I haven't put a timing light on the car, but my throttle response is sharp.... so it's got to be almost right on correct? I got to thinking.... maybe this will contribute to the low mileage.... after the car is driven for about 30 minutes... when I shut it off to go into a store or something, I turn the key to start and it makes the low battery sound a few times but then starts right up.... ? Everyone suggests timing but Idk. I know the battery and starter are good for sure..... if the car has time to cool down some it will start normally.... so it's only when it's hot this happens.....

 

The part about electronic advanced HEI.I thought clearly with a carb a vacuum HEI was used.

Old school carb with old school dizzy.

 

Oh.... no all third gens Are stock with electronic advanced hei distributors and the models that have carbs are electronic control carbs..... but I have heard switching to vacuum advanced hei will provide a smoother rpm.... like they won't jump from time to time therefore saving fuel.... but again this is hear say.

I know that my car runs strong and responds like a monster on crack.... but the has mileage is killing me.... which is why I spoke of switching to tpi or similar.... but honestly I think I just need to redo the top end put a cam I. Know the specs to in, and an intake to match..... maybe port my heads...... but not sure the max lift I could get, and should I machine the heads.... make bigger valves, or just port and cam? This is where I get lost..... I have built big power bbc race motors but this is my first 383 and don't know what works best together...... if you need any engine specs just ask....

 

God this thread is awful. So much bad information.

1. It's VORTEC. There's no x.
2. 383's are larger and a mild cam in a 350 is a tame cam in a 383. Maybe that's why its quieter? What are your cam specs? Could be a garbage old school low-lift, high overlap flat tappet cam grind that barely moves any air.
3. 383's generally need 76cc heads IF they use flat top pistons. Most factory 76cc heads are AWFUL garbage.
4. Vortecs are the best factory Gen I sbc head available, period.
5. You can use the Vortecs with a 383 if you understand their limitations. They will not feed a 383 above 6000 RPMs. With ebtter flowing heads and larger cams, it may drop off in power before that. But you WILL make decent power. You will make MORE with aftermarket heads, but you are much, much better off with vortecs than any other factory GM head. DO NOT USE A HUGE CAM WITH THESE HEADS ON A 383. They will NOT support high RPM ranges on a 383 due to the aforementioned smallish runner size.
6. Vortecs only have 64cc chambers, to keep the compression ratio the same (and to keep it reasonable, 10.0:1 or lower) you need 12-16cc dished pistons in a 383. If you run Vortecs with flat tops in a 383 you WILL be running race gas or you will put holes in the pistons.
7. Carbs can get decent gas mileage if you take the time to learn how to tune it. if you're lazy, they will get terrible mileage. They will never be ideal, but you can make them livable.
8. Vacuum advance for distributors is for gas mileage. I dont even run it and I dont care. Runs great. Vac advance only does anything during cruise. At wide open throttle or high load it does nothing. Distributors generally have mechanical advance and vacuum advance. Electronic advance replaces one or both of those depending on what setup it's in. By the late 3rd gens the computer controlled both of those. The mechanical and vacuum advance were the old school, analog way of doing it.
9. Vacuum secondaries are, also, for gas mileage, because people cant tune Holleys for ****. If you run a manual transmission mechanical secondaries are the way to go. if you run an automatic, go mechanical if you want to learn to tune it, go vacuum if you're lazy and just want it to work out of the box.
10. Mechanical secondaries can and DO get great gas mileage when tuned right. If you're lazy and lack the inclination to learn them you will never get good results from them. vacuum secondaries are a crutch for people who dont want to learn to tune mechanical secondary carbs.
11. A qjet is not mechanical secondaries.
12. Carburetor parts do not make more power. You only tweak the carb to give the engine what it wants. You cant put special metering rods and make 50hp. If the engine makes more power, great, but that's because whatever you tweaked, you gave the engine the fuel/air mixture it wanted to begin with in that situation. The engine wants a specific air fuel RATIO in a given situation (idle, load, cruise, acceleration enrichment, etc). Just dumping MORE fuel in does not make more power. In fact it will make LESS power. You need a RATIO of fuel/air and you tweak a carb to give the engine the right ratio. Different adjustments on the carb tweak that air/fuel ratio for different situations.
13. Oil pressure is determined by hte oil pump, which is attached to the distributor gear. The faster the engine turns, the faster the pump turns, the more pressure it will make. You SHOULD peg the oil pressure at high RPMs.
14. Distributors dont "jump time". That's physically impossible unless the clamp comes loose and it just rotates itself from vibrations. That can happen to ANY distributor. Even then, a distributor can not and will not, ever "jump a tooth". The distributor literally must manage to jump up nearly an inch to disengage from the cam gear, in the process disengaging from the oil pump drive rod, and then fall right back into the place onto quickly moving cam gears while somehow managing to land right on the slot to the oil pump drive rod at the same time. If the clamp is in place this is impossible. if the clam is removed and you have a jumping distributor that can do this, go play the lottery because I still think it's impossible.

15. Mechanical advance is springs and weights under the rotor that swing out at higher RPMs and advance the timing by making the rotor point farther forward in the rotation. Vacuum advance just advances the spark WAY before TDC during cruise conditions for gas mileage reasons. They are separate and both work at the same time. If you have a computer controlled distributor you likely have NO TIMING ADJUSTMENTS AT ALL WHEN THE CAR IS RUNNING. Some people do this to normal distributors on purpose to "lock out" the timing. This is stupid. It causes exactly what you're describing. The spark is too far advanced and causes too much cylinder pressure at low RPMs (ie when starting) and makes the engine not want to turn. This can also hurt gas mileage in a lot of situations. GET A NORMAL HEI DISTRIBUTOR. Tune it for anywhere between 10-20 degrees advance at idle, and around 32 degrees at 3000+ RPM's. From there you can advance it up to 38 degrees and toy with performance. Just be aware that some cars will detonate at 32 degrees, some wont until 40 degrees. The more advanced, the more power you make (basically), but the more risk you take. learn to read plugs and tune your carburetor before you push the boundaries of that. You need to know what the timing is. You can do it by ear to get it running, but before you start leaning on it adn complaining about gas mileage you need to get it right.

 

Well you're about a cocky **** aren't ya.... look ******* I really don't like the way you're talking so I would appreciate you to stay off my posts from here on out.

 

Hey Buell.You do understand he spent time typing up all that advise to help you.Right??. Sometimes it stuff you don't want to hear,but the facts as it maybe.

 

Well I understand he was putting in his opinion.... the problem is that I know what is in my car like a computer controlled quadrajet with mechanical secondaries.... and an electronic advanced hei distributor.... which he is sayin I don't have......

I don't like being talked to like I'm stupid.... and it pisses me off... I greatly appreciate and highly respect everything you and jay have been sayin.... if this guy wants to join in.... then he can do that respectfully.... instead of calling us all stupid.... so **** him he is a punk that just feels like running his mouth off.... I apologize to You and jay for having to read his post criticizing your advise to me. If he had any respect then I would have continued the conversation.... instead he insults you and jay then tells me What I have in my car that I ****ing built.... I built it alone in my ****ing garage so how the **** does heknow **** about my car......

Again you and jay have my respect and gratitude for your response, and if there is ever anything I can do to repay the favor don't hesitate to ask....

 

I think he was saying, that q-jets have vacuum controlled air-valves, but they are also technically mechanical by the throttle blades in the throttle body. So technically you both are right.

He wasnt trying to offend anyone by his post, i think he was trying to correct some false information that was going around.

 

Well unfortunately he chose to sound like a jackass, and I don't wanna hear anything he has to say with that attitude.... right or wrong.....

Let's get back to topic if possible.....

 

Thanks for the support, but honestly it just makes me so frustrated when people repeat things that they dont verify. If you repeat something that doesn't make sense and is not true or generally spread misinformation, you hurt other people. I dont care if they're offended a little. I want people doing searches or just taking stuff in to figure out what to listen to and what not to listen to.

As far as electronic advance on your distributor, that's great... do you still have a computer controlling it? If there's no computer adjusting the timing advance then you have no advance happening at all. If there is then you may be fine after all.

This is not a traditional mechanical secondary setup as seen in a Holley double pumper. It functions much more like a vacuum secondary setup due to the air valve controlling actual secondary airflow. That quote is from wikipedia. You're not wrong, but I wanted you to know that if you go around thinking that a qjet is a mechanical secondary carb the way you and me and the rest of the world knows it, you're being mislead and misinformed and will therefore make bad decisions. You dont need to get rid of the qjet because it's "mechanical secondaries" are causing bad gas mileage, for example. If you get rid of hte qjet it will be because it's a computer controlled qjet and you dont have a computer anymore, or because you cant find the parts to adjust it as easy. Not because it has mechanical secondaries.

 

Holley in my opinion is junk..... people run down these q-jets but they simply do not understand them..... if you know how to tune one properly then if you choose to not like them then fine..... as far as What I said about my timing read the post a little closer.... it didn't say **** about jumping time.... I said electronic advanced has a tendency to bounce rpms sometimes. The bottom line is if you wanna give some opinions that's fine but you need to keep the attitude out of it.


All that being said I know my car and I know it's right..... but I also know there is room for improvement. Now if you would like to discuss the issues I have posted here fine, but do it with respect.

 

Thank You!!.

 

Any time.....

 

Qjets are great carbs. Their only issues are simply those of finding parts and learning to work with them. Plus sometimes its hard to find a suitable intake for a spreadbore carb. Holley Double Pumpers are one of the most time-tested, successful designs for a performance carburetor ever made. Even Nascar uses Holleys. Carroll Shelby used Holley double pumpers on the Shelby Cobras. Chevy used them on their DZ 302 Z/28 from the factory. They are successful because they are so tunable. You can make nearly ANYTHING run perfect with a Holley double pumper if you know how to work with them. Edelbrocks and Qjets aren't quite as useful in that same way. There are definite advantages to both in design, but the modular design that Holleys have allows for nearly infinite adjustments and modifications to run anything from a Top Fuel Dragster, a NASCAR 358, a factory performance car, or a turbo V6. That's why Holleys are popular and why they are so prevalent in racing. The Edelbrocks arent nearly as common in that world, and good luck finding ANY qjet on a racing engine.

The Qjet is probably the most advanced design of the 3 of them. Very good carbs, but the aftermarket support just isnt really there like it is with Holleys or Edelbrocks, which hurts their usefulness on specialized performance applications.

So there's nothign wrong with a Qjet or an Edelbrock, but there's nothing "wrong" with a Holley either. Holley makes a zillion types of carburetors for nearly any application. The double pumper is synonomous with Holley, though, because of its ubiquitousness and history of success. So to just discount them as "garbage" is honestly kind of silly. If you dont want to learn to tune one then fine, they are a little more finnicky, but that doesnt make them bad carbs.

Also, mechanical advance mechanisms bounce around in timing from time to time too. Electronic is far more accurate, especially with modern systems. Just be aware that electronic timing advance controlled by a computer replaces mechanical AND vacuum advance. If you get rid of the computer controlled distributor, you will need mechanical and vacuum advance to replicate it. Or, rather, the computer replicates the mechanical/vacuum advance systems, since those came first. As I said, vacuum advance is just for low-load cruise situations to help gas mileage. Mechanical advance increases the timing with RPM to maintain performance. But I dont think they even make distributors with only vacuum advance anyway, but I just wanted you to be aware so you'll know you have two different timing systems you'll have to tune and tweak to get it working properly, but it's not complicated to figure out.

 

That may very well be.... the bottom line is spread bore gets better mileage always will.... and my qjet can run just as much flow or cfms as your double pumper.... and do so using less fuel during normal driving conditions...... I'm not looking to change carbs I want options of heads and cams.... and things like that.... I would like to get decent mileage also..... so if you have any input you would like to add I'm all ears.... as long as you keep respect in mind.... and stop talking to me like I'm stupid. I'll guarantee I have a much higher Iq than you and I have a doctrine in applied mechanical physics.... so if you wanna play battle of the wits you're out of your league with me......

 

Top Fuel Dragsters??. I mean really???. A 650 double pumper Holley on a Top Fuel Dragster???. Really??. How about the Holley shaft leaks all the time??. A summary of Holleys on the street are vs Qjets is the Holleys are you have to tinker with all the time and the Qjets you don't. You got a rubber jet storage mat?. Ever nick a jet and wonder why you having a problem??. Ya do know it doesn't take much. Why did NASCAR go to EFI's??. You might want to catch up on what's up. When NASCAR changed closed the front door because that slammed the back door on carbs let alone Holleys. Want to guess why Holley is in deep in their own EFI program??. The toilet bowl tech of Holleys is,well outdated. We haven't run one on the RED in yrs. Oh yeah,NASCAR "Holleys" are the further-est thing from what you know as a Holley. Bottom line is appropriate use of a part(Holleys for racing and Qjets/Edelbrocks for the street) is my point. You can't justify a Holley's use on different cars alone and say it was without their own set of issues. Because that isn't reality.

Tell you what.Open this discussion to the thought of spark advance matching cam choices and the timing events of a cam.How much of that do you think relates to some engines accepting total advances of different numbers??. Can't give you a bigger hint than that.

Buell-Honestly I don't remember if you said what you wanted in a RPM range.That would help in a suggestion.

 

I would love to find my power band between idle and about 4500-5000 if possible.... but basically I want something that delivers low end without sacrificing top end horse power to badly.... after all our third gens are road course cars......

 

Sure, it may not even be Holley brand, but nearly everyone still uses a Holley-based design who does anything worth doing in the racing world with carburetors. And I never said "650 double pumper". The only common exception I can think of are the guys who run the individual webers which were so common in Formula 1 for years.

They probably went to EFI because it bears more relevance to the modern automotive market, especially with the modern social pressure from environmentalist movement and gas mileage requirements. They sure took their time, though, didn't they? Didnt seem to be in much of a rush. But yeah, if you run a racing series around optimized 50 year old technology that still costs a lot of money to develop, manufacturers are going to be happier about spending that money if you can make the application seem more relevant to the everyday Joe. it is, after all, simply a marketing exercise.

My double pumper works fine for me on the street. I dont understand how people say they're "race only" carbs. They have a racing pedigree, but you can make them work VERY well. Now before I had it tuned up right and didnt really know how to set it up, it was very annoying and frustrating and I hated it.

No need to "hint", [edited] Ideal spark timing is always going to vary from motor to motor, and from tune to tune, but everyone needs to have a good baseline to work from.

And for the record, when i went to a carb setup I was starting from scratch. I had no intentions of buying an old factory qjet and struggling to tune it and buy a specific intake etc etc to make it work. When starting from scratch, a qjet doesn't make sense. If you already have a qjet and know how to make it work, great, it's probably one of the best carbs ever designed. But it has limitations too. You guys are dreaming if you think double pumpers are truly that bad. If they were they wouldn't be used on so many applications for so many years. They have shortcomings, but the huge aftermarket support for them and the modular design lets you address nearly anything.

 

When you find the need to point to my sentence structure it tells me you have run out of relevant information.So as what has been asked now,what three times,please re-frame from talking down to me.

The truth about Holley's use is as I have stated.And let's flip this around where you are refusing to learn about tuning Qjets.Well we could include you refusing to learn about EFI's as well.Expand your horizons.If a old dog like me can continue to learn,why in god's name can't you end that love affair with the old tech Holley carbs.Trust in the fact the old school that I grew up in isn't all "that".
Fuel curves and spark control is and has been for yrs the real deal............not dump toilet bowl fuel for all rpm's.

 

Im having a hard time figuring out what you're trying to say, but I will attempt to address it...

I did see you think I should move onto fuel injection... I'd much rather have fuel injection on my car than the Double Pumper, but it's because of small issues. The electric chokes on the holleys are bad and the manual ones are just annoying, the heat soak issues I have with boiling fuel, and finally for better gas mileage. But I would rather have a Holley than any other carb.

Even the best carbs (Holleys) when tuned perfect are never going to be exactly right in all situations the way fuel injection can be. But the advantage with Holleys is the amount of tunability in all those particular situations. There are very few things that CANT be tuned with a Holley, and that's why people get in trouble with them on street cars, because they dont understand them and they dont know where to start. In short, people are lazy and expect their carbs to work out of the box, and Holleys definitely dont reward that mentality.

The only thing I'd rather have on my car than my Holley is a fuel injection system. You'd never catch me with a carter, I mean, edelbrock or a qjet on my car. If my car came stock with a qjet, then I would have kept using it, but I dont think it makes sense to retrofit a qjet onto a car that didnt have one to begin with. If I'm going to start from scratch AND learn to work with a certain family of carburetors and invest in all the parts and tools to go along with it (jets cost money, squirters cost money, gaskets cost money, feed lines cost money, etc, etc) I want to start with a carb that has a proven performance record and a huge amount of aftermarket support and a plethora of reference material available. Holley has all of those.

And like I said, Im a believer in the qjet, but investing in the qjet platform when starting from scratch on a highly custom setup isn't a good idea. Even Edelbrocks can work really well, and I much prefer Holley, but my advice to anyone trying to make the choice is to just pick one and stick with it because the more experience you have with a particular type of carb the better luck you're going to have tuning them up to work well. I dont think a perfectly tuned qjet, a perfectly tuned edelbrock, and a perfectly tuned Holley are going to have many noticable differences to performance or practicality. There will be some small differences, but the biggest difference between them is, IMO, their versatility in tuning and their ability to work well even when not tuned well.

But if you're telling me that EFI is better than my Holley DP... I think you're spot on as long as we're not talking about Tuned Port Injection. I think TPI has enough bottlenecks and drawbacks both in design philosophy and technology that it's more or less a toss up, and it just depends on the application. But I will take coil packs, a computer controlling spark, and an oxygen sensor controlling fuel mixture any day over a carburetor, but a fuel injection system worth having is anything but cheap, and you're not going to see very much difference between a properly tuned carburetor and a properly tuned EFI system on a racetrack. Dumping fuel in at WOT is one of the easiest parts. To me the advantage of EFI is for daily driving and practicality. The amount of precision that can be had for nearly ANY situation imaginable, whether 30 degrees below zero at high altitude or 110 degrees at sea level, engine hot, engine cold, etc etc, is just not something a carb can match.

But then again a used holley and an intake that can support 500+ hp can set you back less than $250 if you're smart with your money. An EFI system that can keep up with it can cost you anywhere from $1500-$2500. Carbs have their place, so does EFI. What's the application? What's the budget? What's the goals?

My entire point was "blah Holleys get bad gas mileage blah" isn't a very good argument because they CAN and DO get good mileage if you tune them right. And when i say good, I mean the same as a qjet or an edelbrock and at least within spitting distance of an EFI system.

 

Sounds like you should learn how to work on your precious holleys..... maybe you can get rochester to build you some parts to make that holley work right......

I would appreciate you getting off my post.... no one cares to hear any more of your nonsense...... have a nice day bye bye now.

 

Relent to your question,my suggestion is to shop heads with a 195cc intake runner.The "peanut" 383 I built I tailored the torque curve with 180 cc intake runners so I was all in by alittle short of 4,000 at just short of 500lbs for torque.It is somewhat shy in the hp given a 375hp at 5,000.But off idle I am well into 400lbs of torque.It for that reason that I am suggesting for you a 195 cc runner.I cut down a set of aftermarket 72 cc heads to 67 cc chambers to run low octane gas.I got a set of -18cc dished pistons on 5.7 pressed fit rods.Works out to be SCR of 9.3ish.For you a 64 cc head chamber you going to look for aluminum to help lower the SCR.The Vortec answer with the best case of a 170cc head is a poor choice for a 383.It will short change you in torque and hp and cost you more in gas mileage where less ends up really being less.355's it ok(but just ok but not great)

And yes,the market is hard to build a middle of the road engine in a 355/383.I does take some leg work in research to select smart parts for gas mileage and performance.A good friend of mine in Calli has a pretty stout 355 that is C.A.R.B. approved(which that alone isn't easy to do)where he picked up used a old style Edelbrock EFI cheap on Ebay.Towing through the mountains his sand dragster/trailer he is getting 23 mpg.The used EFI's you have to be careful of because Edelbrock forum has stated they don't support the older 3500 series any longer.There is ways of getting around that,but the end result isn't as good.My point is EFI's don't have to be expensive.The aftermarket has been involved long enough,that there are deals out there for complete stand alone systems.You just have to set your goals and be willing to shop for deal when one comes along.

This long drawn out debate about carbs and now I finally get to suggest what I think which heads would work best for you which I think was the original question.Sadly,your back to just being able to run today's gas at a 64cc head,your kind of saddled with 92 octane gas.Yes,you can play with the timing some,but what's the point of that if you built it for performance in the first place??. Thing is,I do think you need the larger intake runner and with a cam will give you that deep throat 383 sound as well.

FYI-overall I am concerned about only 12 mpg your currently getting too.I suggest you read the plugs to see what they look like as a starting point.I do think you could improve on that too.Timing of total advance of 32 degrees.If your not there yet,that would hurt the mpg.

Buell-I hope this helps.Pretty sure it's stuff you know already and is just confirming that.Hope you a good day Bud.

 

Wow, a wealth of good information being shared in this thread. Maybe not all of it is 100% correct, but the fact that these guys are taking this much time to share their experience is great for learning. The biggest problem I see with this thread is the overall "attitude" of the original poster. Started out as a good topic / question, but now it appears that buell is more interested in trying to prove how much he knows, rather than "learn" anything. buell, you need to "lighten up" on your responses to the guys who are actually trying to help you. They may not have a "doctrine in applied mechanical physics", but they are offering, and sharing very good information. Based on this thread from last year, you were just beginning to learn about Q-jets yourself, so you are not an "expert" either.

https://www.thirdgen.org/forums/carb...ml#post4834962


Yes, I know this is only my 2nd post on this website. I wasn't even going to comment, but when I see this type of negative attitude towards others who really want to help those who are asking for help, it bothers me. We need to share information or the experience of actual "real word" knowledge of what works and what doesn't. This is how this hobby stays alive, and gets passed on to others who may be new to the hobby. Good luck with your combination, I am sure you will get it to where you want it. Listen and learn, that is the best way to get there.

 

Not sure if it has been mentioned or not, but I know when I built my motor it was quiet and then got louder. I think it happens because it is tight and everything needs to settle in. Same thing happens to sleds when we do top ends.....

 

In response to my attitude..... if you read it closely there was some really cocky statements made.... but I think we have resolved all that.

On to the last post concerning fresh motors getting louder..... about how many miles and when did you really notice it get louder....?

I was kinda rushed when I put this motor together so I Know things can be approved on, like cam and possibly heads..... I need to research the specs for the heads I have....889 I believe is the castings. But I have a 2 bolt 350 punched 40 over, with 5.565 rods and flat four valve relief pistons.... that's the stuff I can write in stone...... I'm unsure of cam specs.... was told it was mild.... and judging by the way it runs I would agree..... but still unsure. My timing may be off some I haven't gotten a light yet, but I wanted to figure out the difference between vacuum advanced and electronic advanced dizzy..... before I get too serious about timing..... secondly my power band.... it seems to be from around 2000- 5500.... I would like to pull that closer to idle..... so my questions are mostly about what works best together to yield what results....

 

Buell.You posted you have a 383.Did you use a cut down 400 crank and use the 400 rods??. Are the pistons made for a stroker with 5.565 rods??.

 

I checked my deck clearance and it seems it was close to perfect.... and I bought the crank from jegs ready to drop in.... I got it cheaper than I could have the crank turned.....

 

Not 100% sure on how many miles. It is something that happened gradually as I kept driving the car.

 

LOL, whatever man. I posted up a LOT of useful information, at least listen to it without admitting it because you're only hurting yourself by remaining ignorant*. With all the incorrect, BAD information going through this thread someone needed to set the record straight.

My carb issues with my car are generic to all carbs or due to my specific implementation. A Qjet would probably have better cold-engine manners, but other than that I dont see any advantage.

And lord help you if you have 882 castings. But it could be 993 which could also look somewhat like "889"

http://forums.carcraft.com/70/868456...ech/882-heads/

http://www.hotrodders.com/forum/chev...ot-100256.html

993 heads:

http://www.nastyz28.com/forum/archiv.../t-187438.html



Also as far as deck clearance and pistons go, if you used 5.65 rods you would need to use 350 pistons, thats why they did that to begin with. If thats what you did and your deck clearance was fine, I wouldnt worry too much about it. Im sure it's okay. GM specifically used 5.65 rods so that they could use the same pistons in their 400s as they used in their 350's.

Edit:

*ig·no·rant/ˈignərənt/Adjective:
1. Lacking knowledge or awareness in general; uneducated or unsophisticated.
2. Lacking knowledge, information, or awareness about something in particular: "ignorant of astronomy".

Ignorant does not mean "stupid". It means not informed. That's how I used it.

 

He has asked you a number of times to stop posting.I have a sense that your total experiences is stuff you have read and not done,Holleys aside.Now I am telling you I reported this post to site management to deal with.

 

All what bad info??. Care to explain that??. Bring it.

 

That'd be a neat trick when they have different bores.

 

We stopped using 5.6 400 rods yrs ago.In fact Howards cranks doesn't even make a by it's self a 5.7 crank anymore and have moved on to a 6" rod.Lingenfleter has gone beyond a 6" rods yrs ago as well.There is something to the long rod technology and go way back to the days of Smokey saying put the longest damm rod you can fit into it.

But neat trick is any time you try to figure out the SCR,the formula asks for the rod length.There in lays a issue.

 

With mine I on purpose with -18 cc dished pistons/5.7 pressed fit rods decked my block 10 down to get the 9.3ish SCR.

 

Infernal has no clue just ignore him..... all 400s are 9" deck height with 5.565 rods and 4.125 bore.... every Chevy guy knows that but him.....


So I used pistons that were on 5.7" rods and 3.48" stroke and swapped rods to 5.565" and crank to 3.75" stroke..... it seems when I checked it that it was well within tolerance.... now I did not use a laser depth gauge just used good ole human eye and a ruler.... but I don't think you could get a human hair between the piston and ruler..... just sayin...... lol I truly think my problem lies in my cam.... I have not mentioned this but I have a performer rpm intake..... the stock I broke o bolt off and was unable to remove....

If I do have 889 Or 882 or 883 heads aren't those pretty respectable heads.... especially after a port job?

 

As I have said,best case for a stock head is 170cc intake runner and that isn't enough for a 383.

 

Once the crank stroke has been chosen, the combination of rod length and piston compression height must be determined. If you intend to use stock-length connecting rods, the piston pin must be raised (i.e., the compression height reduced) by the same amount as half the increase in stroke. Using a common example, consider a 383 Chevy with a 3.750 stroke, original 5.7-inch rods, a block deck height of 9.025, and a target piston compression height of 0.025-inch below the deck. Here’s how you’d determine the required piston compression height.
Deck Height - (Stroke/2 + Rod Length + Piston Deck Clearance) = Compression Height
9.025 - (3.75/2 + 5.7 + 0.025) = 1.425
Therefore, a piston compression height of 1.425 (very common) is required for this 383 combo. Note that a 350’s commonly used stock compression height is 1.560; the new height of 1.425 raised the piston pin 0.135-inch, which is exactly half the gain by going from 3.48- to 3.75-inch stroke. As a result, piston position at TDC is identical to what it was prior to the increase in stroke.
The same formula can be used if you decide to use connecting rods that are longer than stock. In that case, the piston pin must be raised by the same amount as the increase in rod length. For example, if you used the 383 described above but swapped to 6.000-inch rods, the piston compression height would need to be 0.300-inch less because 6.000-inch rods are 0.300-inch longer than 5.700-inch rods. That means the compression height would be reduced from 1.425 (for 5.700-inch rods) to 1.125 (for 6.000-inch rods). You can get the same answer by using the formula above. Either way, you can see that either a longer stroke or longer rods, or both, requires reduced piston compression height.


Said better than I could.Curiosity of Hot Rod article.

 

So you're sayin mine is all wrong?

 

With the length of rods getting longer over the yrs,sure seems a 5.7 rod would be better. Actually I know it would be.I don't discount,say a cam swap would be effective,but if you going to spend money on heads,the aftermarket head's runner size is the way to go.Guys have wow'd about the Vortec heads on 383,but don't know what they are missing with the aftermarket answer.

Sorry man.I have to check out of this thread for abit.Been having some chest pains over the last few days and going to the "E" rm to have it checked out.Former heart attack/stroke victim.Catch up with you soon.

 

This is whats wrong with a lot of boards

Someone who knows their stuff repeatedly comes in with good info to help them but get run off because they arent patting them on the back for making mistakes. Like it or not the man was giving buell 100% good info. So I guess hes a punk for helping lol. What a fn waste of time.

Grow some thicker skin people!!!

 

Please inform me as soon as you return....

 

It's not the info he gave that's the problem it's his attitude.... secondly he thinks 350 and 400 have the same bore.... how's that even remotely right.... stfu you don't like it stay off the post. Or come say **** to my face..... I've had it....

 

There is attitude a plenty to go around, if you ask me.

So, do each of you who have posted Board-rules-violating material want to clean it up? Because if you don't, I won't have any choice but to do so myself. The easiest would be to lock the thread (deleting it entirely could be justified). Next would be to delete entire posts that have ANY rules-violating material, which would also take down technical information. What I am NOT going to do is edit individual posts to clean them up - I simply don't have time for that. I'm leaning toward Door #1.

It's up to you - clean it up, or kiss it goodbye.

It wouldn't hurt if you all made a commitment to act like adults from now on...

 

Get rid of it..... I'm done with the bs.... I simply ask for opinion and get some jerk that ruins it for me....

 

Well Buell I'm poked and prodded enough to know it's not the heart.Going back Thurs when I have more time.

Ya know I remember back before there was 6" rods we used to use Buick 5.85 rods re-machined just to get alittle more.They where heavy as all hell and hard to balance.You wouldn't think the difference would be big between the 5.65 and the 5.7 rods,but I suggest it is.Otherwise why would all of us have done the update??. Ask yourself why does 0 deck matter that much too.

 

Brain fart. I got a 383 and a 400 mixed up while talking about stroker stuff, sorry. The point was that you can use 350 pistons with a 3.75 inch stroke crank and 5.565 rods. So if that's what he's done he's still fine with it.

3.75 stroke, 5.565 rod, 1.560 piston for a 350:

5.565 + (3.75/2) + 1.560 = 9.000


Not an ideal rod length, but it will work.

 

Crank center line to deck is the same for a 400 and a 350. 9.025.So if as a example a 6" rod was used the pin height would end up needing ring spacers.The 400 rods vs the 350 5.7 rods is of course .005 difference.Well round about that.

 

On the original topic about sound…
I'd love to get a 502 and have it as quiet or quieter than a v6.
That's the fun. People are taken totally by surprise.

 

Then add to that a 76 cc head with a piston down in the hole and you "could" have a engine that eats gas and doesn't sound good.Kind of like a smog 400.

 

That would be compression.... and the motor doesn't run like it's weak.... so I need to check my deck clearance again huh?