I was wondering about how to advance or retart a camshaft...I have read that when you advance a cam you get more low end torque, and when you retard the cam you get mor high rpm power... now to my question... say I was to get a Comp XFI 280 cam and retard it, how much could I retard it, if there is a limit? I have seen cars that have totals of 30 to 35 degrees of timing, what does this mean? how will compression ration affect it? would retarding the cam 20 or so degrees be to extreme with 10-11 copression?

 

You advance or retard the camshaft with a timing set that's designed to allow you to do so. It's generally only done for fine-tuning or to compensate for choosing the wrong cam grind. Just install it straight up and forget about it.

You're also confusing camshaft timing with ignition timing. The cars with 30 to 35 degrees of timing are talking about ignition advance.

 

Oh... well can you retard ingition timing? would that still make more high rpm power? and would 20 degrees be to much?

 

Ignition timing is an entirely different matter from camshaft timing. Retarding your ignition by 20 degrees isn't something you'd want to do.

 

well...would it not make much difference by retarding or advancing the cam?

 

Not really.

 

ok...well thanks for the info...

 

Back in the dark ages before there was an aftermarket, custom-ground cams were too expensive for most people to play with, so they would try to use whatever tricks they could to squeeze any performance out of factory grinds. Advancing or retarding the cam was one of those tricks.

Adjusting the cam timing is still an option for unpopular or exotic engines that may have limited aftermarket support. For chevy engines though, nowdays there are literally hundreds of different aftermarket cams available to buy off the shelf, which can cover nearly any application you can imagine, and you can even get a custom-ground cam for little more than the cost of an off-the-shelf piece, so there's not as much need to mess around with advancing and retarding the cam. You can get the same or better results by choosing a different cam.

 

good point... what cam would you suggest for a 305 with 11:1 compression? A custom grind for summit is around $300... what lift and duration would you pick...just curious...
oh and its efi, just figured that would be important...

 

What kind of EFI, and what do you want to use the car for? Is there any other work done to it? exhaust? How did you manage to get 11:1 on a 305?

 

If you're replacing a stock camshaft with a 280 cam you'll have lots of top end power and rpm. Start there. if you want to move the cam to evaluate the effect, move it 4degrees.
You can adjust the cam timing using a cam gear offset bushing and lock plate and/or a crank gear with multiple timing keyways.

It is strongly advised that you first degree in the new cam to verify the cam card timing specs and try the motor with the cam timing set to the cam card specs and test the performance before you make any cam timing changes. the effect from adjusting the cam timing is soubtle but effective in some cases. it will not make a small cam, into a big cam and will not make a too big cam into a small cam, but will fine tune the engines' power curve a bit

Advancing the cam tends to bias the low end of the engines torque curve. retarding the cam does the opposite. You're trading one for the other to find the sweet spot.

Big long duration/extended overlap camshafts idle and have better throttle response with increased ignition spark timing at idle. This is a separate tuning issue and requries the the distributor mechanical advance curve be modified to achieve the desired initial, total advance and advance curve rate. A typical 280deg cam usually want around 18 to 24deg spark timing at idle but the same 32 to 36deg at WOT high rpm. usually a stock distributor needs the mechanical advance curve travel amount physically limited, more to achieve this ignition timing curve.

Most (but not all) typical "bolt in" hi performance cams are ground with a bit of intended cam advance already dialed in when you align the normal timing gear marks. This bit of cam timing advance allows for a bit of timing chain wear and usually gives the best overall engine performance.
Start there with you new cam. Dial in and maximize the car's spark and jetting tuning and traction tuning first before considering moving the camshaft timing.

Retarding the cam in an effort to increase high rpm power will not make up for restrictive exhaust or crappy cylinder heads or weak valvetrain or lack of fuel system delivery volume.

I once had to move a camshaft by 9 degress to correct the valve timing caused by a mismatched pair of timing gears. (my fault, not the cam grinder's)

 

Also what style of cam are you looking for, hydraulic or solid, and flat tappet or roller?

 

I want to use it for road racing, trickflow 175 heads ported and polished, 2.0"/1.6" valves, I was thinking reverse flow water pump to allow me to use the higher compression with pump gas, I still have not decided what particular efi to use, maybe commander 950, maybe FAST XFI... I got the copression with KB forged pistons bored +.03...I am still trying to figure out how to set up the exhaust, I want hushpower mufflers, but still havent figured out how long to have the exhaust, ets...for headers, Hedman hedders with 1 7/8 primaries...all of this will be topped off with a Sealth Ram Intake... all forged internals...thinking 2-4 bolt conversion...I dont know if a lifter valley girdle for a 350 would work on a 305, but if it works I will get it...a 7 quart Milodon oil pan, and an external oil pump with full lentgh windage tray, that should be everything...

 

hydraulic roller...

 

I think you're in over your head...

 

i figured somone would say that...but i would take either mech or hyd roller cam...

 

Sonix is right. You're barking up the wrong tree and likely way over your head.
It's a lot lot easier to work within the laws of physics, than against them.

Installing a camshaft that has excessive valve duration (for the application) and then attempting to move the cam timing to allow a motor to operate with excessive high (11:1) compression ratio, on pump gas will not work and will not get you better performance.
Reversing the water pump on a 305 will not magicly make that block into a GEN II or LT-1 motor.
You're headed for a poor performing, knock sensitive, crippled engine that will have a short service life.

 

so what must be changed...the compression, kinda figured...I will probably be told to scrap the 305, but that wont happen...ideas, suggestions? set me staright...

 

11:1 is too high for road racing on premium pump gas. Thats your first mistake.

 

I want to know the hard numbers that gave you 11:1 in the first place. Use an online calculator, and screenshot the results with all the inputted info.
I think you made a mistake, and your setup might still be salvagable.

And yea, it sounds like you've read too many hot rod magazines and have too many buzzwords in your head Leave those to the guys who just talk about hot rods, and drive their tercel to work.

 

The combustion chamber is 56cc, The pistons were 3.17cc with 2 valve reliefs, and a .031 gasket...
I think the setup would do good still with a 9-10 compression or ist that still to high...
Or I was also thinking going procharged...same essential setup but with different pistons, that would get 9 compression with .041 copper gasket with 10-15 pounds of boost...
----------
oh and I am gonna take all the accesories off, and use a electric drive for the water pump and just have an alternator...

 

ya still want to fight the laws of physics. Where do you think the power comes from to drive an electric water pump?

 

what are you talking about? the power would come from the battery, and the alternator would normaly take over when the car is started...

 

first thing you need to do is figure out what horsepower to weight ratio you need to be competitive. Then check your back account balance and start taking weight out of the car.

 

when I said accessories I meant, power steering, a/c, smog pump, that kind of stuff...
----------
also understand...it wont be just a strict race car... It will be a car that I drive daily... yeah, the 11:1 compressionwas dumb, I admit... the supercharged Idea would be more plausible, I think...
----------
and I dont mind sacrificing a smooth ride to get it...I am the only one who will ride in my car, and it wont bother me...

 

And what makes the alternator go around and around? All for free?

We won't get into the size of the arms you're going to need to wheel a Fbody around a road course with manual steering (even a max lightened Fbody) . Or will you be cranking the alternator with one hand and steering with the other?

A belt/crank driven water pump is the most power efficient way of pumping engine coolant on a road race/street motor.
An electric water pump is good for quarter mile sprints. Thats all.
Converting mechanical energy into electrical energy and back into mechanical to spin a electric water pump is not any where near 100% efficient.
Again you're $$$fighting physics$$$.
You can fine tune the rpm and power consumption of the belt drive water pump with custom ratio engine pulleys to optimize the pump speed and horsepower consumption.

If you'll be competing against 5.7L 383ci and 400ci cars of similar weight on this road course, you'll need a $$$radical$$$ N/A 305 or a blown 305 to compete.

 

the crankshaft bro... I am not that dumb...come on man! I never said I was gonna run the alternator with an electric drive...no, I said the water pump, and keep the alternator...

 

F-Bird's point is that the electric water pump is going to consume as least as much power as a belt-driven mechanical pump, and very likely more.

 

http://www.ststurbo.com/

Around 9:1 cr with good quench. water/methanol would allow lots of reliable high(er) boost and power on pump gas on a hot road course.

This guy has a good handle on the laws of physics.

 

...well, I neglected to read the rest of the thing...

 

Just giving ya a hard time there Oxrabidus....... to get ya thnking...

You could get away with a high cr on pump gas with reliability with a Cool computer controled Water/methanol injection system like this one.
www.snowperformance.net

Just have to remember to fill the water tank and clean out the water jet nozzle once in a while.

 

sounds interesting...I would try that...how long would the water/methanol thing last? a day or two? or longer...
I apologize for my rashness, I sometimes get ahead of myself...

 

Sounds like the worst daily driver ever.. if you can afford a supercharger just get a 350 build it into a 383 put all the go-fast goodies on it and youll have 400+ horsepower on pump gas all within a streetable rpm range that you can still kill guys at the track with. Even if you were to build the engine your describing the price would be insane and you would be constantly breaking those expensive parts racing. But it sounds like you got the money so why don't you just get another car and drive that daily????

 

I knew someone would say that...I really dont know...I am set on the 305...350-383, and all the "go fast goodies" sounds bland and cliche to me... yes more power and all that stuff...but...cliche and bland...altough more power is more fun...everyone does it...and I am not everyone...by the way I only have enough to build the engine alone, the supercharger will come in the future...

 

"Bland and Cliche"? So what are you doing then. Are you road racing, or are you building paper engines to impress people?

 

call it what you want then...I dont do anything to impress people...I do it because I want to...if that offends or confuses anyone...it is not my problem...I just come on here every now and then to ask some questions...some stupid, some not so stupid...i think it hilarious how people just watch and listen...that is...until I mention, oh no...the 305!
Yeah I find it bland and cliche...what can i do...at least I am honest about it...and say it...I DO NOT LIKE THE 350...
----------
oh...yes I do race...not so good now...but I do pretty good...considering i have a 2.8 in my car for now...

 

How could you not like a 350???????? i dont understand that statement at all ... You can't really build an engine and then just throw a supercharger on there.. you need the right stuff and the right stuff is the "go fast goodies" that you "don't like" It might not be a good idea for you to be building engines quiet yet. Buy some books or talk to a mechanic before you start stating you want a $10,000 race engine for the street on a budget. your initial post was a good question for a novice but i can't see a novice blueprinting a high revving high horsepower race engine with a blower on it. Sorry if i sound like a **** but thats the cold hard truth..

 

I have read enough to know what I need to put a supercharger on an engine... the machine work I cant do so I will have that done...my reasoning for not liking a 350...simple...it is just what it says...
no one will understand...
the water/methanol tip was interesting, and may go with that if it is better in comparison to a intercooler...but i do not know much about it yet...

and why the vulgar language? you are by no means an ***...I dont know you that well...

 

Under what sanctioning body, and in what class?

 

none...as corny as it sounds...I do not obey the laws...i race on the streets...corny right? but true...

 

Ok, so you don't race then, and you're not building a car for road racing, and you just want to build a hot street car with a 305. That could have saved us a lot of time up front.

 

well that depends...what do you consider racing? to race under a sanctioned body on a road course?
racing on the street through traffic can be considered, "racing"...at least I think...but then again, I am the fool who does not like 350's...
again...corny but true...its what i do, it makes me money sometimes...

 

You are ridiculous, your combo you made up is the worst combination of parts even my unexperienced mind has ever seen! and do you hate the 350 because its so popular? It's popular because it works! a 305 is a small bore engine, and because of that you are restricted on valve size, thus, you can't breathe nearly the ammount of volumetric air that a 350 can. its not just that 45 cubic inches.

 

Well let's start with your budget.. The blower is gunna run you at the lowest from $2000 + unless you go used JUST for the blower.. Your gunna need a new induction system to keep up with it so im gunna say about $1000+ Your going to probably need a billet crank Im not saying you absolutly need one but it might be a good idea, Much higher flowing heads i would go aftermarket and aluminum $1000 plus, descent ignition setup $400+, Cam and strong valvetrain to keep up with blower ~$1600+ for optimal set up, forged pistons and better rods ~$700+, an exhuast system $700+ unless you bend it and weld it yourself, Also dont forget all the small things like. filters, gaskets, you might want to use studs, fuel lines, bigger fuel pump, lubricants, Might wanna invest in a bigger rad $500, electric water pump $250, All the new wiring etc etc etc.... I'd say for a streetable raceable blown engine you gunna need close to $10,000 dollars becuase youll also need a new transmission to handle all that power, some bigger axles and rubber won't hurt iether. Keep in mind those are almost bare minimum prices and youll be breaking parts like crazy a couple grand in the bank would be safe. setting and tuning the engine all the time, I've personally never seen a road race car with a blower. you also don't have an engine to start with yet so theres another $500+

 

...And you don't race thru traffic for money, stfu.

Want to build a real engine? Use what I have in my signature. it works.

 

why the vulgarity...I do have an engine, not in yet though...
I dont seem to understand the anger...why is everyone being such mena people....
tell you what....

lets make deal...

oh...to hell with your set up...

 

about...2 years...from now...I hope to have my engine done...and suspension...the works...
whats say we get together and prove me wrong... prove to me that I am an idiot...prove to me that I dont know jack ****...
mark your calendars if you are interested...
remember my name...
you wont see me until then...
no joke...

**** all who insult me...
no need to be *******s...
just remember my name...

 

Are you drunk or something? take a pic of your 305 then maybe we will be more optimistic....

 

nope...perfectly sober my friend... dont drink at all actually...
just pissed...no one has to insult me, or talk ****...if you dont like my question, dont ****ing answer the question...

 

Your question was answered, it was your following statements, theyre just not realistic.. your waaaaaaaay over your head like siad before but prove us wrong built your phat engine and post pics when your done then we'll all look like a bunch of idiots.