Super stock crossram jetting for dual AFB chokeless 750s

[dvw]

probably right but,,that's way it came,,straight out of a barn ..440..when the .010 over 426 marine motor goes in..it will have a crane r280 roller ..

http://www.cranecams.com/product/cart.php?m=product_detail&p=24695

That's still pretty stiff on the duration. I'd bet 260-265 @.050" would be better fit.
Doug

 

[stage3]

That's still pretty stiff on the duration. I'd bet 260-265 @.050" would be better fit.
Doug

maybe but that's what I have already paid for new in the box from somewhere,,,,,u know,,it has the same specs as the ss572-720 hp motor from chevy,,and theres is a crane also...same lift..duration..and @ .050..appx...

 

[dvw]

I can tell you a friend runs a light GTX (2950). It was running a 440. Eddy heads and a [email protected]" roller, 11-1. Ran 6.15 in the 1/8th. Owner was disappointed. I suggested we try a smaller cam. Lunati sent him a [email protected]". First time out 5.85 in the 1/8th.
Doug

 

[stage3]

I can tell you a friend runs a light GTX (2950). It was running a 440. Eddy heads and a [email protected]" roller, 11-1. Ran 6.15 in the 1/8th. Owner was disappointed. I suggested we try a smaller cam. Lunati sent him a [email protected]". First time out 5.85 in the 1/8th.
Doug

that's interesting...thanks.

 

[Frustration]

set it up per stage 2 specs,,.104 primarys...089-.071 secondarys..supposed to be .069's but my jet assortment was missing that 1...65-52 rods with orange springs.original 3705 carters..runs good with the new porcelain plug wires..finally running on all 8...also..the pinging/detonation I had with the .101's and the wrong metering rod springs is gone....edelbrock says in there guideline that jetting motors up and spring tuning can eliminate a lot of detonation...have to keep the idle high though..cam does not like idling and to put in gear below 1500 rpm's.will slow and die/foul the motor...duration is 320-330....

We had a similar issue with our 426" N/SS motor years ago. Turned out to be an issue with timing. The vacuum advance was killing the idle. It was noticed when we took it to the chassis dyno. Prior to that, we had nothing but track testing. The fix was to "lock out" the timing. Essentially, we have 38 degrees all the time. It now idles perfectly and does not foul plugs nearly as much. The other thing that's supper finicky with a max wedge is the float level. Make sure it's set to the factory spec. When taking the lids off of the Carters or Edelbrocks to change jetting, folks tend to set the top on a surface, essentially changing the float levels. Racers typically make a device to hold the tops when changing jetting so the float level is not changed. This work was done using a solid roller cam .690 lift and 276/284 @ 50. Car runs 10.90's at 123 MPH. Just a couple of thoughts. Good luck.

 

[stage3]

We had a similar issue with our 426" N/SS motor years ago. Turned out to be an issue with timing. The vacuum advance was killing the idle. It was noticed when we took it to the chassis dyno. Prior to that, we had nothing but track testing. The fix was to "lock out" the timing. Essentially, we have 38 degrees all the time. It now idles perfectly and does not foul plugs nearly as much. The other thing that's supper finicky with a max wedge is the float level. Make sure it's set to the factory spec. When taking the lids off of the Carters or Edelbrocks to change jetting, folks tend to set the top on a surface, essentially changing the float levels. Racers typically make a device to hold the tops when changing jetting so the float level is not changed. This work was done using a solid roller cam .690 lift and 276/284 @ 50. Car runs 10.90's at 123 MPH. Just a couple of thoughts. Good luck.

thanks for the tips..im using an older direct connection aluminum body electronic mech advanve tach drive dist with the FBBO limiter plate in it..its set at 16 internally for a total of 36..20 degree's initial.with 1 lite and 1 heavy spring..it does have holes to lock it up with 0 mech advance..how is it to start after warming up with all advance in?that seems like a concern for street use..i know msd makes a start retard..my box is an msd7al2 older unit..

as far as the floats go..when I took the tops off carefully.i always set them on the bench upside down not allowing the floats to touch anything..very tricking floats to set up...when bending the tabs,i was really missing the holleys right about then..it really seems hit and miss with the adjustments..probably will reset them low instead of trying to get them dead balls on to be sure..

 

[Frustration]

thanks for the tips..im using an older direct connection aluminum body electronic mech advanve tach drive dist with the FBBO limiter plate in it..its set at 16 internally for a total of 36..20 degree's initial.with 1 lite and 1 heavy spring..it does have holes to lock it up with 0 mech advance..how is it to start after warming up with all advance in?that seems like a concern for street use..i know msd makes a start retard..my box is an msd7al2 older unit..

as far as the floats go..when I took the tops off carefully.i always set them on the bench upside down not allowing the floats to touch anything..very tricking floats to set up...when bending the tabs,i was really missing the holleys right about then..it really seems hit and miss with the adjustments..probably will reset them low instead of trying to get them dead balls on to be sure..

View attachment 537723

This is a race-only car. From time to time it struggles to turn over, but always does. There are probably better ways to fix our problem, but it was handled that way by an experienced tuner while on the dyno with meters connected to everything. We've left it alone since then. It's been at least ten years.

 

[dvw]

My race car actually runs the floats way high, 7/32" vs the 7/16" called out in the specs. At 6 psi they will not flood. Brings the main circuit in earlier. Also watch float drop. Most carbs have the drop set so the float will hit the bottom of the fuel bowl.
Doug

 

[stage3]

I think this is the main problem with my engines high idle needs .its what came in the car... no vacuum at low speeds to operate the idle circuits..i can increase intial timing with the FBBO plate up to 22+ but IDK..if I set it at the 1600 its now at..its tolerable..instant throttle response now at 20 degree's.no hesitation what so ever.at any rpm..I think a lot more timing in there would offset it but,could create other problems for street use...

http://www.herbertcams.com/cd6r-280-290-650-655-110lc-roller-cam/

 

[stage3]

We had a similar issue with our 426" N/SS motor years ago. Turned out to be an issue with timing. The vacuum advance was killing the idle. It was noticed when we took it to the chassis dyno. Prior to that, we had nothing but track testing. The fix was to "lock out" the timing. Essentially, we have 38 degrees all the time. It now idles perfectly and does not foul plugs nearly as much. The other thing that's supper finicky with a max wedge is the float level. Make sure it's set to the factory spec. When taking the lids off of the Carters or Edelbrocks to change jetting, folks tend to set the top on a surface, essentially changing the float levels. Racers typically make a device to hold the tops when changing jetting so the float level is not changed. This work was done using a solid roller cam .690 lift and 276/284 @ 50. Car runs 10.90's at 123 MPH. Just a couple of thoughts. Good luck.

after thinking about what you r saying about major spark advance at idle to bring the r's down at idle with big cams.,,im going to set my limiter plate at 10 degree;s inside the dist for 26-28 intial,,up from 16...thats as tight as it will go without total lockout...and see what that does,,do u spin your motor and then hit a separate ignition toggle to start it?to avoid starter drag?im looking at msd's start retard 8987 module to connect to my msd 7al2... thanks for your input....