: stock 425/edelbrock performer intake

09-10-04, 08:07 PM
this has probably been discussed before but, will an edelbrock performer intake manifold #2115 work fine on a stock '77 425? im considering a carter afb competition 625 cfm carb to go on it, can anybody tell me how this combo will be?


09-13-04, 02:41 AM
the 625 is too small the engine came with a 795 cfm carb from the factory
if you want to save money take a 500/472 intake and take the middle out of it with a 1/2 inch spacer ,an open spacer works best
to answer your question yes the intake works fine on a 425

09-13-04, 12:44 PM
Doesn't the 425 have smaller ports than the 472 and 500's???

09-13-04, 02:05 PM
No cause its still a big block. I think...

09-13-04, 02:28 PM
I don't think that's the case. I know the 425 had a lot of changes from the previous 500. I'm pretty sure the intake and exhaust ports were one of them.

lux hauler
09-13-04, 07:02 PM
Doesn't the 425 have smaller ports than the 472 and 500's???
I believe the ports are smaller. How much, I'm not sure.

Night Wolf
09-13-04, 09:03 PM
I have a similar question:

I am still going to buy the 2 Cadillac 500's, but I don't think I will rebuild them and do a performance build on it this winter like I wanted.... for a few reasons....

Anyway, my origanal 425 runs great, 85k miles (origanal) when I remove the oil cap, there is some gunk on the cap, and in the vlave covers, but it runs pretty good...

Without going too crazy, I want to put the Edelbrock intake manifold on, and a mild cam... that would be first, the Q-jet will stay (I like them) the next things to do would be to get a nice free-flowing true dual exhaust system, then maybe see about doing something with the 8.2:1 compresson.... for now I will keep the stock 2.28 open rear end... I am on a hunt to ifnd a 2.78 Posi....

Now my questions are, will these mods listed above give the otherwise stock 425 a considerable increase in power? anyone have an idea on what the 1/4mi. time woudl be? And also, if I throw the intake manifold and cam in the 425.... when I get around to getting the 500 built up, will I be able to use the intake manifold, and moreso, the cam even though it has been ran in another enigne for a while? the intake manifold should be fine, but what about the cam and lifters? they wont get worn down or anything by using them in the otherwise stock engine.... correct?

09-14-04, 12:02 AM
Night Wolf, the way I understand it is once a cam is "broken in" in a engine, it becomes part of the engine; you could try it in a differant engine and it could work, but do not bet on it.

The intake man. will be fine.

I was also under the impression that the 425 ports are smaller.

xxn3kr0h34rt, if you've got the original QJet, use it or rebuild it and then use it.

Night Wolf
09-14-04, 11:43 PM
so just slapping the Edelbrock intake manifold on a stock 425... what kind of benifits are we looking at? of course it would help to free up the exhaust too....

IIRC on the Edelbrock website, it said it'll fit a 425.... wich means it must line up with the ports....

I know when you replace the cam, you need new lifters... that wouldn't be good if the cam coudl not be used in another enigne... that really limits what I can do with the 425 without getting into big money....

09-15-04, 02:49 AM
Is your current manifold iron or aluminum?

09-15-04, 11:52 PM
The ports on the 500 intake are bigger but not BIG ENOUGH to cause any problems.
the 425's are choked for air ,but the edelbrock intake will not make a big difference the intake isnt the problem.
take one of your used cams and send it to whomever you can find to do a regrind , about $100 and a set of elcheapo caddy lifters are about $60
set of new SBC springs and some shims $50 and youll have something decent.

Night Wolf
09-17-04, 07:34 PM
How much can the stock bottom end on the 425 take?

I would like to do a mild performance build on the orignal enigne.. first the intake and cam, then exhaust work, then maybe some head work..... but oculd the stock bottom end handle say.... 300hp and 450ft lbs of tourqe, or maybe more? no N20 will be used at all...

It is just that the 500 build isn't practical for a few reasons right now, mostly faimly related issues... but I have a great running, and origanal 425... it actually moves pretty good for stock, but some performance parts would really bring it to life.

Also, I heard that on these first gen cats, that there is a plug on the bottom (like a big allen type screw) that can be removed, and all the beads inside the cat will drain out, and that is bascially like gutting the cat out... is this possible? if so that woudl be a free way to free up some power as well...

Night Wolf
09-17-04, 07:35 PM
Why do a regrind on the origanal cam? won't that just bring it back to semi-new specs? I would rather buy a mild performance cam from MTS.... they had some nice ones there....

lux hauler
09-17-04, 09:59 PM
torque inc sells caddy performance parts too......he can get a camshaft for your combo.

09-17-04, 11:40 PM
To properly do a performance cam for a cadillac you have to reduce the base circle.
Stock cams have plenty of base circle and as much as i dont really like doing it you can regrind them and save a few dollars.
You will have to use longer pushrods but they arent that expensive.

Night Wolf
09-18-04, 08:54 PM
regrind the origanal cam? will that really add much in the way of performance?

I am close friends with the owner of a machine shop... so I know the work would get done correctly etc...

Why would I get the stock cam reground insted of getting a mild performance cam? money? if so, how much? what would be the best way to go with the Edelbrock intake manifold also?

09-19-04, 06:38 PM
Regrinding the cam costs less. Like Torque Inc said the base circle will be reduced so it's like the lobes are bigger. To make up the distance between the old base circle and the reduced base circle you need longer pushrods like Torque Inc said.

"what would be the best way to go with the Edelbrock intake manifold also?"

What do you mean the best way to go? There's only one way, you either have it or you don't.

Night Wolf
09-19-04, 11:01 PM
I am just trying to brainstorm some things....

... so I would get the origanal cam reground... what specs? then go with the Edelbrock intake manifold...

if I do the above, then go with a free-flowing dual exhaust.... what kind of performance increase am I looking at? I suppose this would be a decent area of tune on the origanal 425, then save the big 500 build up for a later date... atleast it'll have more punch then it does now...

maybe I will stop by the machine shop this week and inquire about the cost of the regrind... after the regrind, just get the new lifters, pushrods and valve springs and I'll be set? Thanks for the info :)

09-19-04, 11:49 PM
This reply doesnt have much to do with the intake so much as it does the exhaust. The 425 has so much torque because the intake is so much and the exhaust so little. You can alway deck out the intake but the exhaust is far too restrictive. Get headers fabricated if thats what your going to do to the intake. The q-jet is an awsome carb, I wouldn't change that if I where you.

09-22-04, 12:36 PM
i herd that the reason that the 425 intake flows porely because the runners are actually below the ports on the head, so the center of the intake sit lower that the ports on the heads. because the hood would hit the carb. at least on coupe devilles this is what i have herd. and i thought that the edelbrock intake would cause hood clearence problems. i don't know for sure but that is what idscouraged me away from doing anything with my 425. But why fix something that isn't broke. the 425 has 130K and can still throw molten rubber onto the rear quarter panel!

Night Wolf
09-22-04, 03:35 PM
I would keep the Q-Jet

The 425 has a "low riser" intake manifold.. the air/fuel mixture has to travel UP to get into the cylinders... it does increase low end torque.. but it kills the enigne otherwise... the Edelbrock raises the carb 3", hood clearance would not be a problem (just fit) but the stock AC compressor will not fit, I was told that you would need a 1980+ compressor if you want AC (IIRC it is the A4?)

Also the Edelbrock weighs 22lbs less then the stock.... in general, any build up on a BB Cad engine needs the Edelbrock....

I agree, exhaust is also restrictive... getting rid of the cat will help some too...

09-23-04, 01:04 AM
speaking of dual exasut i have been concidering it because my exhasut has started to leak right in front of the cat. It was ment to be that it would be taken off :') but my dilema now is A: try to make a dual exhaust out of stuff i can find at local car stores, B: just cut the cat off and put a straight pipe where the cat was just to fix the leak, or C: try to find a sysytem ment for another car that would work on the caddy. I have been thinking about the chevy caprices and i figured that those cars would be similar as far as suspension and stuff goes and maybe it would work on the cadzilla. By the way i have a 1978 coupe deville.

Night Wolf
09-23-04, 10:34 AM
well, the hardest part with doing a dual exhaust on these cars.. the cross-member in the front is only cut out on the right for the exhaust pipe to go by... you have 3 options:

1) run an oversized Y pipe thru the cut out, then break it into dual from the cross member back... but this isn't "true dual"

2) run the pipe from the left manifold *under* the crossmember... but then it will be the lowest thing under the car, which means if would be the first to scrape the ground over a speed bump, may be noticable, and forget about every lowing the car (something I am not doing)

3) the best choice, but most expensive/hard work.... go to the junkyard and cut the crossmember in half from a wrecked car... only take the right side, which has the cutout, then cut the left side of your crossmember in half, and install the cutout part where your old left one was... now both sides have the cutout, and it will be nice.... a faimly friend did this on his '69 DeVille when doing a 500 buildup...

09-23-04, 03:08 PM
If the intake fit on a 425 Edelbrock would call it a 425/472/500 intake. They don't, so odds are it doesn't.

09-25-04, 11:09 AM
hmmm either way you look at it putting dual exhaust on is going to be somewhat of a hassle. i think i'll just put a straight pipe on where the cat was and maybe get a flowmaster so it will sound a little better. i don't really want to do a bunch of work on this car because within the year i will more than likely be shipping out for the Army.

09-26-04, 07:04 PM
If the intake fit on a 425 Edelbrock would call it a 425/472/500 intake. They don't, so odds are it doesn't.

sure it will the 425 intake will also fit a 472/500 and edebrock made the pots a little small so even the ports will line up .... it is done all the time

09-26-04, 11:19 PM
this has probably been discussed before but, will an edelbrock performer intake manifold #2115 work fine on a stock '77 425? im considering a carter afb competition 625 cfm carb to go on it, can anybody tell me how this combo will be?


ok, scratch the carter afb. i am now considering a stage 2 q-jet built by jet performance with 750 cfm and electric choke. this will be going on the edelbrock intake. is this a good combo?

btw i appreciate all the responses :thumbsup: i dont want to make any mistakes

68' Big Body
09-27-04, 12:17 AM
And if your out there, might as well give me an answer as well cause my Edelbrock Intake Manifold will be here by weeks end. My question.....what gasket do I need to get to inatall this thing, since according to the info relating to the intake manifold they name either the: Fel-Pro Printoseal - OR -Mr. Gasket Ultra Seal. Truth is I haven't been able to find either of them. Also I ran across a picture of what looks like just a stock metal intake gasket, shapes like a bowl, and covers the entire area, not like just the two (2) seperate gaskets I thought all V-8's used, so different for sure. If that's the case then my car already has the bowl shaped metal unit and can't that be re-used? if not why? I don't mind getting the right one, just want it here by Friday (Oct 1st). I'm also gonna rebuild the Q-Jet while I'm at it, so next weekend is already spent, then on to Dual Exhaust.

See Ya,
Phil ( 68' Fleetwood )

09-29-04, 12:33 AM
In response to the exhaust replies I just took the two mufflers :rolleyes2 off of my car but left the cat on. Is it legal to take the cat off and just put a flowmaster on? This is a '79 I'm talking about so it does need to be smogged still. I life in california and they're all a bunch of conservationists out here(as am I) so Im pretty sure the emissions regulations are tight in the bay area. Also I've got a rear gasket leak on my intake manifold and I was wondering if its a pretty huge job to replace the gaskets. Does the carb need to come off too?

09-29-04, 02:34 AM
The big one's the muffler, the smaller one behind the axle is the resonator. The resonator is pretty worthless IMO, it doesn't make any differance in the sound if it's there or not. It may or may not be illegal to remove the cat (probably is in Cali), but if you do I can almost guarantee it's not gonna pass emissions check.

09-29-04, 08:51 AM
Technically you are supposed to have all emissions equipment that originally came on the vehicle. Some places are more strict than others regarding this and I'm pretty sure Cali is going to be one of the stricter places.

Anyway, davesdeville is right that you will have a hard time getting the car to pass smog without that cat. Best bet is to leave it on.

In fact, on my '69 (which only has one smog check to pass) I am going to put on 2 cheap cats (even though it didn't come with them) in order to get her to pass. Then it's engine building time. :coolgleam