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heads for my 400

1K views 7 replies 3 participants last post by  speed_demon666 
#1 ·
i have recently found a set of heads off of a 283 casting # 3795896 i was wondering if they could be made to perform well on my 400 i'm aware that i will have a scary compression ratio but with better valves and some machine work, steam holes etc will they perform or will they suffocate my engine.

i'm planning on making this 400 into a street strip motor with a comp magnum cam either 292 duration and .501 lift or the 280 .480 magnum an air gap intake cast crank forged scat rods and i have not decided what type of pistons to use, i want forged but thes are pricey, will cast stand up? i'm pretty weary of hyperutectic because i've heard that they are pretty fragile (detonation) this will be going into a 1980 grand prix by the way. any suggestions appreciated.
 
#2 ·
speed_demon666 said:
i have recently found a set of heads off of a 283 casting # 3795896 i was wondering if they could be made to perform well on my 400 i'm aware that i will have a scary compression ratio but with better valves and some machine work, steam holes etc will they perform or will they suffocate my engine.

i'm planning on making this 400 into a street strip motor with a comp magnum cam either 292 duration and .501 lift or the 280 .480 magnum an air gap intake cast crank forged scat rods and i have not decided what type of pistons to use, i want forged but thes are pricey, will cast stand up? i'm pretty weary of hyperutectic because i've heard that they are pretty fragile (detonation) this will be going into a 1980 grand prix by the way. any suggestions appreciated.
With 283 heads, you don't need to bother with making this into a street/strip engine, it will be choked to death way before the cam does anything for you. Plus you can't port them big enough for a 400 before you'll discover the wet side of the port walls. Modern fast burn Ricardo type chambered heads like the factory Vortecs and Fastburns along with the many similar aftermarket heads in iron or aluminum will far out power the best modified SMOG or presmog head out there. It's not uncommon to see an out of the box Vortec head deliver 40 more horses and ft pounds of torque compared to a well prepped camel hump head simply by bolting it on with no other changes.

Hyperutectic pistons are pretty good, they take a lot more loading and abuse than standard castings, its just that when they go it's sudden disintegration rather than a melted hole thru the ring pack. For compression control, if a dish becomes necessary, you want a piston with a "D" shaped dish. This maximizes squish and quench opposite the valve side of the combustion chamber which improves detonation resistance, power output and fuel economy.
 
#3 ·
Get some 200cc heads, like the dart iron eagles.

I like that 292H cam a lot. Pulls to over 7000rpm with a good set of heads and springs.

I run it with 11:0cr on 93 octane in a little car with a manual trans. You should be ok with 10.5:1 cr in a heavy car or 10:1 with 91 octane.
 
#4 ·
thanks for the feedback i got the heads for free so i didn't know if they were worth using. i didnt really want an out of the box head because i'm trying to kep this engine on a budget and a timeline as a student i have a limited amount of money and time to finnish this project. i'll see if i can find some closed chamber heads kickin around school in the shop would the cam choices i made be suitable for a truck application? i have a tired 350 and now today a blown up th350 :( in my 82 c10 and am now interested in putting a new engine and tranny in it
 
#5 ·
Truck? I thought you said 80 grandprix?

Yes, those cams will work in a truck or car. However, in both cases it will need a 4.11 gear and a 3000 stall converter.

If you plan on using the stock 80 truck c10 converter and gear ratio then you will need a totally different cam. Try a compcam 252H or a Edelbrock Performer cam and set up with 8.5 to 9.0:1 cr.

Do you have the complete 400 with heads or just the short block?
 
#6 ·
it was going to go into the gp but as my truck cratered on me 2 days ago is now going to go into my truck and i am aware i will need different gears and stall i picked the 400 up from a co worker for 100$ as a shortblock missing 2 pistons and rods. the block shows nearly no ware in the upper cylinders and is in good condition considering its been stored outside for the last 20 years or so. i was planning on getting a 12 bolt and the tranny will be beefed up with shift kit/servo as now it is basically clutchless and needs an overhaul.
 
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