Tuning a 489 cu in Gen II Crossram Hemi for the street

[jobenz]

Morning, can anyone help me with smoothing out my 489 Crossram Hemi, 675 HP to run better at lower rpm?? Just had the 770 carbs rebuilt by Ray Barton as he said that would be the problem, but it wasn't. Just installed a Tremec TKX 600 with a lower 1st gear, that didn't help either. Timing is set at 32. Anything else I should try to do would help as I do not want to sell my car. Thanks in advance.
My cam is a hyd roller, valve lift, int .573. exh 555 @.050 11.0 compression, aluminum stage 5 heads, TTI headers, Holley 3116 770 carbs.

 

[j-c-c-62]

EFI and use the carbs as throttle bodies?
I should have asked how radical is your cam?

 

[ruffcut]

Yes, camshaft is the first thing that comes to mind. More info would be helpful .

 

[Fran Blacker]

Morning, can anyone help me with smoothing out my 489 Crossram Hemi, 675 HP to run better at lower rpm?? Just had the 770 carbs rebuilt by Ray Barton as he said that would be the problem, but it wasn't. Just installed a Tremec TKX 600 with a lower 1st gear, that didn't help either. Timing is set at 32. Anything else I should try to do would help as I do not want to sell my car. Thanks in advance.

Here's a thread for you. So anybody try a wideband O2 on a crossrammed Hemi yet?

 

[Geoff 2]

A cross ram has a HUGE amount of air [ plenum ] volume in it. It is never going to run great at low rpms because it is not a low rpm intake. The huge ports in Hemi heads do not help either....

 

[67_satellite]

Morning, can anyone help me with smoothing out my 489 Crossram Hemi, 675 HP to run better at lower rpm?? Just had the 770 carbs rebuilt by Ray Barton as he said that would be the problem, but it wasn't. Just installed a Tremec TKX 600 with a lower 1st gear, that didn't help either. Timing is set at 32. Anything else I should try to do would help as I do not want to sell my car. Thanks in advance.
My cam is a hyd roller, valve lift, int .573. exh 555 @.050 11.0 compression, aluminum stage 5 heads, TTI headers, Holley 3116 770 carbs.

If you had enough carb. trouble to need to send them off for Professional help, you may have fouled the spark plugs beyond saving, try a fresh set now that the carbs are "fixed".

 

[autoxcuda]

Try a fuel pressure regulator. And try turning the pressure down.

The 1850 style carbs for sure don't like the pressure. And when coasting to a long stop the carbs bowl would fill to high. Don't know about the 770's. But worth the try.

 

[autoxcuda]

<snip>
My cam is a hyd roller, valve lift, int .573. exh 555 @.050 11.0 compression, aluminum stage 5 heads, TTI headers, Holley 3116 770 carbs.

intake lift: .573
exhaust lift: .555
duration @ .050: ?
lobe separation: ?

My buddy built a 472 auto and 528 4-speed with cross ram 68 super stock clones. What made them reliable on the street was not getting too aggressive with the cam.

 

[68-500]

Whats your initial timing and where is the vacuum advance hooked to manifold or ported?

 

[Fran Blacker]

Ran mine for about5 years. Hope you look through the thread I posted.