GT40s.com - View Single Post - Weber 48 IDA

Earl J. Castillo · 07-11-08, 04:51 PM

Hello,ffice

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You guys are amazing. This was the type of feedback/info I was looking for. I’m no where near done as there are still a number of decisions to address. I thought I was ready to order pistons and decided to keep the compression ratio in the 10.3–10.5 range assuming I was to run the deck height .015 in the hole. Then I was introduced to a Neil R. who told me run the deck height .006 out (above) assuming I would run a Felpro gasket that has a crushed thickness of .041, run the longest rod possible (in my case 5.400) adjust me CR accordingly, Dump my Crower rockers in favor of a T&D shaft arrangement and a custom solid roller cam specifically ground for Webers with a 112 degree centerline? He had just finished a good friends CSX4000 series 427 Cobra with a 427SOHC with Webers! HP and torque was staggering. His previous engine builder is the person I was having build mine, until I saw the improvements he did on his flow bench. Not that my builder was/is some backyard guy, Tim M. has built some championship winning engines. Neil told me to stop reading that Hot Rod Car Craft magazine crap. Another consideration was Tony Jr. at Tony Otto Engineering (TOE). My pockets are not that deep.
Anyway back to this linkage, of the little small things that I can do I want to really understand Webers and how to tune them properly. As well as what combinations work and ones that don’t.

Cliff, Thank you in regards to your post I’m well aware of the different carburetor arrangements/orientation in regards to throttle positioning (idle/part throttle – WOT) air/fuel flow characteristics and parallel vs. over-under linkage setups. This is a “we will see”, if not adjust accordingly. I saw the post here on the GT40 forum “Webers the ffice:smarttags" />Right Way” Interesting arguments.

Randy (Big-Foot), your specs are somewhat similar to what I’d hoped for. I know I won’t be able to reach your HP level due to the heads I’m using. A number of friends have been telling me to use a modern head. I was considering using that very same cam because it was specifically designed for Webers strong vacuum signal and all, until I was told hydraulic rollers were good to 6000. I’m partial to a solid lifter flat tappet and open to suggestions regarding a grind that works well with Webers. Custom mechanical rollers would let me rev to god knows what, but do I need to on the street. I’d be very interested in hearing your input on your cam and its drivability. Unfortunately I’m pushing around 2850-2900 lbs in overall weight, with a final drive gear ratio of 3.89.

In reading posts from Doc Watson (Andy), Canuk40 who run this orientation, I’d want to know if my linkage would work correctly. I don’t understand Andy’s geometry diagrams. Granted he’s building it on top of the air box floor covering vacuum lines, but intentionally arranged the carbs this way. Due to the differences in the throttle positioning is there a way to compensate flow rates by adjusting arm lengths or starting point locations?

~Earl

The people in the cheap seats always boo the loudest.

07-11-08, 04:51 PM	#70 (permalink)
Earl J. Castillo BundleOfSnakes Rookie Join Date: Apr 2008 Location: N. Calif. USA Posts: 12 Rep Power: 1	Re: Weber 48 IDA - Show me your linkages Hello,fficeffice" /> You guys are amazing. This was the type of feedback/info I was looking for. I’m no where near done as there are still a number of decisions to address. I thought I was ready to order pistons and decided to keep the compression ratio in the 10.3–10.5 range assuming I was to run the deck height .015 in the hole. Then I was introduced to a Neil R. who told me run the deck height .006 out (above) assuming I would run a Felpro gasket that has a crushed thickness of .041, run the longest rod possible (in my case 5.400) adjust me CR accordingly, Dump my Crower rockers in favor of a T&D shaft arrangement and a custom solid roller cam specifically ground for Webers with a 112 degree centerline? He had just finished a good friends CSX4000 series 427 Cobra with a 427SOHC with Webers! HP and torque was staggering. His previous engine builder is the person I was having build mine, until I saw the improvements he did on his flow bench. Not that my builder was/is some backyard guy, Tim M. has built some championship winning engines. Neil told me to stop reading that Hot Rod Car Craft magazine crap. Another consideration was Tony Jr. at Tony Otto Engineering (TOE). My pockets are not that deep. Anyway back to this linkage, of the little small things that I can do I want to really understand Webers and how to tune them properly. As well as what combinations work and ones that don’t. Cliff, Thank you in regards to your post I’m well aware of the different carburetor arrangements/orientation in regards to throttle positioning (idle/part throttle – WOT) air/fuel flow characteristics and parallel vs. over-under linkage setups. This is a “we will see”, if not adjust accordingly. I saw the post here on the GT40 forum “Webers the ffice:smarttags" />Right Way” Interesting arguments. Randy (Big-Foot), your specs are somewhat similar to what I’d hoped for. I know I won’t be able to reach your HP level due to the heads I’m using. A number of friends have been telling me to use a modern head. I was considering using that very same cam because it was specifically designed for Webers strong vacuum signal and all, until I was told hydraulic rollers were good to 6000. I’m partial to a solid lifter flat tappet and open to suggestions regarding a grind that works well with Webers. Custom mechanical rollers would let me rev to god knows what, but do I need to on the street. I’d be very interested in hearing your input on your cam and its drivability. Unfortunately I’m pushing around 2850-2900 lbs in overall weight, with a final drive gear ratio of 3.89. In reading posts from Doc Watson (Andy), Canuk40 who run this orientation, I’d want to know if my linkage would work correctly. I don’t understand Andy’s geometry diagrams. Granted he’s building it on top of the air box floor covering vacuum lines, but intentionally arranged the carbs this way. Due to the differences in the throttle positioning is there a way to compensate flow rates by adjusting arm lengths or starting point locations? ~Earl The people in the cheap seats always boo the loudest.