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I have a 1980 with the L-48 350 and TH350C transmission. Stock engine with headers and true
dual exhaust, no cat. I had 3.54:1 diff gears installed. Switched out the stock alternator with
a 150-amp unit. Have electric headlight conversion kit to install, and a new 3-core aluminum
radiator/electric fan unit, as well.
Beyond that, the engine is pure "Snore"vette.
My dilemma is this - I have a SBC 400 block, bored .030 over sitting on an engine stand.
My intention is to build the 400 and drop it in the vette. However, after looking at the cost
of the parts (in excess of $7k - there is a supercharger involved...) I realize this build is going to take a while (I have two daughters and 3 ex-wives)
So, as I am building the 400, I want to make the car more enjoyable to drive in the interim. I want to pep it up without taking meaningful funding from the 400 build, as they are pulled from the same account.
Here is where I stand as far as parts on hand that were bought to put on the 400, but will work for the 350 as well.
Sniper Fuel Injection system, new in box waiting install.
'Massaged' Edelbrock 2101 intake.
Sticking with the stock heads. I'm going to buy heads for the 400, and can't justify buying a
set for the 350 as well. Yes, I know 400 heads will physically fit, but the 200cc runners would
be too large for the 350 as it is.
I am looking for a good Hydraulic Flat Tappet cam to put in. Something better than the smooth-lobed
stock cam that'll liven up the engine. Maybe a slight idle lope, but want streetable vacuum. Will the stock valve springs handle .470 lift? There are
kits available with the cam, lifters, valve springs/parts, roller timing chain for approx. $500. That's a hit I'll take on the non-swappable parts budget if I believe I'll get a good ROI in "grin-factor".
Also looking at some 1.6 roller rockers. You can use roller rockers with a Flat Tappet Cam, right? (The rockers will be swapped to the 400, so that's not a negative number from the budget...)
So given that I will still have the 8.2:1 compression ratio and stock 76cc heads, headers with 2.5" true dual exhaust/no cats. Will be using stock
torque convertor, and 3.54:1 rear end gears. What cam profile would you suggest?
I feel your pain.
I have 4 ex wife's and 3 Sons.
Although 2 daughter's might be a bigger expense than 3 grown Sons.
As per your cam. Comp Cams 268H grind. Not the Xtream, just the old school 268H. Yes it'll work with your completely less than great stock heads and low compression. Yes you can run roller rockers. Yes you will need pushrods. Not sure if the stock valve springs will take the 1.6 rockers with this cam. I think they will. Jebby will know for certain. Perhaps he'll chime in.
First off I would not put a dime into hoping up a stock 400 sbc. Just my opinion.
But if you are there is no problem using 195 to 200 cc heads with 64 cc on 350 ci. You could also install a h roller cam in l48 and later put it and the heads on the 400. The 400 could use dished pistons of some bigger cc for boosted building. Ive built boosted motors with 9.6 static cr and boost level timing retard msd boxes
I drove my vette with highly efficient 3500 and 3800 stall 9.5 inch torque converters for over 100,000 miles in about 20 years.
An h roller with 112 lc of something like 232/238 is very tame in both 350. and 400 ci. I also have and only use all billet steel Comp Camshafts with sleeved on dizzy gears. Never a flat lobe and reused them in build after build.
Just a note. The stock l82 cam is a 222/222 @.050 duration. So I have never seen the point in going into lesser duration 268 cams which are 218/218. My first l82 motor upgrade was bigger 64 cc heads and 278 cam with 112 lc
Note 2. Dual planes have smaller exit ports than say afr 195 heads. So my l82 went to team G single plane 750 carb and the changed the TC to a Vigilante 9.5 inch 3000 stall TC. I also had the 3.55 rearend. With a hopped up th350. Even though my 350 was a 7200 rpm motor it lost it's usefulness and fun. So I went to a high end 383 which raised the stall of the TC to 3500 because of the TQ.
Note 3. Edelbrock 2101 is actually an inferior design when compared to the L82 aluminum which was a performance GM design for quadrajets. We did dyno testing way back when and the EDL lost power VS the l82
gkull makes some good points, and all the above makes perfect sense.
However, the OP isn't working on a L82. He's working with a box stock L48 low compression engine and has stated he would like to keep his stock converter for now.
So, I still believe the 268H cam, which I have been told was basically designed for these low compression engines is an excellent choice. It should work great with his already installed exhaust upgrades and otherwise completely stock engine.
Don't throw good money (and time!) after bad. Do it cheap, once, and quickly, by swapping in a running junkyard engine.
I knew it. I KNEW it. LOL I knew someone would bring up LS Swap, and yes it does seem tasty.
I know folks can come up with countless reasons to ditch the 406 in favor of an LS. I know the 406 can't hold a candle to the newer technology. I get it 100%. However, there is just one thing that 'trumps' all of the rational, well-reasoned,and eloquently-stated opposition in my quest - I want a 406 in my Vette, and that is what I shall have .
When I was test-driving it after a thorough inspection, the main thought in my head was "This thing needs a 406". Seriously - true story .
Despite all of the modernization/updating/electrifying evrything I can (within reason), I really like the idea of keeping the engine generation-specific. Plus I LOVE the look and sound of a Roots supercharger sitting on top. Kind of a visceral/animalistic thing, ya know?
I do appreciate all the input. I have the COMP High Energy Cam (268H-10 grind) in my Wish List. Now just have to gather all the associated parts that need to be replaced after 44 years.
I knew it. I KNEW it. LOL I knew someone would bring up LS Swap, and yes it does seem tasty.
I know folks can come up with countless reasons to ditch the 406 in favor of an LS. I know the 406 can't hold a candle to the newer technology. I get it 100%. However, there is just one thing that 'trumps' all of the rational, well-reasoned,and eloquently-stated opposition in my quest - I want a 406 in my Vette, and that is what I shall have .
When I was test-driving it after a thorough inspection, the main thought in my head was "This thing needs a 406". Seriously - true story .
Despite all of the modernization/updating/electrifying evrything I can (within reason), I really like the idea of keeping the engine generation-specific. Plus I LOVE the look and sound of a Roots supercharger sitting on top. Kind of a visceral/animalistic thing, ya know?
I do appreciate all the input. I have the COMP High Energy Cam (268H-10 grind) in my Wish List. Now just have to gather all the associated parts that need to be replaced after 44 years.
Just throwing a Cam in his old L48 will give it a little more "Smiles to the mile"
And if his new engine is a few years out. Why not?
I wouldn't even change out the cam bearings if they even look OK. Perhaps a timing chain, necessary puchrods, gaskets and done.
I do believe it would help.
Not everyone wants to put an LS in there old car!
I know I don't.
I just bought a 400 block (I want to stay OEM+) with the intention of building a stronger motor than the 350 I currently have, but it might take a year or two before it gets built (no supercharger) and dropped in the car.
In the mean time someone installed a wild cam in the 350. No real power below 3000 rpm, a very loppy idle and no power above 4000 RPM because stock manifold and exhaust.
I want to maximize torque for the street, so I bought the cheapest camshaft/lifters/pushrods combo at Summit and I'm going to do the install before summer so I can enjoy the car a bit more.
gkull makes some good points, and all the above makes perfect sense.
He's working with a box stock L48 low compression engine and has stated he would like to keep his stock converter for now.
.
I know that he said L48 I was commenting on how inferior the 2101 intake manifold is.
When I first got into road racing I did an experiment using a th350. I had a shop build me a extemely low stall converter like 1500 rpm behind a .060 over 327 with a mechanical lifter cam in a chevy monza spider because the stock 5 speed was very weak. My friends and I had installed a full manual valve body so you shifted up and down going around the track and it more like a clutchless 3 speed. The higher stall just gets you going and into the TQ range faster. It proved that you can use a low stall even less than stock TC's even in a hot rodded motor. My take off suffered, but once you are rolling who cares and I got the compression braking benefit. Later hot rod magazine entered a 396 BBC Camaro in the 24 hours of Daytona using the same idea and I think that it was doing up near 200 on the high banking using a full manual low stall TH400
Most people who want a cam in a motor are not looking for performance they are looking for the sound. That is what those 268 (10) cams are. They juggled the valve events to make it sound like a race car. The Comp Cams Thumper cams are another prime example. Radical sound, all show, and NO go!
Be careful whose advice you listen to here……some only think in 6000 rpm driving. If that is you, fine, but if wanting a street car, less duration makes torque, better carb signal, and better acceleration off idle, and a solid torque curve. Torque is what moves the car. High duration only works better at high RPM, where very few real people actually drive there Corvette. Figure out who you are first, and then pick a cam around that.
The racer boys will lead you down a disappointing path…..I know. When comments start with…”when I was road racing” I stop listening.
A running junkyard engine is still a running engine.
Thinking I'd want a 400 (likely a high-reving 377) in my 80, I bought all of the bits to do a compromise rebuild of the spare 60K mile L48 I was about to have. Vortec heads, really nice distributor, a bunch of stuff that I could run for a while, and build a 377 on my own time. Stop me if this sounds like what the OP intends.
I got the L48 heads pulled off, and realized the motor was trashed. Not worth rebuilding, barely worth saving (for the matching VIN stamp). I started selling or giving away all of the SBC stuff I had collected.
less duration makes torque, better carb signal, and better acceleration off idle, and a solid torque curve. Torque is what moves the car. High duration only works better at high RPM, where very few real people actually drive there Corvette. Figure out who you are first, and then pick a cam around that.
Signs of a very limited old school mind set! How much HP & TQ does a wimpy L48 make? I just looked it up.
185 HP @ 4000 280 lb-ft @ 2400 rpm. I couldn't find a 1/4 mile time, But I imagine 4 cylinder cars could beat the l48 vette. With all it's old school wimpy cam TQ. Then lets jump forward to a Using a H-roller cam that I suggested using like whats in a 5.7 Vette ZO6 motor. 405 hp (411 PS; 302 kW) at 6,000 rpm and 400 lb⋅ft (542 N⋅m) of torque at 4,800 rpm.
You put 195cc heads and a roller cam on a 350 it will make more HP and TQ than any l48 at all rpms. The original poster said that he was trying to save money and use a blower in the future. So the cam and heads I suggested would work in both motors. Just do some reseach and look at dyno runs of 268H10 cam with l48 base motor. Very disapointing at all rpm. As I hopped up my L-82 the MPG also increased to the point where I wouldn't even start to look for gas stations untill I was up around 450 miles on long trips and I had a 7000 rpm from a ballanced stock bottom end l82
I knew it. I KNEW it. LOL I knew someone would bring up LS Swap, and yes it does seem tasty.
I know folks can come up with countless reasons to ditch the 406 in favor of an LS. I know the 406 can't hold a candle to the newer technology. I get it 100%. However, there is just one thing that 'trumps' all of the rational, well-reasoned,and eloquently-stated opposition in my quest - I want a 406 in my Vette, and that is what I shall have .
When I was test-driving it after a thorough inspection, the main thought in my head was "This thing needs a 406". Seriously - true story .
Despite all of the modernization/updating/electrifying evrything I can (within reason), I really like the idea of keeping the engine generation-specific. Plus I LOVE the look and sound of a Roots supercharger sitting on top. Kind of a visceral/animalistic thing, ya know?
I do appreciate all the input. I have the COMP High Energy Cam (268H-10 grind) in my Wish List. Now just have to gather all the associated parts that need to be replaced after 44 years.
sell the 406 to me
I already have the ported 190 64cc heads on my 355 currently and the roller cam. My car is just a street cruiser so I'm looking for grunt and torque not so much high rpms and an LS wont work with my sidepipes without spending more than the cost of the engine to buy the custom ls version.
I seriously am planning on going to a 406 eventually. the mild 10:1 355 I build back in 2012 is running great but you know how it is.. You always want more.
I do have a 268h cam and matching lifters with less than 800miles on it sitting on a shelf. I ran a lunati voodoo 262/268 cam in my 355 before the comp 270hr roller and the 270 cam did wake the engine up a bit even though its not that much bigger. The issue I have now is the stock converter struggles and I have a lot of issues with stalling at lights and such unless I set the idle higher.
Remember depending on how my power you end up with you will also need to address the rest of the drivetrain which will become the weakest link. I have another trans and rear end to swap in mine because regardless on power the 3.08 rear end makes it bit of a lazy dog and from everything im told it just gets worse with a big cam which often gives up torque at least if you have a street converter.
My stock l48 sits in the corner of the garage on a stand collecting dust... wasnt even worth messing with.
Hopefully you sprung for the sniper 2 system as its leaps and bounds better than the regular sniper they are still selling for some reason. still... not exactly a cost effective upgrade for your current setup.
Last edited by augiedoggy; Feb 25, 2024 at 10:50 PM.
You've got some options if you want to cam swap your L4Great. The aforementioned Comp Cams Magnum 268H (not the Extreme Energy 268!) is (was?) the most popular option for this sort of thing. There are some alternatives which can also achieve your goals:
Summit Racing 1065 (made by Elgin Performance). <--- I put this cam in my '80 L48 4-speed car with 3.54 gears and a Holley Sniper. Enough vacuum for the power brakes and the headlight systems.
Isky 264 Mega Cam (214/214)
Summit Racing 1103 (214/224 112 LSA)
Whichever you choose, don't reuse your stock, tired valve springs. A new set of "Z/28" springs is not expensive and will work well with the above listed cams. Pick a quality set of lifters as well. I went with Melling 817's. If you go with the Comp cam, it will come with a packet of red goo that they want you to put on the lifter feet and cam lobes when you put the cam in. Throw it in the trash. Get a tube of the Moroso moly paste to use. You've already got headers which helps a ton with power output. If your Sniper isn't controlling your ignition timing, then a proper HEI curve works wonders too.
The great @Jebbysan has a recipe for the new cam break-in that works. I followed his steps and had no trouble breaking in my new 1065 cam.
My 1980's nearly stock L4Great chopping potatoes with the 1065 cam...
To everyone who responded - Thank You. Your input is truly appreciated and welcome.
I know my car was getting 4 mpg after setting timing and 'adjusting' the Quadrajet carb. I am worried that the timing gear set has deteriorated (44 years old), maybe slipped a tooth ..... So I KNEW I was going to be replacing the timing gear set with a true roller set. After thinking about that for a minute, I realized that replacing the timing set was pretty much half way to a cam change. So, I figured since I was half-way there, why not change the cam....?
Comp Cams High Energy Camshaft 12-210-2, Actual Dur - 218/218, Lift .454/.454, 110 LSA lifters
valve springs with retainers, locks, and seals
True Roller timing chain/gear set Harmonic balancer
Water pump (replacing original unit from factory)
Valve covers (just for aesthetics)
Timing chain cover (aesthetics, as well as needed new one due to balancer marking difference, coupled with Moroso Adj. timing pointer set)
Holley Sniper w/ in-tank fuel pump
Edelbrock 2101 intake manifold
3-core aluminum radiator with electric fan
front shocks (already had)
front sway bar bushings (already had)
Electrical headlight actuators
Radiator core support
Adjustable/high tech/cool looking alternator bracket set
new squirrel cage blower fan
There are some other associated bits/pieces/brackets I'll upgrade/work on that are too tedious/trivial to list out.
Not associated but I think this could work as far as audio goes - I have a new radio installed in the center console, with an amp in the passenger side behind seat storage area hooked up to a custom speaker box mounted in the cargo area. Thinking I will remove the amp and speakers, replacing them with powered blue tooth, usb-charged speakers (JBL Extreme 3). Will mount the speakers under the cargo cover, and install a USB charging hub and electrical terminal connections [ground/ 12V battery/12V switched] where the amp was. Ought to sound really good.
EVERYTHING I can reach will be cleaned/painted/polished.
Anyway - This is what I have decided to do, and I am pretty sure the 350 will be a tad peppier to drive until I get the 406 built.
Once again - I truly thank everyone for you input.
Spent the last 2 days (couple of hours after work each day) getting the radiator fan shroud cleaned/painted and installed on the radiator. See pic for results. Cleaned/sanded/cleaned/primed/painted with 600 degree ceramic engine paint. Painted all the bolt heads/washer w/ semi-gloss black 600 degree engine paint. Installed 3/16" (compressible to 1/8") weather stripping between shroud and radiator at top and bottom flanges. Split vacuum (long, small hose from head light vacuum hose assembly) and fit them on the side rails. This results in a 100% seal between the shroud and radiator).
Spent the last 2 days (couple of hours after work each day) getting the radiator fan shroud cleaned/painted and installed on the radiator. See pic for results. Cleaned/sanded/cleaned/primed/painted with 600 degree ceramic engine paint. Painted all the bolt heads/washer w/ semi-gloss black 600 degree engine paint. Installed 3/16" (compressible to 1/8") weather stripping between shroud and radiator at top and bottom flanges. Split vacuum (long, small hose from head light vacuum hose assembly) and fit them on the side rails. This results in a 100% seal between the shroud and radiator).
Originally Posted by Bikespace
That fan shroud looks familiar!
I'd suggest you have a read through this thread before you mount it.
Stock engine Camshaft replacement question
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