25thanniversZ

uncle has a set of 3927186 castings that have been magnafluxed, ex-rayed, intake ported to either 204 or 206?, and milled 100,000 yes 100,000 that I can have cause im the good nephew that helps him at the drop of a hat.....is a 100,000 to much milling????? oh yeah the plan is to put them on my low milage, carbed LO5 roller version, and will the serpintene belt setup work with those heads.....92 model,,,,stearing away from working the swirl heads...

25thanniversZ

the heads were ran 6 times at the strip, but just want to know if there milled to much before I put them on if they will even work with the 92 belt setup

F-BIRD'88

They are probabily usable. They have the accessory bolt holes
in the ends. The deck milling will reduce the combustion chamber size. Raising the compression ratio. You would have to "CC the chambers" to know what volume thay are at now. Not that hard to do.
The actual chamber volume will probabily be between 52 to 58cc's. if the heads were flat milled .100". If they were "angle milled" then the chamber can/will be even smaller. the only way to know for sure is to measure them.
The head milling may require the intake manifold to need to be shaved for proper fitting and alignment. Many times only the bottom ends of the manifold need to be shaved. You can do this at home with a 7" pad body sander/grinder and 40grit paper.
The manifold bolt holes may need to be enlarged.
Because the heads have been milled .100" the effective length of the pushrods is longer. This may or may not cause a problem with valvetrain geometry, requireing diferent length pushrods.
the valves will be .100" closer to the piston tops at TDC.
If you'll be using a real big cam with lots of overlap then valve to piston clearance will need to be checked.
Not usually a concern with streetable sized cams.
So, they are usable but you'll have to check and deal with some
alignment issues.

25thanniversZ

yes they were angle milled...came off a 383 with dome pistons.... .580 lift or so cam

F-BIRD'88

Plan on doing some machineing on the intake to fit them.
The angle of the manifold port face on the heads gets tilted relitive to the intake manifold mating face when heads are anglemilled.
First I'd measure the actual chamber volume to see where
you're at and then go from there.

25thanniversZ

nah I just snag his intake, we both got the same one.....performer rpm

25thanniversZ

any idea what the compression ratio might be??im going at this all wrong..have no idea what thickness in head gasket to get , rod lenght,ect...and I assume the roller LO5 has non dish pistons?ya know the so called caprice motor

Momar

We cant tell you the compression ratio unless you can cc the combustion chambers. If you do that that will give us an idea.

Ben

25thanniversZ

well I wont get them untill tommarrow, but I know that stock they are 62cc and having been angle milled to .100 they have got to be in the 52 to 54cc range....correct?

Momar

I dont know what they will be. If the motor has flat tops and the combustion chambers are that small though you will be running some pretty huge compression. I think my car with the 58 cc chambers figured up to around 10.3:1 with flat tops w/ valve reliefs which means that if that motor has flat tops it will be higher. I know that the L05 I had from a 91 caprice had flat tops. You could likely have 11:1 compression or so, but without more info I cant really say.

Ben

25thanniversZ

thats kinda what range I had figured, im told the numbers off my engine is a flatop setup, as long as pump gas is a go...thank ya sir

25thanniversZ

one thing I have no idea is, which thickness in head gaskets will I need???? havnt a clue lol

25thanniversZ

ok got the 186 heads today, talked to uncle and he said they were milled to 50cc, 2.06 intake....doesnt remember the exhaust side..any way with those heads,

stock flat topped roller LO5,
hooker shorties,
edelbrock perf rpm intake,
edel brock 750 carb,
full MSD ignition,
3'' duals through single chamber flowmasters,
1.6 full rr's lunati

How about this cam........
Comp XR294HR or
XR300HR
rough hp guess????????????

drive is 3.73 posi and th350 aluminum drive shaft
only a weekend driver. and no I dont plan on taking it to 6000 rpm's, but my wanted power range is 2700 up

25thanniversZ

oh and on another note, my pops and his click basicaly run the local airfield so I can get my hands on all the avgas I want if its neccessary

SweetS10v8

just an fyi,(from what ive read..so take it how you will)

AV gas might have high octane but was formulated to to be used at high altitudes(REALLY??) and low rpms and its not good for low altitude/high RPM use, i guess small planes run around 3000rpms??

I have added it to my gas just to give it a nice odor, but never run it straight.....

again, I jsut read this in an article in Hot Rod or Chevy Hi-Performance...I have no proof...just reminded me of it when you talked about it...

25thanniversZ

I usually put 5 gal of avgas per tank, a little noticable in response

Momar

What is the power band on those cams. If you dont plan on taking the motor to 6000(why not) then I would get a cam that doesnt peak any higher than you plan on taking it or you will just be short changing yourself. Also, I have no idea about the AV gas, but think you are going to be running quite a bit to much compression for pump gas. The normal rule of thumb is 10:1 on pump gas with iron heads and with my brothers l05 and 58 cc heads we figured it would be about 10:3 so you would be quite a bit higher.

Ben

SweetS10v8

Did a quick google search and found this....

I have found that with most smaller chamber heads under 80 cc's, every 0.005" milled reduces chamber volume about 1 cc. For larger chamber heads figure about 0.004" per cc. These guidelines leave a little room for error. So if you want to reduce you 64 cc small-block Chevy head to 60 cc's, taking off .020" is a safe starting point. You'll then need to cc the head and take off a few more thousandths to make it perfect

Info taken from this website

(3927186 68-72 1.94/1.50 & 2.02/1.6 290-370hp engines 64 CC Chambers has bolt holes These are the doubble humps as well.)

if this is true your 186 heads Well 64cc minus 20cc = 44cc might want to check for sure...

25thanniversZ

XR294HR adv dur 294in 300ex
rpm 2800-6100
lift .540in .562ex with 1.5 rockers...

XR300HR adv dur 300in 306ex
rpm 3200-6200
lift .562in .580ex with 1.5 rockers

I have 1.6 rockers

Momar

What rear gears do you have? Auto or manual. If auto what stall?

25thanniversZ

25thanniversZ

anybody, all I have left to do is make the call to order the cam.....please help on decision.....comp wouldnt give me a straight answer....must be newbie....

SweetS10v8

what are the cams duration at .050? advertized duration means nothing.... if your not going over 6000rpm you wont need anymore than 220's duration @.050...

Contructive critisisms(meant to be helpful ideas, not personal attacks): You will gain 10-20HP by going to a smaller carb, 750 is way to big for a 305!!!!! And true 3" duals, while looking/sounding good, hurt the already low, low end torque on your 305

Id be willing to say youd gain a good 30hp/30tq EZ peak with alot better throttle responce and the car will feel WAY faster off the line with those 2 mods.....

I ran a 750 cfm on my 11.2@121 S-10. 350 11:1 AFR heads 248dur @.050 .575 lift mechanical roller cam with a Victor Jr single plane intake 1 3/4" headers and all the other goodies......

25thanniversZ

LO5=350 just lettin ya know.....

Momar

A LO5 is a 350, not a 305. I would find out about those heads first. Calculate the actual compression you will have because it is going to be high and probably wont run on street gas. What octane is that av fuel, and do you plan to run it all the time?

Ben

SweetS10v8

my bad i had L03 in my head...lol

25thanniversZ

my bad....
XR294HR
in 242 ex248 @.50

XR300HR
in248 ex254 @.50


and on that note the heads stock are 64.cc they have been angle milled .100 I dont know the math.....but the intakes have been ported 2.06 and found out the exhaust is 1.80


the avgas is like 120oct buddy sells 112oct racing fuel to
and I dont plan on running either straight...I will only mix it, if it even comes to having to use either

25thanniversZ

oh and as soon as I get an idea on the cam, it WILL get ordered tonight and the heads WILL be on by WED...giving nothing goes wrong ofcourse...lol

SweetS10v8

I just think both of those are WAY too big, i have suffered from overcamming a motor and it stunk, my first motor ever was:

350, flat tops, 76cc 882 heads so it was somewhere from 8.5-9.0:1 IF i was lucky....I stuck in a 256dur @.50 cam and it was a DOG!!!

Seriously though, I was reading some sigs and there are people running mid 12's to low 13's na with cams around 220-230 @.050

the more you go over that, the more bottom end youll lose, and if your going not going over 6000 often(be honest with yourself or youll be mad at yourslef later, I was)

I always go one size smaller cam, and put all my money into heads...

Ive read this a lot...and after my AFRs found out from experience

"You can have the best cam in the world and a bad set of heads and you wont make good power, but take a good set of heads with a crappy cam...and youll still make good power"

I think im getting off subject..lol Im talking heads.....

25thanniversZ

your not off subject, I started this thread to get opinions. Oh and the 882's ya had were helpess from the start.....Givin my gears and the gearing of the th350 I built and my tire diameter, and the total weight of my almost stripped 92Z8 (interior) and the rest of the s--t not neccessery under the hood, my car has a pretty damn decent luanch now

25thanniversZ

darnit...ive been abandoned

please fellas, just need some honest opinions from the experts so I can get whichever cam here by tommarrow

SweetS10v8

lol ok, i didnt want to do this, but just for kicks Im breaking out the old Desktop Dyno 2000 with the cam iterator...lol

itll give you an idea of the cam you need, i used it to help choose a cam before and it ran great....

Give me any specs of motor that arent posted...this will be fun

Momar

What do you plan to do with the car? What rpms do you plan on running. I thought you said you werent going to take it up to 6000, but did you mean to or past?

Also, in all seriousness, with that much compression you are most likely not going to be able to get away with straight pump gas at all so you will need to plan on using a mixture all the time or get a different set of heads. I just calculated it and you will have ~ 11.36:1 compression. Do you know what the heads flow or just valve sizes because just because they have large valves doesnt mean they flow well.

Ben

SweetS10v8

As i was re-reading through the post looking for your current cam specs i ran upon this(see above)


Angle mill and Domed pistons are like 15:1 compression and 12lbs of boost or 600hp and 35mpg......kind of an oxymoron

angle milling produces extremely small comustion chambers...especially at .100!!!! now if it was .010 (ten thousandths) that would be different....

i dont know, maybe im totally off.... :lala:

25thanniversZ

no I dont have flow #'s but I can say this for a fact, that me uncle is an all out dragger and doesnt f-@#@ around with his machining and toys if he had them it was for a damn good reason....basicaly they were the poo...lol and if I have to mix fuel.....oh well..its just gonna have to be that way...darnit whatever will I do with high octane fuel.....

and yes the 383 they came off of was freakin scary...little over 600hp and he ran mixed fuel

yes .100

and this was what he considered his daily driver had it in an 81 berlineta stock rearend shifted into third at 120

25thanniversZ

man im sorry, but I have no idea what the specs are on it...all I know is its a stock 92 LO5 roller version (so called caprice motor) with about 2500 miles or so on it...sorry that I ask for help but cant give it....im a tranny mech not an engine mech...lol

SweetS10v8

ok I had to do some assuming here....like, the heads were ported(if they made 600+ hp they have to be) and that they are factory heads they didnt flow that great to start, but to error in your favor I assumed they flow like Vortec Heads.....

Im also assuming 11.5:1 Compression....

The best cam I found for this build was the TPIS ZZ-409 cam..

duration @.050 226/226, Lift .520/.520. 112 LSA.(dont buy from tpis, jsut find a simular spec'd one from compcams or someone)

check out where your power is coming in between the 2 cams, the solid line is the above zz-409, the dotted is your 248dur @.050

the zz-409 is a far better choice, as it offers you more HP and +50lbs tq from 2000-3500 RPM which is where street driven cars live 90% of the time. Your car will feel faster with the smaller cam!!!

And the bigger cam only starts making more power than the zz-409 after 5500RPM and it isnt even substancial..... especially since you wont see 6000+RPM often....I know desktop dyno is like a G-tech pro(known to be off) but it still is a good represenative of the difference the power/TQ difference between the 2 cams will be..

This is the best I can do to prove to you that a cam one size smaller than optimal is 10 times better than a cam a few sizes too big

Only trying to help...

SweetS10v8

KEY:

Green = TQ
Red= HP

25thanniversZ

bud I see your point, I really do, but im not at all concerned about any low end, I would assume not burn out as much as to gain strong upper mid to upper...but yes Im kinda starting to think that maybe I am looking at a bit to much cam....like I said it will only be driven on frie and sat nights....and man,,the heads were great from the factory.....all ive heard about these is that they were the **** in there day and have so much potential


and yes the graph you posted does let me see it in a dif perspective and I thank ya for it buddy......77 is a good year to old man...lol

25thanniversZ

ok according to that chart the 409 cam is starting to fall on its face before my chosen max rpm and my cam choice is peeking about where I would want it...........or am I looking at it wrong?????seriously....am I??

25thanniversZ

screw it......I just ordered the comp XR288HR........ought to be good enough with my 1.6 rr's...did I do a good thing???

SweetS10v8

Sorry, Just trying to help and was basing everything on this...