johnsonm

Woo Hoo,

I got the vortec heads and xe262 cam swapped and so far as I can tell didn't flatten a lobe. Great!!! Runs Awesome!

Now for tuning.

I have CE secondary rods and a G hanger in the feedback quadrajet, which I think are richer than the DR. Are these too rich? I know a little richer will help cool things down, limit detonation etc... But how much is too much? Doesn't bog really, plugs haven't fouled out or anything, just looking for good comprimise and close to optimal performance.

I have heard that vortec heads don't need as much timing advance. Has anyone seen benefit from switch to a zz4 computer or L69 chip for timing advance with vortec heads or will the LG4 computer be ok? I have initial timing set to about 6 deg.

Thanks!

Sonix

iTrader: (1)

I think the CE's should work fine, after checking that https://www.thirdgen.org/rods site
A later letter hanger would basically set you to where it's closer to DR rods, but I don't think you'll need it.
You can play with your air valve spring to get optimum power.

Can't say with the timing, i'm not sure how the LG4 computer does timing, but I don't think it's ideal. Meaning it probably isn't giving you "too much" timing.

five7kid

iTrader: (14)

I have also heard Vortecs don't need as much timing advance. If that is true, the LG4 chip would be "better" than the L69 or ZZ4 chips. Of course, playing with the base timing has pretty much the same effect.

No EGR could give you some light load pinging problems.

naf

iTrader: (7)

I'm running those heads and cam. I'd have to look to see which rods I'm using, car's at home. I'm at 9.4-9.5 compression cyphered from the advertised comp ratio of the crate motor and the change in heads/gasket. With 89 octane my engine seems happiest at 2-4 degrees advanced. Didn't notice any light load pinging but I did have a hint of light bucking under decel when running 8 advanced that I attributed to loss of EGR.

Do what I did: find a hill, run it hard to the top, pull into the school parking lot there (hopefully it's a holiday) and immediately pull a plug to read them.

johnsonm

No hills in central FL. I had the initial set at 12 and *think* I heard something when I jumped on it.

Moved back to 8 now. I cannot hear any audible detonation, even on cheap gas, but I know that is a poor way to tune something.

I am guessing CR is around 9.5 give or take.

I think I am running pretty rich across the board. I have a 180 degree thermostat with holes drilled in the plate installed to help limit overheating while breaking in the cam, and then my rich secondary rods. Could that hide or cover detonation that could occur with a closer to ideal air/fuel mixture and advanced timing?

naf, what computer/chip are you running?

Also, running out of fuel at high rpm's any suggestions on an affordable mechanical pump with a return line. I have gone through 1 carter "muscle car" pump and 2 A/Z or Discount AP pumps in the past 3 years, even with the 305 still in. Seems they last ok for 9 months then the diaphram gets weak?

Thanks!

naf

iTrader: (7)

I'm using the stock LG4 chip/ecm on my 87. I have upgraded the knock sensor and EST to the 350 model. When I first did the cam swap I had the old KS in. It was flat when I stomped it and I played with it for a while until I finally put a timing light on it with everything connected. I could rev it from idle and watch the timing immediately retard then pick back up. The new KS fixed that.

You shouldn't be rich at low/part throttle if your ccc-qjet is properly regulating the mixture. Have you hooked a dwell meter up to it? Vortec heads should be less likely to ping/more tolerant of higher compression/poor gas.

Can't help you on the fuel pump, I'm still running the cheap electric that came with the motor when I got it. Does your vehicle have the in-tank pump? and is it still working?

johnsonm

I still have the 305 KS and module. Let me get a little clarification on what you did to observe it was not working properly. In neutral, with the 4 wire connector at the dist hooked up, you revved the engine to like 3k rpm's and noticed the timing would retard then continue advancing? Would it retard immediatly, like at a low rpm or later in the game, after you built some rpm's?

Do you know if the computer you are using is the later one, don't have the numbers in front of me, but the same one used with the ZZ swap, same one that come with the Monte's and later F bodies? I know my computer is the earlier one (the one that had to be replaced in the zz swap). Would the Knock sensor and module work with my computer? Will an off the shelf KS for a similar year 350 work?

I have hooked up the dwell meter and got my 30 deg +/- swing. This was in the driveway, with the engine temp pretty high after some idling, revving adjusting this and that. I know I was in closed loop (or open, which ever one is being fed back from the computer). But on the highway, with flowing air flowing through the radiator, the water temp stays pretty cool. On fuel injected cars I think they may run a little richer to help warm the engine up (?) I was told the same would apply to the feedback quadrajets via the mixture control solenoid. I will be swapping the correct temp thermostat in this evening though.

About the in tank electric pump. I don't know. I haven't dropped the tank to check for sure. There are two wires (that I can see) running to the tank, I figgured these were for the fuel gauge. I haven't found a fuel pump relay or fuse any where. Do you know of any other easy things to do to know for certain whether or not I would have an in-tank pump?

This thing runs pretty good at full throttle (aside from running out of fuel) but I would have expected more at part throttle. Probably all the things we are talking about.

Thanks for your help!

naf

iTrader: (7)

On the KS, after it was warmed and holding a timing light on it I could quickly blip the throttle and observe the timing initially retarding. I assumed it was because the 305 sensor was misdiagnosing knock from the (larger than stock) cam. I swapped in a KS and EST module from an 87 350 (TPI) and it works properly now.

I'm using the original 87 LG4 computer.

If you need to verify that you're in feedback mode while driving, you can hook up the dwell meter and run the leads under the cowl into the pass seat. You're probably good with the 180 t-stat.

You probably don't have the in-tank pump, but it could help explain why you're having starvation problems if your mech pump is trying to pull through a dead one. Have you verified fuel flow for your mech pump to make sure it's causing your starvation?

johnsonm

Verified fuel flow, like by filling up a graduated cylinder for a specified number of seconds? No. I guess you are saying look into something else as well, like a clogged fuel filter?

Just a plain ole off the shelf, knock sensor and module for a 350 tpi motor is the ticket. No GM performance parts, can't hardly find anymore, zz conversion kit, way over priced just cause they can be, sensor and module... Wow, I'll have to look into it.

Thanks again, you are very helpful!

naf

iTrader: (7)

From one of those maintenance 'manuals':

"Pressure test:

1. Disconnect the fuel line at the carburetor, then connect a fuel pump pressure gauge. Ensure the carburetor float bowl has a sufficient amount of gasoline.
2. Start the engine and check the pressure with the engine at idle. If the pump has a vapor return hose, squeeze it off so that an accurate reading can be obtained. Pressure should be 5 1⁄2 –6 1⁄2 psi.
3. If the pressure is incorrect, replace the pump. If it is within specifications, go on to the volume test.

Volume Test
1. Disconnect the pressure gauge. Run the fuel line into a graduated container.
2. Run the engine at idle until one pint of gasoline has been pumped. One pint should be delivered in 30 seconds or less. There is normally enough fuel in the carburetor float bowl to perform this test, but refill it if necessary.
3. If the delivery rate is below the minimum, check the lines for restrictions or leaks, then replace the pump."

I've had the little filter check valves cause enough restriction to starve the motor even when new.

johnsonm

Much Thanks to naf, you are very helpful.

Ok, just a follow up in case anyone stumbles across this with similar issues and would care to know the results.

Fuel pump was weak. Replaced fuel pump with $15.99 NAPA speacial. Carter M6626 fuel pump, no more run dry on fuel at top end. Engine wanted to pull further than I was interested in letting it go (5800+)

Still had what I considered a lack of perk, at part throttle. So, I got a junk yard ESC module (16128261) from a 90 something van and a new knock sensor for a 350. And now I *feel* like there is a little more response at part throttle acceleration. May just be placebo effect.

Also replaced thermostat (had plate drilled with 3 x 1/8th inch holes) with plain 180 degree thermostat. Now holds steady temperature when running down the highway.

naf

iTrader: (7)

Good deal. One last thing you can check to fine tune is your TPS voltage. The TPS tells the ECM when to bring in the advance. Measured off the two lower leads it should read around 0.40 volts at idle and go up to 4.0 volts at WOT. Don't have to have the engine running just ignition on. You'll have to sneak in some needles/thin wire into the rear of the connector for leads.

If you have to adjust it any don't buy the special small tool. Just pop the cover and lightly tap an appropriate roll pin over the adjustment screw.

You're probably dead-on but it's so easy to check, although you've probably already done it.

Fresh air intake is super important too. With the taller intake I've got limited clearance. I used a drop base and just screwing the lid on caused a change in dwell. I've got most of the pieces/parts to fab a dual snorkle, one more trip to the JY. Would love to find the $$ for a cowl hood...