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HybridZ

chevy 305 into a 73 240


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I like the ZZ4 because it is realatively inexpensive for a NEW MOTOR... and over 300HP... in stock form it has over 400ft-lbs of torque at relatively low RPMs... it will be VERY satisfying to drive around town or on the track...

 

and it has plenty of potential for future upgrades... first off being the valvetrain...

 

I have been told that the bottom end is reliable to 6200 RPM in constant use... it is the top end that will suffer from high RPM abuse.. and that is relatively easy to improve under the shade tree...

 

The ZZ4 is DEFINITELY my engine of choice... especially since it even comes with a dealership warranty... If it fails I just drop it off on their doorstep... no $$$ shipping for me...!!!

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i havent built a 305. i started to and then realized it was going to be a MAJOR mistake. so for a $100 i got a 350. i put my 305 heads on it because thats all i could afford, and man was it a dog. ive had friends and relatives build 305s and were all dissapointed, and guess what, they swapped them ALL for something else. moral of the story, stay ahead of the curve for $100 and save hundreds, if not thousands in the long run.

 

 

the huge limitation to a 305 is that there are no heads for them.

 

dont ever compare a GenIII/IV motor to a SBC. they arent even in the same catagory. 5.3 is nothing like the 305, and has great performance potential.

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i havent built a 305. i started to and then realized it was going to be a MAJOR mistake. so for a $100 i got a 350. i put my 305 heads on it because thats all i could afford, and man was it a dog. ive had friends and relatives build 305s and were all dissapointed, and guess what, they swapped them ALL for something else. moral of the story, stay ahead of the curve for $100 and save hundreds, if not thousands in the long run.

 

 

the huge limitation to a 305 is that there are no heads for them.

 

dont ever compare a GenIII/IV motor to a SBC. they arent even in the same catagory. 5.3 is nothing like the 305, and has great performance potential.

so, you haven't built a 305 the right way and gotten any first hand results to decide with? Friends not liking 305's doesn't mean that every 305 in existance, even built to the hilt, will suck. Your 350 with 305 heads was a dog because there isn't that much of a difference between mild 305's and 350's, especially with stock heads. The gain of higher compression w/ the 305 heads is negated by the poor flow and small valves.

 

I don't know why you think there are no heads for a 305, because any head that will fit a 350 will fit a 305 (you even said you had 305 heads on your 350.. duh). Even the 2.02/1.6 valved heads will fit on a 305 with anything over a .030" bore. Like I said, a good set of heads with a cam/intake/exhaust on a 305 won't be that shy of a 350 in power output.

 

A gen3 doesn't have anymore performance potential than a SBC. The reason people worship them is because they have alot of power in stock trim due to great flowing heads and pretty aggressive stock camshafts, and the 5.7's and some 5.3's are alum block. 5.3's are Very similar in size to a 305. They have a .040" bigger bore, and .182" more stroke. What sets them apart, is like I said, the high stock power level from its good flowing alum. heads.

 

The real builders out there know what you can do with a 305, and the only people who say otherwise are those who haven't done anything and are naysaying them only based on what other people have said. I've built a few semi-wild high comp high rpm 305's for people that have spanked 350's and even a 377, and you never would have known it was a 305 unless they told you.

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the GenIII/IV motors have tons more potential than SBCs. thats like saying a flathead Ford has as much potential as a SBC. the 5.3 is a 326 CI motor. the reason why they are worshed is that they put out as much HP stock as extremly modified SBCs, get 25mpg and have almost unlimited hp potential.

 

bottom like is its worth the extra $100-250 that a 350 will cost you. period, end of story

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I'm gonna ramble a bit...

when I first did my z, I looked at all the stuff I was gonna need and decided that the old 305 I had would save me enough money to put brakes on it, get tires, some gauges and a radiator. i ported the heads myself (I did know what I was doing) added a cam, a carter carb. 235 rwhp and 265~270 lb ft. pistons never off rods, stock valves, nothing special. While it is not any cheaper to build a 305 than a 350, YOU HAVE THE 305. I sold the engine (it was nice looking) to a friend for like 400.00. It's probably still in a 914 in TX. the money I saved let me finish my car & enjoy it. Get it in and get it running.

Luigi

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the GenIII/IV motors have tons more potential than SBCs. thats like saying a flathead Ford has as much potential as a SBC. the 5.3 is a 326 CI motor. the reason why they are worshed is that they put out as much HP stock as extremly modified SBCs, get 25mpg and have almost unlimited hp potential.

 

 

Flathead ford doesn't have as much potential as a sbc because it's a completely different and horrible design vs. the sbc.

If your "extremely modified" sbc's are putting out less than 300hp, then there is something seriously wrong.

 

enlighten me, oh engine master with tons of experience, how a gen3 motor has more potential than a sbc?

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I'm gonna ramble a bit...

when I first did my z, I looked at all the stuff I was gonna need and decided that the old 305 I had would save me enough money to put brakes on it, get tires, some gauges and a radiator. i ported the heads myself (I did know what I was doing) added a cam, a carter carb. 235 rwhp and 265~270 lb ft. pistons never off rods, stock valves, nothing special. While it is not any cheaper to build a 305 than a 350, YOU HAVE THE 305. I sold the engine (it was nice looking) to a friend for like 400.00. It's probably still in a 914 in TX. the money I saved let me finish my car & enjoy it. Get it in and get it running.

Luigi

 

You have the right idea. The swap will be well thought out. When I add aftermarket items to the 305 I will make sure they fit the 350 soon to come very well. My other toy is a 68 400 Firebird that has a 68 Gran Prix 350 horse block , the correct #16 heads, balanced short block, crane cam that keeps the exhuast valves open longer for better exhuast scavaging . I chose it due to the heads are only rebuilt & not modified other than a 3 angle valve job & correct valve springs for the cam , comp cam 1.52 roller tip rockers, edelbrock performer rpm intake & edelbrock 750 carb, hei distributer with a recurve kit, hooker headers with a flowmaster american thunder exhuast & a msd ignition box . I am also changing the 68 from an automatic to a stick. The rear is a 3:55 posi.

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Hey Larry... I just figured I'd start off on the wrong foot immediately rather than ease into it. This way I can screw up and know exactly when and why before I'm even caught making an a$$ of myself:mrgreen:

 

EDIT: Both my last posts in this thread really are intended to be humorous... though post #49 is just a teeny bit facetious and a tad wicked:flamedevi

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The 305 heads suck, don't flow, they do raise compression, but the overall effects are negative when added to a 350. Any other gen 1 head will fit depending on the size of the bore and the size of the valves, but any good engine builder checks all that anyway, right. The combustion chambers of the 305 heads is significantly smaller than the 350's due to smaller cylinder volume. You can get 49 cc chambers on the Dart Iron Eagle heads, that bumps the 305's compression up alittle and offers significantly better flows on both the intake and exhaust. The only benefit of the 305 is the stroke, which equates to torque. They work ok, but your still down on cubes for the serious HP freak lying hidden in all of us. Will it suffice for a z? Sure, it'll work fine, spank most anything out there and live awhile. But you still have 2 bolt mains so your power potential is somewhat limited.

 

All in all, though the 305, when properly outfitted can make some decent power, although not as much as the 350 can or anywhere near what the 400 can.

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Since you already have the 305, just slip a decent cam in it, keeping in mind a torque cam will be better in the engines effective rpm range. use an Edelbrock Performer or Performer RPM intake, or even just a clean beadblasted H.O 305 intake. add some shorty headers, paint it up pretty with some nice chrome or aluminum accessories and run it! Like was said earlier, it will get you going and if it stays nice you can sell it later when you swap in the powerhouse!!

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enlighten me, oh engine master with tons of experience, how a gen3 motor has more potential than a sbc?

 

the heads. when you can buy factory cast heads that flow 330cfm intake at .6 lift it completely blows away any SBC. you are lucky to find ported aftermarket SBC heads that flow that much. and thats just the start. we are comparing something from 1955 to something from 1997.

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the heads. when you can buy factory cast heads that flow 330cfm intake at .6 lift it completely blows away any SBC. you are lucky to find ported aftermarket SBC heads that flow that much. and thats just the start. we are comparing something from 1955 to something from 1997.

 

It doesn't blow away the gen 1 heads, the lsx series motors utilize a 15 degree valve angle head. A comparable head from GM or Brodix flows better, at 358cfm at .6 lift.

 

http://www.brodix.com/heads/-15.html

 

It's not apples to apples as you say. Further the lsx series engines regularly use cams with lifts between .530 and .570 with durations in the 220 to 240 range at .050, which is pretty stout. If we you were to compare like types of cylinder heads, cams, and the like, they'd pretty much be the same.

 

The nice thing is that with the lsx series of engines, they come "factory stock" with the goodies, and the price that you can acquire one for make them an ever increasingly good deal.

 

The bonus for the sbc gen 1 is that blocks are available that handle well over 1500HP reliably, not sure that is the case with the lsx engines as of yet.

 

So, if your looking for inexpensive hp, perhaps the lsx series is the way to go. If your looking to make mondo HP then the LSx series is just as expensive, if not more so than the gen1 sbc IMO.

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the heads. when you can buy factory cast heads that flow 330cfm intake at .6 lift it completely blows away any SBC. you are lucky to find ported aftermarket SBC heads that flow that much. and thats just the start. we are comparing something from 1955 to something from 1997.

 

LS1, I may be misunderstanding your statement. Do you really mean that GenIII/IV series are better "FACTORY" motors (as in unmodified)? I would buy that argument. But to say that they have more HP potential than a GEN I.....I'm not so sure.

 

If someone had an unlimited budget, and built a Gen 1 sbc and a Gen III/IV, I'd bet my house that the difference in dyno numbers would be immaterial.

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Like I said, the only thing gen3's have going for them is a good factory setup and good factory power. That's why you see so many Fbodies going fast.. because it's easy to take an engine that puts close to 300whp down in stock trim, and just put a few boltons and have a 400+hp screamer. I'm not trying to say the SBC has more potential than the gen3, because they both only have as much potential as you are willing to spend money... but the SBC's been around for a while and are proven to be the king of power per $ with a great power potential and a cult aftermarket following. I just get so sick of people saying gen3's are so much better than sbc's just because they are newer and make more factory horsepower.

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Like I said, the only thing gen3's have going for them is a good factory setup and good factory power. That's why you see so many Fbodies going fast.. because it's easy to take an engine that puts close to 300whp down in stock trim, and just put a few boltons and have a 400+hp screamer. I'm not trying to say the SBC has more potential than the gen3, because they both only have as much potential as you are willing to spend money... but the SBC's been around for a while and are proven to be the king of power per $ with a great power potential and a cult aftermarket following. I just get so sick of people saying gen3's are so much better than sbc's just because they are newer and make more factory horsepower.

 

Well said....my thoughts exactly. To me, factory horsepower is irrelevant....its just a starting point (which I intend to go well beyond, lol).

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