New engine and rebuilt 700r4 back in the car with problems!
07-12-2014, 10:53 AM
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New engine and rebuilt 700r4 back in the car with problems!
I figured this needs a new thread for a bit more exposure. The new engine I built a 350 and 700R4 I rebuilt is back in the car. For the record I’m running a Holley Stealth Ram. After priming the engine and getting the distributor in and the wires on correctly I attempted to start her up. I had to put a wrench between the accelerator idle stop and the linkage in order to get enough gas to it to fire. Yup still a one man band. When it did fire up it backfired through the exhaust pretty bad. The more fuel I put to it the less it backfired.
After checking things out I found the fuel pressure dropped immediately as soon as the pump quit running. I pinched off the return line at the tank, turned the key and the pressure built quickly limiting the gage at 70 and held. I assume this is what’s causing the extremely hard start and backfire?
I purchased a Kirban 4567 to replacement the Holley FPR and got it back together. I turned the key and the pressure came up and by the time I got to the other side of the car where the gage is it was only at 20 and held so I turned the key again and looked with a mirror this time and found it dropped again like with the Holley FPR on it but not as quickly.
To those that know the HSR is it normal for the pressure to drop like this? Does the engine being new (never run) have anything to do with it?
After checking things out I found the fuel pressure dropped immediately as soon as the pump quit running. I pinched off the return line at the tank, turned the key and the pressure built quickly limiting the gage at 70 and held. I assume this is what’s causing the extremely hard start and backfire?
I purchased a Kirban 4567 to replacement the Holley FPR and got it back together. I turned the key and the pressure came up and by the time I got to the other side of the car where the gage is it was only at 20 and held so I turned the key again and looked with a mirror this time and found it dropped again like with the Holley FPR on it but not as quickly.
To those that know the HSR is it normal for the pressure to drop like this? Does the engine being new (never run) have anything to do with it?
07-12-2014, 04:56 PM
#2
Stealth ram or ANY other intake designs has NOTHING to do with the Fuel regulator.
You MAY have injectors issues I believe....one or more is shorted, or stuck open allowing the fuel to bleed out quickly after pump stops running.
Holding throttle part open to start is not helpful....the ECM see's that and stops fuel. Get the TPS set right and that should help. If the ECM thinks the throttle is open it will cut other things to prevent a "rev" when it fires.
the regulator is the usual suspect but if you say you have gone thru that and its a GOOD, upgrade regulator, then I'll assume that its ok. Pinching the return line stops the fuel from going that way back to tank. The ONLY other place it can go is thru injectors OR back thru a bad pump.
BTW, 70 psi is wayyyyyyyyyyyyyyyyyyyyyyyy too much pressure for normal running.
If its sending that much pressure without the return pinched off, then that's part of the problem. dial that down. If this engine is 'built' and able to use more fuel, that's done thru the inj duty cycle and inj size, NOT force feeding it. ALL that does at that pressure is spray WET gas that does not burn.
LOW fuel pressure WILL cause it to backfire and burp big time. Start up with the fuel pressure test gauge on the rails. That's easy 'nuff to see whats going on with the fuel. If its running and the fuel is below 40 psi, there is a problem in the pump, reg or stuck open injectors.
It does not need more than 45 psi for an engine that size.. Even a 'charged' motor would use larger injectors, not higher pressure. The stock injector size is probably ok for this motor,.
if this reg has a vac line to the reg, take that off and plug it. This should cause the reg to up the pressure a few lbs. This is just to see if the reg is working, NOT to get more pressure.
Do this:
ohms the inj
use a noid lite if you have one to SEE the inj cycling.
Set TPS to .54v at idle.
Get the fuel pressure set to 40 to 45 psi (idle) max.
double check the regulator.
If the pump is old, it may be worth your time to buy a new one, even a stock pump for now. A better pump can come after break-in.
Start-up with fuel test gauge in place and watch the pressures. Idle @ 40ish, slight drop as it revs but full recovery 1 second later. Steady rpm, steady gauge. A gauge that flickers or bounces is telling you the fuel supply (pump or reg) is bad and unstable.
Hope this helps
You MAY have injectors issues I believe....one or more is shorted, or stuck open allowing the fuel to bleed out quickly after pump stops running.
Holding throttle part open to start is not helpful....the ECM see's that and stops fuel. Get the TPS set right and that should help. If the ECM thinks the throttle is open it will cut other things to prevent a "rev" when it fires.
the regulator is the usual suspect but if you say you have gone thru that and its a GOOD, upgrade regulator, then I'll assume that its ok. Pinching the return line stops the fuel from going that way back to tank. The ONLY other place it can go is thru injectors OR back thru a bad pump.
BTW, 70 psi is wayyyyyyyyyyyyyyyyyyyyyyyy too much pressure for normal running.
If its sending that much pressure without the return pinched off, then that's part of the problem. dial that down. If this engine is 'built' and able to use more fuel, that's done thru the inj duty cycle and inj size, NOT force feeding it. ALL that does at that pressure is spray WET gas that does not burn.
LOW fuel pressure WILL cause it to backfire and burp big time. Start up with the fuel pressure test gauge on the rails. That's easy 'nuff to see whats going on with the fuel. If its running and the fuel is below 40 psi, there is a problem in the pump, reg or stuck open injectors.
It does not need more than 45 psi for an engine that size.. Even a 'charged' motor would use larger injectors, not higher pressure. The stock injector size is probably ok for this motor,.
if this reg has a vac line to the reg, take that off and plug it. This should cause the reg to up the pressure a few lbs. This is just to see if the reg is working, NOT to get more pressure.
Do this:
ohms the inj
use a noid lite if you have one to SEE the inj cycling.
Set TPS to .54v at idle.
Get the fuel pressure set to 40 to 45 psi (idle) max.
double check the regulator.
If the pump is old, it may be worth your time to buy a new one, even a stock pump for now. A better pump can come after break-in.
Start-up with fuel test gauge in place and watch the pressures. Idle @ 40ish, slight drop as it revs but full recovery 1 second later. Steady rpm, steady gauge. A gauge that flickers or bounces is telling you the fuel supply (pump or reg) is bad and unstable.
Hope this helps
07-12-2014, 05:41 PM
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[QUOTE=leesvet;
BTW, 70 psi is wayyyyyyyyyyyyyyyyyyyyyyyy too much pressure for normal running.
If its sending that much pressure without the return pinched off, then that's part of the problem. dial that down. If this engine is 'built' and able to use more fuel, that's done thru the inj duty cycle and inj size, NOT force feeding it. ALL that does at that pressure is spray WET gas that does not burn.
70 was only with the return line pinched to test the FPR.
I wasn’t able to try to start the engine this morning the lady that owns the house with the garage I’m using was still sleeping. I didn’t think she would appreciate being woke up to open headers.
When I went back I tried to start it and she fired right away and is holding pressure at 45 and no more backfire.
I’ve only run it up and down the street a half dozen times to get the rings seated. Sure needs a tune, taking the prom to the tuner in the morning. As for TPS I know .54v is normal but with the modes the tuner told me to set it at .60v. He’s 75 years old so I assume he knows what he’s doing and highly recommended.
Engine:
93 roller block, standard bore
Speed Pro hypereutectic flat tops
Comp single plane roller .501 lift with 1.5’s W/114 LS
Crane Gold full roller 1.6’s making the cam .535
GM Performance roller lifters
22lb Bosch III’s (tuner says should be fine) but might go to 24’s?
Edelbrock RPM’s 185cc, 70cc chamber
Holley Stealth Ram W/58mm TB & new Kirban adjustable FPR
By the way the 700R4 is working GREAT!
To anyone considering doing the job go for it. Comes apart by component and goes back together the same way. Very happy I decided to do it myself. Doing it myself allowed me to better parts in it than having a shop do it. They wanted $1,000 - $1,300 for standard parts and that was with me bringing in the trans. I probably spent $600 for a performance build. 
BTW, 70 psi is wayyyyyyyyyyyyyyyyyyyyyyyy too much pressure for normal running.
If its sending that much pressure without the return pinched off, then that's part of the problem. dial that down. If this engine is 'built' and able to use more fuel, that's done thru the inj duty cycle and inj size, NOT force feeding it. ALL that does at that pressure is spray WET gas that does not burn.
70 was only with the return line pinched to test the FPR.
I wasn’t able to try to start the engine this morning the lady that owns the house with the garage I’m using was still sleeping. I didn’t think she would appreciate being woke up to open headers.
When I went back I tried to start it and she fired right away and is holding pressure at 45 and no more backfire.
I’ve only run it up and down the street a half dozen times to get the rings seated. Sure needs a tune, taking the prom to the tuner in the morning. As for TPS I know .54v is normal but with the modes the tuner told me to set it at .60v. He’s 75 years old so I assume he knows what he’s doing and highly recommended.
Engine:
93 roller block, standard bore
Speed Pro hypereutectic flat tops
Comp single plane roller .501 lift with 1.5’s W/114 LS
Crane Gold full roller 1.6’s making the cam .535
GM Performance roller lifters
22lb Bosch III’s (tuner says should be fine) but might go to 24’s?
Edelbrock RPM’s 185cc, 70cc chamber
Holley Stealth Ram W/58mm TB & new Kirban adjustable FPR
By the way the 700R4 is working GREAT!
To anyone considering doing the job go for it. Comes apart by component and goes back together the same way. Very happy I decided to do it myself. Doing it myself allowed me to better parts in it than having a shop do it. They wanted $1,000 - $1,300 for standard parts and that was with me bringing in the trans. I probably spent $600 for a performance build.
07-12-2014, 07:13 PM
#4
Glad to hear that its doing better...
may have been a sticky FPR...that tiny seat in the FPR is delicate. ANY sort of a gap from a grain of sand will cause it to dump off the pressure and get what you got..
The trans news is great! I'm looking at doing mine when I pull my engine this yr.
In regard to the 22 vs the 24 lb/hr injectors, the Bosch-III is nice in the fact that by bumping up the pressure you CAN get more delivery and not get the wet spray that other inj will deliver when too much pressure is applied.
I spoke to Jon about this when I ask if my bored and 'enhanced' engine needed to go up a size on the injectors...
he said no, just dial up 5 to 8 psi and these B-III's will give 24 lbs/hr from the 22's.
It takes about 30 psi just to get fuel thru the B-III, and that is why the engine will buck and spit so bad when pressure drops off...
Glad its working for you now...I'm sure the new prom will make a huge difference !
Enjoy !
may have been a sticky FPR...that tiny seat in the FPR is delicate. ANY sort of a gap from a grain of sand will cause it to dump off the pressure and get what you got..
The trans news is great! I'm looking at doing mine when I pull my engine this yr.
In regard to the 22 vs the 24 lb/hr injectors, the Bosch-III is nice in the fact that by bumping up the pressure you CAN get more delivery and not get the wet spray that other inj will deliver when too much pressure is applied.
I spoke to Jon about this when I ask if my bored and 'enhanced' engine needed to go up a size on the injectors...
he said no, just dial up 5 to 8 psi and these B-III's will give 24 lbs/hr from the 22's.
It takes about 30 psi just to get fuel thru the B-III, and that is why the engine will buck and spit so bad when pressure drops off...
Glad its working for you now...I'm sure the new prom will make a huge difference !
Enjoy !
07-12-2014, 07:27 PM
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Funny, when I talked to Jon he was the one that said I should go to 24’s but the tuner thought as you said per Jon, bump up the pressure and you’ll have 24’s. All the more reason to trust the tuner.
Good luck with your trans it really wasn't that bad but I did a lot or research before I went into the case. I actually enjoyed the trans rebuild more than I did the motor but then I like going places I've never been.
Good luck with your trans it really wasn't that bad but I did a lot or research before I went into the case. I actually enjoyed the trans rebuild more than I did the motor but then I like going places I've never been.
07-13-2014, 12:40 AM
#6
maybe it was Jon2 that one of us spoke to? That's classic. Son of Jon may be on a different page than the 'ol man !
Maybe Jon sr was thinking like a business owner, and "selling" (as he should do)
I've always been scared of trannys.
Drive trains as well.
About 40 years ago I recall walking up the driveway to a buddies house and seeing STUFF scattered all over the garage floor laid out real nice on papers and organized. LOTS of stuff....
Wuz-zat I ask him...
The transmission out of the Nova he tells me...
He was an aircraft mechanic licensed to service air-frame and PowerPlant. A&P certified. Top shelf wrench. Fearless in the face of broken machines.
I take a closer look like I was looking at a dead body and I see some familiar stuff...and I take 2 steps back like "it" moved
. I had no idea that thing (and that was only a 3 speed auto!) had so many pieces inside. Springs, valves, that damn valve body is enough to make anybody rethink digging into one of those...
Never got the urge to mess with one.
years later at a company where I worked I walk down to the shop on a Saturday to see who's down there doing what.
The shop "kid" is there with his trans on the work bench.
Here we go...
I tell him that if he's gonna need a ride home he'd better let me know now because I'm leaving at noon...
"naw, I'll be ok" he says. He goes on to tell me that he has never taken an automatic apart before and this one is out of his Toyota p/u that's pulled in the shop. The truck he drove to the shop...
He has his rebuild kit there, and a service manual. He is not the least bit concerned.
That was 8 a.m. and he DROVE that truck home THAT night !
So, it can't be all that bad.....
Guess I got a phobia about transmissions somewhere...
I'll look into therapy.
I keep seeing and hearing about good results and it's making me wonder how I get poor results from trans SHOPS ??? ! ! !
Last edited by leesvet; 07-13-2014 at 12:45 AM.
07-13-2014, 12:58 AM
#7
Race Director
Good going with the motor and transmission. 
07-13-2014, 04:06 AM
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He’s 75 years old so I assume he knows what he’s doing and highly recommended.
I ran ~.65 Vdc at base idle (450rpm) and got better off idle response than with stock setting.My prior '88 was building ~300chp while running 48psi of FP with OEM injectors.
What TC did you use with your A4 rebuild?
Did you use a TransGo shift kit?
Last edited by 65Z01; 07-13-2014 at 04:08 AM.
07-13-2014, 07:39 AM
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The rebuild kit was the Alto Read Eagle with the 3-4 power pack and TransGo shift correct kit not the full blown shift kit.
07-13-2014, 09:05 AM
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Wll 2,500 RPM is pretty good for street/strip. I had a 2,000 RPM TC and could launch at 1,900 RPM and pull >1g...
Does she get a nice chirp & wag on the 1-2 shift or too soon to tell till broken in?
Does she get a nice chirp & wag on the 1-2 shift or too soon to tell till broken in?
07-13-2014, 09:21 AM
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Another week without the car but it should be well worth the wait.