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Time to upgrade my l-48

Old 09-16-2018, 12:20 PM
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nick0187
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Default Time to upgrade my l-48

Even though my stock 1975 l-48 is already soooo fast, I'd like to be able to beat a Kia Rio at some point. I am on a budget as most of us are, but would like to get more out of my engine. After doing some research, I know I can't afford aluminum heads, so I'm thinking about going for used vortec heads. I believe I will need a vortec intake and a drop-down air cleaner as well. I know very little about engine building, just from what I've read in the forums and online at other sources. I'm not trying to get 350hp out of the engine, maybe 250 so it's more enjoyable to drive. There is already a set of true dual exhaust, I had the carb rebuilt by lars last year, and I will upgrade the distributer according to lars' paper this winter.

My question is what should I look for when getting a used set or vortec heads? Is there anything special I will need to look for? I found a set of 062 vortec heads and intake with 5000 miles on them from a crate engine for $650, is that a good deal? Should I just keep the stock cam? I'm looking for more low-mid range power for street driving..

I know this subject has been covered a bit, but any advice is appreciated, I'd love to learn more from your experiences and expertise!
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Old 09-16-2018, 12:36 PM
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That would wake it up..yes a small cam would really help too. You may have to pull a plug wire off for those Kias
These run into a lift issue & have the guide boss turned down. , need to make sure they arent cracked. With 5k mi they are probably fine
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Old 09-16-2018, 12:40 PM
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Guide boss turned down, no clue what that means..lol
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Old 09-16-2018, 01:02 PM
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H-m-m-m-m. Getting mixed messages here.

You say your budget does not allow for new aluminum heads. You also are eye-balling some used heads for $650. These will most likely need a minor overhaul that could reach into hundred$ more.

Brand new aluminum ProMaxx heads, complete, valves, springs, retainers, stem seals, guide plates shipped to your door: around $690.
But, and there's always a but. You will need longer pushrods $100 and you will need ARP headbolt set $130.

Something else to keep in mind with buying any used heavy car parts is the return shipping in the event there is something wrong with them. Would cost a small fortune to return. Ask seller for some type of warranty.

Let us review:
Used: heads $650+ (any parts / labor)
New: heads $900
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Old 09-16-2018, 01:11 PM
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Jebbysan
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The valve guide must be machined down on a stock Vortec head to accommodate lift above .450. Comp make a specific tool for this and it can be done on a standard drill press.
Although now you have to buy a dedicated intake manifold. But the beauty of the Vortec head is its high torque capability. The ports are small and flow well......GM did a great job on these for a truck head. Note also that you will need self aligning rockers and centerbolt valve covers to round this off.........
I would hold out for a set of real Aftermarket heads..........spend money now on some long tube headers, an RPM style high rise intake (they will fit with mods on a 73-79 hood) and do the Lars paper on your distributor........it will need some cam but you will be pleasantly surprised. A cam from this point and new valve springs would really wake it up. I like the old school Magnum grinds because they make good power, sound good and break-in easy with their lazy lobes........A 268H Magnum is a great old school cam.
Then.....once you build the cash box up.......swap out the heads for some Dart/AFR/Brodix and it will pick up about 60-70 from there or better.........

Jebby
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Old 09-16-2018, 01:12 PM
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Those Vortecs are limited in the valve lift or in laymans terms: high lift cam. After a certain point of lift the valvespring retainer will actually strike the valveguides, not cool, not pretty. So a trick is to remove some of the material to lower the valveguide, hence higher lift cam.
So you have to ask yourself if you want to get involved with that machining process or not.

These Vortecs heads today are this century's style of the last century's Camel Hump heads. Everybody wanted them. Had to have them to go fast. But as new buyers are finding out, they are limited in valvelift, so some expensive machine work is in order. And some buyers are shocked that they can no longer use their favorite intake manifold due to the different bolt pattern.

Last edited by HeadsU.P.; 09-16-2018 at 01:14 PM.
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Old 09-16-2018, 01:50 PM
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If you are looking to save money, why not just buy a good set of new cast iron modern heads and call it a day? Forget the Vortecs.........
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Old 09-17-2018, 05:50 PM
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Thanks for some good info, I’m still learning a lot about how to tackle this project. I don’t think i can afford to drop 1000 on the motor right now, and if it would even be worth dumping a bunch of money into or getting a new engine. I was looking for some cheaper options to have fun in the mean time before i can drop that kind of money into it. New heads might be out of the budget for now based on the good points you guys brought up. I’d hate to get a set of used heads for cheap but have to dump a bunch of money right back into them
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Old 09-18-2018, 08:05 PM
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If all you want is 250hp then get some rebuilt 1986 C4 '128' heads for about $300. Bolt right up and with the 58cc chambers they will add 2 points of compression ratio over your current heads making the engine very lively until about 4300 rpm when the cam cannot supply more airflow. Add some 1.6 rockers to get about 15 more hp out of that L48 .390/.410 lump stick.

The 128 heads don't flow worth a darn but they add compression and loose 50 lbs over your current heads. Change the intake manifold to a 1980 style aluminum to drop another 17 lbs, change to an aftermarket mini starter to drop another 7 lbs. Change to C4 exhaust manifolds to drop another 14 lb. Aluminum water pump takes off 5 lbs.

Fix the timing to 32'ish total and all together you can add 20-30 hp, 150 ft lbs torque and remove nearly 100 lbs weight from your '75 for about $500-600 depending on how well you shop.

That is the recipe I used. While both HP and Torque in a package is optimal, if you have to pick one go for torque in a street driven car.

Last edited by Dynra Rockets; 09-20-2018 at 07:36 AM.
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Old 09-26-2018, 12:54 PM
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I dropped off my L-48 block crank and rods at my engine builders shop. He supplied everything, complete parts including his warmed over cast 882 truck heads. I dropped off intake carb headers distributor. Motor was balanced broke in and run on the dyno. Made 347 HP and 390 tq his bill $3600 CAD. Entire engine build $4200.00 roughly. Runs great idles nice makes good vacuum choke works on and on. gets 20 mpg if i drive it nice. For me that was the way i wanted to go.
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Old 09-26-2018, 01:58 PM
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The Summit Racing Vortec heads OOF will support 0.520 in of valve lift, and have screw-in rocker studs for $349.

Combine this with a new cam and a Vortec intake, and a bolt / gasket set and you're still probably getting close to $1000.


Adam
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Old 09-26-2018, 02:02 PM
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Originally Posted by Grumpy 427 View Post
I dropped off my L-48 block crank and rods at my engine builders shop. He supplied everything, complete parts including his warmed over cast 882 truck heads. I dropped off intake carb headers distributor. Motor was balanced broke in and run on the dyno. Made 347 HP and 390 tq his bill $3600 CAD. Entire engine build $4200.00 roughly. Runs great idles nice makes good vacuum choke works on and on. gets 20 mpg if i drive it nice. For me that was the way i wanted to go.
You paid $4,200 and got used 882 truck heads and a reworked L48 bottom-end and you're happy about it???...

I'll sell you my Corvette 882 heads with the larger 2.02" valves for only $400 CAD; PM me your address so I can ship them to you. ;-)


Adam
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Old 09-26-2018, 04:03 PM
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A few vendors sell Vortec specific spring/retainer/lock kits that allow higher lift cams to be used without having to machine the heads.
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Old 09-26-2018, 04:07 PM
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Originally Posted by nick0187 View Post
I was looking for some cheaper options to have fun in the mean time before i can drop that kind of money into it.
Headers and loud mufflers.
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Old 09-26-2018, 04:48 PM
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Originally Posted by HeadsU.P. View Post
so some expensive machine work is in order.
I had a set machined for higher lift, cost me about $50 at a local shop. Or buy the tool Jebby mentioned and do it yourself.

The part about the intake is true - but scour craigslist first, that can save a few bucks too.

Last edited by cooper9811; 09-26-2018 at 04:49 PM. Reason: spelling
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Old 09-28-2018, 04:03 AM
  #16  
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Budget power can be cheaper than you think.
Call summit racing, and get a lazy *** lobe k1103 cam and lifter kit for $100, (I suggest the summit kit because it is about the least expensive kit on the market, there are other kits that may work a little bit better, but they are more money, and have more aggressive cam lobes) a new valve springs, seals, and keepers kit for $75, a new cloyes double roller timing set 25-30, gaskets for less than 50, find a late 70's early 80's factory corvette aluminum manifold 50-100 (good manifold that saves some weight) ,and you will be happy for now.
Skip the headers and keep your ramhorn manifolds. Unless you shell out the long green for ceramic coatings and turn more than 5k rpm, headers are only good for heating things up under the hood and [email protected] measuring contests. (Headers need a low restriction exhaust system behind them to work their magic)
This isn't a fire breathing, romp em stomp em combination, but it works, especially when you only have a few hundred dollars in the budget for toys.
​​​​​​

I used the same combination on my 74, and it was good. I say was, because I am in the process of building a full roller 383 stroker. Hope to hear from the machine shop in the next couple weeks.
​​​​
I suggested the less aggressive lazy lobes due to the fact that zink has been removed from engine oils due to catalytic converter contamination. So now you have to add zink additive or find a supplier that still puts the zink in the oil. It is available, but a pita. The more aggressive lobes are very dependant on the zink for lubrication.
Until you have the money for heads, there aren't a whole lot of options, but the above listed components will work well with an auto or a manual trans, and you'll still have good vacuum at idle for accessories.
And, if you find a good set of heads, ie, smaller combustion chambers and better flow, this cam will make you even happier.
​​​​​​
​​​​​​Keep in mind, you are fighting the factory low compression, and if it is still there, a catalytic converter.
When you have the coin, get heads, update to a roller cam, and buy some 2 1/2" ramhorns. Although, when you go to higher compression you will have to start thinking about the bottom end of the motor. Even more coin.
​​​​​
​​​​The flamers will be getting warmed up now, since I have suggested using 1960's technology in an engine upgrade, and have forgone the holy grail of slapping on a set of heads, and on top of that, despariged headers, but it is about the least expensive option.

Good luck at the kia races. Lol
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Old 09-28-2018, 12:04 PM
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Originally Posted by jeffwebley View Post
Budget power can be cheaper than you think.
Call summit racing, and get a lazy *** lobe k1103 cam and lifter kit for $100,ol
Theres a lot of really reasonable and money saving recommendations in there, Jeff; but a a lazy 60s or 70s lobed cam isnít one of them. He already has one of those; why spend money on a Summit branded one? -The horribly low dynamic compression of the L48 motors are definitely a part of the performance and mpg problem. A more modern and aggressive lobe is a no brainer; ESPECIALLY when youíre already recommending he buy new springs.

Totally agree that buying a flat tappet thatís essentially a hydraulic roller lobe is going to lead to major longevity issues- the comp XE series are longevity destroyers, but that doesnít mean you swing back to the extremely lazy 60s oem designs. A High Energy equivalent is about right. Zinc is just a reality if youíre on a flat tappet budget.


Adam
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Old 09-28-2018, 02:10 PM
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Adam, I agree, those lobes are lazy, but he would be getting more lift and duration than the factory cam by a good margin. My concern with the newer more aggressive grinds are longevity. And I have to admit a level of ignorance when it comes to the newer grinds.
I'm just recommending what I have had personal experience with.
I know from experience, the split duration cam with more lift and duration, will give better performance with a stock smog type head. While also not putting excessive stress on the cam and lifter.
Until the man has coin to throw at some heads and other things like a retro roller cam and doing something with the bottom end, something along the lines of what I have suggested will improve the performance now, as opposed to having to wait for the money for heads, roller cam etc...
$300 now and have some fun beating up the unsuspecting kia. Lol
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Old 09-29-2018, 11:01 AM
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That’s all some more great info. Thanks for everybody giving their opinions, I’m learning a lot reading your posts and really appreciate it
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