dkcoleman01

Thanks for all the input you guys gave. This is just an update on what I have done so far with my 496 build.
Block I already had
Heads already had casting number 3856206
Machine work – 650$
Hyd. Roller Camshaft kit – 1000$ (comp cams)
http://www.compperformancegroupstore...=MARKIVCAMHRXE
Short Block Assy. - 1175$ (From Whites Performance)
http://www.whiteperformance.com/RotatingAssemblies.htm
Intake – 200$ (Ebay)
Misc. gaskets, water pump, oil pump etc… - 300$
Total WITH my heads I already have 3325$
Total with better flowing aftermarket aluminum heads – est. 2500$ which would put me at around 5825$
I was thinking about putting the 206 heads on there to bump up the comp ratio but would like to go with AFR heads.
So now I debating if I should go with the 206 heads I already have or just save up for some better flowing heads….

warriorcustoms

iTrader: (10)

Ran a 496 in a boat once it was a ton of fun Always build the biggest you can afford Theres No Replacement For Displacement

Bar50

iTrader: (1)

Just don't under estimate the factory, full size oval port heads, like the -781 or -049. Either with 2.19 & 1.88 or 2.25 & 1.88 valves will flow like gang busters. One can find pretty good deals on the used, take off 454 Mercruiser/Mag heads from guys upgrading power boats. They are GM square ports, -088 or -188 casting numbers....

MackTruck49

Hey guys...the chevelle i just got has a 468 in it, havnt got it running yet its been sitting for 4 years after being built and mated to a tranny and dropped in the car and never finished... it has scat internals and I literally got the car today but the guy who did it has been racing and building for years and it dyno's at 706hp...it has 12.5:1 compression with steel heads...and they were building it to put nitrous to it. I need to obviously look further into this,because he could just be feeding me a line of BS because im still kinda learning...my uncle has an engine dyno, so maybe ill be running it on that to verify. He also says it needs 1100 cfm to supply it what it needs, so ill be looking into this. Can I run this with 93 octane? seems like to much compression for that...

dkcoleman01

I was always told to keep something on pump gas(93) the comp ratio needs to be under 11:1. anything over 11:1 you get into race fuel. Now that is what was told to me for a 12:5:1 ratio I would think no you can't run 93 octane.

Bar50

iTrader: (1)

You can 'fade' some of the octane requirement with aluminum heads. Otherwise, you are right on about pump gas, I would consider 10.5 the edge for pump gas with iron heads.

1961ba427

iTrader: (26)

That dual plane intake looks like a big red flag in regards to the 706HP claim. I have a solid roller 13.5:1 compression 433 (.030" over 427) and it makes just under that with a single plane and a 950HP carb. It was originally built about 20 years ago with an old Edelbrock C454 dual plane dominator intake and an 1150 carb. Swapping to a Team G was worth over 25 HP through out it's entire useable RPM range even with the smaller carb. I mainly went to the 950HP because it has better manners. The dominator was hell on plugs and until the engine warmed up you had better keep it up close to 2,000 rpm to keep them from fouling. Leaning it out hurt the top end too much. The 950HP cured all those issues.
All that being said, it looks to be a beautiful Chevelle and it's still probably plenty strong and will give you tons of fun. 12.5:1 won't run at anything more than idle with pump gas unless your cam is huge....even then I'd run a mix of race gas. My 13.5:1 is okay with about 30% 112 octane mixed with 93. I have even putted around on the street with pump gas and some Lucas octane boost splashed in. I think it's because the 278*/282* @ .050" cam bleeds off so much compression down low. The stall and gears get it into the upper RPM's where it's less likely to lug or detonate too. It's out for a refresh now after about ten years and the pistons show no sign of detonation and an even burn.