350 Engine build for 84 k10

[TB24]

I’ve had the 84 k10 for over a year now, the truck came with a 305 and sm465 from the factory but along the way somewhere, someone put the built 350 that is currently in it now in. I have decoded the block and heads in it and found that it is an 82 350 that originally came out of a van or bus. I also found the heads are the (from what I’ve found) bad 624 casting number.

Jumping ahead to current days, I’ve been driving it pretty rarely due to the drivability of it. It has a manual choke that isn’t very operable, and low end torque is pretty nonexistent (which makes it a little tough on the sm465 imo) but I still loved driving it lol. Unfortunately, I don’t know exactly what all modifications have been done I will attach a picture of the only info I have. I know it has a crane cam with “51” lift. I’m not sure exactly what that means. .510 lift? .451 lift? I thought one of you be more in tune with that nomenclature.

I’ve been waiting to tear into it until our garage was built, a couple weeks ago it was finished so I’m excited about that. The other day I was driving it and something very weird happened, the clutch adjustment rod went through the clutch fork. Extremely weird to me and my dad hasn’t seen it either. Here is a picture of that.


I took that as a sign to shut it down and get started. All that I know about the clutch is that it is a zoom clutch and I guess it is pretty heavy duty and caused the adjustment rod to do that?


Here is all the info I have on the engine. I can tell when looking at the suffix code that the block has been decked, hopefully not too much for my purposes.

The plan is to make it a reliable daily driver that will probably never see anything over 3500rpm, I am 99% sure I will be building around the 12-300-4 comp cam.


Sent from my iPhone using Tapatalk

[bd]

It's really not all that surprising.  That's caused by decades of use with insufficient lubrication of the rod end and its ball socket.  You may discover similar wear at the clutch fork pivot ball.

[TB24]

Thanks BD, that makes sense. How would you go about lubricating that specific area?


Sent from my iPhone using Tapatalk

[bd]

Apply a dab of extreme pressure moly-sulfide bearing grease every service.

[TB24]

I have a few cams I’d like to hear your opinion on. All flat Tappet:
 

Howard’s 117071-12
Advertised duration: 256 intake 262 exhaust
@ .050: 194 intake 203 exhaust
Lift w 1.5 rockers: 0.390 intake 0.410 exhaust
112 lsa
 


Crower mileage compu pro 00238
Advertised: 250/258
@ .050: 192/196
Lift w 1.5 rockers: 0.392/0.399
112 lsa
 


Crower mileage beast 00902
Advertised: 246/252
@ .050: 192/198
Lift w 1.5 rockers: 0.393/0.402
112 lsa
 


Melling 22111
Advertised: 270/278
@ .050: 194/204
Lift w 1.5 rockers: 0.399/0.422
112 lsa
 

Summit 1101 -same as melling 22111 (except 1/1000 of lift)
 

Lunati 06101
Advertised: 262/262
@ .050: 201/201
Lift w 1.5 rockers: 0.393/0.393
112 lsa
 

I am getting a little scared of the quick ramps of the comp mentioned above simply for longevity reasons. A lot I know I’m sorry but they are all pretty similar I just don’t really know the reputation of the brands much and looking for some feedback. The lunati says rpm range 1,000-4,800 so a little higher than the other ones right off idle. I also lean towards longer exhaust duration if I understand correctly that would help.


Sent from my iPhone using Tapatalk

[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


Sent from my iPhone using Tapatalk

[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.


Sent from my iPhone using Tapatalk

[TB24]

Do these look like stock pistons?


Sent from my iPhone using Tapatalk

[bd]

Measure the bore diameter.  An original SBC 350 has a 4.000" bore.  Bear in mind that many aftermarket pistons are clones of original castings.  So there is no way to be sure if the pistons are original without removing them and checking for OEM markings.