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Wtb sbc 305 high rev low comp

2K views 12 replies 6 participants last post by  aisr 
#1 ·
Sounds nuts I know, but it's not for me. The customer wants a 305 to be built with as low static compression as possible with the ability to reach 6500 plus without damaging anything. I tried to guess that he wanted to go forced induction, he just smiled and asked if I could do it. I told him yeah but to be honest I usually just offer a 350 or other bigger sbc to guys who want. Ore power. I have a pile of old 305's lying around because of just this. So what do I do? How do I build a high revving low compression 305 for. Cheap, and don't try the just use a 350 gig, I already tried that, kid won't listen to reason. He wants arp head studs in the build so I know he plans to make some power, but for now he just wants me to start with teardown and inspection of his 305. I have some ideas, but how much power can you make on stock 305 internals? Kid won't listen, he's a paying customer so I won't complain but I need help to do this.

Thanks,
Kevin
 
#2 · (Edited)
not knowing where you are located..
maybe the kid wants a 305.. because of the EPA laws.. that change state to state.. if he goes into the armed forces.. he might have to deal with many different rules/laws/etc..
I know my 86 SS would fail if the 305 wasn't there.. up untill a few years ago here.. and why the 305 is still in it..
maybe he just wants to be different.. who knows..
I know here they kept going back and forth on the rules.. for 5 years and part of the reason my 355 sat in a corner of the garage..
and there is that fear that as soon as I drop the 355 in it they'll change the rules yet again..
these things might not even be on the table.. but you never .

why would a 305 that needs lower compression and buzz to 6-7k be any different than a 350 build.. other than cam..
shouldn't be that hard to find some 350 smogger 70's heads with 76 cc chambers and small valves to dump on it.. as the newer heads with 58cc might be hard to find on shelf pistons to get low compresion.. how low he want 8 to 1 or lower?
 
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#4 ·
" So what do I do? How do I build a high revving low compression 305 for. Cheap,"

just toss out reliable and powerful,,,,

This is the time to instead of dazzling them with brilliance,its better to baffle them,,
explain piston speed to the last detail,
valve train harmonics,
torsional stress and dynamics in the crank shaft,
after a few minutes of this,give them some math to come up with their best formula,then add in everything you know about oiling a high revving sbc and again let them formulate a formula for you to follow

I doubt it goes that far and they will call off the build,or share info as to the purpose of the engine and reason for the secrets.You use all these questions to put them straight
 
#6 ·
No backing down

Kids a Marine, usually not tough customers, but I think this one is particularly thick skulled. Just got back from afghan, single, no family. He is putting this into a 69 camaro he lready had with a ford 9" he also insisted on using a 700r4 for driveAbility, which he also has. **** I can build it, just never did anything quite like this. Thanks for all of the help so far. I guess for track guys this is fairly common? Good advice, after my "yes I know it's cheap" 55$ clean and inspection I'll roll a paper quote outgo him and maybe scare him off. This is California, and he is from. Cali, but it's a 69' so it doesn't have to smog.
 
#7 ·
Kids a Marine, usually not tough customers, but I think this one is particularly thick skulled. Just got back from afghan, single, no family. He is putting this into a 69 camaro he lready had with a ford 9" he also insisted on using a 700r4 for driveAbility, which he also has. **** I can build it, just never did anything quite like this. Thanks for all of the help so far. I guess for track guys this is fairly common? Good advice, after my "yes I know it's cheap" 55$ clean and inspection I'll roll a paper quote outgo him and maybe scare him off. This is California, and he is from. Cali, but it's a 69' so it doesn't have to smog.
ever think i's a street racing thing,
a guy sees the g.m. cid/ltr markings on the block and will think easy pickings..
the guy might not be all that dumb
low 1st gear, high rpm to make up for the 7004r wide gear spilts..
sounds like a racer to me..
 
#8 ·
interesting

well it will definitely be a build to remember. I do not know what amount of pressure bar/psig this will handle safely reliably, or what the stock internals will handle, or how much power he will make. Any estimates? the more I can tell him the better. I always assumed that stock internals were 450-500~ all day but I was never too sure on this. I want to tell him 15psi is safe for this setup but once again, where in the power range is that going to get him with 92 octane? We still need to talk gear ratios and tires so I can get the right cam, and torque converter combo. For the record, he did mention something about twin turbo setup, I have to admit, I am a bit curious now, never seen one like this up close. Thanks again for all of the advice.
 
#11 ·
You won't be able to tell him X amount of boost will be safe or not, 10 psi from a big turbo vs for a small turbo vs twin turbo will get you very different results.

He needs a tuner, someone who has the knowledge of good tuning on turbos, because there is a whole hell of a lot more then just throwing new parts in the bottom end. Nothing against you, build the long block like f-bird 88 said and refer him to a good tuner, boost can get messy quick if its not tuned just right.
 
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