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Edelbrock C427x manifold

18K views 35 replies 6 participants last post by  cdminter59 
#1 ·
Hey I found an old Edelbrock C427x intake manifold & was thinking about using it with my 454BBC. I'm a younger guy & don't really know to much about it other than the things I've heard about it (it was used on the super cars & they ran low #'s) so I'm looking for some more insight on this manifold so I'll if it would be a good addition or not, thanks...
 
#3 ·
As of right now it's stock as far as I know, I bought it used but its very clean & the guy said it MIGHT hav been went thru already but he neva got a chance to see due to his project being stolen. I was looking to go with a .60 over bore with a street cam
 
#4 ·
you need to decide what you want from your engine,and match the parts.Make a list quick before tech gets here.
Ill mess with his coming post
Its all about combination,combination,combination,combination
If you want 375 horse power then all the parts need to be geared to make 375 HP,heads manifold,cam.carb and exhaust
 
#5 ·
I was lookiI was looking to get as much hp as possible without doing to much of extreme mods, jus simply heads IF needed, cam, and the .60... Just going off those few things if I was to get the right parts matching like yu say ABOUT how hp would predict I could get out of the motor?
 
#6 ·
I just got these #'s directly off the motor; Block # 361959, Intake#3883948, Heads#336781. Can yu tell me anything based off these part numbers? Any insite would really help, like I stated before I'm a young guy (25) and this my first time dealing with a big block.
 
#8 ·
That old intake is more or less an early 375-425 horse GM intake copy. If I remember correctly a big cap HEI unit won't clear the end runner.

A good budget street intake. Similar to a Edelbrock Performer.

If you bore it, get a mid dome piston 9-10 to one compression. A mild cam, headers and a 780 vac secondary carb, you will have a torque monster.
 
#9 ·
Okay well the same guy says he has a set of GM part number 3964291 rectangle port heads & I found anotha guy with NEW ROSS RACING PISTONS ALUMINUM FULL FLOATING. CNC. MACHINED. SKIRTS THAT ARE. 060 454 OPEN CHAMBER PISTONS PART #80001,NEW EAGLE H BEAM RODS PART. #CRS -6135-S, and SPEED-PRO RINGS... How does this setup sound for horsepower?
 
#11 ·
You don't say what you are going to use this engine in. First you need to have the block and heads checked out at the machine shop. It would be best to bore it .030 and zero deck the block if it is stock. Check the valve size in the heads. They would be better with 2.19 intake and 1.88 exhaust valves. This engine can produce about 400 hp and 510 lbs. torque with the parts I have listed. Factory crank, factory rods with ARP bolts, KB201 .030 pistons, XE274-3 11-246-3 Comp Cam, factory heads 781's, Fel-Pro Q1071 head gasket, Edelbrock 7161 intake, Demon 1563010VE vacuum secondaries carburetor.
 
#23 ·
Only bore the engine as little as possible. If you can get by w/a 0.030" overbore, do that instead of going out to 0.060". The power it'll make will be basically the same, but at 0.060" over, you may have no room to rebore it later if needed and if you were to sell it, it'll be worth more at 0.030" over than 0.060" over.

You need to start by seeing what pistons are in it now, and go from there. If they're sufficient for compression (and the engine is sound- good bearing and piston to wall clearances, etc.), then basically all you need is a cam and lifters, dual plane high rise intake like the RPM, 750 cfm carb, long tube headers/dual exhaust system and a recurved HEI distributor to have plenty of power for any street driven car.

I wouldn't worry too much about HP numbers- it's hard to NOT make 400 HP-plus! Build it using the correct cam for the compression ratio and as long as you choose and assemble the parts carefully, you could have ~500 HP in a streetable package. But the street manners wouldn't be as good as a torquier combo, IMHO. I depends on how you're going to use it as much as anything. A daily driver usually needs to be milder than a weekend toy.

Even using a cam as mild as the XE268H and those heads along w/using an 18cc domed piston (about 9.6:1 CR) will get you an easy 450-plus HP/550 ft/lb torque. BTW, if you have flat top pistons, the CR will be about 8.1:1 using the 118cc heads and a quench of 0.041".

I take it the rear end has been changed? Because it came w/a low performance 7.5" diff from the factory, and if that same rear end was in it now, it wouldn't last long behind a BBC if you ever got traction.
 
#20 ·
horse power 400 or less,torque over 500 pounds.
My car was 550 lift cam.performer intake,later updated to victor oval port.830 holley,hooker headers,stock forged replacement LS-5 pistons,balanced. heads punched out for 2.10/1.88 valves,roller rockers.careful assembly
 
#24 · (Edited)
Why are you stuck on the .060 bore? When taking a block in to the machine shop usually you would bore the block to what it takes to clean up the cylinder walls. Sometimes boring to larger bores can cause problems such as overheating. I not saying it will happen on your 454 the walls are pretty thick. There is 7 cubic inch difference between a .030 block and a .060 block. Bore it as you like and use Probe forged piston P2465F-060. Take a look at post #12 the parts I listed are the almost same as Vinnie built his engine. The specs on the Comp cam Xe274H is .552/.555 lift 230/236 duration. You will need a good 3000 rpm stall like Hughes HUP-GM30. 400 hp and 510 lbs torque is considered a mild oval port engine. Have the block zero decked. Work on the heads by installing 2.19 intake valves and 1.88 exhaust valves. With this setup your static compression will be 9.687 and the DCR will be 8.269 excellent for pump gas.
 
#27 ·
In this case, it would be a mistake. Let the condition of the cylinders dictate the amount of overbore.

Looking at it from a power standpoint, the extra size is worth about 1 hp and 1 ft/lb torque per ci. So the difference between 0.030" and 0.060" is about 6.5 hp and the same amount of torque, all else being equal.
 
#26 ·
Yes, the horsepower diffrence is small. Just don't do like a customer of mine just did and bored a 454 good std. bore block +.125 on the first build. Wanted "cheap" cubic in. (Cuatomer is ALWAYS right?)

Actually with a .030 bore you have a lot of choices for further builds. +.040 .060 .070 .080 .100 .125 .130 are common sizes for these blocks..

As mentioned, for street use, build for torque and drivability.
 
#29 ·
Okay I'm getting a lil better understanding how it (bore sizes) work, but I was "TOLD" the largest a 454 could be bored is .060... Neways, how do I build the motor for torque? Keep in mind guys, like I stated in an earlier post "this is my first time dealing with a big block" so be patient with me. As of now my motor has 336781 heads, would I be better off using these or swapping them out for a set of rectangle port heads?
 
#30 ·
Keep the 781 heads. The 781 head is one of the most popular (along w/the 041 head) to use on a torquey 454 BBC.

Rectangle port heads are for high rpm use. The crossover point where the rectangle ports pulls ahead of the oval port heads at a higher rpm and lift than you'll be needing, so the rectangles are not for you.

You might want to consider adding 2.19" x 1.88" valves if you have the budget- but for a torque engine this isn't mandatory. Be sure to pay attention to the valve spring installed height so there's enough spring pressure and clearance. If you do get bigger valves, you should look at using 0.100" longer valves to have plenty of room for setting the installed spring height.

781 heads are right about 122cc chamber size. That means you'll need a domed piston to have any sort of compression. Flat tops will have you at or below 8:1.

More: 781 vs. rectangle port BBC heads.
 
#31 ·
Okay well right now I'm looking @ a set of NEW ROSS RACING PISTONS ALUMINUM FULL FLOATING. CNC. MACHINED. SKIRTS .060 454 OPEN CHAMBER PISTONS PART #80001 (Yes I still wanna go with the .060 bore just to have alil edge in a sibling rivalry; my 2dr '80 Malibu vs my brothers 4dr '82 Regal w/455 Buick motor) Would these pistons be a good fit with my heads?
 
#36 ·
I told you yesterday in post# 12 that those pistons would give you 13:1 compression ratio with a set of 118cc chamber heads (can not be ran on pump gas). These are the pistons you need if you want to spend the high price for the Ross name. Bore 4.310 Stroke 4.000 Rod length 6.135 Comp Ratio 9.7 Wt. 718 Comp Ht 1.648 Part# 88767. The end!
 
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