I recently got a 75 with an L48. First project car, hoping to bring it up to around 400hp without changing the engine and on a tight budget. It has auto at the moment and I'm thinking of converting it to manual so everything I do should be aimed at a final stage of me swapping the transmissions.
It was in a good shape, but it needs a new radiator and mufflers.

Since it needs a new radiator- I should probably buy the one with an electronic fan on it and remove the mechanical fan attached to the engine. And since it will require removal of the belt - I should probably change the pulleys to aluminum ones to gain some hp.

And regarding the mufflers. I have dual exhaust system installed by previous owner. Do I need the mufflers? What is the better option for increased performance - buying some good mufflers or leaving it as a straight pipe?

Btw I have a 650CFM Holley carb already. Is it enough or should it be upgraded and to what.

Could you help me out with a good budget radiator with electronic fan, pulleys and mufflers. And other parts that I need to change from stock to reach the goal.

That will help me reach my 400hp mark and wouldn't be an expensive overkill.

I have researched for a while now and every time a certain topic is discussed it usually end up with someone pointing to the best product available. I don't really need the best I just need a good enough product that will last at least 2-3 years.

 

Its going to take more than bolt ons.
Heads, pistons, headers, intake and carb, nice healthy cam, you need to get a "How to build and modify a small block Chevy" book.

 

Swapping to an electric fan will not be money well spent in search of big HP gains. The L48 smog heads should be the first to go, then a nice dual plane free flowing intake, and then install the 650 holley carb.

You can easily get to 1hp per 1ci. but not with the L48 pistons and cam.

Good luck. You need to do more research on getting to 400hp on the late 70s motors, They were the beginning of smog restrictions and the heads don't flow worth a damn.

 

Instead of shooting for 400 hp, why not go for 300? It'd be a lot easier to get there with an L48, then 400, which would be unwise to even try, because you might as well, just drop a crate motor in it, or pull the L48 and replace the pistons. The dished pistons in the L48 limit your choice of heads.

You're going to need a small CC head like the aluminum L98 head, with 58cc chambers to bump up the compression. I did this to my L48 and with a vintage Edelbrock Performer, 650 Holley spreadbore carb, headers and a Lunati Voodoo RV-Marine-4x4 cam (272 grind), I am putting out a lot more HP than the 195 hp it came with. I estimate 300 hp minimum and the car is a blast to drive. I had $1K into the heads total, including new LT4 valve springs and being reworked, another $200 or so into the cam and the car already had the intake, headers and MSD ignition. I did have to order a new set of headers though, as the D-port 113 castings have higher exhaust ports than stock and I experienced leaks until I used the Remflex graphite gasket to temporarily cure that.

Do the research first! A lot to know in doing this, but it's doable.

 

Ok so not 400 but 350 lets say. That is exactly what im trying to find out. Everyone is saying do Heads, pistons, headers, intake and carb, nice healthy cam. But which ones. What would be enough to increase the power to that level. I have kind of figured out the idea of what has to be done. Its just the suggestions of which parts to buy without breaking the bank.
And for radiator - mine has hole in it so i have to replace it and some good / not too expensive suggestions would be nice. And i would prefer to remove mechanical fan.

 

If the bottom end of your L48 is in good shape, you don't have to change out the pistons. Only the heads and a cam. Of course, a decent intake manifold sure helps and the Edelbrock Performer's can be found cheaply for the Chevy small block. Headers sure help too and I just got a pair of Heddman headers for $175 shipped on Ebay. A cam and lifter set isn't all that much either. An aluminum radiator can be found for under $200 and you're going to need the extra cooling capacity. The stock air cleaner is what I use and it works fine.

 

Summit headers are only $119 and fit perfect.
Stay away from Vortec heads no matter what people are going to tell you because you have to have matching rocker arms and intake that only fit those heads and when you decide real fast you want more power then you get to buy more rockers and an intake instead of spending the money on a good set of heads in the first place. Not to mention the heads only allow a 450 lift cam. Get Darts, AFRs ,World something after market.

 

The electric fans are cool ,, My experience with friends is there junk , every season they need a relay or the temp sensor and I do not know of any one who does not have an extra of both in glove box. Keep the oem fan and shroud they will work fine , go buy a good radiator ..

To get 350hp ya might as well get a crate motor it makes no sense not unless you want numbers matching but I doubt thats an issue for you. Dollar for dollar crate vs rebuilt the crate wind hands down.

 

Yeah but my manual fan needs replacement and my radiator too. So I think its better choice to go with electric fans and aluminum radiator. Already picked a Champion radiator 3 row with 2 fans based on reviews. Also my exhaust system is junk and needs almost every pipe there is . Can you guys suggest any pipe + header complete packages that would be decent and not overkill and good priced. I found this one. But have no idea if its any good. http://www.parts123.com/parts123/yb.dll?parta~dyndetail~0000050q~25926~~~ ~~~~0000050Q .. I think it would be cheaper to go with complete exhaust system rather then buying parts separately. Or its not a good idea?

 

ALuminum pulleys will make you no power and V belts use less power than a serpentine. Gm got it right.

Forget electric fans getting rid of mine soon.

Get a Flexalite nylon fan they weigh oz are strong move a lot of air and dont fly apart. Might have to use a spacer. between that and your new rad. that thing will NEVER get hot. Best part is you get a steady temp not this up/down garbage with the electric plus you have nothing to "go out" and leave you stranded.
Summit sells these fans they are cheap.

 

Craigslist is your friend....If your looking to swap to a manual..... Well it would be cheaper to just buy another car with all you want to do in such a short time just to get rid of the car in 2-3 years like you mentioned.

 

electric fans so you can put a upper control arm brace on the car
cheap aluminum radiator - I got mine from Summit for ~150

Vortec heads, 58cc combustion cambers will get your compression up to ~9.8:1
Thumpr cam
Dual plane, aluminum intake
Holley carb (now FAST EZ-Efi)
MSD ignition
side pipes
4 speed transmission

That's my motor, and it's 400 at the crank. That said, it is not a tame motor - you said something about DD - it'd be a pain to drive daily

But it is a budget motor (except for the ez efi)

 

I said I was going to "just toss mine together with some parts I had on my shelf then flip it"

it didn't happen that way - I sold a Buick and kept it.... now, consider my screen name and let that sink in a bit

 

You didnt state milage and budget. First I'd run a compression test to verify the bottom end is in good shape. If so I'd go withs a set of Afr 180/64cc, .015" head gasket and a roller cam, match this with a set of headers and an aluminum intake. This would put you at your goal. You should come in around $4k. If you pulled the engine a went through the bottom end youd be in around 5500 to 6200 but if you do that it dont cost alot more to 383ci. Good luck on your project. Electric rans are nice and free up horse power, but are not a necessity. Afr heads and a roller should be firly easy to hit 400 horse, more if you go 383 and afr 195's.

 

Milage 44K miles. Budget - as cheap as possible And regarding exhaust system. You are suggesting to go with sidepipes? Not that good for me cause im 6'4' and i have difficulty getting in and out of the car so will most likely be touching them with my legs all the time so id rather not do it

 

I would stop right there and not do anything all your going to do is waste money on cheap upgrades that will dissatisfy you and you will sell the car for a loss.
Rear wheel horse power of 400 will cost you a minimum of $2500 to start.

 

as long as you run mufflers in the pipe, the outside of the pipe doesn't get hotter than about 170* (which will burn you if you keep your leg on it - so don't keep your leg on it )

mine stay even cooler, I wrapped my dynomax muffler (what an oxymoron) with exhaust wrap before I stuffed it into the pipe. On top of that, I had my exhaust coated with titanium-colored coating - so you could literally put your hand on it and not get burned.... but it's not cheap, if if the hooker sidepipes were nearly free.

still

headers, hydraulic cam upgrade, heads (the heads on your car don't even make good anchors), intake, carb upgrade, and a HEI refresh and you'll be pleasantly surprised with its gains.... one thing for sure, as long as you have the automatic transmission - shift kit it! and if you feel ambitious get that 1600 stall torque converter out and put a 2200 stall in its place

 

I agree 2500 minimum. 400 horse outa 350 isnt real cheap, cheaper than 500 horse out of a 350. If funds dont allow you to reach your goal, then save up, buy all good parts the first time, if not they cost more to buy the second time around. I went headers and duals on mine. Didnt give me that sinister look but plenty loud enough.

 

Cheap as possible? Listen to what Super Buick Guy or myself had to say. You could keep your bottom end (as long as the compression and leak-down check says it's all good) together and go with the 58cc heads, either Vortec or L98. My L98 Heads were $500 the pair and another $350 to work them, less than $1K for the pair and I'm sure you could do better than that with careful shopping. Because of the dished pistons, you can run a 64cc head, but it's not going to bump up the compression as well as a smaller chamber head, like the 58cc heads recommended. Also you should run as thin as gasket as possible, like the Victor Reinz 0.16 or 0.23 thick gasket to keep the compression up. A thick gasket will add volume to the chamber, defeating what you're after.

Add a cam kit, $100 to $150, then a used Edelbrock Performer and a set of regular headers. The sidepipes are significantly more expensive, so going with true duals will save you some dough too. Bluedawg is right on about the duals. Go with a cam that's going to provide torque from 1,500 to 5,500 rpm, because the L98 heads don't flow much past that. A Holley 650 spreadbore will run you $400 or so, and you can accomplish this for under $2K, easily.

If you go with the L98 heads, specifically the 113 castings, they have the D-port, so you have to order headers that accomodate D-port heads in a C3. Heddman sells a set that does this. Not sure about the Vortec heads and maybe SBG can chime in.

 

If I had $850 to spend on heads I would get a set of " World S/R torquers" or S/S Darts.