rhuarc30

Ok, I promised flow numbers, stock and ported on these heads, I'm running a little behind but I've got the beginning for you. First of all the intake and exhaust ports have all kinds of wierd bumps in them that screw up flow. If I can get my digital camera going I'll post some pics. Second I flowed all the ports on the head and there was quite a bit of difference from port to port, like 10% in some cases. When I'm done they should all flow within a cfm or two of each other (hopefully ).
For those of you who pay someone else to flow their heads you need to make sure of a couple of things. 1 is that they use a radius inlet on the intake port, a lot of "professionals" i've seen don't (lazy b*&***ds) and I tested it on these heads just to see what the difference really was. 20 cfm less on the intake without it! It only takes a minute (I just use modeling clay) and is well worth it. 2 is on the exhaust port, make sure they block off or at leat restrict the exhaust crossover port if they use one of the two center ports. If you don't you'll see an extra 20-30 cfm on the exhaust as the air will blow right through that passage, which it doesn't do on an engine. Don't get me wrong exhaust flows through there, but not at a rate that will really affect anything.
Ok, now that we've said all that I forgot to bring the complete flow chart with me, but the peak numbers were 193 intake and 120 exhaust. I've seen better numbers posted, the intake's pretty close, but I've seen other people claim 20 more cfm on the exhaust. I've never seen it though, the most I've seen on a stock set of these heads is 130 on the exhaust and average seems to be around 118. With my numbers it works out to 62% exhaust to intake flow, which pretty much sucks. I'll try and remember to bring the complete numbers home and post them so we can compare later on. Oh btw the numbers are at 28" of water and .5 valve lift. I'm testing at 6 points from .1 to .6, but the stock heads peaked at .5.
Plans for the porting:
1. There is plenty of room to cut these heads for 2.02/1.6 valves.
I haven't decide whether I'm going to do it or not. Probably, but
I'm going to have to look at it some more.
2. Valve job. This would normally be number 1, but I have to
decide which valve size to use first. The stock valve job is
pretty ugly, so should see some good gains here
3. Clean out all the wierd bumps and crappy casting edges. These
heads are pretty bad so this should show a pretty good gain
4. We'll start into the serious port work now. Go into the pocket
radius the turns, teardrop the intake guide. I may fill the exhaust
crossover passage, once again haven't decided yet. Will open up
the intake port a bit. Should show the most gains from the
pocket work, these heads are reaaaallly ugly there.
5. Move into the chamber and smooth the edge between the seat
and the chamber. I'll blend and polish here, trying to remove as
little material as possible to keep the volume the same.
6. I'll polish the ports so we can see how much gain that is or
isn't worth.
My plan is to test the heads after each modifcation so that we can
see the progress and differences. I'm hoping to get 254 cfm intake and 180 on the exhaust. Get there and this would be one serious set of iron heads, capable of over 500 hp, and with smaller intake ports to keep the velocity up.
I'll also try and keep track of my hours so I can offer an estimated price on what a shop should charge you, or how long to do it yourself. Then we'll know if it's worth it or to just scrap 'em and buy aftermarket.
Feel free to offer advice, comments, and definitly wish me luck these heads will be going on the Iroc project, I've decided to see how much power I can get cheaply on that one.
John

u r sofa king we tah did

cool thanks for the numbers, im running a little behind on my iron head porting project due to having to swap a transmission but i have gotten started.

u r sofa king we tah did

and make sure to unshroud the intake valves completely, thats where you will see a huge gain on these heads.

Swapmaster

That would be awsome to get those numbers. I have a set at the
shop I have been looking at and have been thinking of going hog
wild on. I also have a set of aluminum heads but the iron ones
look like you can do more with them. The aluminum heads look
thin in quite a few places.

rhuarc30

Yep, especially if I cut for the 2.02's.
Hope my forcasted numbers are close, it would be awesome, I'm basing them on the kind of improvement I can usually get with similar flowing factory heads.

rcwest32

This is on the 5.7 L98 head? I thought the 305 head flowed almost that good. 193 cfm is pretty measly. Let us know how you do. I am getting a set to port.

Black 91 Z28

Hey, Search for the title of this post (without the Part 1). There is a post 2 and 3 that lists his results.

David

rhuarc31

The promised part 4 is coming soon (I Hope). I moved to Central Illinois, and most of my crap is in boxes. I did finish the heads, all the way out to a part 5 actually, the final part is pure race stuff though. In short I put the good valves in, cut for 2.02, 1.6 valves (had to do more porting for that to unshroud the valves again), did a three angle valve job, and did some more polishing for stage 4. Stage 5 included welding and a whole bunch more work *NOT FOR THE FAINT OF HEART*. Stage 4 netted almost 270 on the intake and a bit over 190 on the exhaust. Stage 5 got some insane numbers, but at the expense of velocity, pretty much race only stuff. On the dyno at stage 4 I managed to coax 450 hp out of 'em with a comp cams XE grind. For comparison it was around 350 with the stock cam. Oh, and I lost my password for my old account here, hence the new one. At this point your looking at around $1200 to pay someone else to do it, so a set of afr's starts to look a lot more attractive, unless you want to be able to say you did it with the stock heads.

rcwest32

WOW! 270 out of factory heads is very impressive.

Sean Nixon

What comp XE grind did you use?

8Mike9

I recall Rhuarc31 porting thread being much longer that what is up. I actually followed his porting advice on a set of L98's (never flowed) through I think it was his Stage 2, plus a bit. Man that was a long time ago.

I finally have the heads ready to go on the car now (after what? 15+ years?) when I get the block back together. This post is like running into an old friend

Orr89RocZ

iTrader: (20)

He had multiple porting threads over various stages i believe

this is 2002 not 2020 lol ancient thread some of these people probably dont even come here any more

Drew

iTrader: (58)

Bumping threads more than a week old, and expecting people who haven't logged on in nearly a decade to reply, should be public whipping offenses.

8Mike9

I recall following his one thread that was real long, he did some good work...hope I followed it correctly