Thread: 350 build questions

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Fiirsttime build here... I have a 350 block # 3970010... this is a 350 with a 3.48 stroke, I have done a bit of research on this block to make sure it was a 350 not a 327 or 302. My first question is can I use a stock Gm vortec head on this motor with out having to machine anything? I was hoping I could go straight bolt on... is this possible? The block is already bore .030 and I am not trying to build a hot motor, just something reliable that will run good and I do not have to worry about! It is going in a 65 impala that will have a TH350 and 273 gears so it will be a hwy car not a stop light demon! I am on a budget and want to keep things economical. Any thoughts would be helpful! thanks!

L31's will bolt onto your block, no problem, but will require a specific Vortec intake manifold. Also, beware that the L31's are lift-limited to 0.450" at the valve. More lift than that will result in the bottom of the retainers crashing into the valve guide/valve guide seals. Don't use a cam with more than 0.450" lift at the valve or use 1.6 rockers unless you either cut 0.150" off the valve guide height and re-use the Vortec springs and retainers or don't cut the guides and decide to change springs and retainers to those designed to accomodate more lift.

Any cam grinder out there can cut a cam for you with any duration, lobe timing and lobe centerline figures you want, together with a 0.450" lift at the valve using 1.5 rockers. And by the way, there is no downside to using the L31 rail rockers over conventional rockers with guideplates in my opinion.

I concur with techinspector that the L31’s are your best bet from a performance and certainly from a value standpoint. Jeg’s actually has a “kit” that will save you a bit of money and a lot of time. It includes two complete iron heads, a Vortec intake manifold, all the gaskets and all the bolts for about $900 plus shipping (part number is 809-12558060K)

That leaves you the cam, lifters, rocker arms and carburetor. Summit make nice cam kits w/lifters and a roller chain timing set for about $225 and they have a gazillion different grinds/profiles that will fall within the .450 lift mentioned above. Summit has roller tip 1.5:1 rockers for under $100 per set. Add another $250 for a carburetor and your all set.

Have Fun,
Glenn

Thank you both for the information... This is sure to help me find the right parts I need to accomplish my goal!

I noticed the vortec heads Summitt sells claim to accomidate up to a 480 lift so have they done something different to allow for the extra .030 lift?

To gain more lift with L31 Vortecs, you either have to cut the height of the valve guide boss or change retainers to ones that will allow more clearance between the bottom of the retainer and the top of the guide boss.