Bought a set of valves today, 8 x 1.94 and 8 x 1.6. Stainless steel regular diameter shafts. I wanted to get the ceramic reduced radius shaft units but MAN are they expensive. Some other time I guess. Got the set for $120 CDN. Got a set of Elgin springs as well. Good for .500 lift they are $60 CDN a set. Pretty cheap eh ? Helps to shop around.

Found a shop to do the head work. Now I have to pull the heads. Wahoo I can't wait....

RP.

 

What heads you plan on using these on? never heard of a 1.94/1.6 combo..

 

So if the springs are good up to .500lift that rules out a ZZ4 cam do too the exhuast lift is .510.... right?

 

The 1.94 & 1.6 combo is uncommon but not unheard of -- depends on your sources of info I suppose ? It is a little pricey I am replacing 16 valves instead of 8 (1.84/1.5 to 1.94/1.6) and have to replace 16 seats instead of 8.

Using 1.65 RRs my duration will be 205/211 and max lift will be .456/.473. In a simulation with this profile the 1.6 exhaust with 3 angle grind, bowl and port work has really good average lift flow numbers -- so much better than the 1.5 that IMO it is worth the added expense to use them.

adious,
RP.

 

Are the springs meant for a roller cam? I think that 1.6" exhaust valve is going to need a bigger seat pressed into the head but I could be wrong. I know the biggest you can go without new seats on L98 heads 2.00" and 1.56".

Richard, most people buy the cam and then the springs

 

Who sells 1.65 rockers? Comp? Have you talked to anyone at Crane or Comp about going higher than 1.6? It creates some nasty problems.

 

Actually I could get .550 springs for another $15 CDN they are not all that expensive for street pieces. I'm just not interested in the ZZ4 cam right now.

Here is why -- using 1.65 ratio Comp Cams Magnum roller tip rockers my adjusted factory cam numbers are roughly 205/211 & .456/.473 lift.

The ZZ4 shows 1.5% increase in intake duration over my factory cam (when using 1.6 ratio), 4.6% increase in exhaust duration, 3.2% increase in intake lift and 6.3% increase in exhaust lift. If I had my block on a stand like you do then sure I'd throw a ZZ4 or or LT4 or LPE in it cause it would be easy work and probably a smart investment.

I figure I'll wait till it comes time to swap out the 305 then I'll throw in a new cam in the 350.

adious,
RP.

 

Hahaha need I remind you of your advice (once upon a time) to replace springs with 1.6 rockers ????

I figure if I have the heads off I'll replace the springs and pushrods with the rockers. Not wasted money IMO.

I asked a few questions about the seats. The guy I talked to says he has done this combo before on 305 heads. He says it works well.

I first heard about this combo years ago when Jasper Engines was building alot of hot street EFI setups. Sure it will need bigger and hardened seats no matter how I figure it I am in for $500-600... so whatever.

AFAIK the springs are for a roller cammed engine. There was no doubt what the app was when we were discussing prices. ??? I suppose I can call back to make sure.

adious,
RP.

 

I meant most people choose a cam and then get springs with the appropriate specs.

 

Is I dunno a good answer ?

I used Comp Cams Magnum roller tips on my '88 and they had 1.65 stamped on each piece presumably denoting it was a 1.65 ratio ?

I was at Rudy Held last year and they had a set on their shelf which also had "1.65" stamped on each piece. I just assumed it meant 1.65 ratio as opposed to 1.6 ? Never gave it much thought there isn't a whole lot of difference (.05). I can say this -- I ran the 1.65s for about 20,000kms without any issues and that was with a cam spec'd at 217/225 .505/.525, Comp Cams pushrods and Comp Cams conical springs rated for .550 lift. I really beat on that motor too.

I like the comp cams roller tip because I've used them before so thought I'd use them again. Do you have a copy of David Vizards SBC Camshafts and Valvetrain ? He does an assessment of these pieces in his book I'll have to look up and see if he measured them to 1.6 or 1.65 ?

adious,
RP.

 

Yah I'll get it right one of these years... hahahaha

 

Well i hope you kick out some great numbers out of this beast your putting together..sounds very interesting...

Maybe some 13.5's in the 1/4?

 

That would be one awesome 305.

 

But teh 305 can NEVAR lose! lol

Just messin with ya.

 

Well you know how these things go -- always performs less than anticipated.

13s would be REAL nice ! But I'll probably end up around 14.10s or 14.15s. My goal is around 300hp or 1hp per cube with the 305. I'm at 260 right now or so says the dyno.

I don't think heads, headers, RRs and an AFPR will do it. Probably see 30-35hp and fall short some. So I am looking into the numbers on a hi-flow base with runners. Of course all of these parts are transferrable to a 350/400 so the money is an investment in the future (or so I tell the wife HAHAHAHAHA).

If I can build a 13second 305 with these parts I wonder how it will do when I eventually swap to a 350 using the same parts but stronger cam ? Well I guess that is what you are doing eh ?

Seen any good deals for base and runners ?

RP.

 

my g/f's brother is looking for a base and runner setup aswell...
nothing yet.. and I am looking pretty hard.. we almost had a sweet deal on Accel setup but it fell through as per usual!
hahaha hard to find stuff...

I have a edelbrock intake and runners sitting here but not for sale.... Unless I go MINI RAM... heheheheh but I don't see it happening.... YET...

 

I've seen a lot of aftermarket TPI stuff for sale lately, but nothing I would call a deal.

Gerrit: I think you need to go miniram and sell those things to me!

 

richard did i read this right? do you think that your duration will change with the 1.6 rockers?

If so please tell me how or is 205/211 the stock duration?

 

Hey Scott howsitgoin ?

First a pet peeve about sources of information -- I have books on Camaros and Firebirds, I have numerous books on SBCs and I've been to any number of internet pages. I even have some old info from '80s & early '90s car mags (Car Craft, et al).

In a perfect world there would be one answer to one question but I cannot believe the differences in what sources report as facts about our factory cams. GM parts manual says one thing then you open the GM Performance Parts book which says another. One internet site (ours) claims specs as gospel this while the other site asserts another set of specs. In the end after looking at all the varying specifications for a 1991 L98 cam in a 305 -- I chose the numbers that I liked best. Go figure. If I am wrong it won't be by much so who cares ?

Here is the 'factory' specs I arrived at for my cam:
Intake duration 203 @ .050
Exhaust duration 209 at .050
Intake lift .415
Exhaust lift .430
LSA = 116

Now about the changes to the cam with 1.6 ratios, I first read about this in David Vizards book Small Block Chevy Camshafts and Valvetrains. I can't say enough about this book there is no aspect of our valvetrain that he does not inquire of and thoroughly test. Moreover he is an engineer through and through NO Bullsh*t between the covers tons of raw data I learn something new everytime I open it up.

We know that the 1.6 ratio has the effect of moving the rocker on it's 'pedestal' this ratio'ing effect increases lift in one direction and decreases it in the other. For example 1.4 ratio will decrease lift (assuming in both cases a 1.5 ratio starting point).

Altering the geometry also has the effect of increasing the duration, again in one direction (upping the ratio) and decreasing the duration in the other direction (downsized ratio). Now the effects are not a whole lot yet are measurable and therefore in some cases very important to know about. Now I don't want to type in the paragraphs of rocket science written in Vizards' book. Better you go buy a copy I'd love to talk to you about it afterwards there is alot I still don't get.

He does state clearly that a typical small block chevy will see from 1.5 to 2.5 degrees increase in duration at the valve when using a 1.6 ratio geometry. This is according to his tests.

Now I applied a 1.65 ratio in my calcs and split the duration increase of 1.5 to 2.5 in the middle:

Intake duration @ .050 is 203 + 2 degrees = 205 degrees
Exhaust duration @ .050 209 + 2 degrees = 211 degrees

Intake lift .415 / 1.5 ratio = .2766 at the cam x 1.65 = .456 at the valve.
Exhaust lift .430 / 1.5 ratio = .2866 at the cam x 1.65 = .473 at the valve.

So in an earlier post I said the 1.65 ratio makes my factory cam start to look like an LT1 or LT4 cam. To assist in making my point here are some other factory specs that I found for comparisons sake (they are from GM Performance Parts online):

- 203/210 - .476/.480 - 115 - 96 350 LT4 w1.6 roller rockers
- 201/208 - .447/.459 - 112 - 95-96 Gen II, LT1, w center dowel pin
- 202/206 - .403/.415 - 115 - 305 HO, 83-86
- 202/206 - .403/.415 - 115 - 87 350 Corvette, IROC Camaro
- 201/220 - .435/.460 - 113 - 350 300hp crate motor
- 218/228 - .525/.525 - 115 - 96 LT4 H.O.T. crate motor, use with 1.6 roller rockers
- 202/210 - .472/.478 - 111 - 97 Gen III LS1 Corvette 350 uses 1.7 roller rockers.

What I find most interesting is how much power some of these motors make given so little cam.

adious,
RP.

 

Those engines make power due to the cylinder heads they are equipped with and superior engine management. The LT1, LT4, LS1, and LS6 heads are the best OE OHV heads ever made. The aftermarket can't even improve upon them short of CNC'ing them. Even after porting, your 305 heads won't flow or have the burn characteristics of an LT* or LS* head. Those cams are all weaksauce OE smog cams. Well, the Hot Cam isn't. Are just going to add 1.65's to your stock cam? Those #'s you have listed are the lobe centerlines, not the seperation angles.

 

Don't get me wrong I have no illusions about my 305 heads and flow rates. Low-flow-smog-heads is what they are. But they can be significantly improved upon for about 1/2 the price of a new set of Pro-Action Lightning iron heads (BTW: thx for the 'heads-up' on these they are a remarkable head by all reports). Of course the LT and LS heads won't work on my car.

I also have no illusions about what a rocker change will do when installed all by itself. I plan on a number of changes together however that should account for 35-40hp AND without a cam swap. If it works (I get the hp numbers) then I'll be smiling all the way down the track -- if not well there is always next winter...

Oh yeah I understand how they arrive at LSAs and LCAs but I don't understand the impact of say 109 vs. 115 ?

adious,
RP.

 

Interesting valve combination. I assume from the oversized exhaust valve that you found flow numbers indicating a weak exhaust to intake ratio.

Also just to support your information about 1.65 rocker ratios also increasing duration there is an article in this months Chevy high performance that talks about exactly that.

My take on it is that the lift is increased due to the higher ratio everywhere on the lobe so that means that where you had .05 lift before you now have .057 lift. which means that where you had .044 lift before you now have .050 lift this would increase the duration at .05 lift due to the fact that the .05 lift is achieved sooner and also on closing occurs later.

Interestingly though total advertized duration would not change as this is measured from zero lift and 0 x .15(increased ratio) is still zero. Therefore does not start to open any sooner it just opens quicker.

Good luck with your combo

Ric

 

Ratchet

thank you. after thinking about is some later i came up with the same answer too about total duration not changing

 

Total advertized duration not changing doesn't matter.

What matters is that the area under the curve gets bigger. Valves open higher for a longer period of time equals more ponnies all good stuff.

Ric

 

Thx ratchet I hope it works out ok too -- you never know till dyno day eh ? I hope to see about 25-30hp from the head work of course the engine shop says 40-45hp because with headers and all the other mods planned the effects are magnified. I think that is crap.

The conclusion that I drew about the 1.6 upgrade is that the 305s flow so poorly that even a small upgrade to the valve size looks radical to the engine and AFAIK the intake/exhaust ratio improves measurably. I'll have to try and find out what the percentage is ?

thx,
RP.

 

A valve size change does nothing without corresponding work to the bowl area beneath the valve. It's like putting a 5" exhaust tip on a 2" exhaust pipe. You probably already know that.

Ratchet, maybe you could hog Richard's heads out like Jay's?

 

Where's Daz in all this??

 

im tired of all of this..Ill just laugh at the end..

Daz

 

Just a few points to clarify the effect of changeing rocker
ratios. And ported 305 heads.

The .050" duration will not change This is a cam spec
not a valve timing spec. Your valve seat timing duration will not change either,
The valves will start to move and finish moveing at exactly the same timing point.

Your rate of lift will increase, and your total lift at the valve will increase. Meaning that once the valve starts to move it will move at a faster rate then before because of the increased rocker ratio.
What Vizard means is that to compare or illustrate the effect of the increased rocker ratio you will see the "effect of", as if you installed a cam with 2-3 deg more duration @.050" and more lift ( more top end hp but less low end torque). BUT!.. your actual seat or "running duration" and the .050" duration does not change.
Only the action of the valve when in motion changes. (rate of lift)
and (area under the *valve* lift curve).

The 1.94 x1.60 valve combination is the best choice for a 305 head hop up. A 2.02 valve shows no flow advantage and weakens the casting unnessessarily. You do not need to install new seats. The new valve job can be ground on the existing metal.
You CAN match the flow of the LT-4 head (240cfm) by porting those 305 heads. Don't be swayed by others or shops that say other wise. They have never tried it. I and others have done it more than once. You do not need to be Joe Mondello either.
You or the shop yu hire just need to put the effort and time into it.
Even if you only achieve say 235cfm , you'll still have a hell of a street head. Just follow Vizards porting instructions and diagrams for the other factory heads and you'll be fine. The first set I did only came out to 225 cfm but had real good low and mid lift numbers and would work real good on a street 305 with that size of camshaft.

good luck to ya with your project.

 

And you're mr. mother****ing goodwrench........... Did you find all the pieces of your engine yet?

 

"And you're mr. mother****ing goodwrench"

HAHAHAHA ROTF LMAO

 

I'll be banging on your door when I pull off these heads.

RP.

 

OWNED


hahahahahaha

 

ouch that hurts..

lol

Daz

 

Heheh, no it didn't. I'm sure people have said worse things to you.

 

lol keep it coming..

Daz

 

Dante, i'm just ****ing with ya You don't strike me as the type of guy that lets junk like this bother you.

 

hahaha ..it doesnt bother me..I actually think I deserve it..lol..Its like Karma of some sort.....

Daz

 

No man, your engine eviscerating itself was karma. Was your crank one of the Scat 9000's?

 

I dont think thats enough room what ive said and done after all I was expecting it to happen..


added: Yes its a 9000 series number 9-350-375-5700 IIRC
Daz

 

Well i am sensitive so watch your mouth!! Decel... I mean Accel


p.s. If you believe that you are retarded!

 

Ok now that I have read this....I need to know is there any advantage to changing the valves to the LS1 valves? And to using their 1.7 rocker valve train?

I think I have found a solution/modification to the issue of them loosing their needles!!

 

WOW...10 year old thread rehash.

Why not just start a new thread and ask your question or PM the people involved.

Oh yea.....DAZ is all knowing and wise.

 

How bout cause anytime you do you always get the "We've gone over this 1000x times, just do a search for it." Reason i don't search for it is lets face it, 10's of thousands of responses that show up. Half of these response are non factual and personal opinions without facts.

But I see I may have to. Another thing that irks me, I can find more support and willingness to help with a fox body mustang than an f body.

 

I guess you did use the search button to bring up a 10 year old thread.

TGO is the largest 3rd gen resource on the internet. If you can't find help here, maybe you'd be better off with a rustang.

Daz is all knowing and wise.

 

LMFAO, even 10 years later it's still funny.

A lot of good people back then - and you wouldn't have got some officious boy scout telling you what not to post either - like it possibly matters if anyone brings up an old thread.

 

Good to see you're alive and cranky. Still the "village idiot" I see.

 

Your conduct in this thread speaks for itself - basically you pissed on some guy for asking a question.

I live in the West end of Toronto. If you want to meet up at a mutually convenient time and place to back up your words let me know by PM.

 

Check your profile. "Village Idiot"..your own words George.

 

Stock LS valve or aftermarket? Aftermarket may require work to make the valve seat compatible.

Comp Cams LS beehive springs will work on 305/350 TPI stock heads and good for 600 lift.