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#1 |
Registered User
Join Date: Mar 2003
Location: North Central Florida
Posts: 726
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Me and my dad droped my block and heads off yesterday. I was originaly going to go with 40over but the guy and my dad talked me into going 60over!!
![]() How much horse power increase shoud I have?
__________________
1978 Chevy C10 Currently under resto. 350 Getting face lift. .060, JEpistons, Modify heads. More will come with money. |
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#2 |
Account Suspended
Join Date: Oct 2002
Location: Elkhart, IN
Posts: 6,400
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very little if any. all overboring does is square up t he bore. if the block will clean up at .040, go that route, that way if you ever have to/need to rebuild it again, you've got plenty of room.
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#3 | |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
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Quote:
The only time you overbore is to get the bores cleaned up or you have a massively powerfull motor and need the extra clearence for bigger valves. Go .040, you'll still enjoy it ![]()
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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#4 |
Right turn Clyde
Join Date: Nov 2002
Location: Cincinnati, Ohio
Posts: 2,911
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Yeah, what they said. I would have a block sonic checked before I went 60 over. I dont think you will be able to rebuild this block if it needs bored again. Possibley if its just a spare race engine, and doesnt need to be depended upon. Yeah you can sleeve it but who wants a sleeved block?
As for the extra hp? Im gunna guess and say 10 hp ![]() |
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#5 | |
Account Suspended
Join Date: Oct 2002
Location: Elkhart, IN
Posts: 6,400
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#6 |
Happy to be here
![]() Join Date: Mar 2000
Location: Cypress, TX
Posts: 39,023
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You need to talk to the machine shop and tell them what you want from your motor. Since it's getting bored, you will have to replace the pistons. You should decide now what type of pistons, and more important, what compression ratio.
What heads are you running? If they are stock 350 small valve heads, you may be better off buying new heads rather than rebuilding those. If you want more power, consider the Vortec heads. They are fairly cheap, and create great hp/tq gains right out of the box. You will need a new manifold to go with them though. Nows is the time to make these choices while you still can... ![]()
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Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra" |
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#7 | |
Right turn Clyde
Join Date: Nov 2002
Location: Cincinnati, Ohio
Posts: 2,911
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#8 |
Registered User
Join Date: Mar 2003
Location: North Central Florida
Posts: 726
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I am getting SRP Forged pistons. Flat Tops. Was going to get JE but decided not to spend the extra 180.00 My heads have oversized valves and are ported and polished. So if it is not to late I should go with .040?
__________________
1978 Chevy C10 Currently under resto. 350 Getting face lift. .060, JEpistons, Modify heads. More will come with money. |
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#9 |
Right turn Clyde
Join Date: Nov 2002
Location: Cincinnati, Ohio
Posts: 2,911
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If it was mine I would try and go 40 over but thats if its not to late. If the mechinest thinks the block will clean up at 40 thats what I would do.
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#10 |
I'm back with 2nd truck!
Join Date: Feb 2002
Location: Texas
Posts: 3,775
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I agree with everyone and go 40 if possible. If the shop can clean it good and test it to make sure it's a good bore then go with it. I'd rather have 40 than 60 for sure.
On the pistons if you ever want to add anything more like NOS or a larger cam or heads that flow better make sure that you have the bottom end for it. This is where you can spend your money now and not have to redo it later. Get a great bottom end on it then later add a larger cam and heads. You don't need a shop to do this. Adding pistons later will cost you more than $180 for sure.
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1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson |
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#11 |
Right turn Clyde
Join Date: Nov 2002
Location: Cincinnati, Ohio
Posts: 2,911
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So do you have any new news about the block?
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#12 |
Registered User
Join Date: Mar 2003
Location: North Central Florida
Posts: 726
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UPDATE....Block has to go .060. The machinest went .040 and said that wasent enough. I still havent made up my mind completly about what pistons to go with. I know I want forged because I plan on running nitrous. I have been told that anything other that forged will not hold up. Any sugestions on what brand of pistons and rings?
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1978 Chevy C10 Currently under resto. 350 Getting face lift. .060, JEpistons, Modify heads. More will come with money. |
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#13 |
Senior Member
Join Date: Jan 2003
Location: Atlantic City, NJ
Posts: 1,073
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SRP pistons are an excellent choice. Check with SRP for a special N2O piston.
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86 SWB 9.0 LITER T-400-OD 4.11 eaton-4/5 drop Best 1/4 12.51 @112mph no traction ![]() |
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#14 |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
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What compression are you going to run and how much nitrous? Cause hyper pistons can take some power, just not a ton.
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#15 | |
DAMN, I love Big Blocks!
Join Date: Aug 2003
Location: New Mexico, USA
Posts: 619
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Quote:
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Marc Bona Hobbs, New Mexico 1976 1/2 ton GMC High Sierra. 454 c.i.d./ TH400. *Soon to get a mild warming over.* 3.40 rear. ![]() |
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#16 |
Senior Member
Join Date: Mar 2003
Posts: 2,500
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Yeah..........boring a block means more air and gas in a cylinder.
This results in a "larger" engine. This also means more power. As the old saying goes "There's no replacment for more displacement" |
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#17 |
Registered User
Join Date: Mar 2003
Location: North Central Florida
Posts: 726
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Tom just brought up a good question. What compresion ratio should I shoot for? I have 74cc heads and in all the mags the ratio for a 64cc head. So if it says 10.63 what will I have?
I am getting the Edlebrock Nitrous kit. It is adjustable from 50-100hp. Would that be to much for the hyper pistons?
__________________
1978 Chevy C10 Currently under resto. 350 Getting face lift. .060, JEpistons, Modify heads. More will come with money. |
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#18 | |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
|
Quote:
__________________
-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#19 |
I'm back with 2nd truck!
Join Date: Feb 2002
Location: Texas
Posts: 3,775
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But best to go with forged. This way you wouldn't have to worry as much then. Besides after 100 shot you probably would want more.
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__________________
1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson |
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#20 |
Account Suspended
Join Date: Oct 2002
Location: Elkhart, IN
Posts: 6,400
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for a .271:1 increase in compression ratio, i'd much rather have the strength of a thicker cyilinder wall. if this was a racing engine, and not one for a street truck, i could see the slight advantage. on paper or the race track, going with the biggest bore is best. but in the real world, in your wallet, and in terms of durability in this case, less is definitely more.
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#21 |
Registered User
Join Date: Mar 2003
Location: North Central Florida
Posts: 726
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Thanks for the advice. I will go with the lower ratio.
__________________
1978 Chevy C10 Currently under resto. 350 Getting face lift. .060, JEpistons, Modify heads. More will come with money. |
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#22 |
DAMN, I love Big Blocks!
Join Date: Aug 2003
Location: New Mexico, USA
Posts: 619
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1Faastc10 is absoloutley right. I was only making the compression comment earlier in the post, because it's a common misconception that an overbore makes no difference anywheres. Stick with the smallest overbore you can get away with. Not only will you be able to rebuild it again, it will most likely give you less trouble. .060 is most likely OK, but for God's sake, spend the extra few dollars and get it sonic checked. A few dollars spent on that test may save you alot of grief later. Good luck!
__________________
Marc Bona Hobbs, New Mexico 1976 1/2 ton GMC High Sierra. 454 c.i.d./ TH400. *Soon to get a mild warming over.* 3.40 rear. ![]() |
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