Hey Don –

It appears to me that you’ve got a couple threads going here about a 400 build, some heads and a cam selection. It might be in your best interest to re-start this process and focus on one path to consolidate the information and let us help you. We really are a pretty intelligent group and the collective experience here is hundreds of years of engine building and hot rodding so the information you need is here, but not everyone reads all the posts so you’re running the risk of piece-meal responses. A couple suggestions:

1. Tell us what you’re building – is this for a car or a truck?
2. What do you want to accomplish? Will this be a daily driver or a weekend cruiser? Do you want to run this build down the drag strip now and again or just have enough punch to hold your own stoplight-to-stoplight? (Not an endorsement for street racing – but it is nice to dust a rice rocket now and again, eh??)
3. What’s your budget?
4. What’s your time frame?
5. What’s your skill set? Not meant to be condescending, but you need to be realistic about what you can do well. I’ve been doing this for almost fifty years and I still have some things that I defer to machine shops and those people who do precision work for a living. They have the equipment and knowledge and a good one is worth their weight in gold. I knew a lady machinist in southern California years ago and she was worth twice her weight in platinum!
6. Give us the basics on your vehicle, i.e., automatic or stick – what’s the rearend ratio – what size tires, and anything else you got.

Most importantly, you’ll need to build this thing on paper before you ever pick up a wrench. When we try and “build-what-we-got-laying-around” the results are marginal at best. That’s due largely to the fact that we gather “stuff” overtime that may (or may not) be compatible and remember that the technology in cams (in particular rollers) and heads has come a long way in the past ten to fifteen years. As has been eluded to in one of your posts, flat tappet cams are a real crap shoot and if not installed perfectly and run in correctly they will fail. Most here have had bad experiences with the removal of key oil additives to know that a roller may be more up front but saves money and heartache in the long run.

If you’re set on the 400 block it can be a great foundation as long as you understand Siamese cylinder design. Before you do anything, you need to have the block vetted by a reputable machine shop. Have it examined for any cracks and if it’s good, get it decked and have the main bearing bosses aligned bored to make sure everything is square. The 400 is known for running hot, but if the cooling system is properly designed it is not an issue. As such, knowing what you want to accomplish is again important. A boulevard beast that idles a lot is not a good fit for the 400 unless you have a large cooling system and use a well-engineered shroud and a mechanical fan with the stock GM clutch (think Monte Carlo – big car with a 400 and a well-designed cooling system but still notorious for overheating.)

The rotating assembly needs to be selected as a group, i.e., crank, pistons, rods and yes, the cam. Choosing the correct parts to install in a properly prepared block means you will not have to grind anything. I’m not a fan of trimming bolts and leave that to experts like Pat McCarthy as he has the tools, skills and experience to machine components and balance properly.

The heads you’ve been referencing are probably not worth the effort of a rebuild. I’d look to modern aluminum. I think I’d lean toward Airflow Research 195cc heads. As the name implies, they have 195cc runners and you can get them with a 65cc combustion chamber. If you want to err on the side of caution, get the upgraded springs from AFR (part # 8605) to eliminate any valve float issues. No matter which heads you choose, with a 400, they will have to be drilled to match up with the block's steam holes. Before you choose heads, you need know that anything much over 10:1 will give you fits in cast iron and compression over much over 10.5:1 – even in aluminum – requires careful matching with valve timing, i.e., cam selection.

Techinspector is the man to ask (nicely of course) to help you build your “stack-o-stuff” in order to determine your real compression ratio. Listen to him as he’s done this for a long time and if you don’t get this part right, everything (and I do mean everything) else will just not work as intended and you’ll be frustrated with the build. Make sure you get the deck height number from your machine shop as it is vital in this process. All small blocks start at 9.025” but after decking, that number will be less!

The cam should be roller – period. Lift and duration numbers should be a bit tamer than you’re looking at if you want to drive this thing on the street at all. And don’t look for a lumpy sound! It indicates poor design and equates to sub-par performance and says “I-wanna-be-a-badass” but in truth make one look, well – foolish to the knowledgeable hot rodder. I like sound as much as the next guy and am a big fan of 40 series Flowmasters, but not rough idle slop with raw gas running out the tail pipe.

Okay – I've gone on long enough. Hopefully I've not scared you away as we really do want to help, but let’s try again from a clean slate. Tell us what you’re building and we’ll go from the ground up with you.

Regards,
Glenn