the break in, then install what ever spring you will be using when you are done. And as far as the article I was referring to it was not car craft it was Super Chevy April 06 issue in the Tech section :thumbup: .Brian keep that old iron on the road........ :thumbup:
 

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The stock z-28 intake system (the filters and tubes and stuff) can be modified; I read an article once about modifying the stock ducting by trimming down a rain baffle to get abou 5 more hp. I also found this, but I can't see the pics since I'm not a member. The site would be more specialized and is geared for what you have...

$10 dual snorkel plans

...btw I hang around my Jeep, GrandAm, and AMC websites. This is the best for more general advice, and sometimes specialized advice from certain members. :thumbup:
 

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brian0605 said:
On the cam break in I would also suggest removing the inner valve spring just for the break in, then install what ever spring you will be using when you are done. And as far as the article I was referring to it was not car craft it was Super Chevy April 06 issue in the Tech section :thumbup: .Brian keep that old iron on the road........ :thumbup:

Those cams recommend single springs. Use the old weak springs for break-in.
 

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I would not recommend any extreme compcams. Sure, fast ramps make more power and look great on the dyno. But for how long? Fast ramps wear out much quicker and make for a noisy valve train. That is why I would stay with compcams the high energy series cams, 252H, 260H, or 268H, and give up a little power for more longevity and for a more quiet operation. Especially now with the crappy engine oil, a lot of cams are going flat due to "extreme" ramps. And a cam going flat eats up more than just lifters, engine bearings get chewed up from all the metal in the oil.
 

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Before you do anything, make sure you current setup is working to its fullest potential. Otherwise, you won't realize the full benefit of new cams, heads, intake, etc... The nice thing about the late 70 & early 80 GM's is that they have a considerable amount of potential for tuning.

First, address your timing. The mechanical advances in the '80 HEI's don't fully advance until 4600 RPM's (or something close to that). Re-curve your advance so you are "all-in" by about 3000 RPM and make sure your initial & total timing are correct. This should cost your less than $20 bucks if you have a plain-Jane timing light. You should notice a slight seat-of-pants improvement.

Second, address your fuel system. It is a 4 bbl Q-Jet, right? Make sure the idle air mixture is correct (limited adjustment on that year). Make sure the float levels are correct (ie. rebuild it). Have somebody hit the gas & make sure the primary & secondaries open fully (mine didn't on my 80!). Make sure your primary throttle shaft has no play, otherwise, have it bushed to cure the vacuum leak. Also, make sure the base plate is not warped. You may even find some benefits from slightly larger jets/rods. Check that your lines are not kinked, that your tank's pickup screen is clean (drop the tank - yuck), and that your pump is up to the task. Again, relatively cheap here.

Third, let your exhaust breath. Now you're spending a little money.

Then, change cams & intake. Now you're spending more money. The best bang for your buck would probably be to find some decent vortec's & a matching intake/cam. I hate to see people put fresh heads on an old bottom end though. You'll suck oil.

Good luck!
 

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454C10 said:
I would not recommend any extreme compcams. Sure, fast ramps make more power and look great on the dyno. But for how long? Fast ramps wear out much quicker and make for a noisy valve train. That is why I would stay with compcams the high energy series cams, 252H, 260H, or 268H, and give up a little power for more longevity and for a more quiet operation. Especially now with the crappy engine oil, a lot of cams are going flat due to "extreme" ramps. And a cam going flat eats up more than just lifters, engine bearings get chewed up from all the metal in the oil.

CompCams refutes that. Their top engineer Billy G. says the XE is easier on the valve train since the nose profile is more radiused and the ramp toe sets the valve down softer.

If you run crappy engine oil, then why would that be the cam manufacturers' problem?????? Oil degradation has been no secret the last 3-4 years, why would anyone run insufficient oil NOW when installing a new cam??????.

You should have an oil filter to strain most of the particles out of the oil..... true it still frags the engine pretty well. But I have seen more than a few engines in the last 15 years or so that had very flat lobes, and they installed new cams and "kept right on truckin"...... :rolleyes: :rolleyes: But I don't recommend it. (But I did it once to a beater...... that last time I saw it, it registered 100,000 miles more and the engine had not been touched)
 

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My brother in-law and I used to swap cams into 100k plus engines all the time with no problem, and even new/overhauled cyl heads and not had any real oil consumption issues. I guess the main reason is ,we may have had higher milage stuff but, it had been taken care of prior to us getting it. As far as the oil degradation issues, I do know that they have lowered the zinc content in some motor oils. This was due to Manufactures requirements. GM in particular claimed that they were having problems with cat converters plugging up, and that it was from the zinc in the oil. Zinc provides excellent lubrication/antiwear characteristics. If you want to use an engine oil that still has the higher zinc content,you need to use a motor oil that has a dual rating that includes diesel engines,generally with a viscosity of 15w40. I know some of the nay sayers out there are probably gonna jump all over me :spank: :nono: but that's ok , they can come tell it to some of the 2000 model gasoline engined trucks (4.3l GM) that have over 350,000miles and was changed every 5000miles the entire life of the truck. They don't have to add oil between changes and it is generally 1/2 qt low when I bring it in to the shop for PM inspections. The drivers generally drive them 200 to 350 miles a day 5 days a week. :D Brian
 

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brian0605 said:
My brother in-law and I used to swap cams into 100k plus engines all the time with no problem, and even new/overhauled cyl heads and not had any real oil consumption issues. I guess the main reason is ,we may have had higher milage stuff but, it had been taken care of prior to us getting it. As far as the oil degradation issues, I do know that they have lowered the zinc content in some motor oils. This was due to Manufactures requirements. GM in particular claimed that they were having problems with cat converters plugging up, and that it was from the zinc in the oil. Zinc provides excellent lubrication/antiwear characteristics. If you want to use an engine oil that still has the higher zinc content,you need to use a motor oil that has a dual rating that includes diesel engines,generally with a viscosity of 15w40. I know some of the nay sayers out there are probably gonna jump all over me :spank: :nono: but that's ok , they can come tell it to some of the 2000 model gasoline engined trucks (4.3l GM) that have over 350,000miles and was changed every 5000miles the entire life of the truck. They don't have to add oil between changes and it is generally 1/2 qt low when I bring it in to the shop for PM inspections. The drivers generally drive them 200 to 350 miles a day 5 days a week. :D Brian
Note that those are roller cams and highway miles.

I AGREE with you. I think that either diesel or race oils, or even synthetics are the way to go in modern engines, especially when lower viscosity diesel oils are not available for the engine requirement.
 
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