Author Topic: SBC top end kit  (Read 3087 times)

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Offline 19transam81

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SBC top end kit
« on: July 22, 2011, 03:46:03 PM »
Hey guys, I currently have a sbc 355 in my 81 trans am. The guy who sold me the car said it was recently rebuilt with only a few thousand miles on it. After looking up some numbers on the heads, intake, and carb I found out they heads are off a 305 with low flow numbers, the carb is a quadrajet, and I believe the intake is an aluminum one off of a corvette of some year. The block is a '79 4 bolt main out of a truck which is supposedly bored .030 over.The motor has never given me any problems, but it is kind of a dog. So, I was looking around at some top end kits to try and wake the motor up. I want to be able to drive the car often, but also be able to go to the strip and not be embarrassed. So far, this is what I have found and seems to be the best bang for the buck.

http://cgi.ebay.com/ebaymotors/TOP-END-KIT-CHEVY-350-SBC-PERFORMANCE-KIT-_W0QQcmdZViewItemQQhashZitem3f0bf466a1QQitemZ270783506081QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_2178wt_1165

However, I am not very experienced with building engines and was hoping some of you guys could tell me if this is a legit kit or not. Like I said, I don't want something that is gonna give me a lot of problems. I was thinking of going with the dual plane air gap intake and the 230/230 duration .480/.480 lift cam with the 1.6 RR. From what I have read, a combo like this should produce about 400hp/400 ft-lbs. The kit doesn't come with a carb, but I think a 660 cfm carb would be enough for that setup. Seems like a reasonable street/strip setup to me?

I have hooker comp headers into a 2.5" true dual exhaust with aftermarket "flotech" mufflers I believe (supposed to be a knockoff of flowmaster after they lost their patent?) The pistons are supposed to be forged, but we will check the internals out when we tear the engine down to see how much of what the guy told me is actually true. Obviously, if the bottom end is junk we will not waste the money on a top end kit. But, from what the guy said the bottom end is supposed to be strong.

Basically, I am a little skeptical of buying a top end kit off of ebay, but I am a grad student and don't have 5k to spend on top of the line parts. Just hoping for a little input. I know next to nothing about details of building an engine and just want to make sure the important parts of the heads are strong and of good quality. Let me know if I left anything important out. Thanks for the help ahead of time!!

-Cody

Offline Chuckles

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Re: SBC top end kit
« Reply #1 on: July 23, 2011, 01:39:11 PM »
I'd actually suggest getting a set of Vortec heads off a 96 GMC or Chevy pick-em-up truck and get the appropriate intake manifold. They flow really well, are reasonably priced and are readily available at most salvage yards and, they don't use any exotic high dollar parts. Or, even a set of LT1 or LT4 cylinder heads off a early 93-96 Z28/Firebird/Corvette.
« Last Edit: July 23, 2011, 01:42:05 PM by Chuckles »

Offline LilSki

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Re: SBC top end kit
« Reply #2 on: July 29, 2011, 05:23:38 PM »
I don't know much about SBCs but I do know 305 heads on a 350 is a big no no. Unless he had dished pistons installed your compression ratio is way to high. And if he had dished pistons installed then if you put 350 heads on there your compression ratio will be way low.

Also LT1/LT4 heads won't fit on a Gen I block without major changes. But vortec heads would be a good way to go.
Kevin
79 Trans Am: (77 nose), WS6, M-21, 461, Hotchkis TVS, PTFB Contol arms. 
85 Trans Am: Vortec 350 w/LT1 cam/T56, TPI conversion w/Megasquirt II.

Offline Chuckles

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Re: SBC top end kit
« Reply #3 on: July 29, 2011, 06:44:13 PM »
If I'm not mistaken...there's no obvious difference's in the structure or design of the block other than no provision's for a mechanical block mounted fuel pump and it's a one-piece crank seal instead of a two-piece. The reverse flow cooling is the only difference and that's changed easily. Just plug the cooling passage's in the donor heads and walla!

Offline 19transam81

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Re: SBC top end kit
« Reply #4 on: August 05, 2011, 02:51:06 PM »
The pistons are flat top pistons in the block right now. I know a top end kit will really wake this engine up. The low flow 305 heads and stock cam are really holding it back. Basically, I want to know what the best way to spend about 2 grand on the engine would be to keep it reliable enough for street driving but actually have some power for occasional trips to the strip. I also would really prefer not to have to make all kinds of special mods to make an application work. With the Vortec heads, I have heard you must modify them to accept anything over a .480 lift. I would like to have just bolt on performance for the most part without having to modify cheaper parts to make them work. Thanks ahead of time!

-Cody

Offline Chuckles

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Re: SBC top end kit
« Reply #5 on: August 05, 2011, 08:46:18 PM »
A .480 lift is way too much for a 350 anyhow in my opinion. You'd have a problem keeping it idle and keep engine vaccuum.