Tai I moved your post to a new topic.
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Hey George.
How would we all be so much better informed without u George....? Plse dont think of giving up on us...!
Question re. 351C comp.ratio's :- Iam running flattops with 62.4cc. closed-chamber 4V hds. 10.5 ??? Why I ask, is that someone told me it was not much point running Weber IDA's, 180 exh. without at LEAST 11:1 ??? What do think ? ( cam is Sig Erson (Hyd.) 228 @ 50 with 5.45 lift....less duration & more lift, as I was told .... )Iam waiting for a stroker kit... do u think I should use the same cam? - I am going for torgue and dont really want to rev much over 6000.....hence the need for a stroker kit. Ur thoughts would be appreciated. Cheeers,tai
How would we all be so much better informed without u George....? Plse dont think of giving up on us...!
Question re. 351C comp.ratio's :- Iam running flattops with 62.4cc. closed-chamber 4V hds. 10.5 ??? Why I ask, is that someone told me it was not much point running Weber IDA's, 180 exh. without at LEAST 11:1 ??? What do think ? ( cam is Sig Erson (Hyd.) 228 @ 50 with 5.45 lift....less duration & more lift, as I was told .... )Iam waiting for a stroker kit... do u think I should use the same cam? - I am going for torgue and dont really want to rev much over 6000.....hence the need for a stroker kit. Ur thoughts would be appreciated. Cheeers,tai
The Weber carbs were designed to be extremely adjustable. Weber's intention was to make the carbs adaptable to almost any motor for almost any application. There is no such thing as a Weber that is ready to run out of the box. They have to be configured for each application.
The carbs have interchangable "chokes" (aka venturis). When sizing the chokes for a particular application, the 2 biggest considerations are the displacement of the motor and the compression ratio. More displacement and/or higher compression will call for a larger choke. If a choke is sized too large for an application the engine will lose the ultra quick throttle response that is a hall mark of individual runner carburetion.
You do not need high compression to run Webers. Lower compression will simply require a smaller choke than your motor would otherwise run if the compression were higher. The compression ratio of your motor should be dictated by the octane of the fuel, the cylinder head design and the camshaft specifications.
Individual runner carburetion does work better with certain camshaft grinds than with others. I am no expert in this area. The carbs will run with any camshaft, they will just run better with a camshaft having specs that are optimized for an individual runner system. I believe it is the opposite of what you were told, Weber cams tend to have long duration and less lift, but like I said, I'm no expert.
I would advise you to hook up with a tuner experienced with Webers who can tailor them to your motor, and spec a good cam for you. Here in the states, most people think of Inglese Induction Systems first, when the subject of Webers comes up:
http://www.inglese.com
The true compression ratio of a 0.030" over 351C with 4V closed chamber heads & flat top pistons is about 10.0:1 "IF" the block is zero decked. From the factory the true compression ratio of a '70 to '71 351C 4V with closed chamber heads was 9.5:1, not the 10.7:1 that Ford advertised.
The stroker kit is a great idea. It will allow the motor to make more torque, and it will improve the throttle response of the big port heads. The stroker kit will shift the powerband of your motor about 500 rpm lower. You only need a new cam if you want to raise the powerband back were it was, or if you want a cam optimized to run with your Webers. If you do decide to purchase a new cam, my suggestion will be a retro-fit hydraulic roller cam. If you were happy with the current cam, run it & see how you like it with the stroker kit installed before you make a buying decison. The specs you listed for your cam appear to be in the ball park for a good street cam.
Tai, I'm not giving up! Thanks for your kind words.
Your friend on the DTBB, George
The carbs have interchangable "chokes" (aka venturis). When sizing the chokes for a particular application, the 2 biggest considerations are the displacement of the motor and the compression ratio. More displacement and/or higher compression will call for a larger choke. If a choke is sized too large for an application the engine will lose the ultra quick throttle response that is a hall mark of individual runner carburetion.
You do not need high compression to run Webers. Lower compression will simply require a smaller choke than your motor would otherwise run if the compression were higher. The compression ratio of your motor should be dictated by the octane of the fuel, the cylinder head design and the camshaft specifications.
Individual runner carburetion does work better with certain camshaft grinds than with others. I am no expert in this area. The carbs will run with any camshaft, they will just run better with a camshaft having specs that are optimized for an individual runner system. I believe it is the opposite of what you were told, Weber cams tend to have long duration and less lift, but like I said, I'm no expert.
I would advise you to hook up with a tuner experienced with Webers who can tailor them to your motor, and spec a good cam for you. Here in the states, most people think of Inglese Induction Systems first, when the subject of Webers comes up:
http://www.inglese.com
The true compression ratio of a 0.030" over 351C with 4V closed chamber heads & flat top pistons is about 10.0:1 "IF" the block is zero decked. From the factory the true compression ratio of a '70 to '71 351C 4V with closed chamber heads was 9.5:1, not the 10.7:1 that Ford advertised.
The stroker kit is a great idea. It will allow the motor to make more torque, and it will improve the throttle response of the big port heads. The stroker kit will shift the powerband of your motor about 500 rpm lower. You only need a new cam if you want to raise the powerband back were it was, or if you want a cam optimized to run with your Webers. If you do decide to purchase a new cam, my suggestion will be a retro-fit hydraulic roller cam. If you were happy with the current cam, run it & see how you like it with the stroker kit installed before you make a buying decison. The specs you listed for your cam appear to be in the ball park for a good street cam.
Tai, I'm not giving up! Thanks for your kind words.
Your friend on the DTBB, George