[MalibuMike]

Okay guys here we go,when I started my project (1980 2dr Malibu) I "intended" to go with something simple a stock 454 BBC(361959)with (336781) 113cc heads & a cam. Then I found out that if I had it bored .060 I culd make it a 468, next with alil feedback from yu guys I was informed that with 2.19x1.88 valves I culd take my heads up to 119cc. Well with alil research of my own & a performance chart from my69z28.com I've discovered I can take it higher up to a 496 with an addition of a 4.250 crank, mild has slowly turned into wild! I figure I'll go with this set-up & let a real mechanic figure out the best cam that'll work with it best but my question is, goin with this set-up 454 (361959) block, (336781) heads with 2.19x1.88 valves, and a eagle 4.250 cast steel crank if I was to use flat top .060 pistons wuld they be sufficient? If not, why & what kind wuld yu recommend?

(I dnt know any of the compression ratios or how to calculate them)

[454C10]

The 781 head should be around 120cc.

Installing bigger valves is a good idea, but you should also do some bowl smoothing (under the valve at the head/seat interface) and open up the chambers to the gasket where the bigger valves come closest to the chamber wall. Bigger valves can reduce flow because the big valve gets too close to the chamber wall.

Going with a 496 is also a good idea. I would buy a complete stroker kit. The pistons that come in the kit will have a compression range depending on the head chamber volume. In your case, 120cc.

The compression you choose will depend on what cam you are going to use. And this depends on the gear ratio and stall you plan to use.

If you are using a 3.08 gear and a stock converter, then I would setup the 496 with 8.5:1 cr and use a cam around 218 degrees of duration at 0.05". A flat top piston in a 496 with a 120cc head is around 8.5 cr. A 454 would require a 1/8 inch dome to make this cr with 120cc heads.

If you are using a 4.11 gear and a 10" 3000 stall converter, then I would set up the engine with 10:1 cr and use a cam in the 245 degree range at 0.050".

Be aware that your driveline will need to be upgraded to handle a 496. If you don't plan on upgrading, then stay with a 454, which is still too much for the stock driveline.

What transmission, gear, and stall are you going to use?

[MalibuMike]

I have a 400 Chevy transmission goin behind it, haven't selected a converter yet. But I plan on putting a 8.5 posi with 3.73 gear. I shuld remind yu guys this isn't intended to be a strip car, jus something for the weekends...

[cdminter59]

MalibuMike, I would like a little more understanding of the use of the 1980 Malibu. How much of a budget do you plan for the rotating assembly? When you have the block bored be sure to "0" deck it too. It makes setting the quench easier. If you don't want to "0" deck it, check on head gaskets you can get that added to deck clearance = .040. You need to have all the work done to the heads and cc the chambers. You need the chamber size to figure your compression ratio. Are you going with cast parts or forged parts for the rotating assembly, it is up to you.

[cdminter59]

Check out a rotating assembly like this one. With the cast iron heads I would not get a rotating assembly with a C.R. of 10.2. You can always mill the heads to 115cc to bring the C.R. up. Scat 1-91505BI BB Chevy 496 Street And Strip Performance Balanced Rotating Assembly - 8.6:1 Icon Flat Top Pistons - BB Chevy 496 Kits - Rotating Assemblies - New | CNC Motorsports | Car Parts | Truck Parts | Competition Engines

[vinniekq2]

You can also buy a 540 for a reasonable cost.What performance goals do you have?

[MalibuMike]

Welp, looks like cdminter59 has jus completed the rest of my engine build in one simple post lol thanks guys

[vinniekq2]

got to love it when someone gets all the right info to you,first try
good luck/have fun and post some pictures for us

[Mr. P-Body]

Agreed with the kit shown as long as revs are kept "down". We've seen issues with the cast cranks in BBCs when revved above about 6,500. The 4.25" is bad for it. If you're looking to make serious power, spend the extra bucks for a forged crankshaft. We like Eagle, but others have success with Scat, etc. There are American-made BBC cranks, but be prepared ($$).

If a power build, put as long a rod as will "fit" in there. Probably 6.385".

Jim

[cdminter59]

Originally Posted by Mr. P-Body

Agreed with the kit shown as long as revs are kept "down". We've seen issues with the cast cranks in BBCs when revved above about 6,500. The 4.25" is bad for it. If you're looking to make serious power, spend the extra bucks for a forged crankshaft. We like Eagle, but others have success with Scat, etc. There are American-made BBC cranks, but be prepared ($$).

If a power build, put as long a rod as will "fit" in there. Probably 6.385".

Jim

I assumed MalibuMike didn't want to break the bank so I recommended the Scat 9000 cast crank. I like the forged Eagle cranks also. I have purchased two for the 454 in my 67 Camaro over the years. I have the Eagle stroker kit consisting of the 4.250 forged crank, Icon 789 pistons, and the 6.385 Eagle H-Beam rods. I set my shift point at 6500 rpms even with the forged crank.

[MalibuMike]

Yea this was a budget build, wasnt really trying go too extreme but thanks to yu guys I will be able to step it up quite a bit for around the same price range. I'll be sure to post a few pics/vids when it's finished.

[454C10]

use this kit.
Eagle 18022L BB Chevy 496 Street and Strip Rotating Assembly - 10.2:1 Mahle Dome Pistons - BB Chevy 496 Kits - Rotating Assemblies - New | CNC Motorsports | Car Parts | Truck Parts | Competition Engines

with the following:
Edelbrock RPM intake
850 holley
headers and 3"dual exhaust
1.72 roller rockers with tall valve covers
Compcam 292H with the proper valve springs
10 inch converter with a 3000 stall
Hei with MSD conversion
6000 rpms should be max.