Best way to proceed with improving up 427 Windsor street setup

[eschaider]

Ace, you can struggle with where the horsepower you have lost may have gone and you might even get your mileage up into the low teens. You will spend considerable time and monies to get fuel injection in the car and properly tuned. When you are done you might get to 450 RWHP

Imagine for a moment how your 03 Cobra would have felt if you could have taken 1500 lbs out of it. You had a Blown 4.6 w/a KB on it, right? Pretty impressive, right? Well you can do that with this car that is 3/4 ton lighter! You already said you don't care about the under hood originality so put in a blown 03/04 Cobra engine (it does have the right DNA).

As you already know from personal experience you will go from 300/350 RWHP to 600+ with lightening fast throttle response and 20+ mpg, but again this is not new ground for you — you have already been there. Remember that broad flat torque curve the engine had and the bottom end blast? I bet you miss that! Now put that in a 2300 lb car!

BTW if/when you do it, polish the valve covers. When you open the hood it will be wall to wall blown and injected Cobra — with the blower front and center! The visual is stunningly similar to the 427 SOHC powered cobras except this engine is way lighter and easily as powerful if not more so.


Ed

[Dwight]

what air cleaner is on the motor?

what is your rear end ratio? Rear tire size?

What trannie?

Dwight

[Ace23]

Originally Posted by Dwight

what air cleaner is on the motor?

what is your rear end ratio? Rear tire size?

What trannie?

Dwight

Just one of those slim oval cobra setups. It's a paper filter and on the dyno the car made 4hp more with the filter removed. The rear end ratio is 3:23 with a TKO-600. Tires are Goodyear Eagle 315s in rear. In 3rd gear at 6000rpm Pman blew me off the road

[Bernica]

Seems that I would agree with above comments...

Compression
Leak-down
Pull valve covers and check everything in valve train
Fuel pressure?
Timing set up right when cam was installed? (Did they maybe index it wrong?)

Just trying to think of anything I can.

You have tall gearing, but that shouldn't do what you describe. I run 3:31 and have no problem. But then..I am running a big block 482.

[Pman1961]

Fuel pressure is on my list to check at idle and under acceleration on Ace's Cobra. My brothers hot rod truck had a fuel pump issue and experienced similar problems.

[blykins]

252/262 @ .050"?

If that's duration at .050", that's a very large camshaft for a 427. My engines that are around this displacement and use hydraulic rollers have about 12-14 degrees less duration and peak at around 6000-6200.

My guess is that the cam has been changed sometime in the car's life and that cam does not match the rest of the engine/car/goals. Your compression test shows low because the cam is so large and the numbers actually jive for a cam that large.

I'm thinking that if these are .050" duration numbers, the cam is so big that you have no bottom end and you can't run high enough in the rpm range where the cam wants to be efficient.

If those numbers are advertised duration numbers, then that would be a tow truck cam....

I'd change the cam....

[DAVID GAGNARD]

My guess is that the cam has been changed sometime in the car's life and that cam does not match the rest of the engine/car/goals. Your compression test shows low because the cam is so large and the numbers actually jive for a cam that large

and the engine originally came with a dual plane intake and Davinci 950 carb.....now it has a Victor Jr. intake and another carb.....

Makes one wonder what else has been changed on the engine from the time it left the engine builder till now????????

David

[Gaz64]

Originally Posted by blykins

252/262 @ .050"?

If that's duration at .050", that's a very large camshaft for a 427. My engines that are around this displacement and use hydraulic rollers have about 12-14 degrees less duration and peak at around 6000-6200.

My guess is that the cam has been changed sometime in the car's life and that cam does not match the rest of the engine/car/goals. Your compression test shows low because the cam is so large and the numbers actually jive for a cam that large.

I'm thinking that if these are .050" duration numbers, the cam is so big that you have no bottom end and you can't run high enough in the rpm range where the cam wants to be efficient.

If those numbers are advertised duration numbers, then that would be a tow truck cam....

I'd change the cam....

Yes, I agree also.

Either the specs the OP has quoted are incorrect, or the cam is way too big or way too small for the expected outcome.

[Ace23]

Originally Posted by blykins

252/262 @ .050"?

If that's duration at .050", that's a very large camshaft for a 427. My engines that are around this displacement and use hydraulic rollers have about 12-14 degrees less duration and peak at around 6000-6200.

My guess is that the cam has been changed sometime in the car's life and that cam does not match the rest of the engine/car/goals. Your compression test shows low because the cam is so large and the numbers actually jive for a cam that large.

I'm thinking that if these are .050" duration numbers, the cam is so big that you have no bottom end and you can't run high enough in the rpm range where the cam wants to be efficient.

If those numbers are advertised duration numbers, then that would be a tow truck cam....

I'd change the cam....

Following up on this. Per the Comp Cam Slip that is part of the motor build sheet the info below is listed. If this information makes since to you it makes you wonder why a camshaft such as this was used.

*Gross Valve Lift .576 Intake / .576 Exhaust
*Duration at .006 Valve Lift 314 Intake / 329 Exhaust
*At 112 Intake Center Line / Duration at .050 252 Intake / 262 Exhaust