64 Vette….Rebuild 2.0

[folkenheath]

Wow, I didn't notice the other day that they have DIS on that thing, it looks to be 8 coils mounted above the valley plate under the intake, and I see a cam sensor in the Gen VI timing cover.

I'm still surprised they don't have a conventional headed version that will fit under a hood of some sort. I would think the race gas version would be super tall spread port like that, and the conventional heads would be pump gas with the correct pistons. But it would be harder to make 1000 on pump gas with conventional heads, I suppose that is why they did it. Its like a spread port version of what I built 5 years ago. 632, DIS, 4500 throttle body, pump gas, MPFI, shaft rockers, etc. And its spread port, that's a bad @$$ engine right there. But it would definitely not fit under most hoods.

 

[76zimmer]

Got a new lock ring for the fuel sender….the other one was a bit mangled over the years, so far no leaks.
Changed plugs and did a compression test. Very happy w the results.
Checked the valve lash and only 3 of the 16 needed a minimal adjustment….not bad for 12 yrs and a few thousand miles!
Have a bad plug boot to replace. It’s pretty close to the header, does t look like it ever jumped to the header and it never felt like a miss. Lucky I guess.
Going to make some more passes this weekend.

 

[folkenheath]

Have fun Zim! Like my grandma used to say, "put it in R for race"!

 

[76zimmer]

Highs in the mid-upper 50’s, partly sunny, wind outta the north….cool and dry….ideal conditions for best lap ever in this heap!

 

[76zimmer]

Best pass ever today
Carb cleaned and new gaskets.
34* timing, 20# air pressure. Launch from idle.
Wanted to try a few things today but the timing system took a shit at the track.
Engine was pushing blue smoke the whole pass.
Thats it for this year.

 

[mrk5]

Nice!

 

[tRustyK5]

Any thoughts on the blue smoke? Based on the mph and your 60 foot time it seems you're leaving a bunch on the table. 113 mph at the stripe says this is an 11 second car...but the 60 is soft. Do you need more convertor to get it to leave or are you intentionally leaving soft?

 

[76zimmer]

Any thoughts on the blue smoke? Based on the mph and your 60 foot time it seems you're leaving a bunch on the table. 113 mph at the stripe says this is an 11 second car...but the 60 is soft. Do you need more convertor to get it to leave or are you intentionally leaving soft?

Watching a video, it started smoking about 1 second after the 1-2 shift, then kept on until the stripe. I did a compression test (showed 177-187) last week because of a bit of smoke after the shifts but it went away quickly on those passes, now its the last 2/3 of the pass? I have a cheap boroscope, I’ll see how that works in a cylinder….maybe Ill see something. Engine guy thinks its guides/seals, but under full throttle? Probably should do a leakdown, but don't have the equipment.

I intentionally leave soft, a hard hit I think would just spin…I have a 7” street radial and cant get much more under the car right now. A couple weeks ago, I had a little spin, and was regularly 1.98-2.00 60’. This pass I dropped to 20# and drove around the water box, and backed into it for the burnout. Dropped .06 off the 60’ from the last time I ran. But the temp was 20* cooler and only 53% humidity today. 3 tenths was a helluva surprise. Yeah I know its not a rocket, but its pretty cool to go from 12.60’s into the 12.30’s! I only picked up 1-2 mph, so the huge improvement in ET was a surprise.
The cam is retarded 4* to push the powerband up higher, the slip shows that.
The only changes from my 12.67 run were a thorough carb cleaning and new gaskets…the 110 made it start leaking from a few gaskets, and a new set of plugs. I lashed the valves to be sure, only a couple were maybe .002 more lash max. Crane says .022 lash hot, I set them at .018 cold. Its been that way since the rering in 2009.
this engine is a flat top (10.3cr) 750 vac secondary, rpm airgap, competition massaged double hump headed, 238/248 cammed (net lift is .494/505), sj327 stroked to 355. It drives great on the street. Originally built in 94.

 

[tRustyK5]

Definitely no slouch, and from your slip I kinda guessed you were leaving soft for some reason. I'd guess a set of drag radials would allow for a much more aggressive launch, but I'm also guessing you're a little leery of whether the rear assembly will take a big hit or not?

Your trap speed shows you have plenty of power for an 11 second slip, that's a damn decent 327 IMO!! Also, I don't care what anyone says, a 12 second street car is a fast car!

Usually smoke like that in WOT is more ring related, but your compression numbers sure look good. Possible the umbrella seals are done? Maybe as the rpm's get up there it's filling the valve cover area with oil and getting past the seals and guides?

Probably the fastest car I ever rode in was a '72 Vega GT that was well built. Modest cage, narrowed 12 bolt with 4.11's, nasty 327, M21 4 speed. The 327 dynoed at 420 hp and it pulled to 8000 rpm. I still remember how bitchy it was when cold. Even warmed up it idled at 1100. At 2400 lbs it was a beast! I got to see him race a Suzuki 1100 Katana with a fairly experienced rider. The bike got him by half a bike at the stripe. Good times!

 

[ZooMad75]

Dumb question on the smoke. How are you venting crankcase pressure? With your compression readings as high as they are I'm wondering depending on how the crankcase is vented if you are sucking oil vapor.

 

[imiceman44]

Dumb question on the smoke. How are you venting crankcase pressure? With your compression readings as high as they are I'm wondering depending on how the crankcase is vented if you are sucking oil vapor.

That's one of the things I was thinking of.
The other was whether the oil is draining back fast enough from the rockers area, or oil is sitting at the valve stem area until some gets down through there.
Either way it's easy enough to check

 

[max 02]

I don’t know any tech but it sure does sound tits Dave!

 

[76zimmer]

You’re right Rene’, Having already upgraded the diff inner axles to 30 splines, now the weak link is the outer stockers at 17 spline, the new pieces I have are 31 spline, larger diameter, and precision assembled much better than factory, and most rebuild suppliers stuff. Should be good for 500hp. Finding a dragradial that will fit might still be a challenge though. Right now I cant get my fat finger between the fender lip and the tire at rest. The inner part of the lip (only about 1/4” deep) has paint worn off from tire rub, probably from street use, but that is staying in the mix for the future as well. I can gain almost an inch on the inside before frame contact becomes a concern. Hoping to be able to massage things a bit and get a 255/60 in there, but I’ll cross that bridge when I get to it. The 68+ cars are much easier to get a wider tire under it, with the full radius wheel opening compared to mine….much like the squarebody openings.
IMO, coming out of the hole soft may be better than a heavy spin and pedal, or trying to feather it out to avoid spin. Doesn’t take much to eat up that few hundredths of a soft launch. I wanted to try a 1500 rpm launch, it worked decent in the concrete driveway. Testing at 750 rpm produced about 20’ of spin, and 1500 produced about 100’+, but it didnt uncontrollably lite em up. I felt it was worth a try at the strip, with the better traction available, but the timing system shit itself, and they shutdown for the day, and that was the last day. It was inevitable that the new concrete would get painted by rubber at some point….I held out for a full year before making the sacrifice!
The crankcase vent system consists of a modified factory lifter valley oil separater can, shortened to get the RPM Airgap manifold on as it protrudes into the lifter valley. The can is connected to the block internally and on the back of the block is a port that in factory form simply goes to the air cleaner housing for venting, along with a vacuum line from the oil fill tube on the front of the manifold to the carb base. I now have that port fitted with a PCV and hose to the carb base. I checked the hose and its pretty dry, so I Dont think oil is getting sucked in there. Also both valve cover breathers are dry, no mist accumulation on the valve covers or outside of the breathers. I Pulled one spark plug and the first thread was wet with oil. fresh plugs too.

 

[ZooMad75]

I wasn't sure if you still had the can in the lifter valley. Running the line to the base of the carb will have less vacuum at wot anyway. So I'm not sure where the smoke is coming from.

 

[76zimmer]

right, it started 3 passes ago, and continues to get worse. the odd part for me is, it doesn't start until after the 1-2 shift, and only under full throttle.

 

[tRustyK5]

What is your oil pressure doing at the point it begins to smoke? Possible the pan is getting empty at that point, and all the oil is up top?

 

[76zimmer]

I didn’t get a look, perhaps Ill make a 1st and 2nd gear run on the street to have a better look at that.
Ive heard of running a quart less than full to help w crank aeration? I have a 6 qt pan, and just did an oil change before taking it to the track a couple weeks ago. Added 5.5 qts. and 12 oz. zinc additive. The pan has a trap door system in it, and a windage tray on the main caps.

 

[shady]

I was actually thinking oil rushing to the back and getting into the crank. Slinging a ton of it all over the piston walls.

 

[76zimmer]

Something has changed inside the engine…I ran the car for dozens of laps between 04-09, and it never blew blue then, and the engine is the same specs as before the rering in 09. At that time it was a ball hone and new rings. Probability have 3-4000 street miles on the engine, with lots of full throttle activity. Cruising is about 3800-4000 rpm on the highway, and ran several hundred miles on Powertour like that.

 

[folkenheath]

Nothing a 427 won't fix Zim!

Be careful running a quart low if you try it. It's a common thing to do, but I never recommend it on a street car. Drag only cars frequently run a quart low, and pick up about .02 seconds on average. However, with that comes the risk of running out of oil through the big end, especially if it was a big block, but can happen to any engine. Many do it on purpose and shut it off right after the stripe. Then don't start it until they get to the return road. And of course they don't have power brakes or power steering, etc.

What can happen is you may lose oil pressure momentarily right after the big end (or right before if its way too low) because the pump has pumped all the oil in the pan up to the top end in the heads, and it can't drain back as fast as you can pump it up. Many run restrictors in the block so it limits the flow to the valvetrain, and then they can run lower oil without running out before the stripe. It's not something I am willing to mess with, if I see oil pressure drop in the decel for even a couple seconds I add a half quart or so and it disappears. And I'm not running restrictors in a street driven car either, I want my valvetrain to last longer.

With that said, if you pump a lot of oil up into the heads, they can leak through the valve guides. If the guides are wore it could easily cause problems.

It's true under WOT, you shouldn't have any vacuum unless you have too small of carb, or you have a vacuum line hooked up in a spot near the throttle where it creates a venturi from all the airflow going by. You could test this just by removing the PCV from the vacuum source and leaving an open breather for 1 run.

Also, you may want to do a leakdown. Compression is a good test of compression, but leakdown tells you how fast it is leaking out. I've had a good compression test before but a bad leakdown, and the head gasket had a tiny leak between cylinders! So ever since then I do both when diagnosing because the compression test didn't set off any alarms but there was obviously a problem.