273 mild build-----

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DesertRat

DesertRat

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I have decided to keep my 273/904 drivetrain mostly stock, just freshened. I need advice on what hydraulic cam to install and if there is an air/gap 4V intake available for this engine. Also, if TTI headers are the answer for this power steering equipped car or easier options are better suited. I just want the car for a cruise night/show & shine and it will eventually go to one of my grandchildren.
Thanks for any advice you can give, Douglas
 
If it is a 67 or later, the air gap should fit but there will be a manifold to port mismatch. You might be better off with a small port 318 intake to increase port velocity. You also might check into Doug's headers which are essentially the same design as TTIs but without the stepped pipes and are much cheaper. For a mild build I would consider Comp Cams XE256H or XE262H
 
1967DartGT said:
If it is a 67 or later, the air gap should fit but there will be a manifold to port mismatch. You might be better off with a small port 318 intake to increase port velocity. You also might check into Doug's headers which are essentially the same design as TTIs but without the stepped pipes and are much cheaper. For a mild build I would consider Comp Cams XE256H or XE262H
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I'm partial to the solids. Isky E-4, D4B, Carter 625, TTI or Dougs will work.
 
isky 256 super cam custom ground on a 108 lsa.ive run this in a few 318 's.with an edelbrock street master intake.this cam offers great low end,and with a 108 lsa has a very slight chop to the idle.the street master intake is a low rise single plane very similar to the old 273 commando intake.and i agree with the previous post ,top it off with a 625 afb.dougs or tti headers.
 
I sure wish you guys had a video or sound clip of those Isky cams. I'm about tempted to call Comp and see what they recomend for a hydraulic roller. toolmanmike
 
mygwenevere66 said:
isky 256 super cam custom ground on a 108 lsa.ive run this in a few 318 's.with an edelbrock street master intake.this cam offers great low end,and with a 108 lsa has a very slight chop to the idle.the street master intake is a low rise single plane very similar to the old 273 commando intake.and i agree with the previous post ,top it off with a 625 afb.dougs or tti headers.
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108cl? but what if he only has 8.8 comp with 135 cranking psi?

From what I know the narrower the CL the more high rpm scavenging due to the increased ''overlap'' which equals ''more cylinder pressure bled off''.

Sounds soggy to me, especially with a crummy 'street novice' he he intake.jmo:toothy10: lil kiddin ya


Not trying to sell you short, since I've never run the cam you mentioned, but what kind of compression does this 'mild 273' have or gonna have?
And with stock DT gears=2.93's? or?:dontknow:

Desertrat, what do you think?
 
I'm interested in this thread. It sounds like what I want to do to My 273. With a mild rebuild such as this, are headers really that big of a difference? I was thinking of just using the manifolds and going to a 2 1/2" dual exhaust. Mine has 3:91's in the back though. Wasn't sure if the engine would want to breathe more with that gear in it.
 
1wild&crazyguy said:
108cl? but what if he only has 8.8 comp with 135 cranking psi?

From what I know the narrower the CL the more high rpm scavenging due to the increased ''overlap'' which equals ''more cylinder pressure bled off''.

Sounds soggy to me, especially with a crummy 'street novice' he he intake.jmo:toothy10: lil kiddin ya


Not trying to sell you short, since I've never run the cam you mentioned, but what kind of compression does this 'mild 273' have or gonna have?
And with stock DT gears=2.93's? or?:dontknow:

Desertrat, what do you think?
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Yeah, I didn;t even consider CR. Wouldn't take much to get the motor uo to 9.1 or 9.2
 
not trying to start a debate,i just went with what the tech adviser at isky suggested.the cam had great low end response in a 9 to one 318.i ran this combo(intake/cam )in my wifes 73 valiant. this car was driven every where .it had good torque down low,and got 20 mpg highway with 2:76 gears.the street master had the smaller ports and was cheap (25 bucks at a swapmeet)and flows decent to 4500 rpms,which is the end of the cams range anyway.on the note of lsa ,according to schnieder,isky,and crower a narrow lsa builds more cyilinder pressure due to the earlier intake closing point .i just assume they know what they are talking about,but dont take my word on it call and ask them yourself.
 
dart4forte said:
Yeah, I didn;t even consider CR. Wouldn't take much to get the motor uo to 9.1 or 9.2
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Carefully calculate the static compression ratio and cc the heads. My 273 had new pistons when I got it, it calculated to 7.8 to 1 compression. Pistons 45 in the hole and 65cc chambers. It had 115 cranking with a mild 216 @ .050 and 110 lsa hyd.cam. I tore it down and milled the heads .032 thou and the block about .040 to get 9 to 1. I am currently running a comp 270 solid. With 224 at .050 and .468 lift before the .022 lash on a 110 lsa. With lash it runs more like it has about 10 degrees less duration. Very slight lope and pulls pretty good for a little motor. And 150 cranking compression.
I've heard the Summit cams work well in the small engines.
 
Babyblue66 said:
Carefully calculate the static compression ratio and cc the heads. My 273 had new pistons when I got it, it calculated to 7.8 to 1 compression. Pistons 45 in the hole and 65cc chambers. It had 115 cranking with a mild 216 @ .050 and 110 cl hyd.cam. I tore it down and milled the heads .032 thou and the block about .040 to get 9 to 1. I am currently running a comp 270 solid. With 224 at .050 and .468 lift before the .022 lash on a 110 cl. With lash it runs more like it has about 10 degrees less duration. Very slight lope and pulls pretty good for a little motor. And 150 cranking compression.
I've heard the Summit cams work well in the small engines.
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Good example there babyblue.

The isky cam mentioned earlier has 40* o lap.
I found the isky specs=.425 lift 256* 202*@.050 [112cl but instead 108*]
required comp 9.1 .

Thing is, narrower makes more o lap, o lap helps high rpm scavenge , but theres no lift or dur to rev high.
Early lift trying for more velocity but if not timed just right or if you don't have a matched/tuned in exh system it's all kinda lost in translation I think. It reminds me of wrong combos and stingy intake tracts and how I'd sometimes just advance the hell outta the cam.

A factory 340 cam has 44* which came in a motor 57ci bigger w/advertised 10.5 [really only 9.8 or so] with way better ex manifolds, better than spitfire headers or even shorty's. IMO

The Engle cam has 30* o lap which will work real good w/fact exh manifolds or headers and still have a broad power band with plenty of vacuum and hp from the added lift, but I'm no 'expert'.

Bobby from bjr who knows all the flow characteristics of those stock heads could maybe pop in and help.
 
If it's the late style 273 then I would use a performer 318/360 intake as the ports are smaller like the 318 has and will be close enough to not worry about mismatch. For a cam I would use the summit K6901 which has .441 lift on both and 218/228 @ .050 duration, this is just a bit larger than the 318 came with and smaller than the 340. I guess it would be more like a 360 2bbl cam, slight lope and lots of low end TQ. I would top it off with a 670 street avenger, and good manifolds and or shorty hedders, which ever you choose.

This would make a nice street combo. For the heads I would do a 75* bowl cut on both the intake and exh. sides and a good VJ and leave the rest alone. The bowl cut will help low lift air speed. Also I would backcut the valves on both and you should be good to go. The backcut and the bowl cut should help the air flow about 15% with nothing else being done. To me this is the best and cheapest bang for the buck.
 
If you're keeping the drivetrain mostly stock, IMO the cams recommended are a bit steep.

The 273 HP cam had .425 lift I/E, 248º duration, 46º overlap. The engine had a 10.5:1 compression ratio. This cam with a lower compression ratio will be "soft", especially on the low end. As far as I know, no one is producing the HP pistons as a stock item.

The Edelbrock Performer 2176 is an aluminum dual plane 4 bbl manifold that will match up with the stock heads. The factory HP manifold is iron and a single plane unit. The Eddie sits a little higher than the stock unit. A cable type throttle linkage will work fine, but a factory kickdown linkage will need a little "local engineering" to work. Lokar and Bouchillon Performance have cable kickdown linkages that will work.
 
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