Hello everyone. I've found many Google searches have landed me on posts from this forum over the past year or so while researching an engine build that I've been toying with. I figured I'd sign up and throw the questions directly at those experts whose opinions and knowledge I've been reading over.
First off, the vehicle that this engine is going to be intended for is a 100% mud racer (mud bogger). Don't worry, I have a 1972 SS454 El Camino in the garage that should help me somewhat fit in with you muscle car guys.
Anyway, it's a 1975 Chevy with 38.5'' tall Super Swamper Bogger tires, th350 transmission with 3,500 stall converter, np203 transfer case (currently ran in low lock), Dana 44 front differential and 14 bolt full floater rear differential with 4.11 gears. The truck is gutted completely. Estimated vehicle weight with driver is around 4,000lbs. Currently I am running the factory original 350 with a Summit camshaft with 214/224 @ .050'' duration and .465/.488'' of lift, an old Edelbrock Torker intake, Edelbrock 650 carburetor and full MSD ignition. I do OK most times and actually place when I'm lucky.
The classes that I run are dominated by some built small blocks and a few healthy big blocks. My initial plans were to build a 496, but after pricing everythng out I've ruled it much over my budget. Instead I've priced out building a 383 at around $6,000 before machining expenses. I'm pretty confident in the parts that I've chosen (listed below), but I'm drawing a complete blank when it comes to cam sizing, carburetor sizing, and some other small part decisions. That's what has lead me here for the past year and now has me posting.
My plan is to build a solid small block that will have an operating range from 3,500 to around 7,500RPM that will have plenty of torque to kick those Boggers up and keep them moving. If you don't know, the object in mud racing is to wing the engine up fast and keep it tached (keeping the tires spinning as fast as possible). I don't really know what kind of horsepower number will get me there, nor do I care much for building to a specific horsepower number.
First, I have a 4 bolt 350 010 block laying around that I plan to use as my foundation. To keep the engine within my budget I'll likely be doing some of the minor machining myself, such as freeze plug installing and piston ring gapping. Not only that, but I also enjoy doing that kind of thing. I will certainly and obviously having it sent out to be bored and clearanced.
My plan is to use the SCAT rotating assembly with all forged internals including 6'' I beam rods, -7cc domed pistons (advertising around 12.9:1 compression), and all of the other goodies that come in the SCAT kits. In addition to this I plan on studding the mains for just some added "help me sleep at night" mojo.
I'd like to make use of the AFR 210 Race Ready cylinder heads. I like their flow numbers a lot for what I'm intending on using them for. I know with that kind of compression that I may see more horsepower numbers with the larger 227cc heads, but I think I will see my torque numbers fall off which would be a big problem for such a heavy vehicle in the mud. The AFR 210's come with springs that would work well with any cam that should work well with the setup also.
I'd mostly be using an Edelbrock Victor Jr intake manifold with this combination as well. For some other goodies, I'm certainly going to be running aluminum roller rockers with stud girdles, an electric water pump (as if it matters much), and my existing MSD setup (6AL, Blaster 2, Pro Billet).
For the unknowns... the cam first of all. I definitely want a solid roller cam as this engine is only going to be flogged. However, I'm not sure if I'm going to need a small base circle cam or not.
Is this something that is going to have to be one of those "check and see" deals? I know a lot of that also depends on how much lift I go with... so... how much lift do I go with? In other words, what cam would fit my needs? Would I be better suited to contact a cam manufacture and possibly have one ground specific to my needs versus getting an off the shelf camshaft? Would a cam manufacture or very credible engine builder be able to tell me based on my desired lift and bottom end components if I'll need a small base circle camshaft or not? I'm lost when it comes to this.
Now with the carburetor. The only reason my truck has the 650 Edelbrock on it is because I knew that I could buy one and slap it right on my engine, set the idle and go without hassle, and it's proven to be a good carburetor so far. I got schooled on the general in's and out's Holleys when I had a mild 350 and an old, needing-to-be-rebuilt-Holley in a S-10 Blazer years ago. However, I've never dealt with carburetors much. Would an 850cfm feed this engine? Larger? What about annular boosters vs. down leg? I know there's not going to be an easy, definite answer without experimentation, but what could be a good starting point? Also, I do have an old Holley 780 laying around that I could have rebuilt and attempt to use if it's enough to feed this monster.
I will take any additional tips, opinions or anything else that anyone is willing to take the time to give me with open arms. A full blown racing engine is new business to me. So, any help from those of you who have been through it before would be great.
Thanks a ton for reading this far.
Some pictures and video to give the thread some "cool"