327 cam recommendations
- Thread starter Mitch
- Start date
wow that brings back lots of memories, I had the BBC version of that intake on my 1969 CAMARO with a 454 BBC,
the internal runners upper ends extended about a inch or more up into the plenum . I filled that lower intake area around the extended runners in the lower plenum, with fiberglass resin so the floor area around the runner entrance's was filled flush with the runner upper edge entrance's, and found it helped throttle response
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Thunderbolt
Well-Known Member
Cool intake for sure! How does it look like inside?
Thunderbolt
Well-Known Member
The original as cast design looks like it could accumulate raw fuel, and possible go booom?
I think i would have drilled small drain holes into each runner if i had this type of intake as cast
I think i would have drilled small drain holes into each runner if i had this type of intake as cast
Thanks Grumpy. Edelbrock eventually made a plate that sandwiched between both halves to fix the problem of gas pooling and yes, going boom! i dont think it worked that good.
I machined the bottom plenum at an angle and welded a plate , so no more pooling and the intake acts more like an Edelbrock Victor ram tunnel ram. Alot of the SEGA guys are running this and putting out impressive numbers. I still have to figure out how to properly reduce the top plenum chamber, because its huge.
I machined the bottom plenum at an angle and welded a plate , so no more pooling and the intake acts more like an Edelbrock Victor ram tunnel ram. Alot of the SEGA guys are running this and putting out impressive numbers. I still have to figure out how to properly reduce the top plenum chamber, because its huge.
thats simple, I just propped the cover up at an angle, with the open chamber end up exposed and filled 1/2 the upper plenum with fiberglass
resin, so it filled from the carb exits in the upper plenum, to the lower intake plenum wall, then after it solidified I flipped it over and duplicated that
fill, on the other side, so the inner plenum was now a truncated wedge not a rectangle box,
if you take the upper plenum off and fill it at an angle one side at a time, with water while its held at and angle you'll see the plenum volume can be significantly reduced in this manor, (now that I have a welder I just weld in a plate at an angle on both the longer internal plenum walls) you could also do something similar on either end of the upper plenums internal volume to further reduce the internal volume.
thus the internal volume would be a rectangular truncated pyramid.
resin, so it filled from the carb exits in the upper plenum, to the lower intake plenum wall, then after it solidified I flipped it over and duplicated that
fill, on the other side, so the inner plenum was now a truncated wedge not a rectangle box,
if you take the upper plenum off and fill it at an angle one side at a time, with water while its held at and angle you'll see the plenum volume can be significantly reduced in this manor, (now that I have a welder I just weld in a plate at an angle on both the longer internal plenum walls) you could also do something similar on either end of the upper plenums internal volume to further reduce the internal volume.
thus the internal volume would be a rectangular truncated pyramid.
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Thunderbolt
Well-Known Member
Was the huge plenum an old solution for lack of large carbs back then? Or why did they design it like that?
back in the early 1970s when that intake was first available both the carbs available and the knowledge to properly use the intake was lacking in most garages and among most of the people running them, keep in mind at the time a 9-10 second pro-stock car was "fast"
most guys bought and tried the intake out and having less than the anticipated results quickly went back to a single carb intake.
most guys seem to assume you bolt a part on and it should work! only the few people like myself took the effort to tune and tweak until we got the results, because we understood what the intake was was designed to do and understood that the intake must match, displacement, compression, cam timing rpm band and have a matched lack exhaust flow restriction to function correctly, if you stuck an intake like that on the typical street performance car car with a stock exhaust system ,a mild cam and had near zero tuning skills,
it was a lost cause disaster, thus many of those intakes changed hands rapidly at car shows, etc.
btw in "theory" the ideal plenum volume will be close to 1/2 the engines displacement, but that "theory" has long been proven less than ideal , a plenum volume closer to 1/3-1/4 of the displacements proven more ideal because the air flow in a carb supplied intake must maintain fuel suspended in the air flow, and a plenum volume larger than about 1/3rd the displacement almost always results in fuel not being supported and vaporized and held in the air flow stream, once you go to individual injectors pointed at the back of the intake valve it's also been proven that about a 1/3rd the displacement plenum volume works very effectively, keep in mind both the intake port length and cross sectional area, cam duration and LSA, effect the power/rpm band and the EXHAUST SCAVENGING greatly effect's results.
and the compression and cam timing must maximize the exhaust scavenging efficiency
Id point out that a TUNNEL RAM intake is designed to semi duplicate the well documented power increase that the older STACK injection with individual runners feeding each cylinder had, while using carbs to supply fuel, as stack injection was and is considerably more complicated and expensive,
most guys bought and tried the intake out and having less than the anticipated results quickly went back to a single carb intake.
most guys seem to assume you bolt a part on and it should work! only the few people like myself took the effort to tune and tweak until we got the results, because we understood what the intake was was designed to do and understood that the intake must match, displacement, compression, cam timing rpm band and have a matched lack exhaust flow restriction to function correctly, if you stuck an intake like that on the typical street performance car car with a stock exhaust system ,a mild cam and had near zero tuning skills,
it was a lost cause disaster, thus many of those intakes changed hands rapidly at car shows, etc.
btw in "theory" the ideal plenum volume will be close to 1/2 the engines displacement, but that "theory" has long been proven less than ideal , a plenum volume closer to 1/3-1/4 of the displacements proven more ideal because the air flow in a carb supplied intake must maintain fuel suspended in the air flow, and a plenum volume larger than about 1/3rd the displacement almost always results in fuel not being supported and vaporized and held in the air flow stream, once you go to individual injectors pointed at the back of the intake valve it's also been proven that about a 1/3rd the displacement plenum volume works very effectively, keep in mind both the intake port length and cross sectional area, cam duration and LSA, effect the power/rpm band and the EXHAUST SCAVENGING greatly effect's results.
and the compression and cam timing must maximize the exhaust scavenging efficiency
Id point out that a TUNNEL RAM intake is designed to semi duplicate the well documented power increase that the older STACK injection with individual runners feeding each cylinder had, while using carbs to supply fuel, as stack injection was and is considerably more complicated and expensive,
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