Doom86

These heads were rough cut last fall and and I'm finishing them now. They were originally intended for my 86' Z28 but I am seriously thinking about using them to build the motor in my 91' RS.

Before i started polishing today i got some pictures of one of the ports that is 95% done. After the photo i spent time smoothing out the floor transitions even more. I tried to shoot the bowl from different angles so you can better see the dimensions.

It's difficult getting the right lighting for shooting down the runners. I'm going to get some more pictures of them as the work progresses. After today's effort I have one of the head's intakes ported and polished. The exhaust is next and much easier to finish then the intakes.

Doom86

couldn't post more then 3. Here's the runner.

Doom86

With all the intake's finished I took some more pictures to share. I took pictures from different angles so you can see how the contours look from different directions.

The first set is focused on the roof and floor. Both pairs of intake ports floor's are shown.

Doom86

Here is a look down 2 different intake runners. The dust and smudges (glue from cartridge rolls is good for this one) and shadows can make it appear to be blemishes where there really isn't just keep that in mind. If there's any questions or comments please let me know.

Doom86

And finally here's the exhaust port that I finished as well. I still need to do the other 3 on this head. This is all I'm doing today though.

wannafbody

iTrader: (1)

wanna do mine?

camaronewbie

It's been a few years - I remember it being alot of work. But then again, all I had was a $25 electric die grinder and $25 worth of cartridges and carbide cutters, and ALOT of mosquitos in the driveway! Kudos for the effort - have you ever done this type of thing before this? I never had, was scared to death that I was cutting too much - but I paid nothing for my 416's, so I kept telling myself there was nothing to lose. Are you going up in size for the valves?

Doom86

This is my 3rd set of heads I've worked over. The first two went bad for different reasons but were a great learning experience. One I went too far in the wrong place and found water and the other cracked the stud boss when the rocker studs were being pulled. They were both probably fixable but I wasn't feeling too good about the quality of my work.

It's very time consuming so you need to spend your time where it counts and not just mindlessly grinding away. My focus was on the roof, that's where I did most of my grinding. I was shooting for a taller port with better transitions.

wannafbody - this kind of work is very time consuming so it's not free but I don't think my work is worth paying for. I could only recommend paying for stage 1 type porting. Unless you have rules that say you need to use the heads because paying for port work, then machining, will put you well into aftermarket head territory.

Doom86

Sorry I forgot your question. I'm deffinately having these cut for bigger valves when the machining is done. I already have a set of SS undercut 1.94in 1.5ex valves but the more look at these exhaust ports and research the more I think they should go to 1.6ex.

These exhaust ports are huge for how poorly they flow. They are big even in aftermarket head standards so keep that in mind when you port them, BIGGER isn't better here. You want to smooth transitions and streamline the guide boss.

Atilla the Fun

Doom, would you get upset if I critique your porting?

Doom86

No not at all, we can all learn from it then.

radical82

Will you be checking the heads on a flow bench and cc'ing the chambers while you're doing the porting work? Reason I ask, the best improvement on cylinder heads is equalizing the chamber size and flow rates of the runners.... I don't want to criticize your work, to the eye it looks fine, just curious how you intend to keep the flow even from cylinder to cylinder?????

Doom86

I hadn't planned on cc'ing the chambers but I did want to check the runners but I honestly don't know how and can't find good info on how to do the runners.

It would be nice to flow them but I can't find a place around me. Whenever I get them machined maybe I could talk to the machinist, he may know where.

Any advice, critisism, or whatever is welcome. Just like anything I'll take in what makes sense and question what doesn't.

There's no way I'm going to flow them and port them until the runners are equalized though. I'm not trying to build the "best" ever and invest too much time and money that could otherwise be spent on aftermarket. It's a 305 head that you could probably get for free. I will however port them to the best of my knowledge and ability, put some good hardware on them and see what they can do.

Atilla the Fun

CCing the intake ports is easier than CCing the chambers. All you need is a graduated burette, and reassemble the heads. Position the heads so the intake gasket face is level, then start filling the port.
Stock was around 155cc.
Your pics so far do show heads that certainly will be better than stock on a 350, but I disagree with a few things I see. Some of which could yet be changed if Doom decides to.
Equal flow isn't that critical at all. Look at most aftermarket BBC heads. In most cases, the long intake ports flow differently from the short intake ports.
The thing about unequal flow is that some cylinders may run leaner others may run richer. And that does result in compromised tuning. You have to get it rich enough so the leanest cylinder doesn't run hot enough to damage parts, but lean enough that the richest cylinder doesn't make black smoke.

Doom86

Atilla thanks for the information, I'll have to find one of those graduated burrets.

What do you see that could be changed to make these better?

Atilla the Fun

I'm not fast with photoshop, but I want to highlight (circle) the things I'm not kosher with, ans ASK for some clarification on a few things, I am not wanting to do any attacking. I really just want to be sure you get the best results, and everyone who copies us.
I do want to ask if you've ever operated a flow bench, and if so, the details.
I have much experience on a then-new SuperFlow 1020 with EVERY option, including swirl, wet-flow, electronics, et cetera.
I see you SEEM to have done at least one thing that the bench proves is a definite mistake on ANY and ALL production SBC heads. But since I'm not yet done photoshopping, I'll ask when I get the highlighted pics up.

Doom86

Nope I've never used a flowbench before unfortunately. If I had one of those I would probably never want to leave the garage.

When I was rough cutting these I took good care, or so I thought, to not destroy the "good restrictions" that help produce swirl. I'm guessing that the mistake you're hinting I SEEMingly made, is blending the bowl hog too much.

Thanks for taking the time Attila, I do appreciate it.

Atilla the Fun

What am I seeing in the blue outline? I'd get rid of the ridge in the red outline, and the green outline seems to be a destroyed seat insert? If so, then you're definitely going to 1.94" intakes, which is good, because it also looks like you failed to leave the intake throats at 85% of the diameter of the valve diameter. And did you polish the short turns in the intake ports? If so, you need to get some 80 grit, and rough them up.

Atilla the Fun

In the little yellow outline, is that a trench in the port roof? In the little green outline, did you leave all those trailing edges sharp? Your guide ridge is in pink. The blue line is where you want it, or else don't even have one. In the pink outline, the left side looks relatively deep, while it looks like the right is also lower than the middle. Why are you even grinding there? There's no flow on the port floor until the short turn. You'd do better to fill it in with porter's epoxy, convex beats concave. Is the blue outline another trench? More epoxy. And the red outline looks like a big bowl? More epoxy.

Atilla the Fun

What's this shape in the green outline? Are you done in the pink outline? In the blue outline, is that another ridge? And is the red outline also concave? There's NOTHING to be gained from grinding in these areas, leave the intake port floors alone.
Polished intake ports cause fuel puddling. Not good. The short turns should be a radius, smooth in shape, but rough in texture. Otherwise the air slams into the far wall of the long-turn, instead of making the turn. And a rough short turn also helps get puddled fuel back into the air.
No professional porter has ever advocated polished short turns in the intake ports for carbureted gasoline engines. Most of us speak out against it for the above reasons.

Doom86

reguarding the bowl; The blue outline it looks funny in that picture but that's the factory bowl hog with a strange glare from the polishing rolls. If you take a look at the other 2 picture I posted of the different angles you can see it better. I tried to leave a slight ridge there, but always ported with putting 1.94 valves for intakes in mind.

What looks like a beat up seat is actually gorilla tape in thin strips to protect the seats from accidents. I also used it to protect the first 1/8 inch or so of the bowl from the seat. Gorilla tape is very thick almost feels like rubber, it done the job well.

I will go back and redo the guides and remove the ridge leading to them on your advice.

Now the intake port image you are referencing was a work in progress picture and the left side was only rough cut. When I posted that I was sure to note that after the photo the floor was smoothed out, because you're right. I used my finger to gauge it, not my eyes. If you want a good image of what they look like check out the last set I posted, that is both pairs of intake ports on the head finished.

The short turn has a bit rougher texture then the floor does in those last images. The only grinding I did on the floor was to blend in the casting defects that were popped up and lowered it a touch towards the beginning of the port. I didn't remove much metal here at all, it was one of the "good restrictions", IMO, that I mentioned before.

Those indents under the rocker studs, in the intake bowl, I tried to make it level. What do you advise?

The pink circle by the roof/bowl near the valve guide boss was massaged back ever so slightly after the photo. It doesn't look much different though, I just tried to smooth out the transition a bit more. What do you think about that area?

I still need to finish/surface the other head, it's been rough cut as well. But the good news is that the valve guide isn't as finished as this head so it will be much easier to fix that mess up.

I've been using either 60 grit or 80 grit for finishing. Doesn't it look awfully shinny though?

Atilla thanks again man

Atilla the Fun

I've seen gorilla tape in the store, but I never got past the cellophane packaging.
The rocker stud cavities should be filled, but even grinding a bevel on the half closer to the valve will reduce turbulence.

Doom86

Today I went through and done some more grinding, fixing the issues that Atilla suggested.

All of the intake valve guide bosses have been redone and the bosses ridge was reworked changing the angle slightly. The roof of the bowl was also opened up just a bit more between the common wall and the guide boss.

The ridge that was on the roof leading from the guide boss was smoothed out and the defects on roof/bowl (originally outline in yellow) were blended into the roof.

The voids under the rocker studs were also worked. I made the lip of it lower the deeper it is in the port to reduce turbulence.

I did all the work with a double cut carbide cutter and just barely polished it with either 60-80 grit rolls (got them mixed up a long time ago). Also I went through all the intake short side radius's and surfaced them lightly with the carbide tip. I left them a little more rough then before after doing all the carbide work.

All the exhaust ports were also polished.

And after all that I took tons of pictures and didn't get many to turn out good. It's much harder then it looks to get good photos of the runners. The short side radius is impossible to get photos of.

Doom86

couple different angles of a bowl.

Doom86

I did a marathon session on the other head and got it completely rough cut as well. After comparing it to the first head though I may go back and spend some more time in the roof of the bowl/valve guide common wall area and widen it up a bit more. Because I noticed on the original head that my thumb was just floating in that area while the second head it felt kinda snug.

On a side note I have found something great to do with these heads. My 86' has officially become an "extra" car, and I was going to sell it, but it's not worth much in it's current condition and I've never had a "toy" car before so what the hell. Well the motor in it is well spent, but I have this fresh 305 short block I was hesitant to use before but now I really don't have anything else to toy with.

I kicked the idea around of building this 305 last year but didn't since the car has always been my daily driver for years and didn't want any down time.

I think these heads on a 305 with these other parts I have collecting dust; XE268 cam, Performer RPM Qjet, CCC qjet, and the headers exhaust on the car now, would be fun to drive

Atilla the Fun

Assuming you realize the ccc isn't gonna like the XE268H-10, it'll work from 3000 to 6000, if your exhaust is good enough. If 700R-4, then at least a 3.91:1 for a 7.5", or if 200-4R or T5, then a 4.30:1 for the 7.5".

Doom86

The car actually has a TH200C in it right now. Crap trany but I got it for really cheap, connected to the rebuilt 305, when my original 700r died and this was my only car. Bumming a ride 45miles to work isn't as easy as you'd think.

I'm thinking about rebuilding the 700r, or even just fixing it. Having worked in a transmission shop long enough to know they don't always need rebuilt. Money is tight as always, which is why I have these parts laying around for this 350 that's been in pieces for going on 4 years.

After marathon porting session #2 last night I can say I am DONE porting these and they look great to me. Did all the exhaust polishing last night as well. The chambers are really tough to polish, tried putting valves in to protect seats but then they are in the way of the tight spots.

Tonight I will work on cleaning the heads and polishing the chambers.

Doom86

The seats look so nice now that the tape is off and the heads have been cleaned. My only gripe at this point is one head's intake ports are rougher then the others because the first one came out too smooth. In the end though I went over it lightly with a cartridge roll and it's a little better.

Does anyone think I should tap them for screw in studs? I'll be using comp 981 springs. I have a set of screw in studs that I was intending to use but the last 416 heads that I pulled the studs out of there was no way in hell a spring was pulling them, they were unreal tight (I'm talking 2 handed braker-baring) and the very last one cracked the stud boss. The 083 heads that I pulled the rocker studs from came out so easy by comparison.

I spent a few hours working on the exhaust valves. They were rough cut a bit from me working on them before but I finished them working the radius of the margin and back cutting them just slightly not disturbing the valve job. Rough cut was done with a flame tipped stone, followed by 60, 150, then 250 paper.

Doom86

Anyone?

Atilla the Fun

For 981s I wouldn't even pin them.

Doom86

Alright I am posting some pictures of the other head. It's a bit more rough then the first head. They aren't perfect by any means but I think they are going to be a great upgrade over stock. There's a bit of rust in on the roof from me cleaning them up, I must have missed that spot whenever I was surfacing the runners to get rid of the flash rusting.

There is one little ridge that I have got to go back and smooth out that I noticed when I was looking them over today. You can see it in one of the intake runner pics up towards the bowl hog/common wall, that is a sharp ridge.

I think what I'm going to do is put these back together with the valves they came with that I worked over a bit. They were in great condition when I got them so it should be good. If I'm fooling my self here please let me know. My reasoning is that I don't think I'm going to have the money this summer to "do it right" and put the bigger valves in. Since they were in such good condition from the start why not put them back together and have fun with them?

If anyone spots anything detrimental to the performance of these heads that I can fix please let me.

first set of pictures is the 2 pairs of intake runners and the other is just the first chamber.

Doom86

2 more

aaronjohn20

i've got a 355 with the 416's on it. Please let me know how things turn out

Doom86

will do aaronjohn20 I'll keep updating as things keep happening with them.

I went back and did a final inspection and cleaned up some sharp edges and other minor issues. Also I finished up all the stock valves, put a slight radius on the back cut, and radius on the margin, just to pick them up a bit. With that I finally found a good use for my cross buffs and stones from my now old SA porting kit.

Since no one is protesting the idea (or supporting for that matter) I'm going to Jeg's tomorrow to pick up;

Felpro positive valve stem seals x2 pn. SS72527
Jeg's valve shim kit pn. 20590
Manley spring compressor pn. 41830 (tired of renting AZ's)

I already have springs, retainers, locks and rockers. Am I missing anything? Oh yeah I also have a valve spring height tool, gonna need that too.

TxTtopZ

I think they look pretty good for a novice to me! I have yet to venture into this kind of work as I know I will screw up the first time. I read you didnt want to get them tested, but for the sake of honing your skills from porting set-to-set, it would be a good idea to keep track of your skill or lack of . You know, so you will know what worked, what didnt, what NOT to do, etc. Just my thoughts....

TxTtopZ

Also, let me know how they run!!

elano

iTrader: (2)

Nice work!! Please keep us updated!

Doom86

I haven't gotten a chance to get to JEG's to get the hardware for these heads. My plan was to stop by there when I was at the track but it's much further away from there then I thought. I would just order the stuff but I have some crap brake hoses to return too.

After a lot of mess and retesting I got the heads CC'd chambers, intake, and exhaust.

The chambers are damn close to each other. It probably helped that I didn't remove much and I sat them next to each and did them all in a row starting left to right. That's how I port everything actually. One bit at a time on each head working down the line.

Chambers: 57cc
Intake: 169 3/4cc
Exhaust: 63 cc

I retested several times to make sure it was accurate as possible. I'm happy the intake is not huge that was my intentions to get velocity. Most guys have 175+cc on these when done and IMO its because they hog the bowls all the way down to the seats and hog out the pushrod pinch.

The exhaust runner was confusing though I always read that they were huge but that is not huge by any means.

If someone could answer a question for me. If I'm wanting 10.5 compression on a factory flat top 305 what do these need milled to and what head gasket to get perfect quench?

TxTtopZ

Whats the deck height?
Whats the piston compression height?
Whats the head gasket compressed thickness?

Doom86

10:1 was what I was wanting not 10.5.

Well I'm finding that if the stock flat top 305 pistons are usually 0.025 in the hole and have -12cc valve reliefs.

If that is the case then a 0.015 shim gasket would yield 9.71cr as they are. Using the 0.01 milling = 1cc rule taking 0.030 would make them 54cc and yield 10:1cr. And quench would be 0.040.

Does this sound right? Should I be shooting for a different quench?

Atilla the Fun

First, let's assume that the heads still need a light clean-up milling, and 0.0060" off of 57cc would be 56cc. I know from experience that this is nearly always enough milling to get them flat.
SpeedPro H534CP pistons are flat tops with 5cc of valve reliefs.
Assuming the pistons do end up at least 0.022" in the hole, and assuming the FelPro 1094s, and assuming a 0.060" overbore,
Then your SCR is just under 10.451:1. Install your cam 4* back, you'll be fine.

aaronjohn20

wondering if i should of installed my cam 4 degrees backwards also????????????????

Doom86

I'm not machining the block Atilla it's running great. The bottom end is stock flat top. Thanks for the information though.

stock 305 flat top pistons have 6ish cc reliefs from what I'm reading.

Using your recipe with my pistons and bore my calc is saying 10.03:1

But quench is .037. Isn't that a bit too close? Just asking to be sure.

Trying to squeeze all the power I can out of this budget build.

skinny z

I've been watching your build from the sidelines. I don't comment much once Attila has been there because from what I've seen he asks all the pertinent questions. The results speak for themselves.
However, after going over the previous postings, I find a some information either missing or contradictory. To satisfy my own curiousity can you provide: bore, chamber volume, piston dish volume? The rest I can surmise: Piston below deck at OEM stock (.025" +/-). Gasket thickness and bore as most suitable to achieve spec'd SCR (considering no machining of the short block or piston replacement).
Thanks.(Just an interested observer)
What is your cam of choice?

Doom86

It's a 86' flat top 305. Stock so 3.735 bore, 3.480 stroke. It has 6cc valve reliefs. The chambers are 57cc.

The cam is comp cams XE268. http://www.compcams.com/Cam_Specs/Ca...x?csid=86&sb=2

TxTtopZ

Skinny Z. What altitude is the track you run at? Just curious.... I would have thought you to be a little lower in ET, being that you have slicks. I may be building a vortec 350 for my car...

Atilla the Fun

Your intake closing has to match your SCR.

Atilla the Fun

0.037" is perfectly safe for seeing 6200 at the top of first gear. And at 10.03:1, I suggest not retarding the cam after all.

skinny z

My best times (several 12.7x) where at sea level. In fact when I calculated the Air Altitude Density it worked out to be 300 feet BELOW sea level on that day.
I would like to think I could be a little faster too. I'm severly limited with a single Flowmaster 30 series muffler (which might flow 300cfm at best). The car is quite heavy too coming in at 3700lbs with fuel and driver.
It does move out reasonably well with a 1.7 flat 60' time and a 3.27 rear gear. Zero tire spin.
If I ever get this latest project finished, I'll have remedied the poor exhaust (probably with appropriately placed cut outs) and be somewhat lighter as the 86 IROC is being replaced with a 86 Sport Coupe. (No GFX, T-Tops or trailer hitch!)
Thanks for the loan of the thread Doom.

skinny z

My calculations are similar to what beens posted.
SCR of 9.8:1 using the above specs and Attilas suggested 1094 head gasket (although it has a bore better suited to a 350 at 4.100")
The XE268 installed straight up will yield a DCR of about 8.2:1. That's getting up there but still quite streetable from my experience.
Funny thing though, when I calculate the seat timing using the Comp Cams supplied data (268/280, 110LSA, 106 ICL) I arrive at an intake valve closing of 60 ABDC. Comp specs 61. Not much in the difference but worth mentioning.