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 23 Briggs Smallblock Mods Round 2 
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Post 23 Briggs Smallblock Mods Round 2
He snatched the motor back off for another round on a budget. Current specs , 23 stock shortblock, old cast cam 240/240, 110lsa 109icl, manley valves, ported small and fast. 045 deck. 160 compression with this cam, 26/27 deg timing, 35 bigblock carb and adapter, donaldson filter adapter. 2/1 pipe. Jetting at .022 pilot 134 mains “.052”. Made 29 hp at 3600 and 35hp at 4500. This round is getting the following touch ups. Heads got another trim to a total of .061 now. This is just trying to make up for the late cam timing. The smallest part of the intake system is still the venturi in the 35 carb, so it’s getting the old bigblock join the runners trick. Ive never done it on a smallblock but it works excellent on bigblocks along with the big jet change. Also gonna flip the carb around to face front. This is taking a bit of work to blend out the ports to face adapter foward. We will test roller rockers also and see if engine likes them. A few pics of the progress. .


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Sat Aug 08, 2020 1:23 am
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Post Re: 23 Briggs Smallblock Mods Round 2
Kind of Madmax but i like it . He said he is going to paint it , not holding my breath. Going for 35hp at 3600. Maybe 40 on top, but this trick might not even work. Main jets also just got drilled to .059 to start the tune. Anytime a this intake mod is done the jetting has to go way up to compensate for less carb velocity


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Sat Aug 08, 2020 1:26 am
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Post Re: 23 Briggs Smallblock Mods Round 2
First batch of pulls are done. Carb is finicky, wants a pumper, the .059 mains are pretty good. Fat down low, mid12s 3/4500, mid 13s on top and headed leaner. The goal of 35hp at 3600 is gone but it did make 1 to 2 hp more at 3600. The topend is beyond expectations. 42hp at 5050. Its still climbing. I asked him if it throws a rod will he laugh or cry. He said lets call 5k rpms good, lol. This is stock bigblock rockers, he is gonna swap on the 1.5 rollers in a bit


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Sat Aug 08, 2020 3:59 pm
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Post Re: 23 Briggs Smallblock Mods Round 2
I like it. Great to see some motor mod threads again.


Sat Aug 08, 2020 5:45 pm
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Post Re: 23 Briggs Smallblock Mods Round 2
Friend did similarly with big block 25. 33 mph at 5k rpm's with 3 people, 2 fat ones on an uncle j custom

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Sat Aug 08, 2020 7:49 pm
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Post Re: 23 Briggs Smallblock Mods Round 2
Added the rockers , note: these heads are clearanced for bigger lift” figured out fuel pump wasn’t keepin up, final jetting.025 pilots, .067 mains. Carb doing great now. The rockers are worth 2hp on this engine. Badass smallblock . Made 8 pulls all at 44hp with final jetting.


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Sat Aug 08, 2020 8:49 pm
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Post Re: 23 Briggs Smallblock Mods Round 2
Dean, u know once you swap the crank in a 25 bigblock, its then 61 cubic inches, same as the 35 through 40s. Folks still say it's a 25 but it aint


Sat Aug 08, 2020 8:52 pm
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