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low buck junk SBC

General engine tech -- Drag Racing to Circle Track

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CGT
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Re: low buck junk SBC

Post by CGT » Mon Nov 25, 2019 10:54 pm

I seem to remember a tbi 4.3 "Z" in S and T series being referred to as "vortec"....but not the lo3 and lo5 "K" and "M" engines.....could be wrong ....4.3 W prior to 96 for sure....vortec name has been thrown around at GM for a long time.
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Re: low buck junk SBC

Post by prairiehotrodder » Wed Nov 27, 2019 10:18 am

I just realized that my old 78 chevy deck truck has a stock 350 vortec in it that i installed about 6 or 7 years ago and have been running a stock HEI distributor ever since. Never even thought about the cam wanting a mellonized gear on the distributor.
BTW - anyone ever hone out the vortec dist gear to fit on an HEI and save the $96 from GM or $86 from compcams ?

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Re: low buck junk SBC

Post by turbo camino » Wed Nov 27, 2019 11:55 am

DON'T PANIC

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Re: low buck junk SBC

Post by prairiehotrodder » Wed Nov 27, 2019 12:27 pm

Thanks, now you know what its like being Canadian !

I ordered the comp cams one for $86, will be here tomorrow from a wholesaler i deal with in Edmonton. My local GM dealership wanted $96 for the GM gear. i could have bought the Comp bronze gear cheaper.
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Re: low buck junk SBC

Post by turbo camino » Wed Nov 27, 2019 12:37 pm

Weird, Comp 412M is $80 USD, why no 3x markup on that one like the GM gear has?

https://www.summitracing.com/search/par ... =Ascending
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Re: low buck junk SBC

Post by prairiehotrodder » Wed Nov 27, 2019 1:38 pm

turbo camino wrote:
Wed Nov 27, 2019 12:37 pm
Weird, Comp 412M is $80 USD, why no 3x markup on that one like the GM gear has?

https://www.summitracing.com/search/par ... =Ascending
i get wholesale pricing on the comp gear. Its 86 canadian dollars. Wonder if its the exact same gear as the GM ?
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Re: low buck junk SBC

Post by prairiehotrodder » Thu Nov 28, 2019 9:26 pm

Got the junkyard 350 running today ! Runs good with that vortec cam in it. Now i have to wait 6 months to see how it goes. Currently i know that it spins the tires on ice. My $100 turbo 350 even seems to work good. Only new parts in the whole deal are :

oil and filter
Comp 412M dist gear
weiand aluminum water pump
intake gaskets
oil pan gasket
timing cover gasket
ACCEL shorty spark plugs for header clearance.

the motor is out of a 94 chevy pickup
all the roller cam stuff is out of a 98 tahoe
the intake is off an 84 chevy pickup 305
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Re: low buck junk SBC

Post by tchapps88 » Tue Dec 03, 2019 3:37 pm

I'm in the process of building an almost no buck 350 also, got a 1993 truck 350 for $200, gona use the roller setup out of a 1991 camaro 305 engine im scraping, 081 305 tpi heads with home porting and drill press back cut valves, a performer intake i have laying around and looking like the cheapest new cam i like is the melling 22280 which is a step nose cam with 220/224 duration, .495/.503 lift on a 110 lsa for $200 on a cast iron core and has fuel pump lobe.

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Re: low buck junk SBC

Post by prairiehotrodder » Tue Dec 03, 2019 3:59 pm

sounds like my kinda build !! Have you researched the 305 head swap ? I did it once and it was a waste of everything. Maybe you'll have better luck. My experience was that the only thing i gained was compression and it was to much. Detonated like crazy. Put some plain 882 350 heads back on and it worked great.
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Re: low buck junk SBC

Post by tchapps88 » Tue Dec 03, 2019 5:32 pm

416 or 081 has same chamber size as a L98 / zz4 head, main thing is gotta be a factory dish piston engine, with 58cc chambers and a .020 steel head gasket you should be at 9.8- 9.9:1 compression, shouldnt be an issue for premium if quech is decent. if you wanted to lower it a tad to play safe probably could un shroud the chamber a couple cc and end up making more power.

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Re: low buck junk SBC

Post by dave brode » Sun Jun 21, 2020 9:53 pm

dannobee wrote:
Sat Nov 23, 2019 11:57 pm
Vortec heads had beehive springs with smaller retainers. And didn't have valve rotators.
None of the L-31 truck "vortec" head s [906 or 062] that I've seen have had beehives. I've seen a few.

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Re: low buck junk SBC

Post by F-BIRD'88 » Mon Jun 22, 2020 12:11 am

When you do the 305 head on a 350 deal and actually finish the job (full home porting and deshroud relieve the chamber )The finished chamber will be in the 61-62cc zone. great on a flat top 350. Use a non projecting tip sparkplug eg Champion RV8c. The cr will not be excessive it won't be knock prone.. If you just bolt on a #601 or like 267/305 head (52cc) the cr will be very high and it will be knock prone..

The 305 TPI .081 head can also work very well.
if when you finish the job.. porting and chamber work.

Bigger 1.94 or 2.02 valves and full port gives a low cost real perf head for a street strip 350. matching vortecs when all done.

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Re: low buck junk SBC

Post by F-BIRD'88 » Mon Jun 22, 2020 12:17 am

You can improve the TBI swirl port heads (small chamber version best by grinding out the swirl ramp in the in port and fill and re contour the port bowl with epoxy for a nice flowing contour.. You can block off fill the evil twinned egr passages on all these heads with balled up thick aluminium foil. (cooking baking catering foil pans) ball it up and jam in tight
If your 350 has the cheapo 1.54" ch rebuilder pistons in stead of a correct 1.56" ch piston it will be a crappy build no effective quench and likely knock prone.

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Re: low buck junk SBC

Post by dave brode » Mon Jun 22, 2020 7:53 am

dave brode wrote:
Sun Jun 21, 2020 9:53 pm


None of the L-31 truck "vortec" head s [906 or 062] that I've seen have had beehives. I've seen a few.
Fyi - The step that locates the spring on some [most?] of the 906 and 062s is a little tight on the yellow and later blue Z-06 spring. Hack fix method: carefully run a well worn used 1" hole saw down over the step, and it will reduce the diameter of the step a suitable amount.

Fwiw - A friend of mine had a 60K mile untouched bottom end L-31 in a full weight with AC '83 Cutlass. An afternoon bowl blend on 906s. Blue beehives. 218/224, .500 ish lift, less than ideal imo 112 LSA cam with original lifters, stock dished pistons, steel shim gaskets. Performer intake, less than ideal 80s QJ, 2400 convertor, 4.10s. 12.97 at 103 and pretty easy on gas [for having 4.10s].

It seems to me that the 638 casting number tbi and the 880 l-31 short blocks are same as far as pistons and ring pack. Afaik, all '87 up 350s are setup for the roller cams, but the bolt holes for the lifter retention spider are not always drilled and tapped. There are two different cam retention plates on the front. ['87-95and '96 up?]. It is hit or miss on the fuel pump rod hole. The above mentioned L-31 was rough drilled but not finish honed.
Dave

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Re: low buck junk SBC

Post by dave brode » Mon Jun 22, 2020 8:08 am

More fwiw opinion,

I know this isn't a L-31 head thread, but I can't see any logic in running the swirl heads on a racer.

Best bang per buck 350 piston for a nice std bore block is a used Mahle flat top out of the late reverse cooling LT-1. F body and big car]. There are two styles of LT-1 pistons, iirc, the earlier ones [94 back?] do not have Mahle. With an L-31 head and steel gasket, CR is 10-1 or a tad more, 10-3-1 ish with tight quench. Most that used the Mahles have a powdered rod. [note- they take a different ring pack]

I don't know if ebay links are allowed, but look at item # 153976199371 to see a set.

Flow #s here show the L-31 heads really are impressive. http://www.users.interport.net/s/r/srwe ... .htm#Chevy

I'll shut up after saying that imo, the common opinion that the l-31 heads are crack prone comes from the fact that many ended up in the junkyard after being run hot repeatedly due to the oem intake gaskets going to mush and leaking coolant. If the oil is milky, chances are they will be cracked, but not if the oil looks ok.
dave

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