Help.... Timing a 302...

Jetlaag · #1 (**permalink**) 10-19-2004, 06:37 PM

Have a question about timing on my 302.

Let me start by giving some info on the engine.

93 ford 302 roller engine
Holley 650 DP, mechanical secondarys
Edelbrock Performer rpm manifold
Edelbrock Performer rpm roller hydrualic cam - 298 dur. 520 lift(newely installed)
Crane energizer roller rocker arms (newely installed)
Msd 6a ign
Msd pro billet distributor w/ mechanical advance

My question arises from trying to time the engine after I have just installed the new cam and roller lifters.

I have tried to set the timing at the recommended setting of 12-14 BTDC all the way up to 22 BTDC. The engine is popping up through the carburator at both settings if I press reletively quick on the gas pedel and the throttle response is not very good at all.

The Balancer that is on the engine only goes up to 20 either side of the zero mark so I have no idea on how you check the total timing or if I even can with this balancer.

I have pulled the #1 spark plug and checked AGAIN that the piston is on the compression stoke and that the timing mark is at zero at TDC.

I am at a loss of which way to time the engine to make the carburator backfires go away and to have the eng. run well.

Any help is appreciated....

Thanks in advance.
Jack

Bruce Edwards · #2 (**permalink**) 10-19-2004, 07:04 PM

Kind of sounds like you have the valves set to tight. Pull the covers and go over them one more time.

HighPlainsDrifter · #3 (**permalink**) 10-19-2004, 07:09 PM

Jack,
Try checking the firing order of your plug wires. 13726548
Also popping back trough the carb is an intake being left open at the wrong time, check the valve adjustments.
Set the timing with the vacuum advance hose off and plugged.
When all else fails, try advancing the distributor while engine is idling, move it clockwise 1/4 to 1/2 inch, if this helps then your harmonic balancer may be out of whack and need to be replaced.
Good Luck,
Perry.

Bruce Edwards · #4 (**permalink**) 10-19-2004, 07:15 PM

Perry had a good point. Some of the aftermarket cams use different grind and thus have a different firing order. Check your instruction sheet to see if it says anything about firing order. I know that some of them use the 351 order and some use the 302 order.

PatBuckley · #5 (**permalink**) 10-19-2004, 08:17 PM

You made absolutely sure that the timing marks lined up when you installed the timing chain, right?

maxrpm · #6 (**permalink**) 10-19-2004, 08:46 PM

I'd put my money on the firing order. Although both 351W and 302 cams are interchangable their firing order are not. To confuse the issue even more, some computerized 302s (Mercs&Crown Vics) actually used the 351W order. Pretty common mistake. The car will actually run but will not take any rpm. Once, I had a late night thrash setting my car for a day at the dragstrip. Decided to change rear gears,axles, intake, distributor, cam the night before racing(why do we do that?). Left dist installation & firing order to one of my buddies. The car actually ran ok the next morning. Drove it thru the pits not noticing. I did a burnout, staged and made it to about 3500rpm in 1st gear. Went back to the pits and found the mistake. Reset your wires and rev that sumbich!

Jetlaag · #7 (**permalink**) 10-19-2004, 08:55 PM

Thanks for the tips guys...

Yes the timing marks were lined up as well as I could. I used a metal straight edge to be as close to perfect as I could.

I think Perry you may be right on the valve adjustment. I think I may have my my rocker arms tightened too tight. I adjusted them the way the paper work said.

Except,

I rolled the pushrod between my fingers until it ws just barely to tight to turn anymore, then after calling tech's at Edelbrock, he told me to turn the nut an additional 3/4 turn. Even though the installation instructions said on ly a 1/2 turn. So right now they are at 3/4 turn.

Also, after the pushrods are tightened and you turn the motor over a few rotations by hand, are the pushrods on the closed valves supposed to able to be turned with you fingers or not??

Mine were pretty loose after the first adjustment so I re-adjusted all the valves over again. So they were all pretty snug which was what the tech told me they were supposed to be.

I will be in the garage tomorrow reajusting the valves a little looser. Maybe with the engine being run the lifters will be pumped up more than when I originally adjusted them.

Thanks again guys for the help...

Jack

maxrpm · #8 (**permalink**) 10-19-2004, 09:05 PM

Quote:

Originally posted by Jetlaag

Also, after the pushrods are tightened and you turn the motor over a few rotations by hand, are the pushrods on the closed valves supposed to able to be turned with you fingers or not??

Sounds like your valve adjustments are good to me. Or at least close enough to run without backfiring.

Jetlaag · #9 (**permalink**) 10-19-2004, 09:06 PM

Thanks Bruce,

Sorry, I see you answered with the valves too tight before I was reading Perry's post. But thank you both for recognizing the problem that I will try to fix tomorrow.

Jack

Jetlaag · #10 (**permalink**) 10-19-2004, 09:19 PM

Maxrpm,

Interesting scenerio you described in that the engine still ran well enough for you to actually drive the car to race even though you had the wrong firing order.

My 302 is a late model 302 which the firing order is supposed to be 13726548, now, according to my Edelbrock RPM camshaft instruction sheet it states that my firing order is supposed to be 15426378. It makes no mention of early or late model engines, nor does it mention the firing order of my engine the way it used to be. My Haynes manual DOES mention the different firing order of early and late model HO engines

I didn't really pay too much attention to this order because I noted what the firing order was when I took it apart.

Question:

Can putting a new cam in my engine change my firing order???

Could it be this simple as to change the firing order and have it running well again??

Anxiously awaiting any answer to this one...

Thanks agian Maxrpm.

Jack

maxrpm · #11 (**permalink**) 10-19-2004, 09:31 PM

Well, first we didn't drive the car to the track. It drove onto the trailer. It also started and drove in the pits. But when I let out the clutch the car wouldn't rev past 3000 and popped thru the carb. Once I let off I was able to drive(embarassingly) down the track.
And yes, just changing the camshaft will change your firing order. It bolts right in but the grinds are different. Let us know what you find.
Good Luck,
Ed

speedar · #12 (**permalink**) 10-19-2004, 09:41 PM

At the risk of telling you how to suck eggs I would check...

The balancer Bring #1 to 0*(TDC) and by rocking +/-10* with a screwdriver carefully down the spark plug hole confirm the piston topping corresponds to the 0*. If not has your balancer slipped or is your timing pointer out.

As the crank rotates twice for every turn of the cam, your distributor could be 180* out. Coming up to 0* your #1 rockers/valves should both be in the closed position without movement. At this point the distributor rotor (which unlike the crank, moves anticlockwise)should be almost pointing at the distributor cap #1 lead position.

If the motor is running but badly, connect a timing light and set total timing to 36* before TDC. Measure 16* with your wifes best fexible measuring tape (in her sewing drawer) and add it to the 20* on your balancer with a chalk marker so that you know where 36* is. Sewing kits often include a chalk marker for dressmaking. At 2600 RPM check your total timing against this mark and twist the distributor to get it perfect. Your vacuum advance should be disconected while you do this.

Check the firing sequence (anticlockwise remember)

I also got caught out with sparkplugs. I was amazed that 5 were poor and 3 not working at all after a tuning session where the car was running far too rich for a period. It was popping like mad.

lastly... placate the wife.

speedar · #13 (**permalink**) 10-19-2004, 09:47 PM

Speedar's Addendum
I dont really want to post this but if your timing is spot on and you've checked everything else it is possible that you new cam break in didnt go well. This is highly unlikely with roller followers but can happen if the roller follower has turned and whipped off a lobe as a result of a broken link plate

Bruce Edwards · #14 (**permalink**) 10-20-2004, 04:58 AM

If you adjusted the valves again before you have any oil pressure to work the lifters they are to tight. Back them all off and start over. If you adjust them to were the pushrods will just stop turning with the cam lobes on the bottom you should be fine. Do not second guess after you turn it over by hand. The lifters will go down with out oil pressure to hold them up.
You need to back them off so the lifters will return to the top of the travel. You want to adjust them so they just sit off the retainer. A bit loose is better than to tight at start up with a new cam. You can always go back and adjust them a bit tighter if you get a noisy one.

DAVID GAGNARD · #15 (**permalink**) 10-20-2004, 05:13 AM

Jack;

You need to use the firing order for the cam installed regardless of what the firing order was before,as said before,some cams use the "old" 302 firing order and some use the 351 firing order.........check your cam card and use that firing order and I think your problem will be solved.........

David

trularin · #16 (**permalink**) 10-20-2004, 07:02 AM

I think the firing order Perry gave was for a Cleveland.

David is very correct in that you must determine the firing order the CAM was ground for. All this other stuff is good, but will not bare fruit if the wiring is wrong.

Call the company who made the CAM and ask for the firing order relative to the part number.

After you lock-down the firing order, set the timing.

Just my $0.02

Jetlaag · #17 (**permalink**) 10-20-2004, 04:43 PM

Thank you for the help... This web site is awesome!!!

I guess I just had a brain fart as to the firing order and used the old one. But since the cam is sort of the brain of the engine it seems only right that IT determines the firing order...

Yes, the new cam card had a different firing order and after changing only 4 wires to the correct plugs --- she ran like a champ!!

I still went ahead and readjusted the valves just because I felt better about doing it. Now she thumpety thumps just like I want her to.

Thanks again and if anyone is interested in buying my BDR Cobra, it is kinda sorta for sale right now as my wife and I have just found out that we are expecting our first baby... I may have to move for work also, so check out the gallery for pics if you are interested...

Thanks again all,

Jack

maxrpm · #18 (**permalink**) 10-30-2004, 01:07 AM

Quote:

Originally posted by Jetlaag

if anyone is interested in buying my BDR Cobra, it is kinda sorta for sale

Will we get a discount on the price since we all helped gettin her to purr for you?

And, congratulations on your new addition to the family!

trularin · #19 (**permalink**) 10-30-2004, 08:54 AM

Congrats!!!!!!!!!!!!

No reason to sell. Just limited driving time.

Just think about showing up at the soccor match in a cobra while all the other parents are arriving in SUVs. LOL

Or the, "Dad, can I borrow ford tonight." Then there is the elevation to "Father... Sir... may I please use the ford this evening?" LOL

Or, if it's a girl, you can bank on barbed wire fences around the house and armed guards in the corner turrets when she turns 13. LOL

"So, the adventure begins."