305 head porting

[rfoll]

I have a set of 187 heads, (swirl or screw port), with 1.84 valves and 54 cc chambers we are going to install on a small bore/stroke sbc. They are like new and the price was right, as in free. I can do a fair amount of chamber work on them with no worries, but having never having ground on any of these, I am unsure what can or should be done. The exhaust port looks like any other sbc, but I have read things about the similar 093 version that suggested thin areas in the intake bowl. Any advice other than the garbage can or AFR heads is welcome. This is going to be a very low cost assembly, mostly parts and block prep.

[Rizzle]

What the goal, vehicle, use, etc. Would make a huge difference in what kind of advice you are going to get.
If theres any type of performance goal with this though, id suggest finding a better set of heads. 416, 305 vortecs (059??, I don't remember, its been a while).

[Truckedup]

For a low buck build a set of 305 Vortecs are the way to go if you can find them. I've never heard anyone say the #187 head is good for performance. I suppose if you have porting experience you can make them work out ok...

[wyrmrider]

I have a 305 in one of my pickups (86 motor) which I think had the older non preferable heads
But now has street ported heads
I think we ended up with 2.02 valves cut to 30 degree seats and narrowed to around 1.94
used the Serdi cutter to do most of the work then hand blended the bowls
chamber matches the bore not the gasket
I would think the later heads or Vortecs might work better out of the box and ported
so
If you have the equipment and are going to be buying new valves have at it you are just doing a super valve job
get premium exhausts if you are looking for longevity- I have the larger stem valves, IDK what size
If you have to pay someone else then start with better cores
what's the usage ? trans etc I have truck 4 speed
I have 4bbl QJ do you have carb or EFI and what kind?
I have .904 hyd lifters but would recommend hyd roller if you block is set up for them
I have straight springs with dampner but you have more modern choices like beehive
Viton seals especially on exhaust
exhaust seats? I have what is now durabond sintered (back then they came out of Washington?)
measure twice cut once-- studs and rockers? I have screw in studs with 1.6/1.5 rockers
motor has not been apart in 20 years...

[Rizzle]

Anyone know if its possible/what kind of work it is the change the 11/32 guides down to 8mm? If its simple/cheap enough, i think the 1.89"/1.55" 8mm gen III 4.8/5.3 valves would make for a cheap/light size upgrade - paired with factory genIII retainers and beehives instead of buying the conversion retainers. IIRC the stem lengths are similar? Going to look it up now.

EDIT:

so after figuring out what i want. i have decided to go with ls6 valvetrain for the heads that are going on my 383. im just looking to see what you guys think and any problems i might run into.

basically im gonna get the yellow z06 valve spring
ls6 stock valves and retainers and keepers

but now my questions is will these valves fit in the stock seat? i was originally planning on going to larger 1.6'' valves but since im not too familiar with LS stuff. are they the same dimention? or will they require new valve seats on both intake and exhaust? if so i will probably just use the z06 springs and regular valves and just get the special retainers to use them.

any insight would be a great help. thanks

I've done the conversion many times.
The Z06 springs will work great with the right installed height.
You can use LS1 or the lighter LS6 valves. The retainers and keepers are the same no matter LS1 or LS6. I normally use used or take-out valves, retainers, keepers, and spring locators from LS1 heads.

Using K-line part # KLI851ST bronze guide liners you can easily convert an 11/32" guide to an 8.0mm guide.
Stock valve seats will need to be opened up (done during bowl porting) to seat the larger 2.0/1.55" valves. It's a great opportunity to cut 30* seats if that what you want to do, due to the larger diameter valves.

Stock installed height on 083/416 heads with stock retainers is in the 1.70" - 1.72" range. Sorry I don't have my own measurements for Vortec heads, but you can search them on here.
Installed height of LS1/LS6 valves in 416 heads with LS1 retainers is 1.835" on the intake, and 1.969" on the exhaust.
The installed height will have increased, so you use valvespring shims to set the height you need.

Original post link

[rfoll]

What I have is a set of 187 heads that are like new. These are the heads we are going to use. I can think of many heads that would be better, but we are going to use these. I never install heads without at least a pocket cleanup and a little massage in the chamber. My question is about what to do or not do in the bowl of these unique intake ports. It's just a cheap hot rod, a really ugly but sound 240 Z.

[hwp]

These should answer all your Questions about the 187 and 193 heads. They can be good heads if the proper work is done to them as evidenced by the flow numbers of the ported heads.[url]http://www.thirdgen.org/techboard/tbi/2 ... -193-s.htm

[rfoll]

Actually, I read those posts. One of them mentioned the proximity of water in one location, but I didn't quite understand where the area of concern was in the port. These heads are similar, to but not the same as the 193 casting. The combustion chamber is 10 ccs smaller. The roof of the intake port is almost twice as tall as a conventional stock casting, but obviously much narrower. The port at the intake manifold junction is larger than my Vortecs. There is a pretty large bulge right under the seat on the outside wall, and I am unsure how much of it to remove. Because they are so different, the possibility exists that I could ruin the flow at high or low lift or whatever. I don't expect this motor to operate much past 6000, and it doesn't take much to feed under 300 cubes.

[beaker60]

Now remember,,this is just a suggestion,,log onto youtube and look up headbytes head porting.The guys name is Tom Sizemore,,an he's located in Tenn,,he gives excellant explanations for porting the swirl port heads.In his videos,,he will explain everything you need to do to those to get them to flow excellant numbers,,and you can also email him with all the questions you need to ask.He also has other head porting ideas for other heads,,including aftermarket,,like I said,,just a suggestion.If you don't want to do it yourself,,you can ship them to him and he will do them for a fairly reasonable price,,anyway,,check him out,,you'll probably get some great ideas and you can see how he does it.



Arthur

[Bob Hollinshead]

I knew a porter that would cut the swirl vane out of those heads, install bigger valves, and end up with some decent power but they always cracked.

[rfoll]

I went to youtube, he showed the area where the port is thin. Thanks, I had been there before, but didn't get that far. He is hard to listen to for very long. I really don't expect to remove a lot of meat, I just want to know where the best areas to work are. Slimming the guide seems a obvious, and the obstructions under the seat will see work, but other than that, I am unsure. Do conventional throat to valve diameter percentages even apply here?

[Carnut1]

My buddy Thomas at Headbytes does a great job on the swirl ports but that video is for 193 head for 350 engine. There is more meat in the bowls of the 305 version. If you stick to the 1.82 intake which is a safe bet on a small bore engine some straight forward porting on those heads will pay off in nice power. The chambers need a bunch of work as well.

[Carnut1]

Cut the exhaust similar to this roughed out 193 for a nice kick in the exhaust flow. I like 90+ % bowls

[rfoll]

I don't suppose you have a cutaway of the intake port? It's nice to know there is a little more room to grind in the 305/187 head, I would hate to find water. I will for sure do some probing in the water jacket to look for thin areas. The exhaust port looks pretty much like any other 1.5 valve port, so it should be fairly straight forward. Thanks.

[Carnut1]

Sorry but I don't. If you stick with the small valve and keep the top of the bowl in the low 90% seat ratio you will have tons of material. I have cut a few 187' s to 2.055 intake.