Building a 350: newbie finer points?

[mtnrat]

:rollside:

[curtis73]

You suggest changing to 1.6:1 rockers and to bump compression. With my current stock heads I get 8:1, and I know that the vortecks have smaller chambers, any guess on the compression with vortecs. And by bumping compression do you mean by changing pistons or the increase I will get by changing heads? From what I understand increasing lift is better done by changing cams rather than just changing rockers. I would like to retrofit a complete roller system.
Thanks
I agree that changing lift is better done with cam lobe lift, but most manufacturers only offer one lift in the duration you want. Using rocker ratio is a perfectly fine way of playing around with lift within a certain cam spec without having to search for another cam. But, since you're putting in a new cam anyway you might find one with a combination of duration and lift you seek. My small block math is pretty rusty, but I think on a 350, you get one full point for about 13cc???? So if you had a 76 cc head and swapped to the vortecs with 64 you will probably be smack on 9:1
And thanks for the link!!! I'll have to get rid of those heads discreetly. HEEEYYY! I don't have an anchor for the boat yet... maybe they'll do

[curtis73]

I thought of a few more questions:
- in my piston selection, I can get close to my target 9:1, but of course not exact. Since marine engines tend to run cool, how much compression can I realistically get away with on 87 octane? I don't need to be pushing the envelope, but if (for example) my choices are 8.75:1 with piston A or 9.23:1 with piston B it would be nice to know the practical limit. We know my cam is a short duration, and the boat is probably going to be somewhere north of 2600 lbs most of the time.
- The engine I just got today is a truck block, so it has the left side dipstick and the oil pan rail has a little curve in it. Any problem using the automotive oil pan on this since my 305's pan probably won't fit? It at least has a pathetic windage tray
- Are there any special considerations for any of the gaskets that need to be made? If this were for a car, I'd just call and order the FelPro kit. Are copper exhaust and head gaskets out of the question due to corrosion? Are standard FelPro blue line gaskets OK?
- when I pull the exhaust manifolds off the old 305, how do I tell if they're good to use again? I read about a muriatic acid bath to clean off the scale, but how do I know if they're good? The main reason I ask is because I've been looking on Ebay for new ones, but almost all of them are the center outlet. Mine exit on top clear at the back. Since I seem to have trouble finding more rear-exit manifolds, keeping the old ones seems more important.
I can't tell you how happy I am with this new engine. I pulled the pan and heads and it looks VERY nice. Its dirty from sitting a few years, but bone dry and clean. I had expected $300 for the engine and $630 for machine work. I ended up buying the engine for $250 and now it looks like I can get away with a hot tank, a bottle brush hone, a magnaflux, and re-assembly. What I'm saving in machine work I can use to buy brand new Vortec heads. The guy even threw in a set of 40-over pistons for the next build, a flexplate, TC cover, balancer, crank pulley, and a wooden engine crate. God, I love Craigslist.

[SmokinLowriderSS]

By the way... I just won the cam for $33. Now, does anyone have a 350 block for me? I just missed a 4-bolt block on Craigslist for free
You likely already know this then from your experience, nut just in case, I've seen a lot of folks kill bigger flat-tappet cams on break-in. When I broke mine in I was given advice I call good, and had zero trouble.
IF you have multi-piece springs, leave the inner spring out to lower the spring pressures for the break-un & first 8 to 10 hrs of running. It really eases the pressure on the metal surfaces, that and GM EOS in the oil for more hi-stress lubricity. I had not heard aboput the EOS, but I had an oil pan full of fresh (just switched to) Syntech synthetic, and had zero trouble using it (kinda pricey but was last run of the year & storage planned anyhow).
I was also told by my source that he has seen more cam break-ins go sour on synthetic BLEND oil than either 100% either way (synthetic or dyno) and so advised against that. A lot of folks on here swear my Rotella diesel oil for break-in, ya can't really do the engine any harm running it daily either, it's a much higher stress spec oil for severe service diesel use than the worst of the gasoline specs.
I restarted the cam run just set at 9.6:1 (had a span of comp ratios in there too), got t6he list down to under 2 million, and it is almost done. Will post results with corrected heads soon.

[SmokinLowriderSS]

This should help you ID the heads: http://www.thedirtforum.com/castings.htm
Casting # Years Valve size hp level Chamber Size/notes
462624 76-87 1.94/1.50 & 2.02/1.60 Not listed 76 CC Chambers
These are crack prone!
You are going to vortec heads anyway. looks like a great find.
Another good site:
http://www.mortec.com
Lots of GM and Holley references, well organized I think.
462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves
OK, here's the damage, best iteration is in ..... 9.6:!, L-31 Iron Vortech heads ... 1.94"/1.50" valves.
Torque peak is 446@3,000 RPM .... from there it looks like this:
3,000 ... 446 ... 255
3,500 ... 437 ... 292
4,000 ... 425 ... 323
4,500 ... 410 ... 352
5,000 ... 386 ... 367
5,500 ... 361 ... 378
The cam was as follows:
Roller, masurements at .050"
lift .450" both
Inake Duration, 202*
Exhaust Duration, 212*
IVO: -8
IVC: 30
EVO: 32
EVC: 0
lobe centerline, 107.5*
intake centerline 109*

[mtnrat]

Thanks, I will look deeper into the numbers when I get a little time this weekend.

[SmokinLowriderSS]

I thought of a few more questions:
- in my piston selection, I can get close to my target 9:1, but of course not exact. Since marine engines tend to run cool, how much compression can I realistically get away with on 87 octane? I don't need to be pushing the envelope, but if (for example) my choices are 8.75:1 with piston A or 9.23:1 with piston B it would be nice to know the practical limit. We know my cam is a short duration, and the boat is probably going to be somewhere north of 2600 lbs most of the time.
IF your new heads come out with 63cc chambers,
IF your pistons come up flush with the deck,
IF you run a .039" thick gasket (nothing wrong with a good Fel-Pro blue),
IF you do a .040" overbore
You need 28cc dish in the pistons to get 9.05:1
22cc for 9.57:1
17cc's gets you to 10.05:1, run premium & enjoy the extra 10 HP over 9.6.
Any differences to the above, needs to be recalculated. Gonna be some mock-up time here ,,, find out with the crank, rod, and an old piston the deck height flushness (liberally grease up a set of old bearings for the mock-up, should hold pretty decently centered, enough to be close enough, just do 1 cyl, don't really need rings on it IMO, for this check. Could use an old set tho.)
- The engine I just got today is a truck block, so it has the left side dipstick and the oil pan rail has a little curve in it. Any problem using the automotive oil pan on this since my 305's pan probably won't fit? It at least has a pathetic windage tray
Try It and see if it fits. I would think the pan rails would be the same. Make sure you get proper clearance to the oil pick-up, Play-doh works great here.
- Are there any special considerations for any of the gaskets that need to be made? If this were for a car, I'd just call and order the FelPro kit. Are copper exhaust and head gaskets out of the question due to corrosion? Are standard FelPro blue line gaskets OK?
No special considerations IMO. Fel-Pro's are good gaskets. A little RTV at the right places to prevent water & oil leaks, just like on a car.
- when I pull the exhaust manifolds off the old 305, how do I tell if they're good to use again? I read about a muriatic acid bath to clean off the scale, but how do I know if they're good? The main reason I ask is because I've been looking on Ebay for new ones, but almost all of them are the center outlet. Mine exit on top clear at the back. Since I seem to have trouble finding more rear-exit manifolds, keeping the old ones seems more important.
Don't know, sorry.
I can't tell you how happy I am with this new engine. I pulled the pan and heads and it looks VERY nice. Its dirty from sitting a few years, but bone dry and clean. I had expected $300 for the engine and $630 for machine work. I ended up buying the engine for $250 and now it looks like I can get away with a hot tank, a bottle brush hone, a magnaflux, and re-assembly. What I'm saving in machine work I can use to buy brand new Vortec heads. The guy even threw in a set of 40-over pistons for the next build, a flexplate, TC cover, balancer, crank pulley, and a wooden engine crate. God, I love Craigslist.
Congrats.

[Aluminum Squirt]

Hey smokin', I too will be building a SBC, hopefully soon, and I want an opinion. You mentioned some break in proceudres. I was always led to believe that breaking in with synthetic is a no no because its too slick and the rings would never seat properly. Is that an old wives tale that's not applicable with modern machining practices? Did I make this up or has nanybody else heard this? I'm going to run a roller cam/lifters so I shouldn't have any cam break in issues and everything I'm hearing is that old school break in of a motor doesn't really apply anymore. Break the cam in (if applicaple), put the motor through a couple of heat cycles, change oil a couple of times, re-torque everything, and drive it like you stole it-Aluminum Squirt

[curtis73]

Thanks for all the break in tips, guys and the answers to all my questions. I'm going down today to tear apart the 350 and I'll take the parts to the machine shop.

[mtnrat]

What heads would you go with? I have a closed cooling system.