shenango

My 75 L48 is warmed over with 9:1 pistons, mild cam with flow work and planed heads. Motor builder claims 300 hp but that is not backed up by dyno numbers. I have driven cars with 250+ hp and this one will fit right in with those cars. I am considering headers for a winter project but would rather have a little more torque and seat of the pants feel than more top end. I know tube size and length play an important role in performance and a tuned set will give more power than a standard set.
My system now is the original rams horn manifold into 2 1/2 inch true duals into flowtech terminator dual chamber mufflers. The rest of the drive train is a Borg Warner 4 speed and 3.08 gears with 235R70-15 tires. My Qjet is freshly built and tuned and I re-curved the distributor to Lar's spec sheet.
What would you guys recommend for a little more light to light sizzle.
Thanks, Jerry

dochorsepower

If you still have the original 882 head castings, put them into service as boat anchors. Research all of the suggestions on the forum. Your best bet is heads with modern combustion chamber shape and ports.

Kacyc3

^^Agreed, if you end up thinking about vortecs just buy new upgraded ones, you will have 600 in checking for cracks, upgrading stockers with springs, seals, valve job and screw in studs. Or you can buy new ones complete with screw in studs for about 650. I have read some all for use of standard intakes too.

shenango

I am considering headers not heads. my original heads were tuned "old school" and I doubt any aftermarket heads would be a whole lot better.

cv67

Newer heads are 10x better than what you have.
adding 60-80 cfm you will definintely feel
Planed just means surfaced adds no power just good seal.
Long tube headers with 1-5/8 tubes would pick it up

Kacyc3

were you heads put on a flow bench?

If you are using stock worked over heads and the good flowing ram horns, doubt you will notice anything going to headers.

MajD

Did your car originally have a four speed? I believe those came with a 3:36 gear and not the 3:08. If you really do have a 3:08 gear, getting the 3:36 might give you a little more snappy feel on take-off. I agree with Cuisinartvette on the 1 5/8 in headers to give the most low-end torque for your application.

MajD

shenango

The drive line is all original with numbers matching the vin and the Differential housing stamp is AW indicating a 3.08. I also did the drive shaft rotation to make sure of the ratio. What I am up against is a low budget. A gear change at the local Vette shop is $1300. Decent heads would be about the same. Headers with 1 1/2 or 1 5/8 tubes can be had for under $300 and I would be able to do the work myself.
As I said, high HP and RPM isn't my goal I rarely push her past 4,000 RPM. All I am after is a little more snap from light to light.
Thanks, Jerry

7t9l82

The 882 heads can be made to flow better than the vortec heads with a bit of work. The chamber is the bad part of making power with them.I'd point you towards an aftermarket aluminum head which almost invariably will be better than the vortec heads which are getting pretty old themselves. This may be acedemic depending on your camshaft.
if it were me I think I'd be looking for a gear swap depending how you drive the car.

Kacyc3

ported 882s vs ported vortecs?

427Hotrod

If you never go over 4000 RPM....headers aren't going to make a huge difference. Yes some...but not huge with the rest of your stock combo.

I'm with the others....I'd save my $$ and buy even a cheap set of aftermarket heads if I wanted more power. THEN the headers would make more sense.

Clean out the garage and the kid's piggy banks and scrounge up some extra. If you can install headers you can swap heads.

Get super small chambers to get compression up.

JIM

7t9l82

The weak point in the vortec head is when you go to larger valves the improvement isn't great. The screw shaped bowl takes a bit of work to get them opened up and flowing and it's still really a good low speed torque head.

JoeMinnesota

Gears x3. When you spin the motor to 4000 or so, you may not even realize much with a head swap. Gears are the most overlooked basic change that will give instant gratification, especially if you're starting with 3.08's. A change to 3.55 or 3.73 would make it a different car. Just know that you'll be turning some rpm if you spend much time on the highway.

If you haven't already, one thing to consider is a trip to chassis dyno and have them optimize what you have - mixture and timing. Might surprise you. Tough to get a great tune without a dyno and A/F measurements. With that you don't need to take anything apart, can be done in an hour and they may also have some good recommendations.

If you're considering heads, buy a set of assembled aluminum small chambers and bolt them on. Read the online tests - lots of decent products. My new 355 will get a set of Blueprint aluminums.

Good Luck with your improvements!

ykf7b0

Get ceramic coated headers.

Scottd

REAR END GEARS.

A long time ago I had a Camaro with a 305.

Then I added a 350. Still wasn't impressed. Wasn't much of a felt change.

So I added intake, carb and headers.... Still not a big seat of the pants difference.

So then I went from 2.88 to 3.73 rear end and HOLY SHEET, it was as if I had just added a boost button like in the video games.

You want bang for your buck with 'felt acceleration?' DO the rear end gears.

OldCarBum

Swapping your heads or adding headers will change the way your engine responds throughout your rpm range with the additional torque/hp. Swapping rear end gears is a trade off. Going from 3:08's to 3:55's will give you quicker response off the line, but will increase your rpm's going down the highway. If you are looking to improve the performance of your engine by adding torque/hp then do the heads and or headers. If budget is the determining factor, then I would do a good set of tuned headers. If you want more; save your $$$ and do the heads at a later date.

lvmyvt76

I added headers mto my 76 L48, really can't fell any difference, but, you have done more work on your engine than I have(all stock). the carb was refurbished. IF you want headers, put them on, it's your car. They look better and help with a better sound. But heads will make more of a difference and a different cam would also help, BUT, going that far I would look into a crate motor for response from the pedal! also a warranty comes with it.

Redvette_22

A) you can get "good" alum heads complete from Summit for $1100 and you can install them yourself with only intake and head gaskets

B) IF you put on long tube headers (don't even consider shorties) don't bother with the 1 1/2" tube size. The minimum you should consider is 1 5/8" tube size, even at your RPM range you are talking about.....BUT......I would only consider headers...in your case...if you change to better cylinder heads.