2 bolt/ 4 bolt

Froh

n00b
Apr 3, 2024
2
0
1
Tomah, WI
How much more is a 4 bolt engine worth, vs 2 bolt? How much do SBChevy v8's go for these days, say, something from the 60's or 70's?
 

Yav8

Master Mechanic
Aug 19, 2014
277
121
43
Manitowoc wis.
Not very much for the early blocks unless some one is looking for a number match. Good luck with that. 350 block are a not hard to come by in my area. People pull them out think they would be worth a lot some day. There under the bench waitin for the big $$$ day. Time passes buy and some times the owner and the $$$ day never happends. RIght now if I was looking to build a 350 I would start with the Last of the gen 1 blocks. The 638 or the 880 castings that are set up for a hyd. roller cam and a one piece seal crank. No more leaks by the crank no more whipped out flat tappet cams. ( you can still use one if you want BUT WHY ) no more sloppy dip stick tubes. The 880 are clearenced for a stroker if you wanted to make it a 383 so what not to like. 2 bolt 4 bolt thats depends on what your building it for. If its a street strip motor with not lot of power adders the the 2 bolt works just fine. If your building for what you think is a lot of power then a 4 bolt will work for you. Spladed 4 bolts can be added to any 2 bolt block and if its big power you will have them anyway. IF you ge a 880 block it will come with a set of REAL VORTEC heads. Freshen the block add a under .480 lift or upgrade the valve spring and add a .500-.550 lift cam and your some place around 380-450HP. You can't go wrong with a hyd. roller block for any build 2 or 4 bolt.
 
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Built6spdMCSS

Geezer
Jun 15, 2012
5,839
9,766
113
Florida Beach
Splayed 2 bolt is stronger than a factory 4 bolt main.

Don't forget the double hump heads and 3/4 race cam, that sumbitch be jumpin coke cans at the street light.
 
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Ernest

G-Body Guru
Apr 28, 2016
758
1,033
93
Texas
Forget the earlier model engines, go after newer style 350 engines.

They come factory for a roller cam setup, one peice rear main seal and the two bolt main will more than suffice, if you want extra insurance, stud the mains, stronger than the four bolt mains where the outter bolts are fastened into the weaker part of the block webbing.
 

UC645

Royal Smart Person
Apr 20, 2020
1,087
3,085
113
Kittanning, Pa
Forget the earlier model engines, go after newer style 350 engines.

They come factory for a roller cam setup, one peice rear main seal and the two bolt main will more than suffice, if you want extra insurance, stud the mains, stronger than the four bolt mains where the outter bolts are fastened into the weaker part of the block webbing.
Keep in mind the stock lifter holder setup on these engines are limited to around .550 lift (with a 1.5 ratio rocker arm) and 6000 rpm MAX. Otherwise they drop too far into the bores (cuts out small base circle cams too) with higher lifts, dropping out of the dog bones, or can rattle the bones off with enough rpm.

I have no experience with this personally, just relaying info I’ve found around.
 
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78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
1,303
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SW Arizona
Summary...

327 $100 to $350

305 $50 (or free) to $250

350 $150 to $350

350 4 bolt, maybe about $75 to $125 extra if block is in good shape and no damage to crank mains.

Around 2015 top dollar for a 350 Vortec was about $1000 all day long, any where you go.

Now 2024... $500-ish

305 long or short block any where $50 to $150,

Now 2024... 305s, are $200 to $250 for long or short block. Harder to find in midwest where a lot of oval track is going and 305 with 3.801 max bore is standard. Cast # 201, 202, 203 & 776 blocks were used for 305 HO and easy to convert to 4 bolt caps.

Now 2024... 350s, are $150 to $350 short block, $250 to $550 long block, maybe an extra $125 for 4 bolt main. Only if with good heads and no damage to crank.

If you pull cover with cam gear removed look for a "10" and or a "20" cast in. Those are late 60s very early 70s block and highly sought after for racing back in 70s and 80s.

Those blocks can go for as much as $5000 but that has to be a very special market. I have 3 of them and paid about $100 a piece. And yes..., never found any one that wanted to pay $5000 for any of them, probably never will.

If I remember correct... 10 = 5% Nickel, 20 = 10% Manganese basically makes cast steel.
 
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78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
1,303
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SW Arizona
On the 350 880 Blocks, they don't come pre-referenced that I'm aware of. Maybe the later ones were? In Phoenix one of the best known shops for the 383 prep was about $800 each and that was about 5 years ago. I was there this past January but not the topic, so not sure of current price.

On the dogbone stuff above .550... Stock would be true, but sounds like incorrect roller lifters were used.

On the SBC High RPM you keep the lifter under spring pressure separate from the valve spring. I'll find photo of this and post.
 
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565bbchevy

Geezer
Aug 8, 2011
9,619
12,709
113
Michigan
On the SBC High RPM you keep the lifter under spring pressure separate from the valve spring. I'll find photo of this and post.
Are you talking about a rev kit?
 
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SS_Malibu

Royal Smart Person
Supporting Member
Sep 27, 2021
1,181
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Mesa, AZ
When I upgraded my engine, I went with a late model Gen1 block with a one piece rear main seal and roller cam. I’ll never buy another flat tappet engine again. Roller cams are super smooth and climb RPM’s fast and still have that chop at .555 lift. It does have a 4 bolt main but that’s because it came with it. Also, I gave my 305/TH350 combo away so yes, you can still get those for free.
 
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