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-   -   tbi on 70 350 sbc (http://www.hotrodders.com/forum/tbi-70-350-sbc-223739.html)

shortdog 09-05-2012 09:05 PM

tbi on 70 350 sbc
 
bought old 70 chevy, heads shot, believe its a 255hp 9:1 350. plan is to make a daily driver out of it.... have a fresh set of tbi 193s with a aluminum gm intake and 600 carb to boot on stand by.... truck has 3.08s and I have a 700r4 as well. switching to the 65.3 cc will add CR but will it still run on pump gas? budget on this one is much less than shoestring... have enough for head gasket kit... and if it will work what head gasket ( thickness ) should i use.

DoubleVision 09-05-2012 09:41 PM

The 193 heads aren't the hot tip, thats for sure, but they'll work.
You should be able to bolt it together and be fine. Just use the standard cheapy fel pro gasket set or whatever set of head gaskets you can get cheaper. The 193's have a decent combustion chamber shape. Slap it together, test drive it, if you hear detonation back off 2 degrees, retest drive and listen again. If it still pings back off another 2 degrees, repeat until ping is gone.

SSedan64 09-05-2012 09:48 PM

Using the same .015" shim gasket w/193 Head will bump Cr. up about 1 point.
4.00" Bore X 3.48" Stroke.
.025" Deck Ht., .015" Gasket.
5cc Piston, 76cc Head, .040" Quench = 9.03Cr
with 65cc Head = 10.16Cr

May not be low octane Pump friendly.

SSedan64 09-05-2012 09:50 PM

DV, that's what a Buddy of mine did. Only way it would run was severely Retarded. Had poor power, boggomatic. :D

oldbogie 09-06-2012 12:26 PM

Quote:

Originally Posted by shortdog (Post 1588650)
bought old 70 chevy, heads shot, believe its a 255hp 9:1 350. plan is to make a daily driver out of it.... have a fresh set of tbi 193s with a aluminum gm intake and 600 carb to boot on stand by.... truck has 3.08s and I have a 700r4 as well. switching to the 65.3 cc will add CR but will it still run on pump gas? budget on this one is much less than shoestring... have enough for head gasket kit... and if it will work what head gasket ( thickness ) should i use.

Having the casting numbers of the old head would help in figuring out if you're headed for compression trouble or not.

For a carbed daily driver where top end horsepower to race Beemers isn't desired, the 193 Swirl Port makes for a decent head. They pull very well into the 4000 RPM range before they just can't feed the 350 any more mixture. They get pretty decent mileage at cruise due to the spin the ramps put on the incoming mixture through the intake valves. These heads have some of the desireable features of double squish/quench and the spark plug moved inboard toward the valves. These features and the high intake swirl make them tolerant of more compression without detonation. Still one neededs to be careful and not let the SCR get much beyond about 9 to 1. You don't want to compomise on detonation by brining timing advance down as the power and mileage loss quickly becomes significant.

Bogie

shortdog 09-06-2012 08:18 PM

not sure of the stock head casting # but know motor has 90077 miles actual, was tied up in an estate for 9 yrs. all original.... truck runs and drives but has head issues from sitting...have 193s with less than 100 miles on rebuild and thought maybe since stock heads were 76 cc that maybe 193s 65 cc would wake it up tourqe wise and it would be a good daily driver.

thanks

shortdog 01-14-2013 04:45 PM

maybe not head issue after all, could be lifters....starts and idles ok, but drive it and it has no power, pops and cracks...seems maybe floating the valves, thought at first valves sticking, springs weak... but maybe not.... any suggestions....has new plugs, wires, carb, and coil. thanks

SSedan64 01-15-2013 06:26 AM

Have you checked to see if the Cam is going flat, Lobes/Lifters wearing/worn?

oldbogie 01-15-2013 09:25 AM

Quote:

Originally Posted by SSedan64 (Post 1635035)
Have you checked to see if the Cam is going flat, Lobes/Lifters wearing/worn?

That's a big X2, that year is right in the middle of the flat come lobe era.

Bogie


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