Hey, im new here and i was curious as to what you guys think about this build up. chevy 355 with 202 vortec heads and a edelbrock vortec air gap intake. Any recommendations on a cam? This car will mainly be a DD with an occasional trip to the drag strip. Ive searched the forums for quite a while for other 355 build ups but mostly i find 335 vs 350 and 305v 350 threads. Thanks for any help.

 

Welcome aboard TGO!

First, we'll move this from Engine Swap to Engine Tech, because you aren't really asking an egine swap question.

I've never heard that 2.02" valves help Vortec heads. For a daily driver, I'd say it makes even less sense.

The cam is the heartbeat of the engine. You need to choose it based on intended use. Then you need to surround it with parts to make it work right. Something along the line of an Comp XE268 would make a healthy daily driver and respectible strip performer. You will need gears to match use. The intake manifold (I'd recommend an RPM) and converter stall (probably somewhere around 2500) need to match the cam. The heads have to be able to take the cam lift, typically meaning springs, guide-to-retainer clearance work, and sometimes rocker stud securing. You didn't say anything about the intended source of the heads - JY heads typically need work to be performance-capable.

 

Sorry about posting in the wrong section, this motor will be getting swapped into a 86 camaro 5spd. w/ 373s

The motor was built to be a race motor on a very small short track, 202 heads are hot ticket items for this track, they run 350/355's that are limited to a 2bbl carb. I would definately have to change the cam so the powerband is a bit lower, mainly i was wondering if anyone had experience with the 202's and if they would make a streetable motor with a different cam. thanks

 

The big valves in Vortec heads hurt low and mid lift flow. I would assume that the builder put them in there hoping to pick up high RPM flow, which most likely didn't happen. The Vortecs chamber just wasn't designed for a bigger valve not to mention it's the ports that make the Vortecs a good head. Try to shoot for around 10:1 compression and a cam in the mid 220's duration wise and keep the lift under .550. Not sure where the flow drops off with the bigger valves but .500 was about the limit on the 1.94" heads. I would use an RPM air gap intake. Should be a nice street car then

 

Thanks for the reply, i was already planning on about 10:1 compression, the 202 heads have been race prepped,
(p/p and a 5 angle valve job) im also pretty sure they've had pocket work done for the springs as well, basicly he is giving me a screaming deal on this motor cause he wants it gone, how much does head work determine where a engine makes power? I always thought the cam would determine where the engine makes its power.

Dailed_In, could you explain further what you mean about "low and mid lift flow"? does that mean that cams that have low to mid lift wont flow well with the heads? or do you mean that the heads wont flow well in the low to mid rpm range.

Pardon for me being a bit daft, maybe i missed the point of the winking smilie, but i take it you wouldnt recommend this for a street driven car. thanks again

 

Head work changes the flow of air through the ports and into the chamber. If the person who ported the heads just went in and just hogged everything out in search of high peak flow numbers, chances are that the heads will be awful for a street car. They'll work fine in the upper RPM's but down low they wont flow any air due to no velocity, swirl and tons of turbulence. It will cause you a loss of torque, throttle response and driveability. You need to have the heads flow tested to see if you can use them. I would personally get rid of them. Vortecs don't usually resopond very well to port work. The runners are already pretty damn good to start with and the chambers don't respond well to the added flow. Not to mention the big valve definitely hurt the peroformance.

As for low and mid lift flow, this refers to the flow numbers of a head at the low and mid ranges of cam lift. I consider .100" and .200" of valve lift to be the low numbers, .300" and .400" to be mid and .500" and above to be high. The "peak" flow will be at whatever valve lift the maximum amount or air is flowing through the head. Most street cams though have a maximum lift of around .530" so a head that has peak flow any higher than that is a waste. Peak flow numbers are nice for bragging rights, but better power is found in good numbers under the peak. Think of it like this, the valve reaches peak lift only once every cycle, but it has to pass all the low and mid lifts twice per cycle. So it spends twice as much time there as it does at peak lift. It's more important to have good low and mid lift numbers.

What parts are in the shortblock and how much is he asking? I wouldn't mess with the heads if I were you. The bottom end may be a good deal none the less.

 

Thanks for the info, my dad and i were having a bit of a heated debate over what you meant by mid to low lift flow (we were both right)

the block has forged rods and 10:1 pistons, high volume oil pump, im not sure about the specifics of the brand of the pieces in the motor. Im also not sure about the crank (forged or not) he is asking 400 for just the short block, and about 1000 for the entire motor and various other stuff he has (camaro radiator, and other extra parts) Thanks

PS do you think they did all that work even though it seems like it would hurt with a pp to make the head flow better if it was being restricted by a 2bbl carb on a 4bbl intake instead of a 4 bbl carb? The rules this car falls under requires the use of a 2bbl carb.

 

Get the shortblock and any other parts you need. Leave the heads with him.

 

He has a set of untouched vortec heads, he would sell for 250, if those are also 202s should i stay away from them as well?

 

I would. If they're untouched and you put them on a motor with an aftermarket cam in it you're going to need some work. Screw in studs, good springs, rockers guideplates and hardened pushrods. Guides will need to be cut for clearance, heads need tapped for the studs, new seals and a valve job at the minimum. Not to mention I'd want the decks trued up square and the intake port matched to the heads.

 

Find out who did the work on the heads?

If they were done right, you have nothing to worry about with a 2.02 valve

A 2.05 is a good size to run in them for a street/strip motor and make the most HP/TQ

They can take up to a 2.08 valve and make more HP/TQ...But it’s a hit or miss, most don’t have enough material on the short turn to be properly shaped to work with a 2.08 valve.

 

Not in a Vortec head. The chamber is designed around a 1.94. Anything bigger disrupts the flow and kills HP. Even with chamber work there's no room.

 

If a person is considering even putting such a valve inside a Vortec head, I would think it's time to consider aftermarket castings anyway.

As far as buying anything, personally, I wouldn't buy an engine from someone unless they could give me a parts list, build sheet, spec sheet - something - that listed every particular inside the engine. But that may just be me.

 

Then how did doing this make more HP/TQ and make the car Faster at the drag strip????? 1.94 to 2.05

To each his own though.....You have your idea of what works and I have mine.

But as long as im getting more power and quicker ETs from porting..etc I’m not going to do anything different

 

Was valve size the only thing that was changed and were the track conditions identical? How much did you pick up? Guess I can't argue with success. Everything else that I've seen with Vortecs both on our flowbench, engine dyno and as well as other well known builders is that they like the small valves.

 

Nothing else changed on the car. Dont remember what it picked up on the dyno and track becasue it was awhile ago. I'll look it up though I have the info somewhere

Except for valve size more chamber work, shaping the short turn and maxing out the push rod pinch...etc(no welding) Everything else was the same.

 

I found out some more info on the short block, it has eagle rods, aries (sp?) 10.5:1 pistons, and i believe a forged crank. I located some brodix -11 heads that are ready to use for 800. But even those seem a bit steep for street heads. I was told that they would work fine for street though. Thanks again for all the info guys, youve been a big help.

 

I asked Lloyd Elliot about porting vortec heads, and he said he gets about 10 more cfm using the 2.02 1.60 valves vs the stockers. He charges $400 to port them and says he can get roughly 250-180 out of them with the stock valves. $.02

 

oops