This is absolutely correct ^^^^^ You are going to want a closed chamber head at the very least. Open chamber heads are kind of lazy and you are adding to that way too much quench and nearly zero compression. Be sure that you are measuring from the edge of the piston and not into the dish. In a perfect world (actually my world) you want your quench to be close to bur not over .040. If you are .050 down the hole you are going to want to use a steel shim gasket. You will still have too much quench but you will be closer to correct. On that mill I would go either with power pack heads or a closed chamber late 350 head. I would not waste my money on fuelie heads. I have a pair of five seven power packs in the garage but they are not for sale. They are easy to find.
The "416" 305 heads have 57cc chambers with 1.84" intake valves and 1.50" exhaust valves... Just about the same size valves as the Ford GT-40 heads...
What is your budget like? Your engine seems to be somewhat apart, so why not pistons and a rod upgrade? We used to get the "pink" GM rods at the dealer, some may have been Z28 pieces at the time. Freshening up a set of older heads may run into some coin, this is why I went on a quest for aluminum heads. My pistons are about .025" in the hole, the block was decked to clean it up. CR is somewhere around 9.73 : 1. I looked at Flotek, stayed away from the eBay Speedmaster line of parts. Speedway had a lot of heads at the time including some WISSOTA (stock car) steel heads that were around 58 ccs and a good deal at the time. I wound up with a Dart top-end kit that I'm happy with.
My 461 heads cost around $350 to build. New guides, hard exhaust seats, worked the valves, cleaned, surfaced and springs Studs were already pinned.
Yep, I had a guy that does heads for me quote similar recently. And, even better, I bought a complete running engine carburetor to oil pan the other day with a set that is already worked for $150 for the whole deal...
Sometimes less oil in the pan isn't bad, and can actually increase HP. There have been plenty of dyno tests showing that running an engine 1qt-2qt. lower than full results in higher HP when run on the dyno. So if you run the engine at the full mark, and the flow back to the pan wasn't quite up to it, the engine isn't going to blow up by simply being a little low> I'm no fan of high pressure oil pumps when they aren't needed, but never had any issues with high volume pumps. Some of the old Chevy "camel hump" heads had various chamber sizes that don't show on spec charts. I've seen 461 heads with as small as 58cc chambers, and up to 64cc chambers, so need to actually check them prior to buying them to be certain what they are. When I was building the 355 for my Austin gasser I wanted something over 10.5:1 CR, and found a fresh set of 461 heads at a machine shop. I asked them to check the chambers and they were 58cc, which with my flat top pistons put me at around 10.75:1 CR.
I think I have some workable heads. It looks like I can get .024 steel shim head gaskets but only in the stock 4.00 bore. Not sure how much of a problem they might create with the .040 overbore. Still looking for the correct gaskets. I used the calculator RodSTRace linked earlier and this combo gives me 8.56-1 compression with a set of 462 heads. I'm picking up a pair of 462, 64cc heads with the 1.94 valves this week which should get me through the next summer. I would add, the pump I have in is a stock pressure, high volume pump, from Melling. Good oil pump for sure.
Just right for a blower ! I'm in the reverse situation we're I got a short block with a little to much bump for any of the 64cc heads and pump gas, but 76cc heads put me a little lower than I'd like, I need around a 72cc. We should lock our short blocks up in a dark room and see if they can even out our piston dilemma lol
Yes, gasket listed for a 4.00" bore will typically fit all oversizes available for that bore. The shim head gaskets for an SBC are typically 4.100" gasket bore, fit everything but the 400's 4.125" bore or the tiny bore 267 and 305.
I've had good success in the past with Fel-Pro 1096. This is a stainless .015 shim that has proved reliable. I can see where the composite gasket would have an advantage. Thanks!
All I'm after is a decent running, mild, street power plant that gets me home from the Wildwood run without a tow. Reliability is paramount so I really do appreciate the head gasket suggestion along with a bunch of other stuff in this thread. I don't have the cash for a "crate" which would be the logical choice, so this motor is the closest thing to a crate motor I can get my hands on. I don't mind spending on good parts but I have to be careful. I want this on the road no later than next Spring. It should have been this Summer but that didn't happen. I build cars for a living and haven't had one of my own in twelve years so now's the time. I do love the inspiration on this board so post away. As milwscruffy mentioned earlier my car is really light. I'm thinking finished out in the very low 2000 lb. area so even a mild motor will get it down the road pretty nicely. Everything works out and I can build another motor and swap it next winter if it's too lame. My build thread on this one- https://www.jalopyjournal.com/forum...-vicky-body-a-build-thread-with-pics.1197541/
I’m running basically the same smog era 350 dished pistons with 461 heads. This 350 was a Fred Jones rebuild decades ago. Still running the dished replacement slugs your engine has. It’s in a 6k pound 61 c40 flatbed. Does it’s job well. Has pulled over 12k across the scales. No struggles. You’ll be fine
I've done plenty of junky 350s. Use what head you can find. I'm partial to the 461s. Choose a cam accordingly and you will be happy. I've spun plenty of RPM, burned enough tires, and towed heavy loads with nothing more than a decent cam, intake and carb for years. I run all my engines on 87 octane. You can stress all day on little variables, and while everything adds up, little power losses will not kill your smiles
Picked up a pair of near fresh 492 fuelie heads today. The 1.94 valves will work just fine and they already have screw in studs and guideplates. Super clean and in great shape. Not sure what springs are in there but they look pretty stoudt. I'm just gonna' throw them on and see what happens.
@Koz, you mentioned using 1.94 valves but ‘492’s were machined for 2.02 intake and 1.60 exhaust. Was that just a slip of the tongue or maybe a typo and the heads are ‘462’s?
Sorry, Slip of the brain. These are actually 461. I had my mind on something else as I was typing. They are pretty slick actually and will serve my purposes as good as a pair of aluminum aftermarkets for now, (probably for ever)!
Just watch that "too stout" spring pressure is not kind to flat tappet cams. Use what's recommended for your cam choice.
You have a used engine that is not really worth that much in its current condition . if the deck is flat and true then run some thin shim type head gaskets and that will get you about .020" of your squishes back . Some 461 heads with 194 valves will give you more power than the cam in it is going to allow . How much HP you think your going to gain or loose due the pistons being down in the hole .050 ? maybe 5 or so ? The 305 heads don't make that good of power unless you add some valves and other work and they don't flow great . yes they will run but you might gain more with less compression with a better flowing head . Its never going to be a race engine I assume you just want a good runner that can handle pump gas. will you notice the 15 HP or so you might gain with new pistons and rising them up but still being at the same compression ??? I doubt it . Your not trying to get optimum quench so you can run a bit more compression with 9.5 to 1 or what ever your shooting for . quench and deck height have been the big buzz words the last 10 years or so but consider how many 1000's of engines are running just fine that are like yours ? deck heigth and squish gets more critcal wne your running near the detntion point and want to get a little more . Run what you got add a better cam and some 461 heads with a good intake it will still likely make 250 to 275 HP with a old set of 461's or so . 202 valve's will not gain you much and may loose low end were you need it even . the 194's are less shrouded and likely run jsut as good . remember very few chevy's had 2.02 valves mostly Vetts and higher HP Cameros . All the other normal Cameros and such still ran really good with only 1.94 valves . There have been a lot of 12 second 327's built running 194 valves and 561 or 462 castings ( with much higher compression of course ) more than enough for this worn 2 bolt main cast piston small cam engine . If the deck is not perfect to take a new head gasket then tear it apart and deck it . Re ring it then also . At that point decide if the bores are good enough or your going all in. No guarantee a replacement piston will hve the ideal clearance for the existing bore . Zero need for a high volume oil pump robs HP . If its got good oil pressure then its gong to support 350 HP or more just fine like every other good running small. block . Ff it was spinning 6000 RPM then maybe . Its likely y not There are some cheap aluminum heads like the Ebay stuff that work OK that have small combustion chambers . Kid down the rod stuck a se ton his late 80's Firebird and it runs petty damn good . I have had a few dish piston 70,s chevy's that got smaller combustion chamber heads but left the bottom end stock that ran pretty damn good , a 76 Camero i had for example . Was no race car but it made about 250 HP ran great form the $165 it had originally Guys forget years ago 350 HP was a lot for a SBC and most the common daily driver stuff was only around 250 or a bit more . Id run what you have with some decent heads that will work on something else later and save the money for places that will give more bang for the dollar
I'd like to mention this is a fresh, .040 over engine from a rebuilders shop. The bottom end and the bores are excellent. I've never been sure why it was pulled but it has no more than a few hundred miles on it max. When I got it, (locally), it was a short block and had no tin on it. I checked the rods and mains which were dead on along with the bores. Everything is right on. I have no idea of what cam is in there but it is new as well, (very mild stocker I am sure). I put in the oil pump I had here along with the correct pickup along with good sheetmetal. It would be a shame to pull the cam right now as it has everything new including a double roller chain that is spot on. I may still do it though. The only thing weird is how far down in the bores we are. Unless there is something I'm missing this should be a great street runner in a light car. The 461 heads I just picked up are equally fresh and very well done, so I don't see a problem there. The worst that can happen is it's a total pig and I make it through the summer and do it right next winter. I will add this is an 014 block, (Tonawanda), the same as the desirable 010 blocks, so it's not a total POS.
Run it . Get the .026" head gaskets linked above or similar your .050" in the hole plus the .026" gasket . So your at .076" squish . this is not a deal breaker and what people are over looking is its got dished pistons so its never going to be at ideal according to the internet .040" even if you zero decked it half the piston is way way down in there . I bet on a dyno you would not see 5 HP if the compression was the same and only the squish was changed . There is a good chance the 461 heads you have are already milled . So they might be under 64CC any way . ( you could check them ) . Id not worry about the block being 014 or or 010 anything special or valuable . lots of blocks still out there . Unless your building some $10,000 engine based on it any chevy 350 block will work for your needs . Millions of them that are not some supposedly high nickel content that all ran for 100's of thousands of miles and still had OK bores . When I was really young and thought my builds needed every last HP and I some how thought id need a block that was special my grandfather laughed and said boy its likely going to blow up in under 5000 miles or a few races what do you care about how long the cylinders will last . Sure there are preferable blocks given a choice and some have thicker cylinder walls and such but on a street engine about any 350 chevy block will work and 2 bolt mains are just fine . how many pre 350 chevy Corvettes ever lost a bottom end , rod bolt or cap ??? very very few . being as its unknown why it was tore down id get it running and be sure it holds water and all that .
I'll bet you guys never saw this coming. What's your cam recommendation for this motor? I'm thinking a mild RV style grind, max vacuum along with a bunch of torque. Mostly around town driving with the occasional road trip. Needs to have decent vacuum for my brakes. I'm thinking Clay Smith "Torquesmith" or the equivalent Melling or Comp Cams equivalent. I've had good results with these before. Fall Wildwood is a washout so I'm feeling a little better about missing it, (a little)!
I don’t want to hi-jack your thread, but I have a question and it does apply to your situation too. I’m building a 350 for someone else, it’s getting a new Crane cam, an RV type grind that’s brand new. Given the lifter issues we constantly hear about has anyone used GM 12371044 lifters that sell for around $195? Naturally I’ll be staying away from Chinesium lifters that sell for as low as $55, but anybody have a recommendation on a good hydraulic lifter?
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