The Pontiac OHC Six

[horsewidower]

Re: The Pontiac OHC Six

The weather forecast looks pretty clear. So I'll probably take the Skylark and the trailer again.

[hi-jack]
I've been playing with the timing on the Skylark. I've added 6* of advance to all points above 1500rpm and below 70% load ( or whatever it's called, MAP/Baro, not 70% TPS), and will be looking at leaning out the fuel table in those areas and probably add more timing in places from there. Knock sensor isn't working yet, but I haven't done any real troubleshooting on it, the module is just outputing a constant voltage at the moment, so I'll have to be careful at lower elevations, and when I load up the engine on hills to see if I'm too agressive or if I should change my 70% load threshold to 60% or 50%, etc.

I'd suggest that you do that AFTER your 225 mile trip to get an extra engine. That's a ton of extra timing.

[TheSilverBuick]

Re: The Pontiac OHC Six

I'd suggest that you do that AFTER your 225 mile trip to get an extra engine. That's a ton of extra timing.

Then how will I know if it helped?? I've been running pretty much the same timing table since I started controlling timing, with peak advance between 32*-40* in that time, and stuck at 17 mpgs. I drove it 10 or so miles yesterday and it seems to be ok with the extra timing so far. I wasn't datalogging at the time so I don't know exactly what the timing was doing on the highway, but I'm guessing around 36-38* at 1800rpm, I'm probably going to shoot for 45* at 70-75mph and see how it likes it. Climbing the slight grade coming to work, at ~7000ft, and 70mph, ~2000rpm, I'm at 18% throttle per the TPS, so a pretty light load, should be able to crank the timing up. Worse case, I'm bringing my Laptop, a quick key stroke and I can load my old timing table right up.

[horsewidower]

Re: The Pontiac OHC Six

I'd suggest that you do that AFTER your 225 mile trip to get an extra engine. That's a ton of extra timing.

Then how will I know if it helped?? I've been running pretty much the same timing table since I started controlling timing, with peak advance between 32*-40* in that time, and stuck at 17 mpgs. I drove it 10 or so miles yesterday and it seems to be ok with the extra timing so far. I wasn't datalogging at the time so I don't know exactly what the timing was doing on the highway, but I'm guessing around 36-38* at 1800rpm, I'm probably going to shoot for 45* at 70-75mph and see how it likes it. Climbing the slight grade coming to work, at ~7000ft, and 70mph, ~2000rpm, I'm at 18% throttle per the TPS, so a pretty light load, should be able to crank the timing up. Worse case, I'm bringing my Laptop, a quick key stroke and I can load my old timing table right up.

Perhaps add a bit of extra acceleration enrichment so you don't go dead lean when you get a real load.

The only time I get knock is on tip-in from a cruise to passing speed.

[horsewidower]

Re: The Pontiac OHC Six

It was the leaning it out on top of the timing that set off my alarm bells. What is your cruising AFR right now?

[TheSilverBuick]

Re: The Pontiac OHC Six

My accel enrichment is generous enough with a fast enough throttle movement.

Right now my cruise AFR's hang around the 14.5 and 15.0, and both barometrically corrects for it (how I tuned it, targeted those AFR's while cruising 70mph and in the same load/rpm bin), and I need to turn my O2 corrections back on, it's still turned off since last August.

[milner351]

Re: The Pontiac OHC Six

Ah the trailer of doom.... You have more faith in those tires than I do. I'm quite sure they are older than you are!

[TheSilverBuick]

Re: The Pontiac OHC Six

;D

[Scott Liggett]

Re: The Pontiac OHC Six

I really think you and John should go together to get the engine. He can be the tire safety inspector.

[fly4val]

Re: The Pontiac OHC Six

Hi I'm Val. Been a major car guy since the 50's, yes, I'm a geezer ;-)

Great interest in the Poncho OHC-6 project. Very kewl, about the one question, re:forged rods, maybe that was a slick idea per JDZ as he had interests in touring those cars with that engine and was looking upstream for poss future power increases? Some sixes are real torque monsters...like Ak Miller's notch back 65/66? Mustang with a 300 c.i. six?

Personally, I have no probs with 40 y.o. rods as long as they pass all the requisite tests, mag, dye check, straight both ways and able to be re-sized for intended use.

I live now in SoCal; however, there was a real wizard in Denver in the 70's (Paul's) when I lived there. Had him do all the work on the fresh 377 sbc I built, first one in Denver, in those days I think.

Thanks for all the great material on this project, looking forward to add'l updates.

[TheSilverBuick]

Re: The Pontiac OHC Six

Welcome aboard Val!

[fly4val]

Re: The Pontiac OHC Six

Silver Buick dude.....I'd be concerned about the removal of/or replaced by open tubing as the oil feed and causing a gusher amount of oil in the top of the engine.

As an old SCCA B prod Corvette driver/builder; we rapidly learned how stock lifters in the SBC would fill the valve covers at high rpm and starve the oil pump for oil! So Chevy eng'g, probably someone in Duntov's group, came up with a different lifter that moved the peehole from the groove of the lifter to the upper dia. of the lifter body. This effectiively acted as a cheap (factory part!) fix to limit the amount of oil in the v/c and worked like a charm. However, if you used the spec lifters on the street, it necessitated filing or lightly machining a small flat ~0.0.5 that went from the peehole to the main oiling groove so as to allow add'l oil in the v/c area.

[67pete300]

Re: The Pontiac OHC Six

Here's your wrapper for the OHC6:

http://boston.craigslist.org/gbs/cto/2173790198.html

Some assembly required. But the price is right!

[DanStokes]

Re: The Pontiac OHC Six

Really not a bad price - and you can SEE there's no filler in it. A bit of a haul for Randal.......

Dan

[Junk Whisperer]

Re: The Pontiac OHC Six

I think Dan can do it,folks :D! Are you 'game',Dan ;)? ~J/W.

[TheSilverBuick]

Re: The Pontiac OHC Six

I picked the engine up today. Pictures when I get home. I could tell right away it wasn't a '69 engine when I saw it (bypass hose under the thermostat housing), but it came with a manual transmission flywheel (and clutch set), and I got the frame mounts the motor mounts bolt to. If I'm reading the numbers right it's looking like an early '67 230 Sprint engine. Definately interesting seeing a Q-jet on it :P


Dang pete, in 2000 I paid $2300 for an assembled running and driving one that didn't require any filler either :P

Silver Buick dude.....I'd be concerned about the removal of/or replaced by open tubing as the oil feed and causing a gusher amount of oil in the top of the engine.

I'd still have the restrictor in place to keep too much oil from pumping into the cam and valve area. I'd just remove the hole supplying the lash adjusters and replacing it with an external line that maintained proper oil pressure to maintain lash adjustment.