Hey guys(gals), I have a timing issue that I never payed any attention to before. This is in my 88 Mustang that currently has a rebuilt 96 Exploder 5.0L in it. Here are the mods to the engine just for reference.
GT40 heads are milled .010 and have been nicely ported with bowl work done.
CompCams valve springs and hardware.
The camshaft is a TrickFlow Stage 1.
It has roughly 4K miles on it now. Runs great and holds over 40psi oil pressure at hot idle and 55-60 when driving.
I have 24# injectors with matching C&L 73mm MAF as well as a 70mm TB and EGR spacer bolted to a Typhoon intake.
MAC shortie headers with 2.5" exhaust (no cat H-pipe) and Magnaflow cat-back.
The car is a T-5 5-speed and has 3.73 gears.
I had been running my timing @ 15*BTDC per C&L for the brown tube and the 24# injectors. It always felt a little flat at part throttle but ran good and was a little sluggish when cold.
So I started playing with it. I kept advancing the timing and found that it runs best at 25* BTDC. This is with the spout unplugged.
I though, well I guess the balancer has slipped the outer ring, so I got a new Professional Products Steel balancer. It's a nice unit. Put it on, fired it up and it shows 28* at idle with the spout out. Hooked up it is between 35 and 40*.
I just wows me that with 89 octane fuel, that this thing doesn't detonate itself to death. It runs great and I or hear no signs of detonation at all.
The only thing I can come up with is that perhaps the balancer keyway in the crank was machined off a few degrees.
Anyone else ever seen this issue before? Like I said, it runs really strong, I am just confused about the high timing.
You should double check the TDC mark by removing #1 cylinder spark plug and holding a long skinny rod in there while rotating the engine back and forth with a breaker bar and deep socket on the damper bolt. Ideally one uses a dial gauge with a long rod on it, but you can get close without. Be careful not to bind the rod you are probing with.
Last week I went through similar timing confusion in the wife's B2200. In that case I started cleaning up the front cover in the area where TDC pointer should have been, and sure enough found a tiny little triangle pointer.
"The only thing I can come up with is that perhaps the balancer keyway in the crank was machined off a few degrees."
In the last post you state:
"I'll double check it, but 0 was 0 when I put the engine in last fall."
Assuming you mean 0 to be TDC, then clearly the first statement can't be right, unless the outer ring of the damper has the timing marks and has slipped on the rubber bond between it and the inner damper casting.
The check I am suggesting is independent of the distributor, it is only checking the timing marks against the #1 piston location.
Sorry, I have to recheck the piston position. I understand what you are saying. when I put it in the car, I did not check the actual piston position to see if it was completely at the top of the stroke. The heads were already on the engine when I got it. I do know that the timing marks on the cam and crank sprokets are correctly aligned and I dropped the dizzy in at 0 on the balancer. It even lines up the mark on the block with the line on the oen dizzy @ 10btdc like it always did with the original engine. ( I know that doesn't really mean anything). I thought that the balancer had slipped too, so I bought a steel Perfomance Products street balancer good for at least 6500rpm. Same deal with the timing marks. It runs like a scalded dog with the unspouted timing set at 28* btdc. It hovers around 35 to 40 with the spout plugged in at idle.
No pinging, turns over easy hot and runs great.
When I get some free time, I will pull #1 plug and get it up top and compare timing marks then. Been working 10 to 13hrs a day.
Definitely double check the TDC on the aftermarket damper. It could have been designed for a different cover or timing pointer from the one you have, or be BOOB (Bad out of box).
As for the keyway being in the wrong place, that brings up a side issue. It would have been nice if Ford machined the keyway so it is at top center when #1 piston is at TDC, but of course such is not the case. Alas.
You are disconnecting the vacuum advance before checking timing, right?
Also check that the centrifugal advance springs are pulling the weights in smartly when engine is at rest.
The new balancer has different sets of marks for different year engines/timing tabs.
It is EFI (EEC-IV) and has no vacuum advance or weights, it is all sone by the ECM, and by removing the SPOUT plug, it takes out all computer advance and gives you a true timing reading.
Been working too much to play with it. Currently running great with the initial timing at 28*BTDC with the spout plug undone. Trying to sort thru 15yrs of junk in the garage so I can tear it down and build a bigger one as well as working 10 to 12hrs a day.
Hi folks - I hate to drag up an old thread from the dead but I'm having a very similar issue with my 5.0 Explorer converted to Mustang EFI. It's running very retarted at 18 degrees, and theres no way the marks can be right. OP, what did you end up doing? Thanks.
I never figured it out, I just reset it to 13* and it runs good there too, although it will run at 20* with no detonation. It seems to make more power above 2500 at 13* but not as torquey as it is at 20*. It's a T-5 with 3.73's so it stays at 2000 or more most of the time anyway
They talk about making a custom timing pointer when converting an Explorer 5.0 to a distributor-type EFI. They say you should check TDC with a wire, and make a new pointer to show where true TDC is. I'm thinking the Explorer timing marks are way off.
Not to hijack this thread, but I have a similar question.
My 87 Mustang GT has 1.7 roller rockers, but otherwise it is totally stock. I set the base timing to 10 BTDC, but it always detonates under load at around 4000 rpm. I have tried different grades of gasoline, all sorts of injector cleaners, but none of that eliminated the detonation. I have heard that the E7 heads may be prone to that, so it may be something I have to live with.
But now I'm hearing from LxMan that he can use 13 and up to 20 with no problems. It makes me wonder what's wrong with my engine.
When upgrading the topend to all TrickFlow parts (170cc aluminum heads with optional dual valve springs with dampers, 1.6 roller rockers, TrackHeat intake manifold and matching black valve covers. I got all of that together and the issue was the same. Finally pulled the timing cover and the guy that built the engine had put the cam in 4* advanced and it was off a tooth from there. I installed a quality CompCams double roller set. I didn't pull the dizzy. I checked the timing, it was at 18* before I tore it apart and was at !0* with the chain in right. Now it pulls hard up to about 6500rpm like it should.
I took it to the local 1/8 mile track before the timing chain and it went 8.31 @ 83.77mph. Now with the cam right and a brand new World class T-5 built by Tremec, it should dip into the 7's if I can get it to hook better.