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1984 SVO Mustang la2 swap?

5K views 30 replies 6 participants last post by  alboy84svo 
#1 ·
anyone have a write up on this swap? i already have the computer and injectors... do i need aifferent vam? anything else i need to change? any help would be great...
 
#8 ·
Just a few things:

1. You have flat top pistons vise the dished turbo ones? They are probably not forged then, and the compression ration might be too much now.
2. The LA series computers are more likely to knock down the timing on the 84 style intake because the knock sensor input is more "amplified" within the LA EEC.
3. If you are getting pinging, then make sure you have the timing set at 10* BTDC and not way advanced. Pinging is detonation. Detonation means burnt components and/or a blown head gasket.

As for the FMIC, yes, it will bring charge temps down and help, but the car should not be detonating without it. What grade of petrol are you running?
 
#10 ·
ok long story short... i did a headgasket and found out the car has speed pro flat top forged pistons in it... the sticker with the timing marks are gone on my car... there is a notch on it and from what i was told that would be TDC? is this correct? and every mark after that is 2*? so i go 5 marks up and that would be 10*? if i back it up to like 8* or 6* when im in boost it pops... ive been running 91 octane.. which is the best up here... but last night i went to vp racing and got a full tank of 100...
 
#11 ·
Marks sound right.

How do you know they are Speed Pro, and how do you know they are Forged? The top of the piston should look like the pic

Did you set the timing with the SPOUT unplugged?


What do you mean by "it pops"? Like how? From where?
 

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#12 ·
they had a pat number on them...Speed Pro ZL2455F75MM - Speed-Pro Power Forged Pistons i check timing yes woth spout out... when im in like 3rd gear around 2300 rpm and i floor it it pops out the exhaust once or twice... then pulls hard... the pining has gone away today with the 100 octane in it... i have timing at 12* and fuel at 40 psi... boost is around 17 psi... it seems fine now but anything besides this 100 octane makes it suck... everybody told me so far to junk the flat tops for stock... but the block has be bored over... what pistons do i need? and thank u very much for this help guys!!!
 
#14 ·
i've got a bored block i put wiesco's in it that i had ceramic coated in case it goes lean or i want to spray it. If your gona run that fuel and ad more boost you'll want a quality dished piston in it and like navy said the dish will help lower your compression. and be carefull the poping could mean its runnin a little lean.
 
#17 ·
#19 ·
you should have about 46 psi fuel @ 17 psi boost, sounds like its starving, one pump not working? this happened to me before i put in the 190 lph f/p.
 
#21 ·
the fuel pressure is maintained by the Fuel Pressure Regulator (FPR). The SVO originally came with a non-Adjustable one.

As boost comes in, the vacuum hose attached to the FPR will now force that charged air down upon the diaphram, choking down on the amount of fuel that is allowed to return to the tank and force it to the fuel injectors. This is where the rise in fuel pressure with boost comes from.

There are Adjustable FPRs (AFPR), and they should have a baseline adjustment at 39 psi at idle with the vacuum hose disconnected. Now, if you have a stock one, note what fuel pressure is at idle with the vacuum hose on the regulator, and do the math with the boost. If it is say...30 psi with 17 psi of boost, then there should be 47 psi of fuel pressure with 17 psi of boost.

Get on a dyno with a fuel pressure gage hooked to the schrader valve and tune from there. At a minimum, go get a fuel pressure tester from any parts store. Then hook it up to the schrader valve, run the gage to the windshield and under the windshield wiper. Tape the gage down where you can monitor it and go out dancing. Have a friend help out in the passenger seat if need be.

On another note: don't think just because you have fuel coming out of the pump's hose means that the fuel pressure being supplied is adequate for proper operation. A gage and a TRUE air-to-fuel ratio measurement will decide that.
 
#22 ·
i have a aeromotive afpr on it... its set at 40 psi with vaccum off... i checked this with a fuel pressure tester on the valve... it goes up to allmost 60 psi when in full boost... if it was not enough fuel then wouldnt my car still run bad with 100 octane in it?
 
#23 ·
Ok, now I have a couple of things:

1. What is fuel pressure when you have the vacuum hose on it and the car running at idle? It has to be around 35 psi or so if it is at 40 with the vacuum hose off. If that is the case, then you are actually running at about 22+ psi of boost, which would require better fuel that 100 octane. All this is under the speculation that the gages are accurate.

2. I am also wondering if the 35# injectors you have might be somewhat clogged up and not spraying enough fuel and causing a lean condition. That is one reason I mentioned a dyno run to get the true A/F ratio. Just a thought. You can get get the injectors cleaned and new pintles put on for about $25.00 an injector through RC engineering
 
#29 ·
As I said before, you are actually probably running 22+ psi boost then if you are almost at 60 psi of fuel at full throttle. Waaayyy to much for flat tops and 100 octane to hope to NOT detonate.

I expect that the head gasket will be the next issue.
 
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