The autocross went great. This was my first time out with the San Diego Region SCCA and everyone was friendly and welcoming. Here is a shot of the field I ran in (1 of 3 groups):
When setting up the alignment, I had in mind that I wanted the rear to be lively. Well, the conservative rear camber along with the overinflated tires fully accomplished the goal. The course was fast and the car oversteered on the throttle and oversteered on the brakes... tons of fun. My fear was that the front end would push, but it was nicely responsive instead. For the next event I plan to drop the rear tire pressure and bump the rear camber to at least -1.5 degrees. Any suggestions for a good tire pressure to run next? I ran this event on 45psi cold and over 50 psi hot! The tires are 3-4 year old summers with lots of thread depth left.
The other issue I ran into was getting hot in grid. The car got up to about 220 after a few runs and didn't cool down much between runs. This caused the fuel to boil and my idle afr leaned out until I had to adjust it. For next event I plan to hook up my 3rd radiator fan and see if that is enough.
Here are a couple shots my lovely partner took at the autocross event.
Thanks wawazat
Next project: shift boot. The shift boot currently on the car looks good and is original to the car, so why change it? The T5 shifter has a long mounting plate, but the old pinto shifter did not. This means the boot isn't big enough to cover the access hole needed for the shifter. Here is my current setup:
I like the aesthetics but the self tapers/weather striping under the access plate was not an inspiring seal. So I set about improving it. What better place to start than the oem lower boot?
Here are a couple pictures showing my proccess:
Not bad so far, so lets make the recieving flange:
A bit of trimming on the flange and the gasket netted us a matched set:
Finally a bit of mockup in the car:
Well, the new version will certainly seal better, and be easier to service, but... I'm not sold on how it looks. This will require a bit more thought before moving forward.
After some thought I decided to keep the stock pinto boot, as its consistent with the improved stock look I'm going for. However I still wanted to use my sealing ring and new lower boot. Here is how it ended up for now:
First a plate to mount the pinto boot:
Bend up a couple strips and mock up:
Test out all sorts of settings on the new welder and find where the limits of the circuit in the garage is:
Roughly flatten the welds that are proud of the sealing surface:
A bit of dirty welding in on the tunnel to get the nut plate in:
Finally the results:
The plan is to cut a piece of carpet to sit nicely over the mount to create the least noticeable hump in the tunnel. The mounting bolts are not easy to get into the nut plate due to alignment issues with the hand drilled holes but some time with a file and a bur should fix that up. For now, I am tired of this project and the results are acceptable. I'll revisit it when interested again in the future.
Piguin
New Reader
5/17/22 5:10 a.m.
That looks waaaay better.
Once carpet is in, it will be OEM+, although I would be tempted to leave the pedestal visible :)
What did you think of lake Elsinore autocross? I admit I am kind of bummed that they tore down Qualcomm stadium before i could watch any of the autocross events there.
Thanks Piguin!
I am a fan of the Lake Elsinore autocross, it's a good group of people and nice fast course layouts. It's a little expensive but you've gotta pay to play.
Here are a few pictures from the latest autocross:
The car felt good. I ran out of time to change alignment settings, however I dropped initial tire pressure on each corner to 40psi. The rear end was far more stable and had less tendency to oversteer. The issue was that the front end felt vague, and I ended up understeering through some of the corners and had a hard time feeling what the brakes were doing. By the end of the event I was having a hard time launching the car and after the drive home the idle had dropped about 500 rpm. I'll discuss this more in the next post.
Here are a couple shots of a sweet fiesta that came out to the event:
What pressures are you normally running in the tires on this thing? Are you using temperatures across the contact face of the tire to determine what to do with pressures or are you taking more of a try & see method? 40+ psi cold sounds quite high to me.
Curious what you think is going on with the front end of the car.
In reply to pres589 (djronnebaum) :
I'm running some 3 year old khumo ecsta ast 400TW tires. I don't have much data for where I should be running the pressures, so I am in guess and check mode. I just picked up a temp gun so hopefully I can be a bit more scientific in the future. What would you expect for pressures? I am fully open to suggestions.
Edit: The #1 suggestion I get at the autocross from the instructors is to get a set of tires...but I'm pretty cheap and these have alot of tread left.
I'm not a racer so do whatever with this next bit; I would start at 30 psi all around and play with pressures a few pounds at a time, one end at a time, and watch the temps after a run.
I am sure there are people on this board that will come along and offer ideas and hopefully something works.
So I mentioned that the car was launching poorly and idle was down after the last autocross. Knowing that this was a new issue and probably easily fixed I did the logical thing... Took the motor apart.
The Backstory:
I did alot of research when building the motor about cam phasing and had decided to install the cam in a 3 degrees retarded position. For the last few years I've chalked up many idle issues and poor power under 2500rpm to the retarded cam timing. I was feeling motivated and decided I would fix the new idle issue after resetting the cam to 0 degrees.
First enter "service position":
Next pull off the belt drive, harmonic balancer, and timing cover:
Then check the cam timing and find...
It was already set to 0. My notes from the motor build left out exactly where I degreed the cam in. I had assumed that I had gone through with retarding the cam timing to push power up in the rpm band, however logic must have won out at the time and I installed it where trick flow wanted it.
After having already torn the car down to make a change I decided to advance the cam anyway to see how it would effect performance. The cam is ground with 4 degrees of advance already in it and I decided to add 3 more degrees at the camshaft:
Unsuprisingly, when I put the car back together and went for a test drive my idle issues were still present...
After checking timing I found I was idling at 0 degrees of initial advance. I popped open the distributor to find this:
The mechanical advance "bushing" in this distributor is nothing more than a bit of vacuum hose around a post captured by a slot in one of the weights. Here is a picture with a new piece of vacuum tubing in place:
After setting the timing to 36 degrees total I found the bottom end to be sluggish and stumbling. After trying a few different timing settings and finding that the engine wanted lots of initial advance at idle I tried a poor mans "lock out" on the distributor:
This setting would run quite well at idle and up to 3500 rpm where it started to stumble and the power would fall off by 4000 rpm. Then I started making advance limiting bushings to tailor the advance. Here is a 5 degree bushing:
After one of the tests I realized idle rpm wasn't acting how it should when I disconnected the vacuum advance canister. So I checked the vacuum advance at idle to find 0 degrees of advance (on manifold vacuum), and a large vacuum leak due to a ripped diaphragm. Off to the parts store. The 85 mustang vacuum advance can attaches the same way onto the pertronix "stock look" distributor but the actuating arm needed some help:
While playing with the timing curve it has been fun to gain a bit of experience with timing and moving the settings around. Its also been fun to try different tuning strategies such as setting the throttle blades to expose the proper amount of transition slot and tuning idle speed with timing and afr. However it became apparent that the cam position was not an improvement over the 0 degree key position, so everything came apart again and the cam is back in at 0.
The balancer was looking a bit sketchy and the timing cover gasket didn't last through the job so both were replaced. I'm looking forward to trying to optimize timing and idle circuit settings again with the cam in the correct position.
Timing light notes:
The harbor freight dial back timing light is junk and 2 failed within 24 hours (failed adjustment pot). The digital version is quite nice so far though.
The car is running quite well. The timing in the tune is quite conservative and I've switched down from premium to regular 87 octane fuel. While marking the new balancer for TDC I found a cracked spark plug in cylinder #1. The amount of "small" issues I have fixed recently makes me suspect the advanced cam timing may have run just fine without being plagued by other parts failures. I am looking forward to tinkering a bit more with the timing curve then leaving it alone for awhile.
timing light notes:
The harbor freight dial back timing light is junk and 2 failed within 24 hours (failed adjustment pot). The digital version is quite nice so far though.
I could have told you that.
Might be time for a MSD on that motor its cheap and dead reliable.
Time to give the interior experience some more love:
To continue the nonlinear theme that I've started here is one of the ergonomic improvements for the pedal setup:
The original pedal is not in line with the brake and clutch pedals. The multiple holes have allowed for experimentation. So far it is an improvement. I also experimented with a raised platform under the pedals to optimize where the ball of my foot hits the pedals as well as shimming the throttle pivot point towards the driver. Thus far, neither are improvements but I may revisit the concepts later.
Also, I don't think I'll ever get tired of this view:
In reply to AngryCorvair (Forum Supporter) :
Without the jack stands it is the front wheels that should be off ground
This weekend I decided to clean up my spark plugs and check the gaps in preparation for a bit of tuning work. I have a few sets of plugs for a sbf so on a whim I decided to check what the recommended plug is from the head manufacturer. Turns out they want a plug with a flat sealing washer... I have been using taper seat plugs like I always have on stock heads. So off to the FLAPS to get some "racing" plugs:
New Autolite 3934 on the left, old Motorcraft AGSF-32C on the right.
The old plugs seem to have been sealing fine but it's nice to have the manufacturers recommended plugs in place. After opening up the gaps to .045" they were installed.
Last time I washed the Bean I was reminded just how leaky the trunk seals are. The hinges also have slipped in their mounting holes on the body causing the trunk to miss align. After getting a weaker set of struts to put less pressure on the hinges I decided to try to reseal the hinges and trunk seal. After stripping back lots of body filler and a few layers of painted over old sealing material I got to the rusty flange.
A bit of rust reformer, and its ready to get a coat of silicone to hold the old seal back in place.
The hinges and mating surfaces on the body and trunk got a light coat of flex seal. Once dry it'll all go back together.
After installing the O2 gauge I have been playing with timing and idle screws while observing afr effects. One behavior I've decided to focus on is light throttle cruising. At idle I had a fairly steady afr (~13:1) and at part throttle acceleration I had a steady afr (~13:1) however when barely on the throttle the afr would dip into the 11's. After a bit of research I decided to tune the mixture at the transfer slot with idle feed restrictor jets. After looking up the cost of a jet kit I decided to buy a pack of jet blanks and drill them myself. A few pictures:
These blanks come with the proper 6-32 thread and a .020 pilot hole.
First we need a fixture to hold the jets. A small piece of aluminum with a 6-32 threaded hole will do the trick.
At first I was working with a full size drill chuck. I turned out not to be precise enough to hold these small bits. This bit is #58 (.042") but the hole ended up at #56 (.0465").
After switching to the properly sized chuck I started hitting the intended size.
I decided to label my holder in wire gauge size instead of inches because I only have access to standard drill bits. I also thought jet size was equivalent to wire gauge size (turns out its not). While the engineer in me wants them labeled in thousandths, wire gauge size is more accurate as I can only measure the orifice size with standard gauge pins.
Here is where the idle feed restrictor jet lives in the summit carb.
Without knowing what the stock size is I decided to swap to drill size 59 jets (.042") and observe the difference.
As a beginner holley carb tuner it is becoming apparent that there are many overlapping circuits to tune. Different "guides" favor tuning some circuits over others.
To follow up on the idle restrictor tuning, the stock size was .047". When I swapped to a .042" it made a positive change helping to lean out the transition slots to avoid a part throttle rich condition at cruise. The problem is that it has made the carb much more sensitive to fuel temperature. I can watch the idle mixture lean out just sitting at a long stop light. This will require further experimentation.
A change I was hesitant to make too early while tuning this carburetor was a power valve. I had a persistent rich tip in condition that would keep the afr from 9-11 through the rev range if you stayed in it. Even with the accelerator pump cam removed this condition remained at some level. After swapping from the stock 8.5 power valve to a 4.5 power valve I am happy to say this was likely the issue. I can now start to see the operation of the different circuits on the wideband during driving instead of just a pig rich everywhere condition.
I think I overshot the powervalve a bit as I get a lean condition now under sustained secondary opening when the valve hasn't opened yet. I'll probably drop down to a 5.5 after solving my idle issues.
Time to switch up the accelerator pump cam. The stock cam is very aggressive, and the effects can be observed on the O2 sensor with any change in throttle position. Old on the left new on the right:
This has been a positive change. Setting 2 (least aggressive) induced a lean hesitation on part throttle application. Setting 1 (middle setting) was better but not perfect. I currently have it in setting 3 (most aggressive) with high hopes. Will need some time in varying conditions before calling it done.
In an effort to chase down a persistent squeak in one of the rear shocks I whipped this up:
The clearance on the upper spring hat is pretty tight so I want to space it down to definitively rule out any contact. Hopefully the dimensions, pulled from a scaled internet photo, are correct.
Love this car, glad to see you continuing to develop and enjoy it!
