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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Hello everyone, I知 in the process of building a 0.030 over 350 tbi with 95 swirl port 193 heads, with speed pro hypereutectic flat top pistons to replace my 305 tbi. I decided on going with a stock LT1 cam. I looked for an actual cam and found the two most common ones which are made by Melling. They are part numbers MC1335 which are used for (93-94), and MC1336 which are used for (95-97). The 95-97 models appear to have slightly more advertised duration. Also I知 guessing because 95-97 are OBD2 cars, it would not probably work well with an OBD1 system like by 88 tbi system. I have attached a link to melling part numbers below. I would greatly appreciate some thoughts on this.
I'd do a little port work to the heads to make use of any larger cam. Swirl ports loose steam around the 3500-4500 rpm range. Honestly for those heads, I wouldn't go much larger than a Ramjet cam with 1.6 rockers. That would be in the total sweet spot for those heads and still make good power and mileage
However, some people here swayed me towards an LT1 cam.Compared to the cam that I have in my 305 currently, I was under the notion that I would have used this ramjet cam from summit and kept the bottom end torque that I am used to with tbi. I have a speed pro cs1079r now in my 305 and I thought this was the closest to it.
Lastly, I recall that every gm sbc that used these billet roller cams almost always had severely worn distributor gears. I even recall that my 97 Silverado had a really worn gear when I pulled the distributor . It seems that these factory gm cams cut the gear out of the solid billet slabs in which the cams are made of. The speed pro and the melling I bought appear to have a pressed on iron gear. Here are some pics of the ramjet cam
I'd do a little port work to the heads to make use of any larger cam. Swirl ports loose steam around the 3500-4500 rpm range. Honestly for those heads, I wouldn't go much larger than a Ramjet cam with 1.6 rockers. That would be in the total sweet spot for those heads and still make good power and mileage
Not a fan of that cam at all. I had a 96 LT4 cam in a low compression 1-ton 350 TBI with 1.6 rockers. Very strong runner. 255 hp and 315 tq at the tires with stock swirl ports and 8.75:1 compression.
However, some people here swayed me towards an LT1 cam.Compared to the cam that I have in my 305 currently, I was under the notion that I would have used this ramjet cam from summit and kept the bottom end torque that I am used to with tbi. I have a speed pro cs1079r now in my 305 and I thought this was the closest to it.
Lastly, I recall that every gm sbc that used these billet roller cams almost always had severely worn distributor gears. I even recall that my 97 Silverado had a really worn gear when I pulled the distributor . It seems that these factory gm cams cut the gear out of the solid billet slabs in which the cams are made of. The speed pro and the melling I bought appear to have a pressed on iron gear. Here are some pics of the ramjet cam
Distributor gear problem was from GMs lousy quality control on the actual distributor gear itself. Much like the intake gaskets, exhaust manifolds and spider system.
Thank you Fast355 on your opinion. Sooo,to kind of close the loop here, one LT1 cam has 268/271 duration and another has 271/276. I知 trying to understand the theory behind proper cam selection. I知 guessing the higher duration will give me more bottom end?? Which one would you guys recommenced??
Thank you Fast355 on your opinion. Sooo,to kind of close the loop here, one LT1 cam has 268/271 duration and another has 271/276. I知 trying to understand the theory behind proper cam selection. I知 guessing the higher duration will give me more bottom end?? Which one would you guys recommenced??
Longer duration given the rest of the specs stay the same, shifts the power curve higher in the rpm range because it holds the valve open longer.
