351C questions

[Palimino]

Just picked up this engine last week, came out of a '66 5000 chassis, mileage unknown, first compression check was kinda low in the 40-60 lb. range, shot some Mystery oil down the holes and got better numbers, 90-95 (1-3-5-6) and 89-70 ( 2-4), pulled that head and it looks like head gasket could be the problem, not much if any ridge at top of the 3 bores, no gouges/scoring either. Valves look to be 1 7/8" EX and 2 1/8" IN, the manifolds are the "I" beam style. Are these the "small" valve heads I have heard of? Thnx

[Ed Snyder]

Just picked up this engine last week, came out of a '66 5000 chassis, mileage unknown, first compression check was kinda low in the 40-60 lb. range, shot some Mystery oil down the holes and got better numbers, 90-95 (1-3-5-6) and 89-70 ( 2-4), pulled that head and it looks like head gasket could be the problem, not much if any ridge at top of the 3 bores, no gouges/scoring either. Valves look to be 1 7/8" EX and 2 1/8" IN, the manifolds are the "I" beam style. Are these the "small" valve heads I have heard of? Thnx

The 351C is a non-Magnum engine, so -- yes -- it has the "small" valve heads just like the 305s have. The 351E has the Magnum heads. My one ton Suburban has the 351C in it.

[Palimino]

Thanks Ed, just what I thought, now I need to continue with my tear down, inspection of what I have to start ordering needed parts to get this beast running in top shape:signthankspin:

[Palimino]

Ed, what is the major difference between the different heads? Would a little clean up with a die grinder/stones, better exhaust system work etc be beneficial? Thnx Joe

[Ed Snyder]

Ed, what is the major difference between the different heads? Would a little clean up with a die grinder/stones, better exhaust system work etc be beneficial? Thnx Joe

The intake and exhaust ports and manifolds are all larger in cross section (by about 30% if memory serves me) in the Magnum engines, compared to the non-Magnum. I'm sure cleaning up any ports or manifolds would help the flow through them.

[Palimino]

Thnx for that info Ed, any idea where I can get torque info for rods and mains? Was gonna do a complete lower end on this engine, but after looking at a main bearing and rod bearing and checking out the cylinder bores, I think I'll stick with having heads done and new gaskets to get it running again, BTW found this engine in Rogue River. :signthankspin:

[Palimino]

Well the rebuild has started, heads back from machine shop, cleaned, valves ground, seals replaced, Olson's had a gasket rebuild kit, and now we begin...8144

[jagarra]

Here are the torque specs from my GMC Maintenance Manual.

[Palimino]

OK, bottom end back together, water pump housing on, crankcase vent filter ordered, can't seem to be able to locate head bolt torque pattern, any help would be appreciated, THNX

[Funky61]

Quick search on the net produced this

[tbucketnut]

Well the rebuild has started, heads back from machine shop, cleaned, valves ground, seals replaced, Olson's had a gasket rebuild kit, and now we begin...8144

Palimino, if I can ask, what did the gasket kit set you back at Olsons? And was it a valve grind kit or complete?

Thanks,
Steve

[Palimino]

Thanks for the help!

[Palimino]

Steve, it was a complete kit for $500, had my head work done at Westbay in Bremerton, Joe

[Palimino]

Heads back on and torqued, I want to thank all for their help to get to this point!:signthankspin:

[tbucketnut]

Joe,
I had Marvin machine a couple stovebolt blocks this last year, a 235 and a 261, which one I assembled and put in my 53 3100, the other went to a fellow stovebolter in northern cal. He also did a head for the 261.
I took him my pistons and he bored and then honed to fit them, the skirts clearances were spot on and the hone he uses sealed those cast rings in immediately. Really happy with his work there at the Bremerton machine shop. I had been using Bud over in Lakewood but the last few times he has been jammed up with work and seemed to take forever.
Anyway thanks for the info on Olsons, I'll have to go see them soon and see what they are working on.
Also, if you know of a dent free oil pan for a 305E please pm me, I'm trying to locate a few bits and pieces myself.

Steve

[Palimino]

Steve,
I will be getting rid of a '62 305B in the near future, if you know of anyone interested....
Joe

[Palimino]

My bad that is a "C"

[Palimino]

Well this "little" endeavor has taken a turn for the worse, after reassembly, checked compression and had some improvement, now the problem, ??RINGS??, had I know they were like finding unicorn manure I would have opted for another route, EGGE is still looking for a set of rings for this build buuuuuut? Any suggestions? Parts look better for 305's and 401 than the 351's who da thunk.

[sclor]

Palomino:
I would check with the thunder v12 folks. They are rebuilding GMC v12's that use the same bore as your 351. I would think they have crossed the same bridge and have a source for 351 piston rings. They were helpful when I was looking for magnum manifolds for my 351e.
Regards
Steve
New Orleans

[sclor]

Here is thunder v12 website :
http://thunderv12.com/

Regards
Steve
New Orleans

[Palimino]

Thanks Steve, just called them and guess what the reply was, nada, nope sorry, but thanks for the idea.

[sclor]

Palomino:
Don't give up. Do you have part number?

Jolly's site shows Hastings number as 2M306 for 351e. Your 351c likely has 4 ring pistons. With that said, that part number looks like it could be special ordered from Hastings with 1-3 months delivery here:.

https://www.amazon.com/Hastings-2M6306-6-Cylinder-Piston-Ring/dp/B0049N8MI6

Hope that helps.
Regards Steve
New Orleans

[sclor]

Whoops, should be 2M6306.

[Palimino]

Well Steve thanks again, but after talking with Hastings, that listing on Amazon sounded a bit off as they told me they do not sell to Amazon, long and short of it, my local machine shop guy found a set of cast rings and they should be here in a couple weeks!:upyes:

[sclor]

Palomino
Glad it worked out.
Regards
Steve
New Orleans