Heres the story. About a month ago i aquired a 88 camaro rs. It supposedly has a 350 out of a 93 police cruiser with about 60000 miles on it. This should be a lo5 with roller lifters. i havent got to the back of the block to make sure it is a true 350. the engine appears to be swapped. I'm looking to build the motor up to about 300-350 hp. As for cylinder heads I'm looking into a set of old school double hump heads with the 2.02 valves. i may have found a set and am going to see them this weekend. For a cam something out of comp cams extreme energy series.
tl;dr
double hump heads (ported and polished)
comp cams xe 268 for flat tappets or Xtreme Energy XR270HR Hydraulic Roller
new timing chain gaskets ect, ect
need help on springs?
performer rpm intake and something in the 650 cmf range for a carb.
headers with 1 5/8 primaries 3 inch collectors.

and help and suggestions would be greatly appreciated.

 

You pick the cam first, then springs. Usually the cam manufacturer will recommend a spring, or at least required spring specs.
With your heads getting ported, I recommend going ahead and having them machined for screw-in studs and guide plates, and having the guide tops machined down as well, since they probably need new guides or at least new liners.
I also like to machine down the spring pads a little bit. it increases installed height which gives you more room to play with higher lifts while maintaining a good clearance. It opens up your spring choice to more options.

 

What kind of car is this going into? Where do you live? do you need to pass smog? do you live in Cali? We'll need to know this before we can really suggest anything.

Stay away from the "old school double hump heads", why spend your $$ on 40-year old tech when you can get newer heads that flow better for the same price?

Look on ebay for a good set of Vortec's (you'll need a Vortec intake) or World, AFR, Trick Flow heads. As previously posted, pick the cam first. Then build around that.

For a carb? Qjet all the way.

Intake? Performer is good, Performer RPM is better if you can get a drop base aircleaner however, the RPM does nothave provisions for EGR, so you can't use it if you need to pass smog checks.

 

I'm in northern Illinois. No smog here. The engine is going into 88 Camaro rs. there is a drop base air cleaner on the right now. I havent torn into the engine yet to find out if it has roller lifters or not. I was gonna base my cam choice off that. This is somewhat of a budget build, im getting a good deal on a complete rebuilt long block with the double hump heads. less the 30 k on the motor.

 

Got the heads off the engine. tuns out there 1.94 intake 1.50 exhaust. They do appear to have been rebuilt at some point. There were FelPro gaskets on them and the springs have the extra flat little spring inside the main spring. I don't think those heads came from the factory with those, casting number 3917291, but i could be wrong. with a little porting and polishing what kind of preformance could i see out of these heads? i understand that newer heads like vortecs have the potential to make more power, but i have these heads right now and I'm looking to gain some experience porting them.

 

Factory springs do have the flat-wound dampers inside them.
A good port job in the bowls and seat area generally adds around 30 horsepower to a factory type head.

 

I would look for a set of Vortecs before the double hump route.

 

Stay away from double humps. They weren't all the good to begin with and dealing with the lack of accessory bolt holes really sours the deal. Agreed with above, Vortecs would be a MUCH better upgrade from a performance standpoint and they have the accessory holes you will need. The bolt pattern is different and will require a different (Vortec-style) intake to work with them, however.

Those heads are not LO5 (350 TBI) castings. I'm not familiar with -291 small block head castings. LO5 engines should have come with -193 heads (swirl port, 1.94/1.50 valves, 87-up bolt pattern, 64cc chambers).

Agreed with above, single 1.25" diameter springs with a flat dampener coil inside is what the factory used on scillions of SBC heads for decades. Even later Vortec heads used the same springs, minus the dampener coil inside.

 

I don't have an intake yet and the lack of acc bolt holes would be obnoxious. I'll look for a set of Vortecs if i can pick them up cheap. The casting number was for the heads was for the double hump heads. thank you for clarifying on the springs.

 

On my quest to find vortec heads, I saw a thread in another forum about one of two the castings flowed better then the other. It said the 906 casting numbers flowed more, is this true?

 

What about the 416 castings? Any love for those here?

 

I really like 416 castings, but they do take a bit more work to get the flow up to that of a Vortec casting, and cast iron isn't the easiest to work with.
Either will work.

 

No, not true at all. That's a myth that got started from an erroneous magazine article a long time ago. Any L31 (350) Vortec head casting is good.

 

hmm, i have the 416 castings on my 86 z28. i would like to do something with them in the future. thats good news that the difference in the casting mumbers is false.

 

If i do use the double hump heads, how important would it be for me to get new valves and Valve guides installed? this combo would be with a mild flat tappet cam something in the .460-.480'' lift range.

 

That is determined during inspection, looking for wear, slop, or damage.
If they are good then they don't need replaced.
A cylinder head machinist can do a pressure-check and visual inspection pretty quick.
0.001" clearance between the valve and guide is acceptable, but most used heads will have more and need guide liners.

Tight guides and a new valve-job go hand-in-hand.
Your new valvejob will not last long if you have slop in the guides.

Setting up the rocker geometry correctly by using the right length pushrods will help the guides last longer.

 

so i was looking into machining price's and it doesn't seem worth it for a set of old heads. the double humps will be up on Craigslist shorty. summit racing Vortec heads seem like a good deal.

http://www.summitracing.com/parts/SUM-151124/

also has anyone heard anything about the summit racing dual plane Vortec intakes like this one?

http://www.summitracing.com/parts/SUM-226018/

As for a cam what advantages would i see running a roller tappet over flat?
i'm looking for a cam that will make peak power around 5500 rpm. maybe something like this

http://www.summitracing.com/parts/HRS-180245-14/

or Gm's LT4 hotcam?

 

The LT4 HotCam is a known quantity for a mild performance engine. A good choice with Vortecs.

Summit dual planes are all Weiand intakes. Every bit the equal of their Edlebrock competitors. Another good choice for the combo.

 

The LT4 hotcam is a great performance piece for mild engines. It isn't quite as good as a crane/LPE/comp camshaft of equal duration though. The ramp rates and lobe profiles aren't quite as aggressive. It is easily tuned, gets good gas mileage and has a noticeable idle.

 

with all the searching i have done it seems that the LT4 hotcam is a good choice for vortec heads. very solid and reliable. But it does seem that there are better options out there considering the lt4 hotcam is a few years old now. for right now these heads and cam are going onto a stock shortblock. as a college student money is an issue. for the fall semester i have and engine performance course where the first project is to rebuild an engine, that's when the short block engine is going to be freshened up and maybe become a 383 stroker. so this combanation only needs to last the summer and a little into the fall. What kind of drawbacks would i see running a flat tappet cam for the time being? maybe something like:
http://www.summitracing.com/parts/SUM-K1105/

 

dont die on me now thread D:

 

The hot cam should work fine for the 383 as well. I would just get that and run with it. If you do one flat tappet cam now, realize that you'll be spending more money on the cam you want and another set of lifters later.

 

Any input on the summit racing cam i posted earlier. 90 bucks for a cam and lifters doesnt seem bad.i may already have roller lifters in the egine that is in the car now so i wouldnt have to get another set. also would i have to run different length push rods between the flat tappet and the roller cam?

 

I resurrect this thread to the words of PROGRESS!!!!!! its finally begun. The engines out and torn down to a longblock, deleting all of the computer and hvac systems. other lightening will occur. aiming for between 3000-3200lbs and 350 hp. as for the engine, i have a set of summit brand vortech heads a summit stage 3 vortech air gap intake. and for the cam a comp cams extreme energy 268 grind. its going onto a Lo5 shortblock. hoping for about 9.5 to 1 compression with a thin head gasket. headers 1 5/8 primaries and 3" collectors to single full 3 inch exhaust. and thinking a 600-650 carb. Any input from those wiser then I? pics tomorrow. sorry im drunk.

Thank you all,
Josh

 

You can keep the compure controlled carb, it'll run a bit better than going all old school with a vacuum advance dizzy and carb. You can keep the other emissions stuff off if you don't have an inspection for it. As for HVAC...I LOVE My AC, so unless I'm running a pure drag car, there would be no way I would get rid of it. The few pounds and maybe 1-2hp of savings isn't worth the loss of the comfort to me.

 

The engine was a Tbi 350. gotta go to the old school carb and dizzy. Only 90 bucks for a brand new hei distributor from summit. As for the hvac, its just going to be a weekend fun car. My goal is to Go as fast as i can for as little money as i can. can i get away with using the stock pushrods and rocker arms on the vortec heads?

 

I looked back through the thread, and between then and now, I can't determine what kind of heads you have: stock style Vortecs or modified for more lift? and if you're running a roller cam or flat tappet? If it's the "268" roller, it won't work with stock Vortec valve lift capacity.

 

My apologies for not being clear on the heads or cam. the heads are summit brand vortec heads. 67 cc chambers 175cc intake runners and has springs good until .525'' lift. the cam will be the flat tappet grind.

 

Well now this is a tough question. WHICH ONE of you guys have a flow bench????.

 

Well, 1gary i do not have a flow bench. As much as i wish i did, I dont lol. will i be able to reuse the pushrods and rocker arms from the Lo5 with the vortec heads?

 

Pictures from last weekend. motors out and getting torn down. Engine bays getting cleaned up. Any advice on what can be taken out to save weight? looks like I'm going to have to get new rockers, about 60 bucks for the stamped steel ones from summit http://www.summitracing.com/parts/NAL-12495490/ . If i were to go up to the 1.6 ratio would i have to run a larger push rod diameter? hopefully my pics post, its my fist time trying

 

were in il do you live i live in round lake up by the chain i have 89 formula white

 

You don't need larger diameter pushrods. 5/16" for both heads. You WILL need different LENGTH pushrods if you're switching from factory roller gear to an old flat tappet like the XE268. Your rocker arms (self aligning) will swap right over as well onto Vortecs.

Are you really sure about using a flat tappet cam? Don't get me wrong- I use them all the time (successfully). But if I have a factory roller block with all the roller cam stuff already there for me, I'm going to use a factory-style roller cam in it. Better performance and no need to worry about flattening a cam lobe due to the crappy low-zinc oils on the market today.

 

Believe me, if it had the factory roller stuff there i would go that route. it is a flat tappet version of the Lo5. hopefully still the higher compression one, i haven't had the heads off to find out yet. good to hear the the rockers will be fine on the vortecs. I'm aware of the oil issue the the flat tappets bring up, I've heard of people breaking the engine in with the zinc additive and rotella diesel oil. would that be a good route to go for extra safety?