1980 engine mod questions

[zackm58941]

im new to the board, lots of good info here. i have a 1980 corvette with the base engine (l-48) and i would like to get more power out of it. i already have dynomax ultra flows mufflers, the cat off, 1.52 roller rocker arms and a k&n but not enough power. i was looking at the cam and lifter kit along with edelbrock avs carb and aluminum intake manifold form jegs for 350ci motors and was woundering if anyone knows if this is a good power package? its $564.99 or so and the cam doesnt require the heads to be machined, what type of power numbers might i see with all the stuff i have done, ill prob put a set of long tube headers on later, but i think this a good start. do i have to pull the motor out to get the cam out or can i just take out the radiator and shuffle stuff around? oh, does anyone know the stock l-48 cam specs? sorry for a million question, any info would be greatly appreciated! thanks

 

[AKRAY4PLAY]

as for your cam specs, i don't have exact numbers. it is a good low to mid cam, swapping will move power up in the rpm band. it is possible to swap with motor in car, remove radiator and a/c cooler. headers are a big boost in power, stock manifolds really kill perfromance. heads, your stock heads are durable, but not power house makers. you can cut and install bigger valves, port and blend and they will make decent power. i would look to aftermarket stuff for better gains. flow is your friend. a motor with great heads and a weak bottom end will out perform a motor with great bottom end and weak heads. your Q-jet will work great for street apps, just an adventure to tune but once there it is a far better set-up. i would not worry about intakes until you start getting to the 350 hp area. there are a million things you can do to a small block Chevy, budget and power goals dictate options. Brian

 

[zackm58941]

thanks for writting back, lots of good info, i was unsure about switching intakes and i'll prob keep the stock one for now. although i think i'll get a different carb seeing that the stock one needs to be rebuilt built and mine as well upgrade while i do the work now. who makes a good set of headers for my vette? is ceramic coating wourth it for street application or just a nice thing to have? i got the money to do mods, i guess i'll start off with a cam, carb and headers and ill see how that works out and go from there. i would like to get the car to run into high 13's, not sure if these modifications will get me there but its gotta be way better than stock thats for sure.

 

[Glensgages]

YOU would suggest?

...i would like to get the car to run into high 13's, not sure if these modifications will get me there but its gotta be way better than stock thats for sure.

I had a brand new '79 Z28 with the LM-1 (identical to the L-48?), and in '81, we switched the
cam (.450"/288*/218* @ .050"/114* LSA)
intake (327/365 HP Corvette from mid '60s)
carb (650 dbl pump)
heads (64cc/1.940"/1.500")
exhaust ('on-sale' headers)
shift-kit....

Stock, it was track-tested in magazines (I never bothered running it stock) 16.20 @ 85 MPH;
running on the OEM 225/70R15 UNIROYALS, with 3.42:1 gears, on SUNOCO 94 thru open headers, it ran steady 14-forties @ 97, with a best of 14.31 @ 98.
After swapping to 4.11s, it ran 14-teens @ 98; best of 14.08

The Z28 'probably' weighed more than your '80, but (I believe) the chassis/suspension on an F-body of that era might be better for drag-racing;
I guarantee the 8.5"/10-bolt rear is!

Hope this helps!!!

 

[AKRAY4PLAY]

running high 13's you're going to need at least 350hp. i would get some headers for sure. Dynomax, Headman, Edelbrock, etc. all make headers. ceramic coated serves two purposes. they keep from rusting and looking like crap, even though guys have had coating jobs and are unhappy but uncoated will start rusting from day one. second and more important, they keep the heat inside the pipe. this helps keep under hood temps down and exhaust hot and flowing more freely, resulting in more hp to you. the Q-jet has the advantage of small primaries and very large secondaries. this is great for street cars. good MPG cruising around and big flow at full throttle. they are tempermental carbs like Holley and Edelbrock, but they are complex. several books on them are available and will really help you out. it will be cheaper to set your Q-jet up than replace it, and i think you'll be happier. a set of heads, AFR 180's or 190's, will help your cause. do a compression check to see the condition of your lower end before you decide to build it.

get the headers, do a compression check and proceed from there. i would hate to se you waste time and money on a lower end that is junk. i will help you in any way i can, feel free to email me with any other questions, if i don't know the answer i will help find someone that does. Brian

 

[zackm58941]

ive looked at a few different headers, will they usually come with new gaskets and header bolts? as far as installation, ive never put a set of long tube headers in, what are the steps for installation for my application, not sure on how to install the collectors in terms of measuring on the front y-pipe to make sure everything fits right. ive been working on cars pretty much all 18 years of my life and i am a student at NASCAR Technical Institute, a branch of UTI so i wont have problems doing the work to the motor, never done much exhaust work so still learning.

 

[AKRAY4PLAY]

headers are easy to do. the hard thing getting the old manifolds off. you would be wise to get an exhaust mainfold spreader tool. sounds weird, but it is basically a bolt and nut that threadd apart and spread the gaps between the #1 and #3 exhaust ports. this helps eliminate the side pressure on the manifold bolts and keeps from galling the threads in the cylinder heads. Dynomax makes a mid pipe kit that is a direct bolt on to thier headers, it is a true dual pipe set-up and fits very nicely. you already have the mufflers and tail pipes, bonus. the mid pipe kit was about $180 a couple years ago, i don't think the price has changed. the headers are $100 painted and $200 for ceramic. your stock y-pipe will not fit long tube headers, you may get lucky with some creative cutting and fab work to spice them together, but running the dual kit is time and headache ahead.

basically, unbolt the stock y-pipe and remove. remove starter after disconnecting the battery. any accessories that use exhaust bolts as retainers will need attention. remove the spark plugs before removing the manifolds!! it is best to drop the old stuff out of the bottom, and install headers from below as well. the headers should come with bolts and gaskets, throw the paper gaskets away!!! do yourself a favor and get some nice gaskets. copper or head gasket types work well, i use the head gasket looking type. sorry i can't remember the correct name right now, but they are dark grey and have a metal core. Victor Rienz, Mr. Gasket and Felpro all make them. pretty simple really, just a little time consuming, you'll get it. Brian

 

[AKRAY4PLAY]

oh ya, use six point header bolts!! it will save your butt when it comes time to tighten them. the 12 points look good, but are a pain to wrenchs or sockets on. most of the time you'll have one or two bolts that you will need to tighten with an open-end wrench.

 

[zackm58941]

im gonna get the dynomax headers, ive seen that "true dual" front y-pipe on summit.com but i cant find it anymore! that would save me a bunch of welding and cutting, anyone know a site who has one?

 

[AKRAY4PLAY]

i got mine from CarQuest, try your local parts guys, especially the wharehouse depots. the kit is for a '74 Vette, it won't list in any post '74 querries on stock listings. the emissions thing plays to heavily on parts choices. Brian

 

[zackm58941]

i looked on a bunch of sites and cant find that front y pipe for dynomax headers, i remeber seeing one one summitracing.com but cant find it now, ive found true dual exhaust bolt on for stock manifolds but no luck so far.

 

[AKRAY4PLAY]

what are the emissions laws in your area?? most IM laws don't bother with cars over 25 years of age, but yours is only 24. i would not like you getting hosed by the "sniffer" guys. i put in a request to Dynomax for more info on the dual kit, part number and current suppliers. i will forward the info on to you when i get it. Brian

 

[bill81vette]

FYI... new york has emission laws..upstate visual only.if it was built on the vehicle it has to be on the vehicle to pass a NYS inspection...downstate has the sniffer westchester county and LI not sure about other downstate counties...hate to see you spend a Buck of $$$$for something you may not be able to use!!!

 

[Jack]

L-48 came with very wimpy cam. Approximate specs with 1.5:1 RAR are: 0.390" I / 0.410" E lift at valves and ADVERTIZED duration about 280*I/288*E.
JACK:gap

 

[zackm58941]

the emission laws where im from arnt too bad, they'll look to see if a cat is there and thats as far as that goes, ive seen some shops where you can obviosly see it has been gutted and they still pass it. im not worried cause i know a lot of people with shops that do inspections and im wanna get my inspector license when i get out of school. i could always use different reducers to weld up to the stock y-pipe to switch out when it comes time. that for the concern. yaa, the stock cam is weak, haha.

 

[AKRAY4PLAY]

i just got an email from Dynomax, sorry dude but they discontinued the dual pipe kit. this sucks, it was a great kit. sounds like emissions laws are going to get you anyway. it is still pretty easy to mod your existing y-pipe to mate up to the headers, but you may want to considder increasing the size of the single section of pipe so you don't choke the new found flow of the headers. sorry for the goose chase, Brian

 

[nicky d]

the ex manifolds could be a pain pull the head and ex manifold
off together in one shot and trash it. those heads are lousy
if your going to do the headers,cam; carb, it will make a
huge differance IN HORSE POWER . the heads you have now
are 8.5 @1 YOU might want to try 64cc heads to bring up the compression
result to more hp. edelebrock rpm package would be great for your applicatoin
call their service tech dept they will help your L48 .
650 AVS EDELBROCK sounds cool , you can adjust the secondarys .

good luck nicky d

 

[mike weyman]

you'll be hard pressed to bring it to the 13 sec range.you'll need at least 350 hp.
those heads can produce that kind of power, but you'll have to go bigger valves,ported,polished,gasket matched.a 460 lift cam is max for those heads.
you will be into 5 to 7 thousand dollars to make a vette go real fast.
p.s. the rear end in a vette is designed for traction and comfort, not straight line racing.most guys i know swap out the rearend for the traditional back axel. apparently those rear ends use a fair amount of hp.(these guys are running 10's)
oh yeah, these motors will accept a 100 shot of nitro like nothing(bad word , but at least i never said NOS)i'm not a fan of it, but it's easy cheap h.p.