After first 20 minutes with die grinder...

 

How's that for casting flash? Look right in the center of the photo - a big chunck sitting on the rocker stud nub that sticks down into two intake ports of each head.

The other head doesn't have nearly as much flash in the port/bowl areas.

 

Only 30 hours to go!

 

Thank you for your words of encouragement...

 

I hope you have lots of "digital film" and dust masks...

 

"...lots of digital film" - As soon as I go back into the house after they are taken, they are down-loaded to the 20G HD.

"...lots of dust masks" - I only had one new one hanging on the wall, but a new pack will be purchased to cover the need. Also wearing goggles, ear muffs, coveralls, gloves, Summit Racing cap (worn backwards when the goggles are on). Shop vac, car cover, tolerant neighbors...

The pic of the casting flash doesn't do it justice. Looks like something you'd see in a limestone cave. I'm amazed it hasn't broken off and moved to the combustion chamber in these 37 years.

For reference, here's the thread where I asked my "going in" questions.
https://www.thirdgen.org/techbb2/sho...76#post1155576

 

Don't mention it

 

Smart choice. You'll be around to enjoy your work longer that way.

 

Heh, good luck with those heads

 

Don't forget ear plugs. Listening to a die grinder for 30 hours will get annoying quickly.

I think I spent about 6 hours on each of my current heads but they weren't the first set I ported. I should go take a few pics of a single 781 head I still have. My SBC heads probably flow as much as an unported BBC head

Keep bugging me for pics if I forget about them. It's cold outside and I don't like touching metal at -25c. The shed is unheated.

 

It would be good to see other pictures. From what I've seen of other BBC examples, these heads are about as good as you could expect from the factory - casting flash excepted. And, of the closed chamber variety, of course.

The ear muffs I listed are my hearing protection. Work better than ear plugs, easier to put on/take off to boot. The noise of the compressors is as bad or worse than that of the die grinder.

I don't expect to spend much more than 10 hours on these. They don't need as much work as the Worlds I did for the Camaro, and I spent right at 10 hours on them. Good thing, too - just found out today I'll be out of town Wednesday and Thursday night...

 

So, Stephen, has it warmed up any yet? Got up to 60 here today.

Would like to see some of your pics.

 

It is -25 C and dropping here in Cowtown

 

I got some pictures from my BBC port work still need to get em devloped. Did you decide on upgrading the valves? I got a picture of the 2.25's next to a coke can bottem for kicks. 20 hours spent porting them and 2 sets of carbide bits and countless stones, good thing the bits were MAC lifetime pieces.

 

I forget what 60 feels like!!!

 

It's 61 degrees right now, and I'm putting rear pads & rotor on a '92 Lumina.

SSC, I decided against valves for now. The engine guy didn't think there was enough justification for it now, would take a lot more cam and possibly displacement to justify them.

 

I figure by the end of March I should be able to take some pics. I bought a new house and when everything gets moved into the garage in 2 weeks, I'll have a better chance of taking pics. There's currently a snow drift in front of the shed that the head is in.

 

It's -31*C and dropping here in Cowtown. Ain't NOBODY working on their car outside!

 

Two hours total of grinding so far, all the intake ports gasket matched and blended as far as I can reach with the stone.

Now to clean up the exhaust a little, radius the edges in the chambers and bowls. Then I'll be ready to take the rolls to the ports.

 

Think these little guys will in the exhaust bowl will affect flow much?

Me neither.

 

(Focus was worse than I thought).

Decided to follow the order in the SA guidelines, so ground down the rocker hole knub in the intakes (in two of the ports on each head) and did the 80 grit roll work on the intake ports.

 

looking good. keep up the nice work.

 

I had a chance to put several hours together on them today, so I went to work rather than take in-process pictures.

Here's a chamber. I didn't spend a lot of time finishing them - they just weren't that bad, mostly rounded sharp edges and polished off what little casting surface was actually still there (the factory machined about 75% of the chamber surface area).

 

Exhaust port - I didn't go for 100% down in the valleys on each side of the guide.

 

Intake port. Not a polished surface, and I didn't try to remove all evidence of the casting line (would have required removing too much material). Also didn't bother trimming down the guide - there's plenty of flow area there.

 

Finally, SA-ported BBC 702's next to untouched SBC 416's - just for reference...

For the record, 9 hours with the die grinder on the BBC's.

 

It is looking TERRIFIC Tim!

Just wait until you have them buttoned onto the engine and are putting the pedal to the metal--you will be smiling from ear to ear

 

Sure hope so. You're a little nervous thinking, "Did I take too much out of that area? How much difference can it really make?" Things like that.

When I smoothed down the rocker stud nubs (in two intake ports of each head), it broke through the corner of the threaded hole. The stud doesn't actually stick down that far, so I filled in with JB Weld. It should be cured up today, so I can finish smoothing that down. That should do it for the heads - back to the builder for assembly with the new springs.

The other remaining tasks are to gasket match the intake and headers. Weiand left plenty of material there, so I'll open them up a little. The Hedmans are 1-3/4" round, the exhaust ports 1-3/4" square. Plan to run a MIG bead around the primaries on the outside of the flange, then open up the corners. That alone will probably make the biggest difference in performance - the head porting is icing on the cake.

 

curious to see the #s...hey Scribner opens the 29th....

 

I did the final cleanup last night, one final look before putting them in the back of the Camaro to take them to the engine builder for the valve job & assembly. Found more casting flash near the intake guides on one head (interesting that the other one was okay, must have been the lighting). Spent an hour and 5 small tapered rolls getting that cleaned up.

This morning when I went out to the Camaro to come to work, it wouldn't shift. Stuck in reverse when the shifter is in park. Jacked it up real quick, took a look - the shifter cable is all sloppy down there. Now I get to find a new shifter cable.

Does it ever end?????

 

well the LT1 is throwing codes today..so I guess it never does end.....ses ses ses..... :lala:

 

I'm out of town again on business travel, going to KC for a wedding Fri-Sun. Big snow storm coming into town.

The builder thought the porting work was okay (more than needed, but that's all right - it'll be ready for the bigger cam). Showed me a 454 bare block that would make a nice .030-over 427 with my rotating assy & heads. Not this time around, I'm afraid.

First race of the season at Bandimere is April 25th, 1st test & tune April 12th. Not sure I'll be ready for the T&T. Borrowed a MIG welder to work on the headers. Haven't even looked at the disk brake conversion parts since last fall.

What fun would it be if we didn't have unrealized dreams?

 

My garage is full of them......guess I'm having fun now..

 

Yeah, if you got everything you wanted all the time you'd be rich--and what fun would that be?

 

Picked up the assembled heads from the builder during lunch. He said several of the valves had been ground off-center by a few thousandths. Golly, think that might cause some high-RPM or rough-running problems?

The seated spring force (Comp 924-16's) is about 30-35 lb more than it was with the crate take-off springs I used last year, and doesn't vary (had 5 w/~10 lbs down with the old springs). Open (.600 lift) is about the same -> slightly higher, except the crate springs would coil bind long before that.

Now I've got to clean up the block, port-match the intake and headers, get it all back together again.

After I get back from this week's business trip, that is...

 

They showed me the fit of my valves in the new guides, when I picked up my heads last summer. I think the machinist said there was about 2/1000ths (.002) of play when the valve was inserted. I jiggled it around and it didn't jiggle much at all.

 

This isn't the clearance between the stem and the guides, but the co-axial relationship between the valve sealing surface and the stem. In other words, when the valve closed, it had to move sideways in order for the valve sealing surface to meet the seat sealing surface.

I found the cam card tonight. I didn't have it right in the previous post. The specifics are: General Kinetics C2H-270-HT (270 advertised duration); single pattern; .510" lift (1.7:1 rockers - stock); 224 duration @ .050"; 110 degrees lobe center lines exh. to int.; intake lobe centerline 110 ATDC. A bit more than an "RV cam", with a pretty steep ramp rate (higher than typical ratio between .050" duration and advertised duration). For reference, my previous cam had 280 advertised duration on the exhaust, but only 214 @ .050".

I found a set of Hedman hedder gaskets at a local speed shop (apparently a customer didn't like the small round openings). Here's a pic showing one opened up to match the port (on the left), and as-received (on the right). Gives you an idea of the work I have ahead of me to match the hedder flanges.

 

Until the 9" shatters from the torque...

5-7,

Get a precison lathe handy? You could quickly check the valve concentricity with an indicator. If it's off by that much, you might want to contact the supplier. I wouldn't use them, since it's going to create radial load on the stems and seats. But that's just me.

 

I guess I'm not explaining things properly. He was talking about the way the valves were ground previously - the valve face sealing surface was non-concentric to the stem by a couple of thousandths on some of the valves. He cleaned them up so they're back where they should be now. As for the supplier, the newest valves are 6 years old, the 4 oldest are 37 years old.

He did a 3-angle job (didn't even comment about the back-cut suggestion), left a fairly wide sealing surface (he said - compared to all-out racing job. I didn't see them, don't have a dimension). Said that would protect them against today's gasoline quality.

9"? What 9"? I've got an 8.2" 10-bolt. I doubt excessive torque will be my "problem", as I'll probably reduce it slightly. Maybe not, though. Would be sweet if both low- and top-end improved.

 

hey 5-7..Ive been reading a lot about porting..getting ready to do my new heads. I find it interesting that you are matching your headers to the ports...some of the info I read says Not to match the exaust ports..that that step down is ..well I cant explain it ..here is one quote...

In most cases, you never port match the exhausts. Many stock exhaust manifolds and virtually all tube headers will have larger port sizes than do the heads. You want that "step" from the port to the larger header tube or exhaust manifold because, as pressure pulses flow back and forth in the exhaust system, it acts as a "reversion dam" by resisting back flow of exhaust gases into the port. If you end up with the rare situation where the stock exhaust manifold has ports smaller than those in the head, you will need to port match. Use the same technique used to match the intakes.

This comes from Standard abrasives web site...Im a little confused about this....

 

My header ports are smaller than the exhaust ports in the heads. Therefore, the flow hits a step down as it reaches the headers. This is the opposite of what the instructions describe (path gets larger as the flow goes out, typically).

I actually intend to open the headers slightly more than the port - 1/8" or so. But, for starters, I've trimmed the header gasket (which is actually slightly larger than the header port as delivered) to the port; I'll open up the header flanges to that plus the 1/8", then trim the gasket to the flanges.

 

Or maybe I wasn't reading it propcrly. As long as they are ground concentrically NOW, you should be fine. I can't remember the last time I heard of valves that needs to be "spin balanced". Yeah, I doubt that the original supplier is going to warrant those valves today.

The multiangle seat grinds are not a problem as long as a decent amount of the 46° seat width is there for durability. Then again, I tend to err on the side of caution instead of all-out power. That's just me.

A 10-bolt behind a Mk-IV? O.K. Just don't hit it with too many clutch dumps. You are kidding, right?

 

This guy tends to err on the side of caution as well. So, I'm sure there's plenty of 46 degree face there.

Why not a 10-bolt? Stronger than a '57 rear end. I've got US Gears and Superior axles in it, along with the Powertrax. The weak spot seems to be the fact that the outer bearings use the axle for the inner race - which is improved on the aftermarket axles.

What's a "clutch"?

 

Yeah that kinda hit me on the way to work...sometimes the ol'e brain takes awhile to wake up.

 

You and me both. Sometimes I feel like I have no nards left...

Automatic, or planetary? A 10-bolt might make it under a light car with too little rubber, but that's a lot of torque all at once. A housing with a couple more cover bolts might be better suited, but you'll find out how well it holds up soon enough. This is gonna be interesting. Keep us posted, please.

 

I've been running this 10-bolt since 1998. The 3.73's went in last June, along with the new axles. The shop that did the work specializes in drivetrains, and except for the 21 year-old axles being pitted at the bearings and replacing the carrier and pinion bearings as a precaution, they said everything looked good.

The tranny with the shift kit and about a 50-50 mix of AMSOIL Dexron and Super Shift is amazingly quick on the shifts - almost harsh. I am considering a stiffening cover to help strengthen it a little, but the rear does not appear to be the weak link.

If I was running a rock crusher, no doubt there would be two extra bolts in the cover...

Port matching the headers has taken me longer than the head porting work, and I'm still not done!

 

Hey 5-7 You still looking for a shifter cable...I found my stock cable in the shed..I thought I got rid of it...ya need it?
PS. I was just swapping intake heads and cam...now my blocks at the machine shop.......talk about snowball effect, huh!

 

Local dealer had a new one (updated post on the Tranny forum). Shifts better than ever, now.

Back out to the garage for some more weldin' & grindin'. I picked up some .030" MIG wire, hope that helps reduce the tubing blow-through.

 

iny one know how mutch you can mill theas head. and still be ok.