73-87 Chevy _ GMC Trucks > Projects Posts (NOT VEHICLES)

350 Engine build for 84 k10

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bd:
For a discussion that is specifically tailored to the 350 in our trucks, read through Camshaft/ intake/ HEI upgrade questions! and other threads with posts by Rich Weyand.

TB24:
Thanks bd, I’ve read all of those threads multiple times. I want the rpm range the 12-300-4 offers but have just recently heard some things where the quick ramps of those grinds may not have the life of the slower ramped grinds. If you recommend the comp grinds I won’t worry as much. Thanks


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bd:
Honestly, I make no recommendations on camshaft profiles other than to advise against choosing too extreme a profile for a given purpose.  Nowadays, due to the "on everybody's shelf" motor oils that are universally marketed by retailers, breaking in any flat tappet camshaft is risky.

I do recommend installing a high-quality double roller timing chain and gear set at zero degrees (unless recommended otherwise by the camshaft manufacturer), followed by setting and/or validating suitable camshaft endplay and valve timing for all aftermarket cams.  NEVER install oil galley restrictors when using a flat tappet camshaft!

With regard to all flat tappet camshafts, suitable service lives begin with liberal pre-coating of the lobes and lifter feet using ultra-pressure cam lobe lubricant during the assembly process, followed by proper break-in using single-wire, low-pressure, break-in valve springs and ZZDP enriched mineral oil.  After break-in, valve springs can be swapped out, if necessary, with the springs recommended for the specific profile by the camshaft manufacturer.  For the greatest service life, continue using ZZDP enriched oils for the life of the engine.  Beyond the break-in period, mineral and synthetic oils perform equally well to satisfy personal preference as long as they are suitably ZZDP enriched.

FYI - When an aftermarket camshaft wipes a lobe, it generally occurs within the first 20 minutes of the break-in process.  Inadequate lubrication and excess spring pressure can grind a lobe flat in that brief time span.  It's highly recommended to check the oil for a pearlescent sheen at the end of the camshaft break-in period, after the first 20-30 minutes of running, followed by changing the oil and filter after no more than 100 miles of driving.  Of course, replacing the oil and filter sooner has no adverse effects.  If the motor oil manifests a pearlescent sheen, it contains fine metallic particles that indicate accelerated (Oh, crap!) wear.

TB24:
Thanks again bd. It’s sometimes overwhelming picking something like a camshaft with so many different companies and reading so many different opinions. I’m really leaning towards comp or lunati at the moment.

Finally got some work done on the engine. Took a cylinder head off to see what had been done piston and bore wise (and gasket thickness) and found what I suspect is factory bore and pistons. That paired up with the very big cam makes me think they kinda just threw a cam in there and didn’t really look at CR and other stuff like that. I’ll put a picture on in a bit to see if you guys think it’s the factory pistons.


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TB24:




Do these look like stock pistons?


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