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How to mellow out a 505 stroker?

So you had the intake off and verified it's a solid roller?

Its not uncommon for the intake to head surface to leak resulting in crappy idle and burning eyes.

If there are no vacuum leaks, your initial timing is 24°, and you loosen the lash to 0.022" - 0.024", it should have an acceptable idle, but not great. Although opinions vary considerably on acceptable idle.
So you had the intake off and verified it's a solid roller?

Its not uncommon for the intake to head surface to leak resulting in crappy idle and burning eyes.

If there are no vacuum leaks, your initial timing is 24°, and you loosen the lash to 0.022" - 0.024", it should have an acceptable idle, but not great. Although opinions vary considerably on acceptable idle.
 
Hey BSB67,

Thanks to you and other experts on this site! I’m going to try the debug steps you suggested.

1. Check for vacuum leaks. Use the trick of spraying carb cleaner in various places to check for increase in idle?
2. Increase initial timing to 24, while limiting total timing to 34-36. May need to seek help of HalifaxHops or other expert to limit the total mechanical advance.
3. Take another try at tuning my Holley 850DP.
 
FWIW pay attention when AndyF posts in your thread... He's built more strokers & spent more time tuning & dynoing than just about anyone...
 
I have had no luck using a spray for finding manifold leaks. Hand over the carb is the best for me.
 
what is a 905 head?
closed chamber or open?
do not use thick gasket if you loose quench
 
Big cam with high(er) compression and a single plane intake on a street car is asking for headaches, especially when braking is concerned. There's a lot of things you can do to tame the motor (on your own or with suggestions from members here on the forum), my suggestion would be to switch to a dual plane intake to make it more streetable along with an appropriate cam. I've done this to my 383, 906 ported heads high compression 3 bolt mechanical roller with solid lifters and can stop at a red light without a vacuum canister.

You can play with it until you get it right (or give up), but it might be quicker to tear it down and do it right so you have what you want for a street car.
 
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Big cam with high(er) compression and a single plane intake on a street car is asking for headaches, especially when braking is concerned. There's a lot of things you can do to tame the motor (on your own or with suggestions from members here on the forum), my suggestion would be to switch to a dual plane intake to make it more streetable along with an appropriate cam. I've done this to my 383, 906 ported heads high compression 3 bolt mechanical roller with solid lifters and can stop at a red light without a vacuum canister.

You can play with it until you get it right (or give up), but it might be quicker to tear it down and do it right so you have what you want for a street car.
Disagree, if you got kicka$$ alum heads , go single plane .
 
What applies to a short stroke sub 400” engine doesn’t necessarily translate to a long stroke 500” engine. Doing anything prior to driving and trying to optimize the current configuration would be an exercise in futility.
 
With stock heads and a dual plane intake my car still kicks lots of ***. Confidently stopping without a vac can on the street.

There are different variables involved because of displacement but the end goal is the same.
 
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