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destroking a 350

17K views 107 replies 23 participants last post by  machine shop tom 
#1 ·
Hello, I'm looking to build a high-reving chevy. I'm unfamiliar with gm engines being the ford man that i am, could i use a 305 crank in a 350? if so what mods would be needed? and what kind advantage if any could be gained?
 
#5 ·
If you just want a high winding small block build a 302, those are about the highest winding small blocks out there. Of course you will have a hard time finding a true 302 (big money) so you could take a 283 crank and a 327 block and build your own. I am not sure why you would want to do this. The parts (pistons, rings, etc..) will be more expensive. I would much rather have a 377 (400 block with a 350 crank). More cubes about the same price (maybe less) and a LOT more power.

What are your plans for this engine? Why is RPM so important?

Royce
 
#6 · (Edited)
because...

I just wanna be different, and ive never built a chevy before. besides i've done a few ford 345 strokers, and think destrokin a chevy may be a nice change. rpms are very important becase i want the novelty of spinning a small block to around ten grand on the tach.

I just wanna be different, and ive never built a chevy before. besides i've done a few ford 345 strokers, and think destrokin a chevy may be a nice change. rpms are very important becase i want the novelty of spinning a small block to around ten grand on the tach.
 
#8 ·
The old DZ302 would rev to 8,000RPM. If you are serious about trying to rev to 10,000RPM I think you better look into building a Honda or something. In all honestly reving a SBC to 10 grand is not realistic or wise. There is really no reason to do it. If you have VERY deep pockets you can make it happen. As mentioned by spinn it won't live very long.

Do you know what RPM stands for? RPM = Ruins Peoples Motors

Royce
 
#10 ·
I used to have a 350 with stock rods and ARP bolts. It turned 7000 rpm quite often. It seems to me that a 283 bored 60 (289ci?) with an oil cooler, good rods, bolts and forged pistons in the bottom and a 525" 1/2 mile circle cam and Vortec heads topping it off would turn 7500 on a regular basis.
 
#11 ·
yup

Yeah its gonna be expinsive, but i do have the means to build most of my own parts, so that wont be as costly as it could. and true there is no reason to do it, i just want the novelty of knowing i can do it. you'll never catch me sittin near a honda muchless building one.
 
#14 · (Edited)
If you can afford it,they make a 400 block with 350 size mains and splayed main caps,the true dz 302 also had 350 size mains,but unlike other small blocks,they had small journal rods all at a minor 3 inch stroke,I believe JE pistons makes the slugs to fit it all up. In my opinion,that would be the king of all revers in the small block class. You would also need one awesome valve train and some darn good rods,and a pan that holds about 10 gallons of oil"just kidding".

321 cubes
 
#15 ·
I have a 383 stroker with a cast crank, Eagle H-beam rods, SRP pistons, Crane circle track cam(4000-7200 rpm), Edelbrock Victor Jr. heads and intake with a 780 Race Demon carb. This engine spins 6500 regularly, dependably, and as a street motor. I built it for around $5000.:thumbup:
 
#16 ·
.

I had an idea abou the valve train, If i were to use really stiff springs with a low lift long duration cam (to prevent valve float) and forced induction to get the airflow back, would this be a good idea as far as a valvetrain?
 
#22 ·
have you ever heard a motor turning 10 grand? be realistic. build a 327. 350 block with a steel large journal crank, solid roller cam, & a damn good set of rods. 8000-8500 rpm is all you need to turn it up. thats a hell of a lot more rpm's than 99% of all street cars turn. you should be able to build it for around $4,500-$5,000 & be pretty safe. i had a stock large journal cast 327 (307) crank, stock rods with arp bolts, solid lift cam, in a 350 4 bolt block, & i turned it 7,500 rpm all the time (till a rod broke 5 years later), but the same rods had been in two engines before i got em'. i didn't even put in new rod bolts.

it can be done. the dirt track boys do 350's all the time with cast cranks, stock rods, & turn em' 8,500 rpm.
 
#23 ·
yup

yes i have seen 10,000.in fact I've seen 14,000. but that was an IRL V-10. I don't have the 3 million plus to get one, so i wanna see if i can spin a V-8 up to atleast 95, i know its not very realistic, but as I've stated before I'm doin it for the novelty. I want a streetable engine that can turn high a few times in short bursts without comin apart.
 
#25 ·
Well,like said about some dirt track motors do 8000-8500,but I can tell you that its not uncommon to lay out 20,000-25,000 grand for a proper one,and those guys are tickled to get one season without scattering one also,and they don't even get held to that mark the whole time,I think if it were me I would let my bank balance dictate my red line,over 6500 starts to become very expensive,its like the build price squares per 500 rpms after that.
 
#26 ·
an oiling mod,

well i've found an oiling system mod (to the mains and main bearings) that will help with the rpms, ill get the link up as soon as i find that page again. i figure you guys could get some use out of it to. the 2.8 in my blazer is rated for 4500, but i spin it up to 6000 because of it. if you do a search for performance mods on a 2.8 you should be able to find it.
 
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