Archive

Author Archive

Accelerator Pump Jets

June 14th, 2012 No comments

So, last October I went to Thunderhill and had some carb tuning done at MCE. They did a nice job – leaning it way out and boosting the HP and torque about 15 points each. However, once they were done, there was a big hesitation right at the beginning of accel that was really disturbing on track. I asked Scott about it, and he suggested that with it leaned out, it wasn’t getting enough gas right at the first push of the throttle, so the accelerator pump probably needed bigger jets. It’s taken me 9 or 10 months to finally get around to replacing these things! I had some in the garage already. The existing jets were 28 (primary) and 31 (secondary). I watched this video here, which gave me a great instruction on how to pick and install new ones.

 

I tried out 31 in front and 37 in back and took a test drive. Better! but still some hesitation. So I put a 37 in front. Great! the car is off the line like a mountain goat. I may try out 37/40 at some point, but the 40s I have are a different shape, and I don’t have the necessary drilled screw, per the video.

 

I’m looking forward to getting this on track again to try it out. There’s some chance of me going next weekend to Laguna. However, it’s a 90dB sound limit! I’ve been metered at 94.5 at Laguna before but then passed the 92 limit by just lifting a bit when I passed the booth. Not sure about 90. We’ll see how it shakes out!

 

–Update

There was still some initial lag. I took a look at the throttle action and pump actuation. I saw that not much was happening at the beginning of the throttle action, so I have moved the cam to position 2. I reset the clearance at WOT to .015. The jet seems to start much earlier now and that may be what I need. I also learned from the video that I should have the 50cc pump diaphragms in there for these .037 nozzles. Not sure if that’s what I have! I’m on the borderline though if not, so I think I’ll run this and see what happens.

Categories: Uncategorized Tags:

Fuel Lines

May 26th, 2010 No comments

I re-did all my fuel lines. Earlier, I described that I’d used the hard line, and then mated -6 fittings and braided line to it. Turns out I need -8 to fully supply this motor, so I re-did them all. Finding a route that stayed away from heat, was well protected, and wasn’t inside the car, was a challenge, but I think I did pretty well with it. In 2 areas, I passed the line through sheetmetal. Ordinarily, you’d do that with a bulkhead fitting. These areas would be pretty hard to reach though (if not impossible) with the car together, so tightening the fittings to solve a leak or something would be really hard. I ended up putting a rubber grommet in the sheet metal, and putting heat-shrink tubing on the fuel line. If I hadn’t put the heat-shrink on there, the line would have ended up cutting trough the rubber in time, and then cutting into the sheet metal. It might also be weakened itself, by the sheet metal rubbing on it. Combining that with mounting the line securely so that it won’t move around, makes for a pretty solid setup.

Fuel pressure regulator installed and connected
Fuel pressure regulator installed and connected
Fuel Lines - IMG_7275.JPG
Fuel Lines - IMG_7275.JPG
This is covered with heat shrink tubing to protect it from debris, and to keep it from rubbing through the rubber grommets where it passes through metal.
This is covered with heat shrink tubing to protect it from debris, and to keep it from rubbing through the rubber grommets where it passes through metal.
securing the line so it does not move around is key in keeping it lasting long.
securing the line so it does not move around is key in keeping it lasting long.
Fuel Lines - IMG_7279.JPG
Fuel Lines - IMG_7279.JPG
pressure testing the lines is important
pressure testing the lines is important
Fuel Lines - IMG_7252.JPG
Fuel Lines - IMG_7252.JPG
Fuel Lines - IMG_7255.JPG
Fuel Lines - IMG_7255.JPG
Fuel Lines - IMG_7241.JPG
Fuel Lines - IMG_7241.JPG
These Aeroquip soft jaws make the job much easier
These Aeroquip soft jaws make the job much easier
heat shrink tubing prevents it from abrating against anything - this hose will cut through other metal over time
heat shrink tubing prevents it from abrating against anything - this hose will cut through other metal over time
making large hoops to maintain the minimum bend radius of this hose
making large hoops to maintain the minimum bend radius of this hose
later on I ended up with a 30 deg fitting on the right, to ease this bend out
later on I ended up with a 30 deg fitting on the right, to ease this bend out
Fuel Lines - IMG_7246.JPG
Fuel Lines - IMG_7246.JPG
a bulkhead keeps things simple when passing through sheetmetal.
a bulkhead keeps things simple when passing through sheetmetal.
fuel tank outlet
fuel tank outlet
Categories: Fuel, Photos Tags:

Headers

May 26th, 2010 No comments

I ditched the old Doug Thorley headers because they wouldn’t work with my new motor. Too bad, because they were nicely made. I bought a set of Hooker Super Comp headers, part number 6111-HKR and have set about modifying them a bit. I ground out the tubes to match my heads’ exhaust ports, had the flange re-welded on the outside instead of just the inside, and am modifying the collectors.

The primaries on the left side are all within about .5″ of each other in length – impressive! On the right side, tubes 2-4 are close to each other, but a couple inches shorter than the left. Tube 1 is almost 5 inches longer than 2-4! It’s the best I can do, I guess. Hooker says they are “tuned” equal length primaries. I guess “equal” is relative. True equal length headers would cost a lot more. Tough to make.

To make up for the difference between left and right, I’m extending the collector .7″. The left-hand collector needs to be 18.2 past the ends of the primaries and the right hand needs to be 18.9. It’s not really possible to get very exact with it, because the ends of the primaries really vary (+- 1/8 or more). But, I’m getting real close.

Making the exhaust system is fun and challenging. I’m sore from lifting pipes into place over my head, fitting, removing, cutting pipe, lifting into place, etc. The headers are a real tight fit. The driver’s side one has to go in first. I have to lift the engine and move it over towards the passenger’s side in order for the pipes to clear the steering box and shock tower on the way in. Luckily I did install some Ron Morris engine mounts that allow for side to side and front to back adjustment. So, lift, move, put the header up and a couple bolts in, then shift the motor back to center and drop it. Then install the passenger’s side. It all has to be done multiple times in the fitting process.

headers - IMG_7271.JPG
headers - IMG_7271.JPG
headers - IMG_7272.JPG
headers - IMG_7272.JPG
I ground out the tubes to match the large exhaust ports of my AFR heads
I ground out the tubes to match the large exhaust ports of my AFR heads
I had my engine builder, Bob Gromm, TIG the flanges on the outside with phosphor bronze. This makes them strong, and seals up the thin areas left by my grinding
I had my engine builder, Bob Gromm, TIG the flanges on the outside with phosphor bronze. This makes them strong, and seals up the thin areas left by my grinding
This is the stock collector that comes with the Hooker Super Comp 6111-HKR. It's too short and too big for my application.
This is the stock collector that comes with the Hooker Super Comp 6111-HKR. It's too short and too big for my application.
I cut and deburred the collector and prepared it for welding
I cut and deburred the collector and prepared it for welding
This is the header next to my new collector pipe. The new pipe has a slightly smaller ID, which should be better for my torque curve.
This is the header next to my new collector pipe. The new pipe has a slightly smaller ID, which should be better for my torque curve.
I ground the edges of this down a bit because it's a thicker gauge than the old collector and I thought they should match up.
I ground the edges of this down a bit because it's a thicker gauge than the old collector and I thought they should match up.
tacking the new collector to the old. I cut off a piece of the reducer to use as a joining band
tacking the new collector to the old. I cut off a piece of the reducer to use as a joining band
headers - IMG_7432.JPG
headers - IMG_7432.JPG
new collectors with ball and cone adapters, tacked together
new collectors with ball and cone adapters, tacked together
headers - IMG_7439.JPG
headers - IMG_7439.JPG
headers - IMG_7440.JPG
headers - IMG_7440.JPG
headers - IMG_7441.JPG
headers - IMG_7441.JPG

Transmission tunnel repair

February 19th, 2010 No comments

So, a previous owner installed some kind of wacky shifter. In order to make room for it, they cut a big chunk out of the frame that goes across the transmission tunnel. Since I’m trying to strengthen everything now, I am going to change the shifter out, and Ray and I will build some custom shift linkage (more pics of that later) that will fit better. We’ll bend our own rods, and use rod ends instead of the stock shift linkage mounts.

Because we’ll be making the new linkage and replacing the shifter, I repaired the hole in the frame. That will certainly make things stiffer, since it’s one of the few crossmembers that exist in this old unibody car.

Categories: Photos, Sheet Metal Tags: ,

Img 2820

May 24th, 2009 No comments

Img 2820

Categories: Interior, Photos Tags: