The "Tan Brick" aka my 1997 Express Cobra conversion

[Fast355]

You're having trouble with the L31 ignition? Maybe you've already mentioned it... Biggest problem we see is moisture in cap. Insert a hose nipple in one vent in distributor and connect to ported vacuum and problems go away. On LS powered vehicles the coils tend to fail around 150k miles. Then its chase, chase, chase after that unless you replace the set. For low cost maintenance the distributor is nice.

Ramjet / HT383 cam that I installed in the bus is working well. We're seeing much improved fuel economy. Should have switched years ago. Might install more cams this winter if we have the time. Had to spend some time with idle corrections to prevent surging but otherwise minimal changes were done. 302 in Suburban also had surging issue... again, changing spark values for idle speed correction solved problem. Suburban is providing 20+ mpg on highway when not towing. Better than our 4.3 powered '95 Blazer ever was.

I'm sure that full floating axle will be fun. Big brakes will be nice, too. One of these days I should take measurements to see if the '09+ rear disc hardware is a bolt on for the older vans.

Edit: I see the CC test replaced stock pcm with an 0411. I'm not sure I'd attribute all the gains to the ignition as they did.

I vented the distributor years ago to a vacuum port I added in the throttle body just above the throttle blade. I hooked a vent hose into the TB bonnet similar to the way an opti spark is vented in later years.

I think the FF 10.5 will be great too although my guess is that it weighs 450-500 lbs with the drums on it. The 13 x 3.5" drums should be a nice upgrade. I already put tue 8600 GVW front calipers and pads on it when I put the Hydroboost and 1-ton master on it.

I totally eliminated idle spark correction with my 215-220 @ .050 cam and the idle has been rock solid. I had played with the values but the old cam really liked it just being diabled with all timing maps having the same values.

My brothers 1999 5.7 with the LT1 cam and tuned black box was also very good on fuel, especially after a set of Hooker 1 5/8" long tubes and Hooker 2.25" dual exhaust went onto it. He saw 20-22 mpg on a few roadtrips. With the 40 gallon tank in the truck on a trip we went on we went through like 3 states before we had to get gas.

Good the see the 395 Marine cam is working well for you. I never have been a fan of the factory L31 cam. I never felt it had enough duration split to work well with the factory heads.

Finally I am guess you have a ton of cracked manifolds on these buses. Have you tried the Doug Thorley Bus headers on one yet? I don't know how long you plan to keep them in service but they are $615 and they come ceramic coated and well built with 14 gauge tubes and 3/8" flanges with headpipes to bolt up to the stock 3" pipes. I now often find myself pulling uphills unloaded in Overdrive that caused me to downshift to 3rd before. With 7,500# behind it I pull in 3rd gear with my 29" tall tires and 3.73s. The torques gain and MPG increase was very noticeable after adjusting the VE and MAF tables. The heads run cooler too, allowing me to dial in a few degrees more timing across the board.



The last trailer I towed for ~250 miles was about 6,500# with an older Jeep Cherokee on it. Running 65 mph @ 2,600 rpm in 3rd gear I was able to get 14 mpg. I don't recall finding a single uphill run that caused it to downshift.I LOVE the torque.