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  #1  
Old Feb 9th, 10, 9:02 AM
grovey grovey is offline
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Tim
 
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Default 434 sbc build ?'s

I'm tossing around the idea of a 434 build. I have the chance to buy some used stuff, and thought it might be a decent attempt at a budget 434. I have a 2 bolt 400 block, and was just going to do a cheap 406, but this has me thinking. I have a few concerns though. First is the crank. It's a 4340 piece, int balance, but the rod have been turned down to small journal. This tends to make me think it will be easier to clearance the block. The rods i'm looking at are scat 6" sj i beams. the pistons are j&e small dome standard bore, mic at 4.125. My concerns are.... as a rule, will i get a good ring seal with a good hone job in the used block ? How much hp/rpm will the scat rods handle with the smaller 3/8 cap screws? Will i have a fortune in balancing because the rods journals are cut to 2.00 ? And how much can i mill those domes on the j&e pistons safely ? I'm thinking afr 210 elim's with the big chamber for heads. Looking for 11.1 comp, custom solid flat cam with small base circle and around 260 at 50, 300 duration, 575 lift. I'm looking for opinions, and suggestions, and for that matter holes to be poked in my theorys. I know it's far from a perfect build, but I can't swing a new block, so that option is out. When would it run out of steam with said cam ? If it'll live, what kind of power do you think it would make? I'm thinking in the 550 range with tq on demand. Opinions ?
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  #2  
Old Feb 9th, 10, 9:44 AM
marks412 marks412 is offline
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Default Re: 434 sbc build ?'s

I'm no expert, but If the block is a stock bore, I think I would replace the pistons with a flat top, 4.155 bore, .030 over piston.
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  #3  
Old Feb 9th, 10, 11:31 AM
Dave427 Dave427 is online now
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Default Re: 434 sbc build ?'s

If you are using a GM block I would build a 406. If you want a 434 I would buy a World or a Dart block.

Dave
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  #4  
Old Feb 9th, 10, 1:23 PM
Lilracr Lilracr is offline
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Default Re: 434 sbc build ?'s

You need to have the thrust wall sonic tested for thickness, I would add splayed caps for strength, you keep the cylinder pressure down, limit the RPM and get a good balance on the rotating assembly you will be fine.

The cam and cylinder heads will make it a lower RPM brute, but should be good to about 6200-6500 at most.

550hp should be close if everything goes together well.

A 406 would be easier on the block and would work better with the cylinder heads, but it's all in the deal your getting.
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  #5  
Old Feb 9th, 10, 4:19 PM
grovey grovey is offline
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Default Re: 434 sbc build ?'s

A new block is outta the question, it's not that i WANT a 434, but i can get the fresh ground 4340 crank for 250.00 , and the j&e pistons and a set of 6" h beams for 150.00. While i could'nt use the rods for this crank, ya can't beat the price, and having a free set oh 6 " h beams isn't a bad thing. So.... you really think it'll top out before 6500 with what i mentioned ? I don't want a bigger head than those. I can't see me ever building a bigger sbc than this, and they would still work on a 406 imo.If i went 406 it would be all scat's cheaper stuff and 195's for heads.
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  #6  
Old Feb 9th, 10, 5:01 PM
DRIVESHAFT DRIVESHAFT is online now
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Default Re: 434 sbc build ?'s

I think your math is flawed somewhere.
You arent going to be able to get 434 ci with only a 4.125" bore
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  #7  
Old Feb 9th, 10, 5:30 PM
Rugburn Rugburn is offline
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Default Re: 434 sbc build ?'s

For a 434 I would not use a stock block. Its hard enough just to find a good block for a 406 build. I havent done the math, but i dont think your gonna get 11:1 with domes on a 434. Most likely gonna need a dish or a flat top at the least.

If you go with the 406 I would still use the 210 head IMO. And the 434, 220 or bigger. Think about it, your in big block territory now. I run the AFR 227 on my 406 in a heavy truck, still have plenty of TQ and good street manners with a 260 @ .050 cam.
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  #8  
Old Feb 9th, 10, 9:07 PM
grovey grovey is offline
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Default Re: 434 sbc build ?'s

yeah, i guess it'd be a 427. it's kinda hard for me to believe that that 210 head would choke this motor, but thats why i asked. any advice on the balance job ? am i asking to much without knowing everything about the crank ?
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  #9  
Old Feb 9th, 10, 9:50 PM
67chevelle406 67chevelle406 is offline
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Default Re: 434 sbc build ?'s

Quote:
Originally Posted by grovey View Post
yeah, i guess it'd be a 427. it's kinda hard for me to believe that that 210 head would choke this motor, but thats why i asked. any advice on the balance job ? am i asking to much without knowing everything about the crank ?
I think those heads would be real nice on A 406 the combo of parts is really most important. Factory 400 blocks are known to be weak i would just build A 406 or get A dart block.
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  #10  
Old Feb 9th, 10, 10:24 PM
kirkwoodken kirkwoodken is offline
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Default Re: 434 sbc build ?'s

Quote:
Originally Posted by dave427 View Post
if you are using a gm block i would build a 406. If you want a 434 i would buy a world or a dart block.

Dave
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  #11  
Old Feb 10th, 10, 10:57 AM
dave_silva dave_silva is offline
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Default Re: 434 sbc build ?'s

Quote:
Originally Posted by Dave427 View Post
If you are using a GM block I would build a 406. If you want a 434 I would buy a World or a Dart block.

Dave
I agree, I had a lot of headache building my 434. Had to cut notches for each rod on the pan rail and the bottom of the cyl skirts. Then I got the cam and had to cleanerance the rods and rebalance. I had to line bore/hone with the new billet caps, including the front cap. I had to get a Champ Pan because it has kickouts for the rods, the rods would hit the regular pan.

Then I got it all going and after just 4 races the crank broke. When disassembling found that the #2 cap webbing broke (of course right at the bolts) causing the crank to snap. This was an Eagle 4340 crank and rods with billet caps. I was running a 4bbl with a 1" restrictor plate, had this thing been running without a restrictor, it would have blown a part the first race IMO.

I think I would have saved a bunch of time and money I had just gone with an aftermarket block. After you do all the machining, block prep, new caps, etc.. I think it is the same price or close enough to justify.

Of couse this could have been that I just had a weak block, but I would not make that gamble again.
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  #12  
Old Feb 10th, 10, 11:23 AM
cstraub cstraub is offline
 
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Default Re: 434 sbc build ?'s

A 434 SBC will need more head then a 210cc runner, more like 230cc. King makes a bearing that will adapt a large journal rod to a SJ 2.00" pin size. Turning a Chinese crank down to 2.00" can be okay or not. Depends on how deep the nitriding went and this will vary. They offer this type of crank but those cranks started as 2.00" journals.

Don't know the power you want out but I also say a 406 would make a good street piece. What you will save in that Crank you will spend in a good oil pan, and a good pan is around $800.
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  #13  
Old Feb 10th, 10, 1:59 PM
grovey grovey is offline
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Default Re: 434 sbc build ?'s

Well i guess that settles it. Way to much fuss for me. I can't even get a straight answer on the crank. the seller said it was an $1,800.00 new, but does not know the brand since he bought it from a machine shop used. lol, i think i would know. Thanks for the info provided.
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  #14  
Old Feb 10th, 10, 2:16 PM
DOUG G DOUG G is offline
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Default Re: 434 sbc build ?'s

Used parts of unknown past is a big gamble...
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  #15  
Old Feb 11th, 10, 7:39 AM
grovey grovey is offline
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Default Re: 434 sbc build ?'s

Lol, yeah i get that. I knew from the start it was risky, just wanted to hear to what extent. I got some decent info on the rods and pistons, but the crank was an unknown. The guy even said he was just going to keep it now. I don't think he liked all the questions i asked that he didn't have answers for. Oh well....
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