Sorry if this post isnt allowed since its a van. But anyway its a 93 cargo van long wheel base 305 and a 4l60e, it has 105k on it. Recently experimenting with it i inatalled a k1102 summit cam kit with a double roller chain as well. The results were better than i though they would be. Down low feels unchanged above aout 2800 it starts pulling much harder than before.

Ive got a very nice set of 081 heads to replace the 187 swirlies, im curious how they'll perform consodering they flow less on the exhaust side. After this will be a set if headers. Im told the 2nd gen Camaro headers are a direct fit. Then a nice dual plane intake and a tbi adapter.

Oh whats everyones thoughts on the bigger holley throttle body with the factory style injector pod mounted on it. That would be my last mod maybe..

I do have a 350 im building but this is just about trying to have fun with what I got.

Misspelled

 

I kinda like it -the light bar is a "hick"detail,but perhaps you are in a hick area.I have a '91 G30,so familiar with these vans.I think 187/193s are nowhere near as bad as the reputation would suggest-at least for use below ~5200 rpm.Beware using a 4bbl manifold with an adaptor to mount a TBI-I tried that once and the part throttle mixture distribution was very bad...perhaps someone else has had better results mounting a TBI on a carb intake than I did and will share some details on how it was done

 

While not the right forum, I'd love to find an 83-95 G20 panel van. Why they all have rust, I don't know. Well, I do, but can't fix that fact...

 

I'd like a 1978-82 G10 SWB

 

Yeah im definitely in the country, helps on empty single lane roads to see deer too. I used a dual plane intake on a 350 with an adapter plate and a k1103 cam and it ran very well. Ive had lots of tbi equipped vehicles but i never really tried to see what i can do within reason. And most parts will transfer to my 350 when its done, probably late next year.

 

Sorry i know its not the right type of vehicle but this forum from what ive seen most people know their stuff as far as tbi things. She does have a little rust, ill be cutting that out ober the winter and I have a parts van with a good body for patch panels. Im not going for perfection , i just lovely old van i dont care how ridiculous it looks. I hauled more firewood in it than a longbed dodge could.

 

I need to get a tune bad, it shifts way too early now at WOT with the cam. Id like the rev limiter removed and the shift points around 5300. My future plan is a 4l80e, ill have to find what wiring is swapped from the 4l60e to make it work. Anyone know of anyone that still tunes?

 

there is a guy on here,fast 355,who likes chevy vans-I kinda recall he mentioned the light truck small cap HEIs have rev limiter built into the ignition module:the module can be swapped for a different #module without rev limiting.My 91 G30 has 350/4l80e.

 

Cross posting of models within the GM family is fine by me. I own several different GM vehicles, and some share engines

Post on!!

 

Thanks ive read his posts, i always wanted to try the tpi swap like he did. Thanks on the module info if anyone happenes to know a part number that'd be great.

 

Wait you couldnt see the best part... The wing. Lol. Anyone care to guess what its from?



duplicate

 

thinking about it,the module difference is spark advance instead of rev limit.The wing is cool

 

Its from a fiero gt, It looks ridiculous so it stayed..

 

...this is what I want. Bad.

 

Yeah I call mine the welfare version.

 

I've been working on the 081 heads here and there, Lapping all the valves and new seals. I cant get over how clean they are. Curious as to where it'll lose and gain power, Probably a loss down low and a little more midrange.

 

Now I have that damn theme song bouncing around my head.

 

I love it when a plan comes together...

 

I pity the fool...

 

I think the Fiero wing looks good-If I end up with a standard body Chevy van,I am going to consider a Fiero wing My g30 is a box truck. One thing to watch out for with these vans is rainwater pours on the battery and can flood the acid out of it if the battery top can let standing water drain inside...

 

The change over from loss to gain will happen in the 4,000-4,500 rpm range. Probably lose 15-20 ft/lbs through most of the low-midrange for 10-15 hp above 4,500.

As for running a carb style dual plane. Swap the injector wires at the PCM for the left and right injectors.

Finally the rev-limit and speed limiter in the TBIs with the electronic transmissions is programmed into the chip.

Does your van have the fleet vehicle governed TBI option?

 

I have both an 83 and an 87. Neither have much rust at all. Both rusted around the dog house opening because of the carpet added by the conversion companies failed to let the dog house seal to the metal.

 

I've not heard this advice before. Can you explain how this helps?

 

Because the injectors alternate in firing left and right. The factory TBI manifold has a different cylinder pairing than the aftermarket manifolds. If you look at which throttle body bore feeds which cylinder you can see the difference. Even the GM TBI Vortec manifold is flip flopped and responss positively to swapping the wires. Had a guy I was tuning a carb intake with adapter plate on a stock L31 Vortec do the flip. His fuel trims went from near zero to -10%.

 

Fast355 you are the TBI Guru !

 

Well that's great info Chris. Thank for that.

 

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I know a guy who has one that needs to be finished. He might be interested if the right price were offered.

 

I decided against headers for now, I don't think the 305 will be taxing them too hard. I had a true dual exhaust system installed exiting in front of the rear tires and I got the 081 heads done as of today, Took about 7-8 hours over a few days. Bottom end still feels good but it really woke up from 3000 to about 5200. I don't think the head swap would be as noticeable without the cam. I got tunercats hardware, software a couple weeks ago. I got my shift points and lockup dialed in nicely, no more standing on it for a downshift. The 081's wanted 10 more degrees timing than the 087's that they replaced, I went up to 14 and got some very light pinging when loading it up so I backed down to 10 to keep it safe until I learn how to build a real timing curve. I installed 350 injectors and changed it to 61 lbs in the software, feels better at wot. I need to get a wideband and see where my fuel is or datalogging hardware, According to my plug readings it seems about right, But that's all I can do for now. I added a injector pod spacer, I also installed a vette servo a while back, Best thing coulda done to the 4l60e for the money. I'm sure there's more power in dialing in the tune but I'm still researching and taking in as much as I can, Overall I'm very happy with it and would do it all again.

 

IF you gained power down at 3,000 rpm it is from the timing advance change. The 081s will not outperform a set of 187s until over 4,000 rpm. That being said the cast iron manifolds are not a restriction per say, they more lack any kind of scavenging effect. If you could find a set of Doug Thorley headers they would be ideal. The ones they once built for the G-vans had the collector even with the transmission crossmember of my 4L60E. They gave even my 305 a tremendous shot in the arm in the torque production department. I can show you what a real timing curve looks like for the 081s when I sit down and boot my laptop up. Vette servo is ok, but does nothing for the holding power in overdrive. For that you need the Superior Billet Servos which I highly recommend.

 

I kinda wish I had went with headers, I started too then I spent the money on the tunercats stuff and just had a new exhaust installed, now I would be out $280 for the exhaust plus the cost of headers and another exhaust, So I'll be using the manifolds for a while. lol The specs on my cam are 204 int./214 exh @50 and lift is 0.421 int./0.444 exh. The cam was the first thing I done, I bought it for a 350 I had, then I sold it so I decided it too throw it in the 305, It was worth it all day. I would really like to see a tpi timing table if you have it, Be nice to compare.

 

TPI Timing map has a huge hole in the midrange where the timing is retarded for the TPI units resonance effect on cylinder pressure. I used the factory CCC Q-Jet van timing table as a starting point for a TBI conversion on an earlier LE9 305 van and it worked well. I also have an 85 L69 Monte Carlo SS timing table and an 83 GrandPrix LG4 table. The non swirl port, non Vortec 305 heads are all similar in burn rate. Those being the 601, 416s and 081s or similar.

This is the LE9 van table. It is physically smaller with less resolution but fill in the values that match and interpolate the blanks between manually. Big box of a van does not need alot of WOT timing on 87 octane, will detonate badly on a long hard uphill pull with more than about 26-30° total. My standard HEI had 26° total at WOT and had a 20° vacuum advance canister giving 46° total at high rpm, light throttle on my 83.




This is the 83 LG4



This is the 85 L69 although I feel it probably has too much WOT timing for the van with its stock torque converter. Could always try it and see what happens. Then again you never know, my LE9 had factory flat tops with 6cc worth of valve reliefs and was higher compression then a TBI 305 with its flat top piston and 53cc 601 heads. It had a 194/203 @ 0.050 cam on a 112 LSA stock. Mine was also stock converter in the 700r4 and 3.08 gears. In addition to being lighter and more aerodynamic the Monte SS had a wider 115 LSA cam with 202/207 @ 0.050 (less cylinder pressure than a 204/214 @ 0.050 on a 112 LSA), a ~2,000 rpm stall converter and 3.73 gears. The Grand Prix had dished pistons and an 8.6:1 compression ratio with a 3spd TH200C and 2.43 gears. The LG4 also had the smallest cam at 179/194 @ 0.050 on a 109 LSA. The WOT timing on the LG4 was the least but so was its power output of only 145 HP.




Set the distributor to 6° and set the Initial value to 6° in the BIN file.

 

Thanks for those, I'll look them over and see If I can come up with something better. Here's what I'm running for now, There is still 9.8* of bias in this as well, I'm unsure if I should just zero that out when building a table??

 

Leave the bias values alone. Was that the stock table or after adding 10°? Assuming your initial timing value matches the actual initial timing value and you have not jacked with the bias values that map is not far off the stock CCC Q-Jet van. I set the Off-Idle and Idle tables to the same values. What module do you have? Is it a factory GM one? The 048 module will retard the timing over 3,500 rpm. The 369 module will advance it 2°. If it has a 369 module that will give you around 26° total timing. Might be able to sneak another 2-4° into it in places but you should not be too far off.

PS if the balancer ring has slipped replace the balancer. It is a bomb waiting to explode especially with the rev-limit increased.

​​​

 

A genuine GM balancer is only $65 plus shipping on RockAuto. Better off safe than sorry. Not to mention they are balanced with the ring in a specific spot and likely out of balance which will put stress on your crank snout and front main bearing.

 

I wish we had talked before you had your exhaust done. Summit racing has a very nice header and bolt together dual exhaust system for the G-vans that exits in front of the rear wheels. I installed one on a dual rear wheel cutaway RV and it ran very nicely. Had previously installed a 406 TBI small block in place of the TBI 350. Really helped perk up that 400. The owner chose to add a bolt-in universal H-pipe setup right behind the transmission cross member. Under heavy load, towing a boat uphill sounded great too. Nice and mellow idling around as well as cruising at speed but the perfect V8 sound under acceleration. The pipes were a little narrow for the wider RV body but it allowed a pair of long 3" tips to be added. Long tube headers will give you more of a torque increase than the heads or the cam, likely more than both combined. I have seen the comparison on a bone stock smog 350. The 350 gained 53 ft/lbs of torque with the 1-5/8" long tubes compared to the factory log style manifolds like the vans use. Scaled for displacement that is 46 ft/lbs on a 305. I promise I am not inflating how much more midrange torque headers will give a gen 1 small block from their scavenging effect. A 305 with decent heads, mild cam and long tube headers will have more torque through most of its rpm band than a stock 350 makes at peak. Years ago I ran a 305 bored 0.040" with flat top pistons, zero decked with a 0.038" compressed head gasket, stock 081 heads, Melling CS274 cam (stock 350 cam), edelbrock performer TBI intake, stock 350 TBI unit, thorley tri-ys and the factory 2.5" dual pipes with a X-pipe and the factory mufflers. Put 191 hp to the tires and 278 tq. Saw a stock 350 TBI dyno done, it made 140 hp and 220 tq at the ground. My stock as it came from GM 97 Express van with the 5.7L Vortec put down a whooping 185 hp and 250 tq on the same dyno.

https://www.summitracing.com/parts/s.../model/g20-van

 

This is the H pipe crossover kit we used on it. Used the V shaped pipe to give some added clearance under the 4L80Es tail shaft and the massive driveshaft. Some form of crossover is essential on a true dual exhaust. It evens out the back pressure and helps further scavenge the cylinders giving you even more low-midrange torque. H-pipe is easier to fit than a X-pipe unless you have both pipes side by side on the driverside like the stock 80s G-van true dual exhaust tubing I have on my 83 G20.

https://www.summitracing.com/parts/sum-642022

 

One other tip I have....The mechanical fan is a noise making, HP sapping, fuel economy robbing parasite on these vans if you are not towing anything. I used a pair of fans from an 06 Nissan Maxima that fit my 28" wide radiator like a glove after cutting down the mounting tabs. Some vans have a 31.5" wide core and some GM FWD cars have that dimension as well. I like the Nissan fans because they are so easy to get dual speeds out of. There are 4 wires in them. 2 sets of coils that are linked together. Wire up one coil and you have low speed. Wire up both coils and you have high speed. Wire the matching coil of each fan to the other fan and hook it to a relay, you get low speed. Hook the remaining coils together and you get high speed. I wired one relay to a constant ground and hooked up the positive wire to switched keyed power to trigger the low fans on the key. Then hooked the 2nd relay directly to the power feeding the relay, and used a 185°F temp switch in the passenger side head to trigger high fans. Running a 170°F thermostat was perfect. I also added a relay to the a/c clutch signal to invert the signal to a ground signal. I wired the new ground signal to the same relay as the temp switch. I used cheap weatherproof fuse box with 6 fuse terminals and 5 relay spots to house the relays and fuses. My a/c was colder around town, my engine never got over 190°F in the heat of summer and it made the van much quieter and got 1-2 mpg better. The way it worked was simple, when I started the van the low speed fans came on to give the engine compartment some air circulation, as the temperature came up the thermostat opened and the coolant temp would stabilize. If I beat on the van and it got over 185°F the high fans would trigger. As soon as it cooled off the fans would go back down to low speed. If I turned the a/c on the fans would come on high speed and stay on high speed until the a/c clutch cycled. When the clutch cycled the fans would drop down to low speed. Then when the a/c clutch kicked back in they would return to high speed. During the winter time where engine temperature was not a problem, I would remove the fuse for the constant on fan, saving wear and tear on the motors and allowing the engine to warm up more quickly. If the engine ever needed the fans to come on, it would trigger the now low speed function through the remaining relay tied to the temp switch. If I turned on the defrost the activation of the compressor would also turn on the fans on low speed. Low speed was more than adequate for cooling the engine and a/c condenser in cool weather. One other thing, with the temperature switch in the head controlling one relay, if the engine was shut down above 185°F the fans would run on low speed for several minutes to help cool the engine and engine compartment. I did this setup when I was carbureted and it really help keep the fuel from being boiled out of the float bowl when the engine heat soaks after shut-down.

I got my fans out of a wrecking yard and robbed two housings of the more powerful 5 bladed condenser fans and motors. Paid $20 for the whole thing with the matching harness pigtails.

 

Fast. Thanks for all the advice and help I sure do appreciate it. Sorry I haven't responded back sooner, I been pretty busy with work and all that. So I got a datalogger and worked on that for a while, All my blm's were at 94 and it was running pretty rich. After some tweaking over and over and over again and again, Remember I'm new to tuning and wanted to do this myself, I got my them within 5 of 128. I'm calling that a win for now. It's running very well, I also installed a 180 thermostat I've modified the timing table, I'm use to setting up carbureted distributors so I just applied some of the same theory, I cant use knock counts at he moment because They never stop even when Just the key on and its trying to pull 24 degrees of timing at any given moment, So I had to zero out what its able to pull until I figure it out, I also installed a new knock sensor with no change. This has been going on for some time I believe because I always had to run extra timing to get it to run okay, Making me thing my balancer had slipped, I have a new one anyway. But its running great, Pulling hard for what it is.

 

Does it still show knock counts if you unplug the knock sensor?

 

@BrianPaul69

Send me pics and asking price of what he has, and location. Thanks.