Bought a 454 block -8999289 bored 100 over with pistons and rods balanced.Now I need to figure out what heads 781 or 049.

Was thinking of 10.5-1 comp.,but like mach. shop said why stop there.Go with like 13-1 and run race gass.If I go 10.5-1 and try to juggle the half 91 octain and race gas,a guy could skip the race gass if none found and maybe ruin engine with detonation with lower octain.

Anyway just up to what I want and spend.Then it's on to the cam and intake.I suppose 780 holley will be to smallish to.Let alone the suspension "All if provided funding is there" graemlins/thumbsup.gif

do your gas stations carry 93? i've got a 10.25:1 small block, and run on the 93 available from every gas station around here with no probs whatsoever. if i had to choose for you, i'd go with 10:1, that 454 will still have a lot of grunt, and with 13:1, you loose a TON of streetability. not only in terms of gas, but it will be a power monster! huge cam, carb, single plane race motor. the 10:1 motor will still allow a racy cam, but you'll be able to run pump gas, and cruise around all day with stump pulling low end torque.

Hi Dan,

I haven't heard from you in awhile. Glad to see you're still around. I don't think you'd be happy running race gas. All of sudden that 30 mile trip to Correctionville will cost you $12 instead of $4.50. :eek: Go with the 9.5:1 and continue to enjoy driving your car. Like Matt said you'll have more than enough grunt.

Chris

Hey Chris


I haven't heard from you in awhile.

I come in here almost everyday,but no posting's.And just need to get it all right the first time.A huge investment for me,funding is hard to come by.
I have been driveing car all over in town and,if ya want to call 60 mile radius to car shows.Probly less this yr. though on second shift now.
Guess I need to be more conservative 11-1 :eek: with the heat and humidity here in summer.Besides by the end of summer reg.gass will be up to 180-2 a gal. anyways. :mad:

i still wouldn't go as high as 11:1.... you'll still need more octane than pump gas can offer, unless you put in a huge cam to bleed down your dcr, pull back the ignition timing. you probably won't be as happy as you would with a lower compression motor. you'd end up with a peaky motor, with a narrow power curve that has a cam that will give you only power in the high end. 10.5:1 i'd say is the absolute max for the street, and you may still run into ping depending on your setup. i'd seriously look at putting together a motor between 9.5 and 10:1 that will give you a nice, broad power curve.

So...if your engine was 11:1 CR(Static) and you put in a solid lifter cam that was, say 242@.50 with .575 lift and .604 exhaust....would that lower his DCR enough to run pump gas?

No, but it depends on the cams valve event timing. He'd need to be in the 255@.050 range at the least.

10,25:1 is a nice place to be given cam selection and ability to run on 93 pump. Have those 781 milled to 115cc.

Also, unless he meant it in jest, if your machinist was serious about his " why not go 13:1" comment, then I would stop taking any advice from him whatsoever. Choose your parts and give him the machining specs to shoot for. Design the 'system' yourself.

With 3.73s you don't want or need a 7000 rpm cam. A solid cam with 240/250 @ .050 or a hyd with 230/240@.050 is all you'll want. To get cams this size to give a decent 8:1 DCR you'll want 10:1.

049s have some HUGE chambers. Must be all of 122cc. You can mill heads to get the right compression. What pistons you now have will dictate the size of chamber to get 10.1:1.

What are your ET goals? 13-1 is waay too much compression IMHO..guys run in the 10's with far less compression than that..no offense,just curious..

049s have some HUGE chambers. Must be all of 122cc. You can mill heads to get the right compression. What pistons you now have will dictate the size of chamber to get 10.1:1. My 049's started out around 121-122cc. After flat milling .040" off they checked out at 113-114cc.

10.5:1 with "781" heads :D

Thanks for all the input guy's.Lot's a good ideas here.Car will be 90 percent street 10 at track.I just need to get it right first time around.

10.5:1 with "781" heads :D [/QUOTE]

That's probly more what I was thinking to.Shop just need's to know for shure comp. ratio.And a good warning not to be running car with not enough octain under any circumstances.