Tumblershawn

Hi
I picked up a 73 454 a couple weeks ago. The PO put a 1970 CE 512 block and HP Cam (forged), but left the stock 73 275 HP intake. He also put on an HEI distributor out of a 75 I believe, as well as Hooker Super Competition Headers and Sidewinder pipes. Other than scorching my legs a couple times (including a softball sized third degree burn on one leg after it tossed an improperly sized fan belt during a test drive and heated the exhaust nicely) it's been a dream come true. As I plan a two stage resto (stage 1 this winter, tighten the bolts, clean it up, new PS, brakes, and some HP mods) I'm spinning my wheels (literally and figuratively) trying to decide where I should spend my HP budget this winter. Does anyone have a guess as to what kind of HP the above combination might produce, specifically the headers and exhaust over stock There aren't any dynos in my neck of the woods, sadly. So far, I'm leaning towards new intake and lifters, if I can ever figure out compatibility. Any thoughts or advice would be appreciated.
S

ajrothm

A performer RPM intake and 750 holley DP would wake it up big time...

As for the headers/side pipes, if the side pipes have baffles in them, they can be grossly restrictive... I'd pull the baffles and build something into the side pipe to quiet it down with less restriction... Maybe a couple of 4" bullet mufflers on each side inside the pipe or something...

Your car has a ton of hot rod potential... All depends on what you want to do with it..

Tumblershawn

Thanks! Does the Performer RPM fit under the stock 73 hood? Also, any point to upgrading the dual snorkel air cleaner? I'm just using the base atm and have a K&N 14"x3" filter with the Xtreme filter top on as well. Looks like hell. Seems to flow air though.

ajrothm

I'm not sure about the RPM fitting under the 73' hood... It would probably be close. You'll have to use a repro LT1/L88 air cleaner base with the 2" drop. Use a 3" filter. Make sure to use a carb with no choke tower or machine it off. It would probably be very close fitting since the 73' hood had a slight raise in it.

You can machine the carb pad down on the intake for about another 1/4" of clearance.

Intake and carb is the first round of performance mods you need to make, along with a good tune up and really dial in the jetting/timing.

Tumblershawn

Thanks aj
I found an L88 air cleaner base. The PO put a pretty shiny Edelbrock 4bbl w electric choke on there, I haven't ran the numbers on it yet to check the CFM, but it's not a double pumper. I'll get the intake next and see how it performs with that carb, and go from there.

Thanks again

Tumblershawn

Hi - one more question - I ID'ed my carb, Edelbrock Thunder AVS 650 cfm. Do you think the upgrade to a Holley 750 DP is still a good upgrade? Or try a new intake with existing carb?

Thanks!
S

ajrothm

No harm in trying the 650 carb since you have it.... It's pretty small for a 454 but since your engine is so mild, it will probably run fine. Normally the minimum I'd recommend for a performance 454 (atleast 400 hp) is a #3310. Holley 750 vacuum secondary..

You can always change the carb later...

The money you save on the carb could buy the intake and a good tune up/oil change...

Tumblershawn

Thanks aj, appreciate the advice. The Edelbrock is still pretty shiny, so I think new intake as you suggest then to from there.

Thanks again

S

7t9l82

by all means if its "shiny" don't do anything.
sorry, i sound like Mike Ward.

augiedoggy

Even edelbrock will tell you that 650cfm carb is much too small for a 454.... I have a 600cfm version (carter rated this same carb at 625cfm) on my 355 and dyno200 shows I would gain about 7hp and a bit of torque if I upgrade to even a 700cfm carb. 750 made even more but then the response would start to get mushy.

Tumblershawn

Excellent, thank you.

S

Tumblershawn

A question, actually, why does Summit and other vendors list so few compatible carbs when I filter for car/engine, is it the hood clearance issue? Pis there something specific about the mating surface configuration?

S

augiedoggy

At one point gm actually used a carter carb on the c3 corvettes... it will work without issues the intake manifold is the main thing that effects hood clearance. Pretty much any 750cfm carb will work without issues as long as its jetted correctly, which for a stock 454 would be a stock 750cfm out of a box.

(The edelbrock carb is a carter/weber "AFB" style carb. edelbrock bought the molds and rights for these from carter and has the clones made in china now.)

Tumblershawn

Ahh ok thanks. Guess I'll do some research on manifold heights!

Shawn

labhound

The only height on it I found is 5.40", I have read other post saying it should fit under the hood.
Let us know, I have a '74 with a 454….

Alwyn678

I run the Edelbrock and it is GREAT

Tumblershawn

What manifold and arir cleaner are you using Al? Any hood clearance issues?

Thanks

S

augiedoggy

hmm your smiley face holds the american flag as if to imply your eledbrock carb is American... did you see my post above? The intakes are made here but not all the products they market.
(just busting chops here but honestly I have an edelbrock/ carter/weber on my c3 as well since it came on the car it also came with the edelbrock box which states its a product of china) Although mine is not the newer AVS (adjustable vacuum secondary) series so maybe those are made here?

If your edelbrock has the electric choke I think you will find most drop air cleaner assemblies wont work beyond the very mild 1- 1 1/2" ones.... that was my observation anyway

learje

hiya, i have managed to get a Performer Air Gap and a Holley 750 DP(Street HP without choke) under the hood of my 73. best i can tell im one of 2 folks here who have done it. other guy was years ago, and i dont think he has posted in a long time. heres a link to a one of my threads, doesnt go deep into the details of gettin the air gap under there though.

http://forums.corvetteforum.com/c3-t...-gap-fits.html

first thing id recommend is to carefully check or just go ahead and change the motor & tranny mounts. when i replaced mine it raised my engine 1/4".

heres a pix of the drop base air cleaner i used. unfortunately i cant tell who made it, it was on my car when i got it. 1 3/4" drop



heres the lid i used: http://www.summitracing.com/parts/trd-2231/overview/

i couldnt get any of the solid top dome style lids to fit. iwe tried a bunch at a local speed shop.

ended up using a K&N 2" element...needless to say w the 1 3/4" drop base ive got only 1/4" inch over the top of the carb, so i had to cut the vent tubes down to almost nothing.

imho every car is different...a little bit of body sag, twist to the frame etc, may keep u from gettin the Air Gap under there. mine has about 1/4" clearance...

hth

Tumblershawn

Thanks Learje! That gives me some hope. So the million dollar question, was it worth the hassle to fit the RPM in there? Was this an upgrade over the stock manifold? What sort of performance improvement did you see?

S