In my quest to get as close to 12's as i can with stock L98 with HSR, i was thinkin of taking the heads off to clean them up, put in new springs/etc and possibly cleaning up the stock ports. Basically a mild port job in which i clean up the stock castings and smooth things out to see if i can pick up a few CFM here and there. maybe openin up the exhaust port alittle since it could use work.

Another thing i was really concerned with was the HSR base manifold ports dont really line up with the stock heads. the head port wall/edge buttes out into the flow path and i was thinking of port matching those head ports to the manifold. This should smooth out the flow path

would this be very beneficial to performance gain? like 10-20whp? Would it be worth the time and effort? I know the stock cam isnt much and probly already is getting all the power it can out the stock heads, but i have a buddy making good power with vortec heads on a LT1 cammed 9.5 to 1 carbed 350 small block. his heavy 83 truck runs as fast as my car does, so its got to be pushing 350hp on motor easy. Stock LT1's with bolt ons make near 300whp in great tune and 6 speed. they have a mild cam like a L98 but with more lift. The heads just flow better. So that got me thinkin with 1.6 rockers and ported heads, i could pick up 20-25whp or so and be more like an LT1. i dyno in the low 250 range now as it is.

 

I would say go for it if you are on a budget. For the money you will spend on porting them out you might beable to find some aftermarket heads for the same price.

 

I'm putting a HSR on my friends stock L98 with headers, will also add a stall convertor to help things up, do you think 2400rpm would be enough?

And I agree find some used aftermarket Al.heads, like Jegs or something... That and a nice cam will make it scream............

/N.

 

2400 stall aint bad, but i like my 2800. HSR peak torque is abit higher than TPI. I think my peak is around 3500rpms

but anyway, the whole point in porting stock heads is that its cheaper for myself to do it than buy aftermarket heads. I dont really want to spend money on aftermarket heads on a 150K mile shortblock and especially since i plan on building a motor within a year or so. For that motor, i want good heads that probly wont work on a mild 350 like a L98. Dont really want to buy things twice.

i'm just trying to squeeze as much out as i can with this current setup.

 

My thought is, yeah, as long as you don't accidentally find a water passage when you're porting, it's probably worth doing. Anything you can do to make the engine more efficient at moving air should increase power - as long as you can tune for it.

Of course, I was also thinking that you could go with undercut valves, Ti retainers, etc. etc etc., but that kinda puts a bit of a dent in the whole "budget" aspect of it..

 

thats my thoughts. i found a basic porting guide online that picked up 15-17% more air at low lifts just by cleaning up the heads which is all i plan to do. that translates to 19hp on a 300hp motor, which is exactly what i'm working with. so i may just do this afterall

 

I tell you now, while you're in there throw in a new camshaft. Go with the LT4 hot cam and leave the 1.5 rockers on if you don't want to mess with milling the guides. If you're willing to mill the guides go with the ZZ4 camshaft. I really wouldn't pull the down that far and not swap the camshaft and timing chain. Think of it this way, it'll be cheaper in the long run.

 

i want to but even with .492 lift on 1.5 rockers, i'll need to get screw in studs and possibly mill down the guides...which is 200 dollars in machine work i hear which i do NOT want to pay. i might as well get aftermarket heads for that. then the cost of new pushrods/valve springs/guides/rockers, i just dont know if i can do all that at once but i'll see here soon

 

If you're into porting your oun heads then I strongly recommend "Max Performance for Small Block Chevy's" written by David Vizzard. I got one at Books a million bit I think I've seen it at Autozone. I ported my 083's according to his outline. You can cut a bunch out of the valve guide and bowl area. Just don't go crazy as others have said cause you can hit the water passages. I added some budget stainless valves and screw in studs. Using a CC264 roller cam with 1.6 rockers for .528 lift. Didn't have to do anything to the to the top of the valve guide as the retainers and springs for this cam can handle the lift. I'm also going with the HSR and there is a bit of mis-allignment to the heads. I gasket matched the heads to the stock (Fel1204 I think) gasket and am using a Fel 1205 gasket. When you get your long block together you can put the intake base on to get the final gasket match on the intake. I also rounded the runners on the manifold where they meet the plenum. Just slightly to improve the transition from the plenum to the runners on the intake. Every little bit helps I think.

 

Go for it....while your in there and the possibility of a cam swap....you can get a lunati 207/213 with about .450 lift so screw in studs won't be needed.....or you can go to the 213/219 with .471 so screw in studs still won't be needed. .475 and above is where they are recommended. I would also clean up the face of the pistons as well and make sure no sharp edges are on it....if there is some....clean that up(makes detontation a minimium) and takes care of hot spots in the cylinder.

I would go with teh 213/219 personally and get that thing tuned as well. I see 12's in your future.

http://www.holley.com/types/Chevrole...c%20Roller.asp

 

i agree, i do see some 12's coming with alittle bit of work and any small cam with more lift than stock.

I'm gonna talk to my local machine shop to see how much screw in studs will be...if its 150 or less, i may do it anyway and get a hotcam or 305/503 cam or anything similar. I'd like to do this as cheap as i can cuz i just dont see the point in investing much into this high mileage shortblock.

i got alittle bit of extra money coming my way i just dont know if i want to invest it on drag wheels/skinnies with tires or a cam swap and continue to use my spare iroc wheels with et streets on them

 

I would probably keep the et streets and add the cam. If your not wanting to do the screw-in studs....the 213/219 would be a good jump in power with teh right springs and new timing chain.

I might use the extra $150 for a little milling for a little jump in compression for a cam.

 

thing is i could get a hotcam or used CC305/503 for 100 bucks when those other cams new are 250 or so. lol

but i'll call the shop tommorrow to see about some milling and screw in studs work to see what they charge. i have no idea what i want to do now.... port the heads and add a cam? do wheels and no porting of the heads? do both wheels and heads? ahhhhh this car is killing me

 

Whatever else you do, spend your money/efforts on the heads. That's why I went 2.5 or 3 years without buying anything for my car - I wanted my AFR 195s that badly, because all of your POWER mods depend on having good airflow.
If you've got the money for wheels or whatever afterwards, then great, but by all means, get the best heads you can, or get the most out of 'em that you can... (Yeah, I know that you already know this, I'm just throwing "my vote" into the mix!)

(And now I'm sort of tossing around the idea of selling the AFRs, without ever having installed 'em...)

 

hell yes you can get great numbers out of the stock heads. I did several posts on this many moons ago. Here's a couple links
https://www.thirdgen.org/forums/tpi/...d-project.html

https://www.thirdgen.org/forums/tpi/...n+head+project

 

i've seen those posts along time back and i was impressed with the numbers you got. Just with a stock cam tho, will any gains in head flow translate to hp or is the stock cam already maxed out with the stock heads? I see desktop dyno says 20 and other articles i have seen say 15-20 or so on stock motors with 15-20% increase in flow in the heads

 

You will still notice a good improvement with the stock camshaft. You're going to make everything more efficient so the entire torque curve will be fatter plus it'll extend it a bit. Anytime you make something more efficient in the line it helps support the parts that aren't as efficient. I've also heard it said that killer heads and a decent cam will always outdo decent heads and a killer cam.

 

1991 is right, you will see an improvement with just heads, either porting the stock or adding aftermarket. As with any improvement you will see more if you support it by modifying other things to match. Intake and exhaust improvements, cam, etc. It all depends on your goals and your budget really. Since you've already got the HSR and headers, heads and cam are the next logical improvement.
The thing to remember is that while your shortblock is stock, your intake and exhaust are not, so right now I'd say that by opening up your heads you will see a larger improvement. It's kind've like the advertisements you see for how much hp improvement a set of heads will give you. They build a fairly healthy motor and put stock heads on it, then swap 'em out for a set of their heads, guess what you see a huge number because the heads were the bottleneck around a bunch of other good parts. Thats similar to the situation you're in now. Right now your heads are the bottleneck around a stout intake and good exhaust, so definitly some work there or there are some pretty reasonable aftermarket iron heads available. So I expect you will see a bigger gain than if you just did the head work on a totally stock set up. Though I wouldn't expect 100 rwhp, depending on how much work you do you might see 30 or 40.
Do remember though that even as good as I got those heads, the intake will still outflow them.
1.6 roller rockers will definitly help out the cam, though a step up to a mild aftermarket cam would be something I would really consider. Like 1991 also said, while you have the motor torn down that far, you'll save yourself a lot of headache and money by doin it now rather than later, and a HOT cam can be had pretty cheap these days.
I originally started that project because I had a thing for what I oculd get away with inside the rules of stock class racing, which were pretty tight.
One other thing it comes down to is a time vs money equation. How much is your time worth? To do a good job and make these heads flow well will be the work of many hours of labor (cast iron is a beotch to grind on). Also how much other work do they need, god forbid you pull them off and find a crack, or a need for valve guides or seats. I've sold many a set of aftermarket heads just by showing them how much money they will be into their heads after just a cleaning, guide replacement and valve job.
In short, if you like having the bragging rights of saying you did it with stock heads, or know for sure you don't need any other work done to the heads and are on a shoestring budget, go for it. If not, lots of kick butt heads available out there for reasonable money.

 

Right now i'm on a tight budget. I just graduated this past spring from college and currently looking for a job. Until then i got a part time job to pay some bills i really want to do something to the car this year because it bores me and i'm ready for more speed LOL i'd liek to see how quick i can get it on stock stuff so far but who really cares, it still feels slow on the streets Heads and cam would be awesome,i just want to do it cheap and not sure the stock block will like it.
I only plan to clean the casting flaws and smooth the short side radius. maybe some valve guide work. nothing major. so i dont think that will take tooo much time.

I just dont know if I want to go with aftermarket heads for this motor yet. mainly because of my budget at this time lol. And soon as i get money i'm gettin a bigger motor anyway or all new forged setup so i can spray it/turbo it w/e.
Hotcam or any decent cam will require screw in studs so thats money spent on the heads. I dont want to dump too much money into these stock heads. Just wanted to do a easy clean up and see what it gives me. I'm gonna price things out here and hopefully go from there.

I agree tho, while i have the heads and front of the motor torn apart, might as well get a cam in there of some sort

 

Ok i called the machine shop and they said they can do screw in stud work for 115 bucks. i dont think thats too bad at all.

milling the heads at .020" will be 100 bucks for the pair. but not sure how much gain that would give me. i hear its 1cc for every .005" so thats about 4 cc decrease in volume to 60 cc over stock 64. stock compression is 9.3 i believe so i guess 60 cc will get me to about 9.8? i dont think i'll need much higher compression with a hot cam tho

I think they said 90 bucks to have the valve guide boss machined down for better seals and the seals are 25 bucks for the pack. This way i can gain clearance from the retainer to the boss which is said to max out at .480 lift. I hope to run .525 lift. I have retainers and locks but no springs, just stock replacements laying around. I wouldnt mind shimming the springs but then i'll need offset locks and retainters for that i believe. So it may be better to just have them cut the bosses down.

200 bucks or so for head work doesnt seem to bad. This is getting interesting, i may just do the cam swap sooon lol Now i just need to start collecting parts lol. I got a tuning cable for datalogging coming in and i'm ready to go.

 

Keep us updated. I am very interested in how your setup will compare to mine when your done since yours will be very similar to mine. I am having problems right now with my engine but hopefully they will all be straightened out before the racing season ends and maybe we can compare some track times.

 

Can I make one suggestion? Get a "practice head" from a wrecking yard and try a couple of chambers there first. That way, if you have an "Ooops", it won't be a "Damn"!

 

that would be a good suggestion but i think i may wing it on this one. i've ported an intake manifold before so i'm not exactly going in blind even tho one time isnt enough to qualify me as 'skilled' lol

 

Well, they are iron. So that will make the likelihood of any serious damage from a slip less of an issue than if they were made of aluminum.

I was more thinking of accidentally hitting a water passage that you didn't know existed. What you could do, is check with a few wrecking yard to see if you could locate a "backup" (but not buy) incase you discover something you wish you hadn't.

Good luck and I hope you obtain the results you are hoping for.

 

i wasnt planning on really hogging these heads out or anything. i just wanted to smooth casting flaws, gasket match to the HSR, and polish the exhaust ports. some valve guide smoothing and short side radius smoothing also. this should make just abit more flow as seen in Rhuarc's posts on his experience with porting L98 heads. I just want to slightly improve what i got now for the cam which is now looking like a realistic possibilty in the next month or so.

If anything does happen, and the car will be disabled for a long period of time, it doesnt matter to me. i store it in the winter so i have a few months left this year. I dont drive it much as is so if it breaks, i have plenty of time to get it working again.