1984 SD4 Resurrection

[FieroWanaBe1]

I think I will wire both the switch and relay in the normally closed side and have 12V power switch on with Key Accessory.
If anything happens to the switch the control relay would default to pump run, it would only switch off when vacuum is achieved.
The data sheet shows the contacts on the switch are rated at 25Amp, and 10 million+ cycles, But I would definitely run it through a relay to preserve the contacts.
The switches used in the Summit or Jegs vacuum pump kits seems to garner a lot of bad reviews on the web, that looks more a switch with a spring adjusted preload, and lacks hysteresis or tuneability.

I don't know how GM is switching their pump on and off, I assume it is BCM controlled and is monitoring the GM CAN channels, I'm fairly certain GM is putting MAP sensor in their boosters as a reference.

And emergency pump override is still a good idea especially if it needs to be towed. A cursory google search shows quite a few complaints about a lack of brake pedal with people living at altitude on startup in the CTS. I would still like to plumb in the factory engine vacuum lines, so if the pump isn't working, I can still use engine braking to generate some vacuum.

[The Dark Side of Will]

At high RPM overrun, the engine will generate all the booster vacuum you could ever need. Use a check valve so the BBvac pump isn't trying to pump down the manifold at low manifold vacuum.
OEMs use aux vacuum pumps for operating regimes in which the engine is not making much vacuum, like idle or boost for turbo engines.

I do note that on Fieros, which use pressure cycling switches to control the A/C compressor, there are ALSO high and low pressure safety cut-out switches in the circuit. When GM switched to A/C pressure transducers with ECM compressor control, they got rid of the safety switches. Regardless of how reliable the pressure transducer is compared to the pressure cycling switch, the ECM can detect a fault in the pressure transducer and disable the A/C compressor in response. Disabling a BBvac pump because of a failed sensor is not a good option for safe operation of the vehicle, so I'm curious about how GM handled that capability.

My diesel Jeep has a cam driven mechanical vacuum pump. I actually haven't looked at what my diesel Benz has for running the booster. My diesel van uses a hydraulic booster.

[ericjon262]

if I were to run the brake booster off of a vacuum pump, I would also run a smallish reservoir up there, which should help limit duty cycle to the pump, as well as make brakes a little more consistent.


There is another option as well, have you seen the all electric boosters that are used by teslas and some other cars? I'll see if I can find a link.

[ericjon262]

here's a link to a youtube video about them. They're on ebay for about $250-$400

https://www.youtube.com/watch?v=SRZ8XDN ... erfastMatt

[FieroWanaBe1]

I have seen those boosters, I am just not sold on their use in high performance driving yet, seems more like a brake by wire deal, my concern is how pedal feel would be.
I have thought about a vacuum reservoir, but have to think about that more, and look deeper at the plumbing to the booster, which itself holds a volume of "air". The switch I ordered should have an adjhustable bandwidth which should help the duty cycle.

[ericjon262]

I might try one on another project, I'll make a separate thread for discussion later.

[FieroWanaBe1]

The throttle bodies I found on amazon (also similar models on Ebay for double the price) appear to be a clone of, or at least an assembled in china version, of the KMS DCOE throttle body:
https://en.kms.vankronenburg.nl/product ... ebody-twin
Which in turn appears to be a close copy of the Jenvey DCOE throttle, or vice-versa.
https://store.jenvey.co.uk/throttle-bod ... std-tbsxxi
Which is good, because it looks like their are multiple sources for a TPS solution that should be relatively easy.



I also ordered a Bosch 0227100211 Timing Module for controlling the dual output BAE 801 Coils I bought.
http://microsquirt.info/Bosch_211.htm
https://docs.gestionaweb.cat/1662/datasheet-bae-801.pdf
Ill need to find some connectors, hopefully domestic or I can make an order from AUS:
https://www.efihardware.com/products/37 ... r-plug-kit
https://www.efihardware.com/products/14 ... r-plug-kit
https://www.efihardware.com/products/38 ... plug-Bosch

[FieroWanaBe1]

Iron Head flow numbers.
Ran on a SF-750 @ 28" H2O
New graph Below.

[Shaun41178(2)]

That's pretty good flow

[FieroWanaBe1]

I think the flow stalls after .500 lift because the short side radius is very abrupt. I also think some work on the valve seat may help, it has a simple 45 degree seat and valve currently.

[FieroWanaBe1]

I reflowed the test today.
I plugged the EGR port to see if it lowers exhaust flow. No effective change.
I redid the intake, but changed how I mounted the dial indicator over to a mag base, because I did notice deflection, I should reprint those parts with CF nylon to see if that helps, but It did affect the numbers from low lift flow a lot. and the mid lift was offset by .050.

[FieroWanaBe1]

I pulled the shortblock from the car tonight.

I was always wondering what kind of clutch was used. What a nice surprise.

The 4-2-1 header looks salvageable mostly surface rust. but I think the primaries will be to small for the 801 head.

[The Dark Side of Will]

Need a spare clutch?

[FieroWanaBe1]

Your "spare" might be in better condition than mine, ill have to pull it apart and see the insides this week, I had originally planned on running a spec stage 2 unit, but 4 cylinder flywheels are all gone except used these days.

[FieroWanaBe1]

I pulled the pan off last night.

1. Lots of crud.
2. I have never seen journal braces like these
3. No obvious signs of stress, cam journals look a little rough, but not ruined.

I suspect based on the deposits in the cooling jacket, someone ran BARs leak in the coolant.

[The Dark Side of Will]

Nice rods, but the pan is on the sludgy side.
Looks like the oil pickup is welded? Was the bracket modified to make up for the extra thickness of the main cap toppers?

Going to have the block tanked?

I've read that Ross pistons tend to have stiff skirts that beat the cylinders up and oval the bottom ends of the bores in the perpendicular direction over time.

[FieroWanaBe1]

Nice rods, but the pan is on the sludgy side.
Looks like the oil pickup is welded? Was the bracket modified to make up for the extra thickness of the main cap toppers?

Going to have the block tanked?

I've read that Ross pistons tend to have stiff skirts that beat the cylinders up and oval the bottom ends of the bores in the perpendicular direction over time.

The pump pickup isnt welded, just RTV and sludge. It is bolted to the cap straps, it must have been modified when built. The engine also has the large sump Moroso drain back oil pan. Ill have to pull off the shelf and snap a photo on the Canton dry sump pan I have.

I think I want to find a harmonic Dampener for this engine, it has the stock 84 v-belt pulley and flange, not dampened. I will ditch the Aluminum Cam gear and go to the straight cut steel gear I bought. If I can get away with another 1/4" of stroke, I'm sure the engine will have all sorts of harmonics it needs help with.

I haven't given up yet on running a hydraulic cam, but I need to verify that the relocated valve centers with the 801 head play nice on this earlier block and I don't need offset lifters.

Spoke with techs and Jesel today, they can offset the lash adjusters on the 801 rocker kit, but it's now $1350. I want to find a used set. But lost my Old Europe log in and my registration email has been shut down, A couple of user post up try ign to buy/sell/trade SD4 parts frequently. Hoping someone has some. Asked about info on this head on speed-talk, maybe someone has some information on how they assembled these engines.

cc'd the intake on the older iron '322 SD4 head, 180cc.

average velocity in port is 230 at peak flow.

[FieroWanaBe1]

Pistons where pounded out of the block Sunday afternoon.

[FieroWanaBe1]

OId Camshaft, I emailed Lunati for information.
I assume the name means cam is a 295 Duration @ 522 peak lift.

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I would like a cam that goes to at least .600 lift, hard to find flat tappet cams that high, but Isky offers one.
Solid roller is a huge jump up in lift and duration.

The oil pump is seized, pulled it out and part of this bushing came with, I think that may be the failure mode of the engine, that or the pistons froze in the block first:

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I test fitted the head with the 1.7(Im thinking they are) roller rockers. I'm not sure they will work. The pushrod cup to fulcrum distance seems to short, the exhaust pushrod wasn't happy sitting in either cup of the lifter or rocker. The studs were also too long (even shorter per the SD4 build guide) and the pushrods are too short, since the surface is supposed to be raised .3" per Pontiac.

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exhuast rocker issue.jpg (39.15 KiB) Viewed 14569 times

[FieroWanaBe1]

I may have found the right rockers for use on the duke heads, if the information is all true through the 801 head. It been confirmed, mostly, up to the aluminum 437 head. Most manufactures have dropped the Duke from their catalogs, but BBC roller rockers have been used on the duke heads.
1.606 is the distance from valve centerline to the rocker stud.
A BBC rocker length is 1.650, Crower sells rockers with a set back for longer valves, .050 would be the bet fit, 1.6" from valve center to stud center.
I would like to use a 1.8:1, Crower PN 73685-8. for use with an ISKY Cam PN 951292 (292 Dur, .577 Lift w/ 1.7) Netting a .611 total valve lift.

Then on to the stroker woes. Not all SD4 blocks are equal. Mine is a very early (1983-1984) block, as the GM program matured the block changed. Block cast with Super Duty, instead of SD2.5 on the side appear to have different internal stuff going on. Almost all have roller cam bearings, and 5 journals. They also have longer piston sleeves.
Not mine. It is cast SD2.5, has a factory 3 journal cam bearingss, and the sleeves measure at 5 1/8 with a tape.

Pictures from fastindyfiero's turbo build show a deeper sleeve than my block at the base inside, by at least 1/4-3/8 of an inch, this makes sense as the Fiero moved from GTU to GTP-Light, it became a 3.0L and stroke grew to 3.625"

Now the math:
Factory Duke Deck height: 9.175" w/ 3.25 Stroke on 5.7 Rods = 0 deck Compression height of: 1.850"

Ross piston build:
5.125 sleeve-3.25 stroke -1.85 CH = .025" in the hole for the pin. Why did Hot Rod recommend a 5.7 Chevy rod with this block, when factory 3.00" stroke was on a 6" rod? The piston pin is barely still in the hole, and I'm sure the piston has beat the bore up.

Stroker Maths:
Factory Duke Deck height: 9.175" w/ 3.48 Stroke on 6.2 Rods = 0 deck Compression height of: 1.235"
5.125 sleeve-3.48 stroke - 1.235 CH = .410", That is better, and maybe something a piston mfg can deal with.