273 camshaft selection help

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69f8dart

69f8dart

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I am toying with the idea of putting a cam in my 69 373 engine. It's a two barrel , I will either up the two barrel size or try to get a four barrel manifold,any suggestions on what parts to look into? I am just looking for some sound and a bit more performance
 
A '69 273? 1st 2 years had odd bolt angles and 5/16 screws, so, the intakes are hard to come by.
Otherwise, ethier a LD4B or Performer from Edelbrock and a 500 cfm carb will handle most duties.
Now about the cam.....what gear ratio and tire size do you have? Headers or manifolds?
 
Hopefully Rumblefish will answer your question. Your 69 was the last year for the 273 and has a hydraulic cam. Because of the small bore and small port heads you don't want too much of a cam but there are a lot of good cams out there. A 4 barrel carb is a plus and headers and a free flowing dual exhaust will help also. http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=624&sb=2 Here's a relative mild cam that would be an improvement over the stocker. You can use the stock springs if they are in good shape and it will work with stock gears and convertor. toolman
 
stay under 480 lift and go short on duration. i think comp cams has some fast flank short duration cams.

The 273's also kill the bottom end if the overlap is to long.

You can gain on the top end, but like asked what gears are you running, because you are going to transfer the power from 1500-3500 peak torque to most likely 2500 and up and that is going to make it a little sluggish from a dead stop..
 
I will be using headers , so the 69 273 can use a 318 style manifold? I was told that the angles were diff on all 273's? I have stock gears in there now, I will eventually swap the rear, but I still would like to keep the ratio street friendly, a slight lope from the cam would be a plus too,
 
rumblefish360 said:
A '69 273? 1st 2 years had odd bolt angles and 5/16 screws, so, the intakes are hard to come by.
Otherwise, ethier a LD4B or Performer from Edelbrock and a 500 cfm carb will handle most duties.
Now about the cam.....what gear ratio and tire size do you have? Headers or manifolds?
Click to expand...

This is correct and good advice, and any 318 4 barrel manifold will work from 67 up. There was a 318 Polysphere before that, those manifolds will not work. Valve springs will limit RPM so if you are not changing them go small on the cam.
 
So is it possible to have a slightly lopey idle with a camshaft with keeping the lift under 480" ?
 
Yes, the "Lope" will come from the cam centerline. Mostly seen at 110. I would not go less than 108 on your engine. A 112 would be close to stock and smooth.

I can only assume (And I hate that) that your stock rear gears are 2.76. Do you know what they are for sure by chance? And what you would like to go up to?
Is a higher stall converter change out OK for you or maybe to be done in the future? Or do you want to keep it a stock stall converter? (Which would be fine.)

Once you know that, I'd feel alot better about making a recomendation.
 
Yes, I do plan on changing the gear ratio, I need to find a good 8 3/4 , I was thinking 3.90's. I am not totally against changing the converter, so if it's needed that's no problem. Thanks again
 
OK cool, I just wanted to be clear. Because if you were not wanting/willing to change out the converter, that would limit the cam shaft profile/size.

2 Comp Cams come to mind. Ethier the replacement 340 cam they offer or the XE268, which has more lift. Considering the heads performance, or lack thereoff because it is stock, but having 3.90 gears for that get up and go, I'd go for the replacement 340 cam because it has less lift.

Re-worked and ported heads would most likely work real nice with the ethier cam, the edge goes with the XE268H. You could probably use some compresion.
 
I think a better question is do you have a stock solid lifter cam, I know that some of the 2brl 273s had them, if so you will need to change even more if you want a hydraulic changeover, or you can get the mild solid lifter cam from schneider cams. www.schneidercams.com
 
Good point Duke. I think (Though) tha the 69 year was a Hyd. cam and never thought twice about it.

Schneieder makes nice stuff. He's been around for a while now.
 
The replacement 340 cam , will that have a slightly lopey idle? And I should not have a piston to valve issue right? I really appriciate all the input !
 
It should since it is ground on a 110 centerline. This centerline is most commonly used by Comp Cams and is a typical sound you here at the cruise in's.

The low lift was choosen due to the stock low performance heads and piston clearance.

You need to check piston clearance, use clay.
 
The small valve size of the 273 makes piston contact rare.

I had an old Hot Rod mag from 1969 were they put a .500 lift cam in a 273 motor with 3.23 gears (that were totally wrong for the cam they said)

No problems and the 273 was 10.5 to 1 compression
 
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