273 commando Build

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stroker402 said:
update .... update
My 273 commando is still running strong . seems to get fast and faster every year with more miles put on it .
I tried tweaking a couple afb carbs for more power but the one carb that really turned the 273 commando on , was a holley dp 700 carb . It just loved it in All rpm ranges . I jetted down a couple sizes on each end and it loved it . throttle response is awesome and the top end power pull is just a rush. it screams ! haven't taken it over 5900 rpms yet , cam peak power is 6400 rpms . just keeping it there so the engine last longer .
Click to expand...

LOL, don't you know that a 750 cfm is too big for a 273? Good 273's are freaky aren't they. My 340 is still on the stand waiting it's turn.
 
all I can say is.......... don't believe everything you read here what people are saying about the 273 . I've been wrenching on these old mopars for 50 years .
 
Stroker, Well that doesn't tell me anything. What timing do you see: static, mechanical and total with vacuum advance? How do your plugs look?
Richard
 
Richard Sweet said:
Stroker, Well that doesn't tell me anything. What timing do you see: static, mechanical and total with vacuum advance? How do your plugs look?
Richard
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Richard ........... my 273 runs the best with 16* initial 18* mechanical 24* total curved with fob plate . don't remember what number arm is in vac adv can . hooked up to vac source .
mopar electronic dist with pertronic ignitor III , high volt coil . rev limiter set at 5900.
 
Last edited:
Stroker,
I don't understand how total can only be 24* at the crank? 16+18 = 34. If vacuum is added, it will be even more. What is an fob plate? Do you use a dial-back timing light to see advanced timing? What am I missing? Is the timing not additive?

A page from a Sun manual specifies: 10* @ 500rpm (vac disconnected); 11-15* Centrifical only @ 2500 rpm; and 28-38* total @ 2500 rpm, at the crank, for a 273 w/ 4 barrel.

Does your carb have adjustments available, other than the jets?

Don't you read your plugs, or do you go by how it runs and performs?

Thanks, Richard
 
stroker402 said:
Richard ........... my 273 runs the best with 16* initial 18* mechanical 24* total curved with fob plate . don't remember what number arm is in vac adv can . hooked up to vac source .
mopar electronic dist with pertronic ignitor III , high volt coil . rev limiter set at 5900.
Click to expand...
34° total.
 
Richard Sweet said:
Stroker,
I don't understand how total can only be 24* at the crank? 16+18 = 34. If vacuum is added, it will be even more. What is an fob plate? Do you use a dial-back timing light to see advanced timing? What am I missing? Is the timing not additive?

A page from a Sun manual specifies: 10* @ 500rpm (vac disconnected); 11-15* Centrifical only @ 2500 rpm; and 28-38* total @ 2500 rpm, at the crank, for a 273 w/ 4 barrel.

Does your carb have adjustments available, other than the jets?

Don't you read your plugs, or do you go by how it runs and performs?

Thanks, Richard
Click to expand...
sorry................ meant 34* total timing
 
Richard Sweet said:
Stroker,
I don't understand how total can only be 24* at the crank? 16+18 = 34. If vacuum is added, it will be even more. What is an fob plate? Do you use a dial-back timing light to see advanced timing? What am I missing? Is the timing not additive?

A page from a Sun manual specifies: 10* @ 500rpm (vac disconnected); 11-15* Centrifical only @ 2500 rpm; and 28-38* total @ 2500 rpm, at the crank, for a 273 w/ 4 barrel.

Does your carb have adjustments available, other than the jets?

Don't you read your plugs, or do you go by how it runs and performs?

Thanks, Richard
Click to expand...
no other carb changes but 2 sizes smaller on jets .
 
FBO Ignition sells a limiting plate used in the distributor that allows you to set initial higher while limiting mechanical timing. You can always weld up the slots and file, but the plate is plug and play.

I ran one on my 273 and have one on my 5.9 Magnum. Both wanted lots of initial.

Here's the link. I emailed Don a question about using the plate in my 273 and he called me back to discuss. Unbelievable customer service.

FBO Ignition - Home of the HRR688
 
66fyssh, That's a good site and it has some articles that helped me understand electronic distributor settings. I don't have an electronic ignition so I am relatively ignorant about that tuning. Thanks for the info and the reference.
 
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