Gsoleski

I just got a 91 355 short block with roller provisions. I need to take it to the shop to have freeze and galley plugs put in along with cam bearings. Has new flat top pistons on it right now. I have a Cloyes double roller timing set too. Here's what i'm planning on so far:

-LT4 hot cam (Duration at .050 in. 218/228, Lift .492/.492)
-Vortec heads and lifters with porting if I can learn how to do it
-LS6 springs with Comp 787-16 retainers
-Edelbrock Vortec carbed manifold with a q-jet
-Summit HEI distributor
-Shorty headers

Would this get me to my 375-400hp goal? Any input is appreciated! Anyone have a link with how a 1 piece RMS oil pan gasket goes on with all those O rings? Also what do you guys prefer? Advanced or retarded cam? that timing set allows me to go either direction by 2 degrees.

zraffz

I'd run a little more cam. From personal experience I went with a 224/230 duration .525"/.525" lift 110 LSA (Grind XR276HR) on a stock bottom end with vortec heads (aftermarket springs/retainers/locks). That's a safe cam for stock rods as it will be shifting around 6,000 RPM.
We figured my motor to be in the area of 385 horses with 9.4:1 compression (that seems to be the number sticking in my head with stock pistons and steel shims).

I can tell you in a 3,000lb vehicle with 3.73s it walked away from my bolt on/4.56 gears LT1 Z28 like it was standing still.

Gsoleski

I have 1.6 roller tip rockers. That would put it at about .525 lift correct? I'd just rather not need all the money into the heads for the machine work.

1986Z28OWNER

iTrader: (1)

224/230 duration is alot for 350 ci. Being that you are obiously running vortec heads with a dual plane intake this thing will be running out of air by around 6000rpm if not less. I would almost like to see 4 degree less duration on the exhaust 218/224. I am only running 224/229 on a vortec headed 383... But the dual plane I originally had on it couldnt keep up still. we kept giving it more plenum volume in the form of carb spacers, the more we gave it the more hp and tq we made. Ultimately I switched it to a single plane. Complete cam specs are 224/229 @ 0.050", 0.563"/0.578" lift (1.6I/1.7E) 110 LSA installed on a 108 intake centerline. Overall If you got the LT4 cam run it, but dont buy anything bigger(but hey, thats my opinion.)

Gsoleski

The car will rarely ever see 6,000 rpm. I've only had my L69 that high one time. I want it to mainly just be a street machine with a few trips to the track. What kind of head work do you have done to your vortecs?

1986Z28OWNER

iTrader: (1)

CHE Bronze guides, 2.02/1.60 Ferrea comp plus hollow stem valves, Intake & exhaust bowls blended to match bigger valves, std 3 angle valve job, raised the roof of the exhaust port 0.075" and opened them up around the guide, modified for screw in studs and guideplates, PSI 1512ML dual valve springs, Ferrea titanium retainers and PPP Super 7 titanium keepers.

RazorN8

I had a XE262 in a basically stock 350 from a '93 van with vortec heads (performer rpm intake, headers and some other small upgrades) and it was a great street setup. I walked away from plenty of turbo ricers with it. Much bigger than that cam and you will start losing your low end and you wont have as much fun on the street. +1 for the 218/224 duration cam. Go roller if you can afford it though.

Gsoleski

It will be roller for sure. Whats the difference between the 218/224 vs the hot cam 218/228? Why would the 224 be a better choice?

RazorN8

I didn't have the specs on the hot cam. I suppose there won't be a huge difference. I just thought I would add my experience with a similar setup.

Gsoleski

did that rpm intake fit under your hood without any issues?

RazorN8

It was tight. I ended up buying an aftermarket aircleaner that sat lower because the stock one pressed into the heat fabric on the hood. It will work with the stock air cleaner if you want though.

cuisinartvette

If you are not an experienced porter dont take a grinder to the Vortecs
id stick with the smaller cam with those heads if it were me.

Ozz1967

iTrader: (4)

If you can afford it, I'd get rid fo those roller tip rockers and get a set of Comp Cam's Pro-Magnum steel Roller Rockers. I'm sure people run roller tips and don't have any issues but I've also read some not so flattering things about them.

Ozz1967

iTrader: (4)

I didn't by the RPM intake because on my power bulge hood, I was afraid it woud run the carb top up into the cowl induction components. Good to know it otherwise fits under the stock hood.

Gsoleski

thanks ill look into those. I found out my pistons aren't really considered flat tops. here's what I have to work with

1gary

X2

redneckjoe

awe man, that sux.
id wait and get some flat tops,...and check the bores out.

slowyenne

cuisinartvette is right, leave the Vortecs alone, I've been told by professional porters that the factory valve job is virtually impossible to improve, and most of the time they flow less if you touch them, unless you really know what are you doing.

You may want to take a look to the next links, I'm myself in the middle of an EFI conversion and were really helful.

https://itunes.apple.com/us/app/engi...5158?ls=1&mt=8
https://itunes.apple.com/us/app/engi...4443?ls=1&mt=8
https://play.google.com/store/apps/d...vys.engine2lbx

1gary

I am not sure why you guys bother with the production Vortecs.By the time you end up trying to mold them with machine work for a useable format wouldn't you just be better off buy the Bowtie versions??. It occurred to me that GM made them with a perfect size intake runner at 180cc's for a 350 c.i. engine. Dual intake bolt patterns,but yes you have to buy the raised intake for it.For the money it just seems to make more logical sense to buy the Bowties.

slowyenne

Well, you're right 1gary, if memory serves me correctly they are called "fastburn" and seem to be a mix between the vortecs and the bow-tie 'cause although bowties have more material for porting and deck milling they flow less than the vortecs.

Try the app (Engine 2LBox) it features a quick way of calculating max potential HP.

zraffz

I was unaware a 224/230 duration cam was a lot for a 350... I'd call that the most aggressive you want to run in a stock cube vortec 350.

My 242/248 duration 383 must be way too much cam! Maybe that's why I need the 4.10s and 3,200 stall with the trans brake?!




By the way those are stock GM pistons. You can achieve about 9.4:1 maximum with those, 64cc heads and shims. After that you'd need to o-ring the block to get smaller shims and more compression or mill the heads.

1gary

Best case for the production Vortecs before hitting water is 170cc for a intake runner.And the ruff intake runner on the production Vortecs are to keep the air/fuel mixtures suspended.So to smooth port them destroys the Vortec effect.Really the only thing you can do to them is to improve the exhaust port.The Bowtie's on the other hand come out of the box either a 180cc runner or a 200cc runner for the 383 SBC's.

RazorN8

+1 for not porting the stock vortecs. I did it and I doubt I gained much if anything.

What O-rings are you referring to? The 1-piece RMS oil pan gasket is nearly identical to the 2-piece RMS oil pan gasket. I would use a 1-piece rubber oil pan gasket though.

IIRC Advancing the cam moves the power lower in the RPMs (better low end torque) and retarding the cam moves the power higher in the RPMs (better high end horsepower). If I were you, I would install the cam straight up.

Gsoleski

When I get back to town this weekend i'll take a pic of the orings i'm talking about. I should have some parts coming in next week. Found a good deal on some vortecs. they have screw in studs and Manley components for $200 and were just magnafluxed.

cuisinartvette

Sorry not trying to be negative
In the right hands the vortec can sing but you will spend 1000+ getting them done whats the point
Had a hard time picking up numbers on a set
Think at around 244 int/190 exh I stopped just not worth it
They went 22x and 150ish out of the box
Gm did a good job and had a specific purpose when they designed them.
Its like obsessing why a TPI intake wont be a top end power maker..its not designed to be.
A fat chick can dance doesnt mean she will look good doing it lol

Gary is right on NOT smoothing out the ports.....
Have more than one flowsheet where just doign that alone picked up NOTHING not just on vortecs, too. If it makes you feel better you can but know youre wasting your time.

To be honest Id rather have a slight carbide finish in my own stuff at certain points rather than the pretty stuff we sometimes post up pics of

1gary

Thought of him buying a set of Vortecs for $200,all he needs to do is ask himself why so cheap.

Now I thought the title was to help him build this engine.But what do you do if he won't follow a majority suggestions??.

I do know a bulk of the money "has to be spent" on the top haft of SBC's if anything is going to be gained from them.And he has to put on his big boy pants because it will cost him a grand or more for anything decent.


I guess it gets back to a old saying:You can lead a horse to water,but you can't housebreak them. Yeah,well something like that.


The whole thing is hinged off guys not knowing what they are missing out on.When we do-over heads,cam,induction system of some sort,customers who may have had their engine in the car say two yrs,tell us that can't be their engine because it never ran like that before.Some want to check casting numbers because they swear we switched engines. Oh well, I guess on another thread......................

Gsoleski

I just started my first full time job out of high school I can't afford to buy a nice pair of aluminum heads right now. I just want to get the ball rolling on a 350 because my 305 goes through a quart of oil a week. I will be saving up for aluminiums, but like I said this is a low budget build



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sofakingdom

iTrader: (1)

The trick to working with stock vortecs is just exactly that: work WITH them, not try to FIGHT them and re-make them into something they aren't. Because some of their limitations (especially the GINORMOUS valve guides) are so expensive to completely get rid of, that by the time you do, their "budget" appeal is COMPLETELY destroyed.

As said, the intake ports should be left alone, with the possible exception of cleaning up any casting flash or weird angles left over where that cutter got jammed into the port throat. DO NOT alter the basic shape of the port or change ANY dimensions significantly unless you KNOW WHAT YOU ARE DOING and can MEASURE the results, and have LOTS of cores to start over on after you scrap the first ones!!!

The exhaust is a whole other matter; they have the same sucky exh port as any other small block Chevy head. Those respond to the standard techniques.

Frankly, if I was trying to build a "budget" stock Vortec motor, I'd use replacement LS1 valve springs & retainers (not get all wrapped up in the "higher" versions of the LS motor unless the price is the same), and a roller cam in the high 2teens or very low 220s of .050" intake duration and about 8 - 10° more exh duration, and right close to .500" lift. Something along these lines http://www.summitracing.com/parts/cca-08-422-8 An all-around "better" cam especially for a carb application than the HOT cam (which is "compromised" in order to work with EFI).

There is no spreadbore intake available fo rVortecs above the "Performer" level that I'm aware of. No "RPM" or Air-Gap. Might be a Chinese knock-off like Pro-Comp or something but I don't buy any of that kind of stuff so I have no clue.

That'll be PLENTY of power to drive around and enjoy for a good while; easy on the budget both to build and to maintain.

Gsoleski

Thanks for the reply. I will leave the heads alone and keep a cam like that in mind. Here's a link to an oil pan gasket with the o-rings. I'm wondering where those go.
http://www.summitracing.com/parts/fe...make/chevrolet

Gsoleski

Got my heads yesterday.They were cut for bigger valves, and have manley screw in studs and guide plates. Unsure of springs but the heads went to the shop today to see what the max lift is and what the combustion chamber size it. Just want to make sure they were never shaved down. Also, pulled my lifters, dogbones, and the retainer from a totaled truck with 40k on it. Next I think will be pistons and figuring the compression ratio.