[glhs#116]

So, no guts no glory, right?

1971 Pontiac Firebird Trans Am. Original 455HO block. Edelbrock round port CNC chamber 87cc heads.

I made my winter project doing some porting. Did as much homework as I could.

First oopsie was draining the coolant from the radiator but not pulling the block plug. But I run coolant and I cleaned up fairly well and WD-40ed the heck out of stuff. Didn't see any signs of corrosion in the bores apart from some very light colouring and kept stuff fairly doused with WD-40 whilst apart.

Made my goal to be fairly conservative. I basically gasket matched the runners on the intake and almost nothing else there (HO intake). The Edelbrock heads have gasket matched openings but it necks down pretty fast and the finish is rough. I basically smoothed and opened the opening on into the port. I knocked back the pushrod and head bolt bulges. The only real shaping I did was to attempt to "waterfall" the short turn.

As far as the two bulges I saw that the pushrod bulge actually has plenty of meat. You can almost eliminate it and still have quite a bit of thickness. Anyway, it didn't seem so critical in airflow terms as the pushrod bulge. Now the pushrod bulge clearly doesn't have much margin to play with if you're going to really try to knock it back to make that cylinder wall side port wall a continuous curve. So I thought about it, tried to search on it. eventually reasoned that even if I had a breakthrough the hole is blind in the block and the headbolt (ARP mine) have a machined washer with ARP goop on both sides and torques to 100 ft pounds. I felt that was unlikely to be able to pull anything. So I did go far on them and I did have one very light crack of a breakthrough. Stopped as soon as I detected it. Was a little more careful on the other ports and I didn't have any other breakthroughs.

Now, first test drive and I noticed that when I'd sort of power through a turn (not hard) I'd produce quite a smoke show out the back. It had me wondering about oil slosh and such but then when I had it on the motorway as I powered past a lorry I thought, "aha! It has to be the valve seals. I didn't replace them." It made a lot of sense. I'd had the valves in and out of the head several times, left the valve seals in. Of course they would be torn up. Spark plugs showed oil fouling on three badly, three medium and I had two cylinders that seemed perfect still.

Took a while for valve seals to arrive. Changed them on Monday night. Just did a test drive today. Was fairly hopeful, I'll admit. Car definitely seemed to be running a little better. Got to the first few turns where I'd smoked before and no smoke. Felt good. Then got to a bit of an uphill with a series of bends. Took it with a bit of throttle and BAM! I'm James Bond again. Smoke show. On these small country roads with traffic it's hard to get many places where I can just stand on it and not many places are straight. I was trying to think. New valve seals on now (used WD-40 and the plastic applicator so they all should be good). What's left? PCV valve? Suddenly a problem with oil ring in one of the holes? Can't think why. And, I suppose, I've got to consider the possibility that oil is getting sucked past that 100 ft/lb head bolt and washer. Could it be?

Anyway, was hoping for a few more experienced folks to bounce it off. Pretty bummed. I can't even really explore whether the heads have changed the performance if I dare not give it much stick. I felt like the sweet spot for triggering smoke was to go heavyish in the primaries (but before secondary tip in) and hold it there for a few seconds. I feel like it starts smoking then even before lift-off. It's not a simple case of a sudden lift-off giving smoke or a downshift.

Only other thing that happened at the same time was I had to seal up my well plugs on the QuadraJet. One of the primary and one of the secondary wells were leaking so I had to seal up all four. As far as I can tell that's holding fine. But I guess I won't know for sure until next time I take off the carb and see if the gasket is swelled.

Sam

P.S. I guess the other thing to mention with full disclosure is that I haven't precisely reset the valve lashes. I had them lashed from the bottom, not the top. I did a sanity check of hand turning the motor twice over before trying to fire it. It does run, idle and everything fine. But I haven't rechecked all the lashes. Some might be lashed a bit tight, I suppose, if the set screws moved a little (I did put all the rockers back on the same posts etc.). I did also visually check that none of the set screws were visually much out of line with the others. But let's say lash was a little tight somewhere, it wouldn't give you smoke, would it? I will relash of course. Just trying to mention anything that could be relevant