I have a 1987 fiero 2.8 liter I put a 2006 Pontiac G6 3.5 block with the 2.8 heads and intake but 5 mins idling the exhaust is glowing red what could be the problem ?
Did you replace the injectors with larger ones? You added 25% more displacement, so you likely need to add more fuel. Without it the car will run very lean.
It's distributor I can turn it down and stop the glow but then it has no power
Fiero balancers are known for slipping, so you might want to verify top dead center on cylinder #1, make a new mark on the balancer, and then recheck timing.
But I'm with you I feel like it firing with the exhaust valve open That's the only way I feel it could make the headers glow And it on both sides They get bright red like the eye on a stove on high
Originally posted by fieroguru: Fiero balancers are known for slipping, so you might want to verify top dead center on cylinder #1, make a new mark on the balancer, and then recheck timing.
How exactly do people do this with an assembled engine in a car?
I have found TDC on a shortblock with a dial indicator measuring the piston's height (measure angle with piston some depth in the hole on upstroke, measure angle at same depth on downstroke, then find angle midpoint), but there is no such access to the piston with a cylinder head installed.
I did it the other day by wadding up a piece of paper into a cone, stuffing it into the #1 spark plug hole, pull the coil wire, then tiny bumps on the starter till u hear the paper "pop" out. Then u just passed tdc on comp stroke. Lost my plug wire pattern the udder day and did this trick to get me close to #1.
I have been a mechanic for 25 years I build motors , transmission and differentials I know all the basic stuff about vacuum leaks ,bigger injectors just not to sure about displacement and air flow and stuff like that Some people said the motor wouldn't even run but I proved them wrong I believe it timing myself just don't know if it is valve timing or fuel timing or fire timing
I do know that the valves in the 2.8 and the 3.5 are the same size only difference is the 3.5 has larger intake ports cause the heads are taller So the only difference between the two engine's is larger pistons roller lifters and larger intake port both engine's take the same oil filter
How exactly do people do this with an assembled engine in a car?
I have found TDC on a shortblock with a dial indicator measuring the piston's height (measure angle with piston some depth in the hole on upstroke, measure angle at same depth on downstroke, then find angle midpoint), but there is no such access to the piston with a cylinder head installed.
Correct, the best way in short block or long block form is with a piston stop (without the head you can bolt a bar across with a bolt in the center to stop the piston).
Not stupid at all Thank you for bringing that to my attention The 2.8 pressure is 40 to 47 the 3.5 is 50 to 60 I this that may have something to do with the problem I'm having
So many questions... Did you replace the pistons to bring up your compression? What did you do with the cam phaser?
I know *some* G6's got the 3500 based on the 3400, not the 3900 so perhaps that's the engine you are using and my question about the cam phaser is irrelevant...
Using 2.8 l ecm and sensor Wanted it to look like factory engine just a more durable bottom end The 2006 3.5 (3500) doesn't have phasers Until 2010 I'm going to change out the fuel pump and see if that helps 10 to 20 psi of fuel pressure may cause a lean condition
changing the fuel pump might not help. holley makes an adjustable fuel pressure regulator which will allow you to adjust pressure up to what you need. Stock regulator is non adjustable so changing pump will not increase the running max pressure. sleek
If this is a lx9 they had return less fuel rails. You can use 3400 rails or 3500 rails with a corvette return less fuel filter. What did you use for the timing wheel? The 3500 has a 24x wheel that is not compatible with the stock ecm.
but if you didn't change your pistons, your compression ratio is ~7.5:1 instead of around 9+:1 ...
2.8 pistons have a flat top, IIRC 3.4 iron head pistons have a slight dish 3X00 have a deeper dish since the head combustion chamber is smaller
You should have gotten custom pistons to get the right compression ratio with iron heads or potentially swapped in 3.6 LFX pistons which gets you to 10:1ish but you might need different rods with those, not sure.
[This message has been edited by lou_dias (edited 05-25-2023).]
Originally posted by Kalel: I don't go by marks I make sure #1is on compression stroke with a gauge and make sure piston is all the way up
Were you able to find TDC within +/- 2° using this method?
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Originally posted by lou_dias: but if you didn't change your pistons, your compression ratio is ~7.5:1 instead of around 9+:1 ...
I have my iron-head V6 running with a 7.4:1 compression ratio, and it mostly runs fine, so I don't think that's the cause of OP's glowing manifold problem. But I don't know OP's exact compression ratio.
Initially, my engine did have overheating problems, but that was solved when I discovered the ignition timing was retarded by 17° relative to where it was supposed to be.
If you outfitted a 3.5 with the Fiero heads, ECU and sensors, but used the injectors from the 3.5 I would expect the engine to run rich. The Fiero uses batch fire injection, while the 3.5 uses sequential injection. You are using the injectors from the 3.5 which should deliver the appropriate amount of fuel with a single cycle of the injector per power stroke of the engine. But now those injectors are firing 3 times for every power stroke of the engine.
Oh and the 3.5 got cam phasers/variable valve timing in 2007 for the Malibu/Saturn Aura/Pontiac G6.
I believe it's got to be firing with the exhaust valves partly open...
How could it be possible for an exhaust valve to be open at all when the piston is at TDC of the compression stroke... unless you're suggesting that the exhaust valves are never closed properly? But then, how would there be enough compression to actually fire?
[This message has been edited by Patrick (edited 05-25-2023).]
I'm not saying the valve timing is off I'm saying it may be firing late But I'm not sure I know the valve timing is right or a valve would hit a piston
I believe it's got to be firing with the exhaust valves partly open...
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Originally posted by Kalel:
I'm not saying the valve timing is off I'm saying it may be firing late
You're suggesting that the plugs aren't firing until the exhaust valves are starting to open on the exhaust stroke? I don't think that's remotely possible for an engine that's actually running... even running badly!
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Originally posted by Kalel:
I know the valve timing is right or a valve would hit a piston
Are the intake and exhaust valves rocking at TDC of the exhaust stroke?
[This message has been edited by Patrick (edited 05-26-2023).]
I have a 1987 fiero 2.8 liter I put a 2006 Pontiac G6 3.5 block with the 2.8 heads and intake but 5 mins idling the exhaust is glowing red what could be the problem ?
I'm not qualified to chime in but it seems you have the answer to that question because you have 25 years experience. The timing is too retarded at idle and you are right. If you have everything from the 2.8 and glowing the exhaust manifold you are firing the charge too late. Your 25 years experience would lead you to get a temp gun and make your idle temp at about 650-700F and see how the manifolds look like, they should not be glowing. If you make that happen and the manifolds are not glowing you are very close to your target.
It's either a timing issue/cam alignment or as someone else suggested, the valve lash was not set correctly and the exhaust valves are not fully closing...
I've seen power gains work weird when adjusting the distributor...it feels like you are gaining power buy making the timing worse but then it starts to lose power and vice versa. I'd just pull the cap off and make sure when #1 is at tdc that the distributor is pointing at the #1 wire where your cap was. If it's not, your timing will never be right.
Another option is to ditch the distributor and go with a '7730 ECM conversion with DIS.
Also, this is a non-interference motor/head. Your valves will never hit the pistons even with bad timing.
[This message has been edited by lou_dias (edited 05-27-2023).]
I don't think that's remotely possible for an engine that's actually running... even running badly!
