69 valiant 273 suggestions

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mightyss

mightyss

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might be buying a 69valiant 100 4 dr, 273 2bl, 7 1/4 2.76 open..... ok, heres what i want to do: headers/duals , 4bl(500-600cfm), 4:10 suregrip(i have both for the 7 1/4), 265/50 14 rear tires, cam (specs??), motor (.30 over)(would like to stay w/stock heads....at least for awhile, then maybe 302's)was rebuilt about six years ago(car only has 57k on it). i want a cruiser that will be run at track(what could it run w/above combo) on occassion. any and all suggestions appreciated, as they will determine whether i purchase car. not looking to run 13's.....14's would be nice though................steve
 
69signetv8 can probably help you a lot more with the 273 build than I can, since I took the 273 out of my 66 in about 1979. The old brain cells have faded fast since then.
Hey Jimmy boy, where are you. This fella needs some 273 build advice. :)
 
mightyss said:
might be buying a 69valiant 100 4 dr, 273 2bl, 7 1/4 2.76 open..... ok, heres what i want to do: headers/duals , 4bl(500-600cfm), 4:10 suregrip(i have both for the 7 1/4), 265/50 14 rear tires, cam (specs??), motor (.30 over)(would like to stay w/stock heads....at least for awhile, then maybe 302's)was rebuilt about six years ago(car only has 57k on it). i want a cruiser that will be run at track(what could it run w/above combo) on occassion. any and all suggestions appreciated, as they will determine whether i purchase car. not looking to run 13's.....14's would be nice though................steve
Click to expand...

I'm on it Sid :salut:


Hi mightyss (Steve),
I think you sound pretty much on task for a 273. The 273 is a great winding motor. I have talked to many about my 273 and there's a couple of ways you can go. As you stated above, keeping it fairly stock with added bolt-ons... Your motor is already 30K over from it's last re-build so with your stock heads get a "for say" Edelbrock dual plenum performer intake. (off idle - 5500). The dual will help in better bottom end launch. Get a 600 CFM carb (no larger). Upgrade to electronic Ignition if not already. Headers a must, with crossover. If you want to bracket race or do 1/4 runs, I would upgrade your rear at least to a 8.25 posi. Your gears for the track are fine, but could be too steep on the highway. Mine are 3.91s and I'm running about 3500 RPM @ 55-60. Now if you want to play alittle, and have one "hell" of a 273 without going to a bigger motor, you could do what "I" should have done to begin with. :sad2: Keep everything as above, however pick up a 340 profile cam. Try to get your hands on a set of closed chamber heads with adjustable rockers/push rods. Oh and at the same time...get them ported..more breath, more ++HP. With any "if" any $$ left over you could go for a 2500 stall. This package, I'm sure would put many larger blocks to shame. :) Sorry Steve, I'm not sure what your runs would be, however if a few members read this thread they may quote a few numbers from what we built here :evil2:

Maybe, you might get other idea's from members

DSCF0016 (Small).JPG
 
I'll pop the numbers into my desktop dyno tonight to give you an idea of where you will be. I'll have to guess a bit on the head flow numbers though. I have the drag sim too so I can give you a rough estimate on that too.
 
Dartfever I'm very interested to here what numbers you come up with
for horse power and 1/4 mile
I have a 273 60 over, stock compression, stock heads, 509 purple shaft solid cam
holley 650 vac., 904 trans low 1st gear,2500 stall, 8 3/4 391's

I haven't been to the track yet and was woundering what to expect
I was hoping for mid 14's or better
 
Bill, how's the bottom end with that set up? Is it kind of doggy off the line with that .509 Purple Shaft cam, or do the converter and gears get it into the RPM power curve quick enough to cover any low end sluggishness? (Is that a word?) :color:
 
69sig, thnx for the reply. i agree, dual plane edlebrock, 600cfm(holly/ carter). it still has points, so mo po upgrade electronic for sure. the rear is where we differ, i had a 7 1/4 sg behind my 2nd 69 valiant w/strong 318, etc...never gave a whimper(always left 2 nice black marks too). i have 3:55,4:10, and a borg warner, and a dana powerlok suregrip(plus a chrome cover..lol). 284/484 purple shaft(340, i think) cam is what i was thinking too. better heads will come, but not yet(i kinda like to see what can be done w/273 first). tranny rebuild (shift kit) will come too, 2500 stall sounds good. is a crossover exhaust really important, i was contemplating putting side exits on it?

p.s. this wouldnt be my first a-body...it would be #12 !! ive have 3 dusters, 2 darts, 1 barracuda, 5 valiants(favorites!)....everything from slants to big blocks too.

ps.s. 69sig, i luv your car, same color as my first 69 valiant. im assuming it also has 273 in it? what mods have you done to it? track tested?????

p.s.s.s. i had a 273 commando motor, 4 spd,8 3/4, in a 64 valiant....can you say FUNNNNN !!! could catch rubber in first 3 gears ........ahhh youth....
 
Ok here goes

mightyss with the comp cams purple plus pp284h
hp 318@6000rpm
tq 320@4500rpm
1/4 mile with 4.10 is 14.03 @ 103.8mph

paynter with the 509 solid
hp 324@6000rpm
tq 321@4500rpm
1/4 mile with 3.91 is 13.74 @ 104.1

I actually had a head flow file for your stock heads so it should be close. Used 10:1 compression for both engines. If you want me to try something else just ask.
 
Oldvart
it's boggs with current double pump Carb, so I'm rebuilding a 650 vac.sec. I hope this will cure some of it. I'll let you know here in a couple of week.
when I bought the car I just wanted it to sound nice so, I put a big cam with lots of Dur.
 
Bill, that's kind of what I thought. :) The vac. secondary is much better for an auto on the street. The other thing you might try, and it's worked for me in the past, is a 4 degree advance keyway for your cam. If memory serves me correctly, it brought my torque curve down to start about 700 RPM lower. Made quite a difference on the bottom boggies.
 
mightyss said:
69sig, thnx for the reply. i agree, dual plane edlebrock, 600cfm(holly/ carter). it still has points, so mo po upgrade electronic for sure. the rear is where we differ, i had a 7 1/4 sg behind my 2nd 69 valiant w/strong 318, etc...never gave a whimper(always left 2 nice black marks too). i have 3:55,4:10, and a borg warner, and a dana powerlok suregrip(plus a chrome cover..lol). 284/484 purple shaft(340, i think) cam is what i was thinking too. better heads will come, but not yet(i kinda like to see what can be done w/273 first). tranny rebuild (shift kit) will come too, 2500 stall sounds good. is a crossover exhaust really important, i was contemplating putting side exits on it?

p.s. this wouldnt be my first a-body...it would be #12 !! ive have 3 dusters, 2 darts, 1 barracuda, 5 valiants(favorites!)....everything from slants to big blocks too.

ps.s. 69sig, i luv your car, same color as my first 69 valiant. im assuming it also has 273 in it? what mods have you done to it? track tested?????

p.s.s.s. i had a 273 commando motor, 4 spd,8 3/4, in a 64 valiant....can you say FUNNNNN !!! could catch rubber in first 3 gears ........ahhh youth....
Click to expand...

Your welcome on my input Steve. Thanks for your comments on my Signet :thumblef: Mine is a 273 rebuilt 30K, I have most what's listed without cam and headwork and stall..basic stock with just bolt-ons. If you have read through this thread the dyno numbers (I think) are very impressive for a 273. :thumblef: The re-build I listed is pretty close to the same profile as a Cammandowith the headwork. I've have read much about rearends..Your driveline will be only as strong as the weakest link. If you think it's fine...great. As far as crossovers, perhaps someone else has some pointers. Mines a daily driver so, because of the bombs the crossover tunes it down some. HP adds in this department would not be much I would think...but any is a (+) :salut:

Jim
 
bill paynter said:
Dartfever I'm very interested to here what numbers you come up with
for horse power and 1/4 mile
I have a 273 60 over, stock compression, stock heads, 509 purple shaft solid cam
holley 650 vac., 904 trans low 1st gear,2500 stall, 8 3/4 391's

I haven't been to the track yet and was woundering what to expect
I was hoping for mid 14's or better
Click to expand...

Bill, 60 over....does she ever heat over??
 
I find all this very interesting because I have a '69 273 in my '65 Barracuda that I plan to swap for a '70 340, but before I do that I'm switching the intake to a 273 commando 4 bbl intake with a '67 AFB (I think it's 500cfm) and I hope to get some better power than I've had up till this point (up till this point it's had a 340 intake with a large AVS carb and it hasn't run right, mostly because of mismatched ports I believe).
 
65s said:
I find all this very interesting because I have a '69 273 in my '65 Barracuda that I plan to swap for a '70 340, but before I do that I'm switching the intake to a 273 commando 4 bbl intake with a '67 AFB (I think it's 500cfm) and I hope to get some better power than I've had up till this point (up till this point it's had a 340 intake with a large AVS carb and it hasn't run right, mostly because of mismatched ports I believe).
Click to expand...

Low HP on bottom end or top...or all around? I could be wrong but with stock heads i would bet that the 340 intake is alittle overkill. When you change I would really like to know the differance (if any 65) I like to think....keep them balanced from carb to crank.
Good Luck
 
Low HP all the time, bogs when you hit the gas, can't squeal the tires ever. Runs rough (set timing, etc....). It's just been terrible. I hope all that will change and I'll post when I get it all together. Thanks for the hope.
 
69signetv8 I can drive it on the street all day in the summer and it won't get hot, runs 190-200 no fan shroud however, when I get on the freeway it does get a little warm 200-220 I haven't tried any long halls yet, I think the 2500 stall conv. may be the reason for it getting a little warm.

Oldvart
thanks for all the info.
I will deffently try the timmmg tip
 
I have a 67 cuda fastback with a 0.030 over 273. It has a Hughes cam and a 500 cfm Edelbrock carb , stock intake, iron exhaust. I had the heads angle milled to try and get the compression up. Problem is, replacement pistons are 0.50 down in the hole. The result is an 8.2:1 motor. Custom pistons are very expensive. I thought about magnum heads but the valves wont fit without griding . I ran the car one time and it went 16.62 at 84 mph. Thats with a 3;23 7.25 pegleg rear axle. and stock 904 trans. I would like to keep it in the car as it is the orignal motor, but there are few gofast parts for it. I bought a 340 block and im building that.
 
That's why I got rid of my 273 about 1979. Even back then it was hard to find any good parts, and the need for speed just outgrew the cubic inches available. I liked the original 273, but I just love this little Vart with the 360. Move over big dog, the little Vart needs some room to flex its muscles. :)
 
i know the 273 head bolt angle changed, and this affects my choice intakes, no? what were the breakdowns on 273 head change? everything else is interchangeable w/ other la blocks, right?
 
I think the 64 & 65 273 had 5/16 bolts . They changed to 3/8 bolts in 66 on up. Most everything will bolt up from a 318 & 340 LA. The 360 has a different oil pan ,crank and front cover. The water pumps and timing tabs switched sides around 1970.
 
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