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  #31 (permalink)  
Old 01-28-2010, 07:31 AM
How fast is fast enough?
 
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Cobalt, his timing is off for sure, but he's looking at about a 7.5:1 static compression ratio with a DCR at about a 6:1 with 8 degrees initial timing. With no compression there's not much room for making power. I do agree taht his timing needs to be bumped up though.

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  #32 (permalink)  
Old 01-28-2010, 08:32 AM
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Sorry AP, but I don`t agree with that logic. A bowl is round and rather simple piece. And just about anyone that can port will tell you to start with the basics, the bowl first. The port is where the airflow is coming in, this is where velocity is or lost. I will go as far as to say you can also do a basic clean up in the port, but as for porting itself don`t as it`s not recommended if you`ve never ported heads before. I follow the practices and beliefs of smokey yunick on many pages, and porting is one of them. His words are you spend 10 to 15 years learning the trade at a shop or you pay someone else to do it. If you got no proof to back up the claims of the work such as a flow bench your basicly blowing smoke.
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Old 01-28-2010, 08:40 AM
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Quote:
Originally Posted by cobalt327
I'm thinking there's a basic problem- either with the timing, carb, or ?- but something in the basic tune, that's keeping the engine from performing better than it now is.

In that car, a worn out 283 ought to feel strong. A 307 w/that mild cam- even w/too low CR- 4-bbl, aftermarket intake, 4-speed, 3.90 gears, etc. should be making a better showing than it is.
trust me it still feels ok for what it is and it SOUNDs fine but theres no way its putting out the power i want which is why i came here, i still managed to smoke hondas no problem but after riding in other cars i can tell somethings just not right. and this explains it lol

ill be picking up that hei from skip white that is CHEAP, he sells mini starters too CHEAP as well which is what i need for my headers to work so i think this will put me where i want to be with the car.

Would i be fine with keeping my cam or should i switch to the 250h-268h cam series i feel like the cam i have is wrong for my setup but clearly i already screwed up what i've got so i'm trying to get some more input this time lol.
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  #34 (permalink)  
Old 01-28-2010, 08:47 AM
How fast is fast enough?
 
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1, Velocity isn't everyting, and the bowl is where you stat because it has the biggest gains, not because its the easiest.
2, Smokey was great in his day, and a hero for the hobby, but he is dead and his theory has been sgnificantly updated.
3, flow testing in itself is VERY limited, unless you happen to be in a bracket that races flow benches, I saw bar stool races once so maybe there's flow bench racing too...
4, If people never try things they haven't done beore we'd all still be living in caves. I'm not advising going in blindly, but a person needs to start somewhere, this is a good place to start.
5, you don't even need to be a car guy to understand fluid dynamics, its all just fluid dynamics.
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  #35 (permalink)  
Old 01-28-2010, 08:49 AM
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I agree with Cobalt's logic, what is there should feel better. Maybe it needs a better tune, maybe something to do with the OP's comment about it feeling stronger with the hood open. Maybe he should try running it without the hood, could be the air cleaner, or the air cleaner/hood combination is choking the carb.

Also agree with the fact that the current heads are terrible and comp ratio is low, but car is light, has a deep low gear in the 5-speed and 3.90 gears with relatively low weight. It ought to rip the tires right off in low gear even with a plug wire clipped.

V8fbrx7, how big is the current air filter, and what is its configuration(flat base, drop base, etc)?? How close does the hood and scoop come to the carb and/or filter??
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Old 01-28-2010, 08:52 AM
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Quote:
Originally Posted by v8fbrx7
trust me it still feels ok for what it is and it SOUNDs fine but theres no way its putting out the power i want which is why i came here, i still managed to smoke hondas no problem but after riding in other cars i can tell somethings just not right. and this explains it lol

ill be picking up that hei from skip white that is CHEAP, he sells mini starters too CHEAP as well which is what i need for my headers to work so i think this will put me where i want to be with the car.

Would i be fine with keeping my cam or should i switch to the 250h-268h cam series i feel like the cam i have is wrong for my setup but clearly i already screwed up what i've got so i'm trying to get some more input this time lol.
If you are going to switch something a smarter switch would be the heads, you can't crutch a low compression ratio enough just by changing to a smaller cam. You will always be chasing your tail with the comp that low.
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  #37 (permalink)  
Old 01-28-2010, 08:58 AM
How fast is fast enough?
 
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Quote:
Originally Posted by v8fbrx7
trust me it still feels ok for what it is and it SOUNDs fine but theres no way its putting out the power i want which is why i came here, i still managed to smoke hondas no problem but after riding in other cars i can tell somethings just not right. and this explains it lol

ill be picking up that hei from skip white that is CHEAP, he sells mini starters too CHEAP as well which is what i need for my headers to work so i think this will put me where i want to be with the car.

Would i be fine with keeping my cam or should i switch to the 250h-268h cam series i feel like the cam i have is wrong for my setup but clearly i already screwed up what i've got so i'm trying to get some more input this time lol.

7.5:1 static compression. That is a HUGE problem. This needs to be addressed, even if you do no port work at all putting those 416's on will net some improvement, especailly down low. For a good street engine you need to be between 9:1 to 10:1 as a general rule. You're way outside of that. Even using the smallest cam you could find couldn't bring your DCR up enough, you need to raise the static compression. Take the whole top end off, reuse your inake, use the new ignition you're getting, and use the 416 heads with the springs you currently have. check installed height when you swap them and change the seals.

If you don't want to put forth the effort to port the heads that's fine, but you need to at least run the 416's. I would port them, but I actaully enjoy working on cars, going fast, and getting dirty so I'm a little biased.

If you decideto port them PM me and I'll send you a few cartridge rolls and a mandrel, so all you'll need to buy is an electric grinder setup and some stones or a carbide bit.
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  #38 (permalink)  
Old 01-28-2010, 09:03 AM
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I'll put it like this:

Be dam sure that you've tuned what you have to be its best. Otherwise, the changes you make won't be in proper context, and you will have a hard time saying what change made what difference in performance.

But in a larger sense, this is just one more reason to not build engines smaller than 350 cid. Had this engine been a 350 w/anything approaching a correct quench figure, the point would be moot.

The new heads should do fine for you. My thinking is that the interface between the last angle of the valve job and the rest of the bowl is the most important area to smooth, even if you do nothing else to the rest of the head.

And for God's sake, leave the push rod pinch alone. There's nada to be gained here, especially in your application. I know who'll disagree w/this- and that's fine. But take it from all those who've already done this and concluded (verified on the flow bench) that there's no gain to be had here, until you've done a LOT of other things first.

Back cutting the valves w/a 30 will be far more helpful, IMO. And, FWIW, I'd leave the 1.84" intake valves in it. Save the money for a different set of heads sometime down the road.
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  #39 (permalink)  
Old 01-28-2010, 09:16 AM
How fast is fast enough?
 
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Quote:
Originally Posted by cobalt327
I'll put it like this:

Be dam sure that you've tuned what you have to be its best. Otherwise, the changes you make won't be in proper context, and you will have a hard time saying what change made what difference in performance.

But in a larger sense, this is just one more reason to not build engines smaller than 350 cid. Had this engine been a 350 w/anything approaching a correct quench figure, the point would be moot.

The new heads should do fine for you. My thinking is that the interface between the last angle of the valve job and the rest of the bowl is the most important area to smooth, even if you do nothing else to the rest of the head.

And for God's sake, leave the push rod pinch alone. There's nada to be gained here, especially in your application. I know who'll disagree w/this- and that's fine. But take it from all those who've already done this and concluded (verified on the flow bench) that there's no gain to be had here, until you've done a LOT of other things first.

Back cutting the valves w/a 30 will be far more helpful, IMO. And, FWIW, I'd leave the 1.84" intake valves in it. Save the money for a different set of heads sometime down the road.

The last angle, INCLUDING the SSR, will be the lowest hanging fruits.

Agree on the PRP, but straightening out the walls of the runner (especailly the outside wall and roof) help, if you go into the runner go there first.

To port these heads you'll need a $50 investment in tools and about 1 hr per port to do a ood job on yourfirst try. $50 doesn't seem like a huge cost for a 30hp increase.
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  #40 (permalink)  
Old 01-28-2010, 09:45 AM
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The short side radious is a chapter unto itself, IMHO. If you don't savvy the importance of its shape and function- leave it the hell alone.

If you fully DO understand it all, you're a better man in that regard than I.

There's a lot there to be known, a lot to be gained, and a LOT to be lost- never to be re-gained- if you F- up the short side radius.

I was fortunate enough to have had in my possession some really quality ported heads, done by a guy in Taft, FL., Bo Law.

Back then, his shop was a hole in the wall w/a rough crowd hanging around drinking beer. He drove a black on black Elkie w/a BBC of various types and tunes- all bad.

The heads I got were done there about 1970-'75-ish? I don't know (or much care) if he himself ported them, but they were on an engine that ran VERY well.

And while I had them, I made templates from brass stock of the SSR, bowl far side and other parameters were measured and recorded.

What I saw when comparing these templates to a stock head, is to get where you want to be, you'd like to be able to ADD material, rather than remove it, AFA the short side goes.

I believe this is why the old Bow Tie heads were able to make the power they did. The material was there to do things that cannot be done w/an OEM production head.
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  #41 (permalink)  
Old 01-28-2010, 10:12 AM
How fast is fast enough?
 
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defintely true, but smoothing a contour rather than leaving a sharp edge will help. It'll be far from ideal, but its even farther from ideal where it sits now.

There are a lot of templates and cross sections out there to give an idea to what to do. This is where self education and research will pay off.

There is a large greay area between stock and a perfect max effort deal, these heads will fall somewhere in the middle, how far up depends on how much is put into self education.
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  #42 (permalink)  
Old 01-28-2010, 10:30 AM
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Quote:
Originally Posted by ap72
but smoothing a contour rather than leaving a sharp edge will help.
Even a simple, seemingly unarguable statement like that will need qualification- there are instances where a sharp angle is EXACTLY what's needed.
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  #43 (permalink)  
Old 01-28-2010, 10:43 AM
How fast is fast enough?
 
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Quote:
Originally Posted by cobalt327
Even a simple, seemingly unarguable statement like that will need qualification- there are instances where a sharp angle is EXACTLY what's needed.
A seemingly intellegent comment like that needs supporting evidence to discern it from troublesome ramblings. Has anyone ever bennefited from a sharp SSR on a 23 head for a sbc, or is it ALWAYS blended in.

sharp edges serve a purpose, to seperate flow from the boundary and create an eddy, the purpose of blending the SSR is so it allows the flow to NOT seperate. This is why SSR can pick up so much, because the sharp edge left from the factory greatly reduces the flow on that side of the valve.

At VERY high lifts the SSR can be cut adbruptly but that is done to bias flow. At low lifts (street engines) you can gain more power by picking up the additional flow by smoothing it out.
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  #44 (permalink)  
Old 01-28-2010, 10:58 AM
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Quote:
Originally Posted by ap72
A seemingly intellegent comment like that needs supporting evidence to discern it from troublesome ramblings.
Is exactly why I pointed out your 'observation' in the first place. Your statement, " but smoothing a contour rather than leaving a sharp edge will help." is ambiguous.
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  #45 (permalink)  
Old 01-28-2010, 11:02 AM
How fast is fast enough?
 
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point taken.

You know if we put together about 10 guys off of this site in the same garage, we'de be dangerous.
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