Cam Swap in Truck W/AC

[legopnuematic]

Going under the knife, each picture under hood is around 30 minutes apart from each other. Luckily all of the bolts came out without issue, even the exhaust manifold bolts came out good. Started at 12 and had to leave for a school event at 2. Just need to do torque converter bolts, starter, motor mounts, and bell housing bolts.

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Sent from my Moto Z (2) using Tapatalk

 

[legopnuematic]

Its out. Didn't go too bad, but the motor mount's hips were a little bit wider than the manifolds so it took some gentle prying to let it slip by. Had to cut the spark plug heat shields as you can't get the engine out with the manifolds still in and shields in place.

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Going to take this as an opportunity to clean and replace some things, new power steering hoses, motor mounts.

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[legopnuematic]

Would you believe this engine was rebuilt only 30K ago and installed 12 years ago? If I didn't have the paperwork from the shop that did the work for the PO I wouldn't believe it.

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Truck sits a lot higher without that weight.

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[bucket]

Must have been cheap paint.

 

[Rusty Nail]

Good job!

When you get finished with that - there's an engine over here what needs teh pullin.

 

[legopnuematic]

Interesting developments:
-When I pulled the fuel pump off to get to the motor mount nut it fell apart, the pivot rod and arm just fell off. Making me think that that was the cause of the noise. Which is good and bad- good that I (believe I) found the root of the problem, bad that I might not have had to pull the engine to fix it, BUT there are a lot of things that I want to correct that I haven't been able to- like the flex plate and the starter gear have crashed into each other a few times and the flex plate has some teeth that are chewed up decently bad, new power steering hoses, new motor mounts and trans mount, fix the radiator shroud, fix the oil leak at the pan/RMS, make it look like it didn't come out of a motor home from the junkyard.
-Because when it comes to things like this I am worse than a 6 year old on Christmas, I pulled the intake and pulled the lifter I suspected to be bad out- It looked brand new, BUT I compared the pushrod to the #6 intake pushrod the #8 pushrod was around 0.030 shorter than the other one. Which might explain the weird rocker geometry I was seeing, and I believe that too short of push rods can cause the valve to not receive the correct amount of lift.
-Since I will be pulling the heads I can see how much of an overbore it has and what I might be looking at for a compression ratio and just a general checkup on it
-I did rotate the flex plate slowly both directions to get and idea on timing chain slop, I got maybe 10 degrees of rotation before the rotor began to move, I suspect it might be stretched some.

 

[legopnuematic]

I am now 99% sure that the fuel pump is the culprit for the noise. I went through my stockpile of SBC fuel pumps and compared.
First is a Carter off of my 79 350. Pivot rod and arm held securely

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Second is the replacement pump that was on my 76 when I bought it. Rod and arm held in. Note the RTV all over the place, can't wait to see how much of that stuff is in the oil pan.

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Third is an AC off of my 71 400, rod and arm also secure.

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The pump I pulled out of the 76. Rod and arm NOT retained.

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[legopnuematic]

Must have been cheap paint.

If there is a tier lower than cheap I think that is what they used.

Good job!

When you get finished with that - there's an engine over here what needs teh pullin.

Hey, for enough Pepsi (Coke or RC works too), cheeseburgers, and beer battered onion rings I'd be game.

 

[Rusty Nail]

Sweet but my first thought involved chicken wings?

 

[68post]

If there is a tier lower than cheap I think that is what they used.


Hey, for enough Pepsi (Coke or RC works too), cheeseburgers, and beer battered onion rings I'd be game.

Wish you were closer..lol, I could meet those terms !

 

[Rusty Nail]

 

[68post]

I plan on sticking with the poor mans fuel injection: The Quadrajet.

I think I will go with the Howards Cam's CL112001-14 it seems to be right around what I think is best suited for the truck. I did send in the recommendation form to Howards Cams so I'll see what they recommend, but I think it would probably be the one above or very close to it.

Alot of cams out that will work fine for you, the Howards cam seems like it will also.
I'll be using the smallest VooDoo cam in a much smaller engine. Same seat duration with more .050 duration and more lift. 207* / 213* @ .050, .437" / .454", 112* LS.

You should consider a rocker arm upgrade of some type - the stockers are approx 1.37 to 1.44 instead of the advertised 1.50. With these small cams it isn't a bad idea to use 1.6 ratio and of course check your pushrod clearance or just use a "Louis Tool" before assembly.

 

[Rusty Nail]

Dude, nice catch! @68post .

Factory rocker spec tolerance was crappy, at best and 68post is 100% correct or better... I have previously touted the benefit of aftermarket rockers within the bounds of this MSB.
I like the 1.5 Comp Magnum roller tips primarily for the low, low entry price and the fact that they are simple. You can find these in MY vehicles!
The simpler = the better
The benefit(s) of ensuring uniform lift across ALL valves simply cannot be overstated.
It is difficult to quantify a $300 set of rollers in a street truck - half of that money can be spent on something else.

 

[legopnuematic]

Got it tore down to a short block on Friday before work, Verified it is a 350 and it has been 0.040 over bored. On the invoice from the shop that put the engine in for the PO it said 5.0l, so for two years I wasn't 100% if it was a 350 or not. Now I know it IS a 350 (~356.5).

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Two bolt main. Further throws the theory of "all 3970010" blocks are "fo-bolt-mainz." My 79 350 is also a 3970010 with the 010 cast into the sides of the block and it too is a 2 bolt main.

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Had a double roller. Has some play in it so I will put a new one so my new parts will be at peak performance.

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I guess this is a re builders tag on it. Above the oil filer boss.

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[legopnuematic]

Block #

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Glad I pulled it on Thursday, Friday this happened and kept on into Saturday.

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Some good and bad news. Good news is that the drivers side head is from what I have gathered- one of the best smog era heads GM produced. Casting 3973487, 75cc chamber, 1.94/1.50 valves. The ports are bigger as cast than my 71 400 heads were after I ported them.

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Now the bad. The passenger head is one of the worst heads cast. Casting 462624. 76cc chamber, 1.94/1.50 valves. The ports are way smaller than the drivers head and the chambers are 1cc smaller. I can see on both heads that they have been fly cut at some point, I need to check the chamber sizes to verify this, but in my mind its not good to not have mismatched heads to that extent. On top of that the 462624 head has a tag epoxied on it that is stamped Mexico..

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The whole "might as well" situation is starting. Since it has two mismatched heads, if I were to find another 3973487 head, chances are it would need to be reworked so that adds the cost of having to source a good head, get it shipped, cleaned, valve job, seats machined, decked. I figure that would cost a good few shekels to do. Then for $350 each, I can get two Summit (made by dart) 152123 heads, which have 72cc chambers and bigger ports. This should make some more power and then they would be matched, then comes the put headers and duals on it, but since it is all apart now is the best time to do that stuff to it.