Winfield su1a

Marmon4x4

Marmon4x4

Junior Member
Just pulled out an old Winfield SU1A that’s been on the shelf for the last 45 years and though It might be worth putting in a 276 I’m getting ready to build for my 38 sedan. Sent it to Isky to get profiled. Came back with a card with info. Want to know what to expect if I use it. Will be running 59AB heads, stock intake and carb, Harmon and Collins dist, Fenton headers, mild porting and port matching. Duration @ .020 270 intake. 258 exhaust
Cam lift .370 intake. .350 exhaust
Duration @ .050. 240 intake. 230 exhaust Valve lash. .016/.018 Will idle be excessively lumpy? How about low and mid speed drivability? Any help will be much appreciated
 
Marmon4x4 said:
Just pulled out an old Winfield SU1A that’s been on the shelf for the last 45 years and though It might be worth putting in a 276 I’m getting ready to build for my 38 sedan. Sent it to Isky to get profiled. Came back with a card with info. Want to know what to expect if I use it. Will be running 59AB heads, stock intake and carb, Harmon and Collins dist, Fenton headers, mild porting and port matching. Duration @ .020 270 intake. 258 exhaust
Cam lift .370 intake. .350 exhaust
Duration @ .050. 240 intake. 230 exhaust Valve lash. .016/.018 Will idle be excessively lumpy? How about low and mid speed drivability? Any help will be much appreciated
Click to expand...

It will have a slightly lopey idle. Fair off idle power, so so mid range.
 
It will be lumpy, for sure, as it has a lot of overlap. I think it will want at least another carburetor, to get the best of it and better valve springs, of course.
 
This might help and it lists another Isky carded SU1A but, the timing for the lobes is reversed on it.

It will give you a idea of where the cam lays, compared to other race cams.
 

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I wasn’t sure if it would work for me. I may end up with 52 mercury grind. Don’t want to have too much cam for the rest of the build. I am going to use Zephyr springs depending on cam choice. I also have a Winfield R1, need to know more about it.
 
Been running an SU-1A in my 39 with a 276 cu in engine. I like it, still plenty of low end torque. Been running it for close to 25 years now. With OD I get over 20 mpg running a 390 cfm 4 barrel. Sounds great. Very similar to an L-100.
 
Winfield cams being among the first ones around are probably the most pirated ones in existence. Over the years I have had at least 15 different cams stamped SU1A come through the shop. Only 3 were genuine Winfield ground by Ed himself.
I ran one of those at Bonneville in 1953 and turned 129. The same engine with a 404A the next year turned 137.
Of all of the pirated ones some were of the same timing and lift and several were totally different. Who knows what they were. One thing all of them including the real ones had in common, they were duds as far as a high performance cam.
Not even a good street cam unless you like a super lumpy idle.
All of the originals I checked were 280 or more duration. Way too much for a NORMAL street engine.

Here are some of the ones I checked over the years.

SU1A (One of the many)

In 28-72
Ex 69-26
In .355 lift
Ex .330 lift
In .012
Ex .014
Velocity .004
Lobe seperation 112


Winfield SU1A (1953) (Another one of many)
360 lift 280 duration on the intake 28-72
360 lift 286 duration on the ex. 74-32
111 degree lobe separation

SU1A (1953) Yet another.
In 28-72
Ex 71-29
Lift .355
Lobe sep. 111
Velocity .005
 
I just found the cam card on the Winfield R1. @.020, 256/246. @.050, 226/218. Lift .332/.322. Maybe this would be a little more streetable?
 
when looking at the timing of a cam for street use, check the closing of the intake valve. This determines the dynamic compression of the engine,because, compression doesn't start untill mit closes. O the L-100 a cylinder with a static CR of 8:1 will have a dynamic CR of 6:1. This is one reason the L-100 didn't work very well in a stock engine. The loss of compression reduces the amount of torque the engine can produce. I don't have the information handy for calculating this, but I'm sure somebody does.
Gramps
 
Marmon4x4 said:
Intake 18/58 @ 020. Ex. 53/13 @ .020. Intake 3/43 @ .050. Ex39/1
Click to expand...
The Ex numbers @ .050 don't add up I think the 1 should be -1:
18/58 @ .020 = 256* 110 LC
53/13 @ .020 = 246* 110 LC

3/43 @ .050 = 226* 110 LC
39/1 @ .050 = 220* 109 LC

39/-1 @ .050 = 218* 110 LC

276 CI (3.312 x 4) 8/1 Static CR

R1 dynamic CR = 6.72

SU1A dynamic CR = 6.04 (28/72 timing)

Added:
Those numbers are for sea level reduce by .2 per 1000 ft elevation.
 
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You’re right about the -1 on exhaust closing. After was scratched out on the card and before was written in. What’s the drivability for the street look like? Should I be looking for something else?
 
I think the R1 would be more streetable. I would call it more like a 3/4 race cam. Compare it to the Harmon-Collins 3/4 race cam.
 
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