Very nice! Your machining skills are impressive.

The thing I like the most about your design vs the standard sandwich adaptors is that the remote oil filter can be plumbed ahead of an oil cooler. This will save the oil cooler in the event the engine grenades.

The posi suggestion brought to mind a problem I solved on a customers car a long time ago that was posi related. Without going into a detailed explanation the problem turned out to be tires. Both rear tires had identical size markings however when both tire circumferences were measured there was a 1.5 inch size difference left/right.
Suggest measuring tire circumference @ the center of the rear tire thread.

Rear tires of identical circumference = a happy posi unit

When in reverse the motor wants to torque counter clockwise when viewed from the cockpit. Suggest checking motor mounts for tightness, integrity etc. Hood open & brake torque in reverse should give a visual on motor movement.

Dog bone & bat wing bushings are also suspect.

C beam bolt torque OK?

I'm a cheapskate so -- maybe get her a pillow?

There is no way on this earth that port size has anything to do with cracking a manifold.

The cracking that you or the previous owner experienced is a dimensional problem or a quality control issue with the manifold when it was manufactured,

If an intake manifold is installed on an engine that has been decked and/or has had the heads milled the manifold must be machined to match that particular engine. Normally just the front & rear (china wall) seal areas need to be milled off to allow the manifold to fit deeper into the engine valley. Extreme cases require metal removal from all 4 mating surfaces & the proper intake gasket thickness for a proper fit up.

You will do much better with head ports that are bigger than manifold ports = no reversion. If this is a grocery getter just paste anything together. If you want HP @ +6K rpm it needs to be set up properly.

Quick check: Set the manifold on the engine without gaskets & check if the bolt holes line up. If the manifold sits high the end rails need to be machined. If the manifold sits low use shim stock to raise it up. Shim both sides the same amount. When you have it lined up measure the thickness of the shims, add .020 = thickness of intake gasket required.
Good luck

Intake air reversion (read severe turbulence) will occur if/when the head port entrance is to small & creates a "shelf" area @ the mating surface..

Depending on the heads being used it may be possible to bevel the intake port to match the manifold exit port size eliminating the reversion area (shelf). Theoretically this change could be beneficial. IE: Large air volume from the intake flowing into a smaller head port may create a positive pressure behind the intake valve producing a better cylinder fill.

Cannot say if the above actually works in practice however my semi-functional brain cell(s) say it is a possibility.

Luck with your project.

was not aware of your 383 configuration, my bad.

If figured using a percentage scale an increase to a 52mm TB from a 48mm is basically the same increase percentage wise as a cu in increase from 350 to 383 = good to go.

CFM flow numbers here:

http://www.gmtuners.com/flow/index.htm

48mm TB flows 780cfm, IMHO this is plenty for a street driven car with a 350 cu in engine. Increasing TB CFM moves the power band up the rpm scale & lessens off idle/low rpm throttle response unless the car has a stall converter &/or
rear gears of 3.50 & higher.

Just my opinion, your car your call.

Been a long road, Grats on getting it sorted.

Has the ignition timing ever been checked?

Unplug the single black weather pack wire connector for the tan/black stripe wire located @ the top of the brake booster, set timing @ 6 degrees, plug the connector together.

This is going to sound dumb but stranger things have happened. Is the emergency brake completely disengaged?
On mine if I do not hold the button in until the lever is all the way down on the floor the E brake is still applied.

One thing for sure you certainly have patience. If this were my job I probably would have torched the sucker by now.

Good luck.

Might try driving it for awhile, make adjustments as needed.

The following info was found some time ago, never had a need to try it perhaps a forum Guru will comment.

RESET BLM'S

Open the hood on your Corvette after the engine has sat overnight or fully cooled off.
Then turn the headlights on.
Unhook the Negative or positive battery cable for 5 minutes.
Reconnect the battery cable.
Shut the headlights off.
Then without touching the gas,
start you car.
Let it idle till the engine is fully warmed up & the main cooling fan kicks on & cycles off.
Then shut the engine off.
Restart your Corvette.
Go for a 10 minute ride in town & on the highway.
You have just reset all BLM tables.

The IAC may be dropping out to early suggest trying the base idle @ 550 to 600. If that works leave it until the ECU relearns the system.

Mine had a microscopic flat spot off closed loop idle what finally eliminated it was a TPS setting of .58. It still gave 31 mpg left lane interstate. AC off, 6sp car. Ran it that way for 3+ years.

If the bolt threads are damaged the manifold or head threads in the aluminum are damaged.

Ace hardware or NAPA should have the proper size tap to hopefully clean up the female threads without them needing heli-coils. Take a good bolt with you to determine the thread size. Purchase a tap & 2 new bolts. If you can use bolts that are slightly longer get them.

Some grease on the tap will collect the shavings.

Suggest WD40 while it is running. Spray all the gasket joints. If the motor "catches" & runs smooth for a second or two you have found at least one vacuum leak.

Did you dry fit the base manifold to check manifold to head clearance? If the manifold has been milled for use on a block with zero deck or with milled heads you will need thicker manifold to head gaskets. If you had trouble getting the manifold bolts started in the heads it more than likely has been milled.

Quote:

You need a good digital voltmeter that will read voltages less than 1 volt.

The setting is .54 = just over 1/2 volt.

Merry Christmas "Doctor"

L98 injection is batch fire not sequential. It does not make any difference which connector is attached to an injector.

Suggest cycling the ignition. Key on for 5 seconds then off, repeat 4-5 times this will fill the fuel rails etc.

Check the firing order.

This may help

[URL=http://s863.photobucket.com/user/churchkey/media/vettevacuum2520lines.gif.html][/URL]

Amazon 69.95 & free shipping

search "digital inspection camera"

This system may work:

A piece of cloth taped over the end of a length of heater hose then tape the heater hose in a vacuum nozzle & suck the bolt out of the runner.

Good luck.

Nice job!

FYI - A post on CF = a fellow dropped a bolt down the distributor hole while working with it removed. Maybe stuff a rag in the hole to keep debris out?

Check the wheels at the inside & outside lips for lateral & radial run out = .030 maximum on each plane.

If the rear jack stands are placed under the body jack points = to much half shaft angle. Place the stands under the shock mount bolts, retest.

Inspect all u-joints for signs of wear. Any redish dust = a failing joint.

Car in gear/park engine off have someone try to turn a wheel forward/back while you inspect each joint. There should not be any play/movement between the shafts & companion flanges/front yoke.

If all checks ok have the tires balanced on a Hunter road force balancer.

GL

What BillH said.

Suggest checking the 6 universal joints if any have been replaced they will have grease zerks.

If injectors came with the new engine = not worn better spray pattern that equates to better fuel atomization.

Timing chain & gears are not worn out = camshaft timing is not retarded. Throttle response coming off idle & in general should be crisper than the old engine.

Welcome, very nice ride.

It is clamed that C5 brakes work better than C4 brakes because of the C5's increased pad area. IMHO it is because the C5 calipers have a larger piston diameter of
1.62" compared to the C4's 1.5". C5 calipers = a change in the front hydraulic ratio that provides more pad pressure for a given pedal pressure. You can acheive similar results using an eariler year master cylinder with a smaller bore size. Your master cyl = 15/16". 88-91 master cylinder 7/8". While the master cylinder is off the vehicle suggest a DRM brake bias spring be installed it will improve rear brake performance.

If you require statistical data on the hydraulic ratio changes I'll pull it off my shop computer.

What vetteoz said.

Summit & other vendors sell red caps & high output coils. The red caps will work on our screw on cap distributors with a quick modification. Whiz wheel the "L" off the spring loaded distributor lock on screw. Remove the remaining pieces, use the hold down screws from your current distributor.

Good Luck.

You can check the amount of charge in a system by checking the low side pressure.

Have the vehicle in shade & insure the interior is at ambient temp.

A floor fan or box fan blowing at the condenser is recommended.

Windows up, start engine, AC set to lowest temp setting, recirculate, max blower fan speed, exit vehicle, close doors.

Use some type of device to hold the throttle open @ 1500 rpm.

Allow the system to operate approximately 5 minutes to normalize before reading pressure.

The low side quick read: up to 80* ambient temp 28# up to 90* 28-32#, over 90* 32-36#.

Pressure below above #'s = add more freon.
Pressure above stated #'s = let some freon out via recovery equipment.

Its not an exact science as some would lead you to believe, a difference of say 2# will show minimal if any difference in vent discharge temps.

Center vent discharge temp = 36 to 48* Discharge temps vary dependent on temp blend door, recirculate door operation, cleanliness of the evaporator, fan speed of the blower motor, loose vent ducts etc.

Rinsing the condenser aids freon cooling. A garden hose works, commercial condenser solvents are available.

The compressor will run without freon in the system for charging purposes. To enable the compressor: Remove the E connector plug from the low pressure switch. Use a jumper wire or paper clip to connect the terminals inside the E connector.

Leak testing with an electronic tester = best results. Mine will pick up a leak as small as 1/4 ounce yearly.

Good luck

Quote:

Yep, handy stuff. 3M calls it Strip Calk.

Agree with Matatk. Fresh master & a complete fluid flush/change. Brake fluid collects moisture over time which equates to a lower fluid boiling point = loss of pressure.

Valvoline synthetic brake fluid works well for me.

Probably a timing thing. Streched timing chain + according to conversation on CF the opti can be off a number of degrees internally. Being a standard shift the engine will go from load to no load instantly, cam & ignition timing will change instantly if the timing chain has stretched. It will probably happen again.

Since it sneezed (old biker & track racer term) suggest checking all vacuum hoses & caps on the intake as they tend to blow off when there is an explosion in the intake manifold.

GL

Did it backfire out the exhaust or sneeze through the intake?

Taurus - Lincoln Mark fans really move some air. Do not have a good link to post however Google will get you info on the fan.

Quote:

When I had the 89 auto I found that it was crisper around town using "3" instead of OD. Select OD when cruising @ 45+ MPH.

91 may have a "range" button same as the 90, no "gauges" buttom. (unsure about 91 dash)

The analog gauges on my 90 read high. Suggest checking radiator in out temps with a digital hand held pyrometer to compare to the dash gauge. Or you can monitor the upper radiator hose. As soon as it gets hot when the thermostat opens see where the temp gauge is sitting. It will probably indicate 3/4 hot.

Fans do not run when vehicle speed is 55+ mph.

Main fan should cycle at 228* without the AC on. If memory serves the temp trigger switch for the main fan is located in the thermostat area. Will check later to verify. Switch in right head (exhaust manifold area)is for temp gauge.

Main fan runs when AC is selected? It should. Coolant temps will actually be lower when the AC is in use. I use the AC mode to keep it cool in traffic.

For summer operation: Suggest connecting the 2 fan relay ground wires together. Relays are grouped together, left side of fan shroud.I use male/female insulated spade connectors. Both fans run when AC is in operation or 228* engine temp is reached. Jumper wire is disconnected for cool weather operation.

If this were my project:

Loose the ASR & ABS.

Convert the dash to the aftermarket analog unit. Other LSx products are available.
http://vettaid.com/ReplacementGauges/19901996Corvettes.aspx


Use a Howell harness.
http://howellefi.com/gm-ls-series-pro ... ls7-2006-08-products.html

GL

Suggest a length of .030 or .035 MIG welding wire to gauge clearance.

GL

E = M X A explains rotating mass difference or for that matter anything involving movement.

One should also figure the swept brake area differences between rotor diameters. With all other factors being equal a larger diameter rotor will pass more brake surface area past the brake pads per wheel rotation = better stopping.

GL

Quote:

Spent 1/2 hour looking for the old injectors. Cannot find them so --- cannot help with #'s.

Injectors are batch fire, if one shorts it can stop several if not all from functioning properly.

Your problem appears to be heat related & could be injectors or the ignition control module in the distributor. (ICM)

Will check my take out injectors when I'm at the shop tomorrow & post the number that is on them. Maybe when I break for lunch.

Egr is under the plenum.

Still using multi tech injectors? My 90 ran as you described when the stock injectors began to fail. Suggest ohm checking them, engine cold & hot.

A taller tire on the front will decrease the scrub radius as compared to stock suspension design & tire size.

A smaller tire will increase the scrub radius.

If you have the same results with another oil gauge you may be experiencing cavitation at the pump pick up.

Suggest modifing the pump pick up or build a new one.

The problem is the stock 90* cut off at the pickup inlet which will cause cavitation. For a visual watch water as it drains from your bath tub. You want the inlet to be cut at a 45* angle then heat & roll the edge to form a flare. Get the pickup pointed at rear of the pan & 1/2" off the floor of the pan. Some SS screen material shapped like a bulb can be clamped to the pick up end.

Luck.

Here's a "how to set" on base idle, tps & IAC. This one is a bit wordy but its what I have on this computer.

Technical Information Bulletin Rev. B 5-31-04

How to Adjust your Early C4 TPS and Idle Speed
by Lars Grimsrud
Colorado Corvette Crazies (CCC)

The Ultimate Corvette Tuning & Beer Drinking Fraternity
Lafayette, CO

This tech paper will discuss the procedure for correct adjustment of the Minimum Idle Speed and for adjustment of the Throttle
Position Switch (TPS) on the early C4 Corvette TPI systems. These steps apply specifically to the 1985 model year, and in
general to other years. Later model years do not have adjustable TPS’s.
NOTE:
The Minimum Idle Speed sequence outlined in this paper is taken directly from the 1985 and 1986 GM Corvette Service
Manuals with some clarifications and simplifications added by me. Be aware that there are aftermarket manuals that outline a
different sequence. I have used the sequence in this paper and verified that it is correct for the model years noted. You may
choose to use the procedural sequence outlined and recommended by others.
General
Idle speed and off-idle throttle response on the early TPI systems is determined by correct adjustment of the minimum idle speed
screw combined with a correct setting of the TPS. I’ve seen many of these cars that have had their idle speed “corrected” by
well-intentioned mechanics and owners by simply screwing the minimum idle speed screw in a few turns. This really messes up
the settings, and will not make your car perform properly. Doing a correct setup of the TPS is one of the easiest ways to make
your car feel and respond better. To maximize the benefit of this procedure, I recommend that you first remove your Throttle
Body (TB), disassemble it (it’s incredible easy – there are a total of about 5 pieces in it…), clean the TB up really good with
some spray carb cleaner, and put it back together. A nice clean TB will really put an edge on the performance improvement you
will get by doing this procedure.
NOTE: If you disassemble and clean your Throttle Body, including removal and cleaning of the IAC, it is recommended that
you measure the extended length (protrusion) of the IAC “tip” before you re-install the IAC. If the “tip,” or “needle” of the IAC
(referred to correctly as the “Pintle”), is extending out too far, you will jam it into the seat and damage it during re-installation.
So before you install the IAC, measure the distance from the very tip of the Pintle to the surface of the IAC body that the gasket
seats against (with the gasket removed). The distance should be 28mm (1-1/8”) or less. If the distance is greater than this, you
must retract the Pintle into the IAC Body. There are two different styles of IACs:
If your IAC has a “collar” around the electrical connector end, simply push on the Pintle with firm hand pressure while rocking it
slightly side-to-side until it retracts.
If your IAC does not have a “collar,” compress the Pintle Retaining Spring towards the body of the IAC and try turning the
Pintle clockwise as seen from the Pintle end of the IAC. If it turns, keep turning until it retracts to the 28mm position. Then,
return the spring to its original position, with the straight part of the spring end lined up with the flat surface under the Pintle
head. If, however, the Pintle does not turn, use firm hand pressure as described above to retract it.
Once set up, install the IAC with the gasket and torque to 13 ft-lbs.
The Service Manual has instructions for doing the following operations, but the directions are scattered through several sections
of the Manual. Here is the complete, step-by-step process for doing this (not including TB rebuild). All specs and steps are taken
directly from the Manual (all 3 different sections), and this process is absolutely correct.
Tools & Equipment
You will need the following tools and equipment:
1. A set of Torx wrenches. You can buy a complete set in a nice, genuine plastic pouch at Sears.
2. A good digital voltmeter that will read voltages less than 1 volt.
3. A paper clip.
4. A small screwdriver.
Procedure
There are two electrical components on the TB that you will be working with: The TPS and the Idle Air Control Valve (IAC).
Make sure that the connectors for these two components are easily accessible and that you can easily disconnect the IAC.
You will also be playing with the diagnostic connector under the dash. Remove the cover (if it’s still in place). Bend your paper
clip into a “U” shape. You will be playing with the two top right hand terminals (“A” and “B”) in the connector.
• First step is to set the minimum idle speed. If nobody has messed with this on your car before, the set screw will be covered
by a pressed-in plug. It’s located on the driver’s side of the TB. Remove this plug if it’s there.
• With the IAC connected and the ignition “OFF,” stick the paper clip into the diagnostic connector from “A” to “B.” This
grounds the diagnostic lead.
• Turn the ignition to the “ON” position without starting the engine. Wait 30 seconds.
• Now, with the ignition still in the “ON” position, disconnect the IAC connector at the IAC.
• Remove the paper clip from the diagnostic connector.
• Start the engine and allow it to reach normal operating temperature. The idle speed will probably be really low, and you
may have to coax the engine a bit with the gas pedal to keep it running for a while.
• If your car is an automatic, set the parking brake and put the transmission in “DRIVE.” If your car is a manual, leave it in
neutral.
• Adjust the idle speed screw to obtain 400 rpm in drive or 450 in neutral.
• Shut off the engine and re-connect the IAC.
NOTE: Some later year GM Shop Manuals recommend disconnecting the distributor ECM wire (“Timing Connector”) near the
brake booster. This will prevent the ECM from altering timing – and idle rpm – during the rpm adjustment. Early GM Manuals
do not contain this step. If you disconnect the timing connector, you will get a Code 42 stored in the memory of the ECM. The
memory must be cleared of this code after re-connecting the timing connector.
That’s it for idle speed. Now on to the TPS.
There are 3 wires stacked vertically on the TPS. You will need to be able to measure the voltage between the two top wires.
You can either buy a special harness connector that breaks these wires out (from Mid America), or gently pierce the insulation of
the wires with the pointy prongs on your volt meter. You can also stick a paper clip into each of the two top locations of the
connector and clamp onto the paper clips to measure the voltage. Whatever is easiest for you.
• Turn the ignition to the “ON” position without starting the engine.
• Loosen the TPS Torx adjustment screws.
• Set your volt meter to a low scale DC volt setting that will accurately read less than 1 volt.
• Measure the voltage between the two top TPS wires.
• Adjust the TPS by rotating its position until you get a reading of .54 volts.
• Tighten the Torx screws and recheck the voltage. Re-adjust if necessary to make sure voltage is right at .54.
• Turn the ignition “OFF.”
You are now in perfect adjustment on idle speed and TPS output. Start the engine. It may take a few seconds for the car to
“catch on” to its new settings.
Questions, Comments & Technical Assistance
If you have questions or comments regarding this article, or if you notice any errors that need to be corrected (which is quite
possible since I’m writing this from memory…), please feel free to drop me an e-mail. Also, if you need any technical assistance
or advice regarding this process, or other maintenance issues, feel free to contact me: V8FastCars@msn.com

Lf upper = 14.3* down
Rf upper = 14.2* down

For a base line: also checked the chassis front/rear angle at the sill plates..
.2 degrees high in the rear.

Luck with your project.

So you want the front upper arm anti dive angle? Will check the 90 for you after dinner.

As far as the squat/anti squat instant center rear goes I believe DRM makes different front mounts for the dog bones & changes that angle for the better. I do not have DRM brackets so cannot help with that aspect. All I'm saying is that if your making brackets might as well make the ones that locate the components in a better place than stock.

Might try a search for roll center heights, changes etc.. I have seen some cad illustrations on the net but do not recall if the control arm / dog bone angles were specified.

Chow time.

Not an expert, believe that switch was eliminated for the 90 up models that use the speed density engine management system instead of the maf.

I put the ES12A in the wifes Jag instead of 134 & am pleased with the results. The ES12A uses the same screw on can adaptor as 134 uses.

Have no affiliation, got it here:

http://autorefrigerants.com/co00033.htm

My oval track engines always had screens over all the gallery holes held in place with epoxy to prevent valve train debris from entering the bottom end. Might be something to consider for the next build.

Do not know your set up however if any sustained rpm over 3K, suggest an oil cooler if you do not currently have one.

Also suggest a good trap door oil pan designed for the zig-zag tracks.

Luck with your new build.

Did you just change the radio? If so you need to install 2 resistors in the original radio wiring harness on 90 to 93 models.
If the resistors are omitted during the radio installation the AC will have the same problem as you are experiencing.

Just pull the fuel pump fuse.

All spark plugs out.

Throttle fully open.

Begin testing.

C5 caliper pistons are 40.5mm diameter
Converted = 1.62 diameter.

To find the sq in to calculate the hydraulic ratio between master cylinder & calipers.

Using caliper piston diameter 1.62 & equation
R squared X pi.

Piston sq in = 2.06 X 4 pistons = 8.245 (rounded)

Master cylinder sq in

3/4 = .44

7/8 = .60

15/16 = .735

Divide the master cylinder sq inch into the total
caliper sq in.

If using a 7/8" bore master cylinder the hydraulic ratio with C5 calipers will be 13.74

As a comp, stock 2 pot calipers with 1.5 inch pistons & using a 7/8 master cylinder the hydraulic ratio = 11.78

IMHO a ratio in the 14 to 1 range is ideal for power assisted brakes.

Manual discs require a hydraulic ratio in the 17-18 to 1 range.

Luck with your projects.