(I think) Timing chain issue... might explain dyno/starting/timing issues..

I've read thru this a few times now, and am still convinced it is a coil binding issue.

I think we're all just guessing here. We probably don't have enough information to nail it, but I'm not seeing how coil bind results in the symptoms described. Are you basing this on your past experience? Can you provide more details of what symptoms you saw?

That being said, you need to isolate the two components, "carb" and "engine".

A vacuum leak could cause the backfire as could a timing problem. The cam could be installed too retarded or advanced, the spark plug sequence could be close but not right. I think the odds of it being the carb are low, but anything is possible. Did he find it in a junk yard? Swap meet?



Also, you should have one of these:

Proform 66787 - Proform Universal Degree Wheel Kits - summitracing.com

This will show you all of your camshaft timing events, as they happen. There is also a video available to buy, and probably something on you tube as well.

Agree 100% here. Start from scratch and get #1 to TDC. Time the cam to the crank using the degree wheel. Don't cheap out and try to reuse the timing set. If the new one has that much slack in it something is wrong, like the block has been align bored. Start over with a new block or get a shorter than stock chain. Do you have someone nearby that has a carb set up? It may be easier to take your carb to a friend's house than to buy a used (and suspect) one on ebay or craig's list.

Keep us posted and good luck!
 
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Quote:
Originally Posted by woodsnake View Post
I've read thru this a few times now, and am still convinced it is a coil binding issue.
I think we're all just guessing here. We probably don't have enough information to nail it, but I'm not seeing how coil bind results in the symptoms described. Are you basing this on your past experience? Can you provide more details of what symptoms you saw?


On my 68 with a 289, running less cam, I had similar issues with early engine performance. I wasn't getting the back firing, but the engine always sounded "flat", even when it sounded sweet.


Quote:
Originally Posted by woodsnake View Post
That being said, you need to isolate the two components, "carb" and "engine".
A vacuum leak could cause the backfire as could a timing problem. The cam could be installed too retarded or advanced, the spark plug sequence could be close but not right. I think the odds of it being the carb are low, but anything is possible. Did he find it in a junk yard? Swap meet?


I agree, the carb may not be all of the problem, and I am lumping base plate vacuum leaks around the intake, anywhere, in the 'carb' department. My point here being to isolate one from the other.

Good point on the installation, I don't think I saw that the cam and gear set were installed "straight up, dot to dot".

However, if it were either advanced or retarded, it should still be consistent.

The backfiring (either thru the carb or out the exhaust) is indicative of a timing event, and that is all about the valve train. Other than when the current is sent thru the wires to the plugs, (from the cap), or when the plugs receive the signal, (wiring order at the cylinder heads), the only thing left is the valve train.

If he has a set of heads and springs that are made for a 5.0, and he is running a 5.8, from my experience it makes perfect sense that he is having some kind of coil springs (binding or floating) issue, and this would cause poor overall engine performance.

I also agree that I can't see it from here, or hear it run either.

That's why I'm trying to separate components, symptoms and causes to figure it out.....
 
Slap on that timing gear/chain set I loaned you and see if the play is similar. You use any of those parts I brought by ?

Was planning on using the timing set temporarily to check the play. Haven't used the carb... honestly think mines okay, I just need to verify the floats. I think Im going to worry about the valvetrain/timing chain stuff first, then worry about carb when I attempt to re-tune thoe whole thing later.

Part of the issue (resolved a while ago) was Marlon decided to turn my mixture screws about 2 turns too rich... which mean hard starting (and didn't help richen my WOT/high rpm A/F ratio at all).

To comment ona few things above... the timing chain was originally installed straight up, dot-to-dot.

Also, the timing is fairly consistent once I get it running... its just the numbers its consistent at (30-40 degrees) don't make sense and are off.

Coil bind could be at play, I do need to do that preload setting thing and I need to check that the valves are all opening/closing all the way. The springs are the ones that came with the heads and aren't exactly the Compcams recommended spring rates/pressure #'s, though they're close and both companies (CC and Trick Flow) said they'd be okay.

Not sure whether the heads are designed for a 5.0 specifically or not. This p/n head is one of the special ones that comes with high-lift springs and machined for 1/2" head bolts from the factory, implying (at least to me) its meant for 351ws. That said, the springs could still be ideal for a roller 351w. Once I get time early next week expect a lot of questions and pictures of my valve springs/stems etc.

Any more thoughts on the timing chain play? Is it probably at least a major contributor to my issues or is it unlikely to be the cause of the ****ty performance/difficulty timing it/hard starting/etc?
 
I'm gonna go with " The timing gear, even as 'loose' as it appears to be, is not the cause of your problems."

My thinking is heads/springs/valve train, then perhaps fuel issues.

Maybe I'm just cynical, but I was breaking roller rockers almost in half because of "bad gas".
 
Not sure S-car, maybe? I'll check when I put her back together.

edit: Actually, I'm using the MSD wiring harness to the MSD distributor. I'm pretty sure you can only hook it up one way. MSD ignition - MSD wiring harness - MSD distributor input... not much room for things to be wired backwards.

I really don't think it has anything to do with the distributor. Exact same symptoms, two completely different and good distributors. One old but proven and no issues with older combos, one brand new MSD. Both with new rotors, new caps, clear vacuum advances... I'm going to check the shear pin and gear but if thats not it I really don't know what it could be.

I did call Compcams and their tech guy, tough he didn't have a set # of allowable play, said that it was too much play as far as he was concerned and that the chain could be replaced under warranty.

He said the easiest way to check for coil bind was to insert a .060 feeler gauge into the springs at max lift... so long as it fits, no coild bind is present. He also agreed with me when I told him I don't think I have any valve float issues (his description of what that feels like doesn't sound like anything I've experienced, plus its a high-rpm problem and one thats made less likely if anything by my stiffer-than-optical valve springs).
 
When I ordered all my parts from summit, they sent me checvy valve springs. I sent them an email, and said, 'are you sure'?
They said,' no problem'

Right springs for the same cam part number for a GM application.

Did the .100 on a cold, compressed spring, plenty of room. Then blew a roller rocker after it had run for almost a half hour, sounding really sweet, and after it had been driven a half mile......

Did you do any reading over on small block ford tech??

Ask them what they think could cause all your problems, and see what they have to say. Can't hurt at this point.....
 
small update:

Well, I installed Rusty67's old chain and it also had about the same amount of slop/play as my current one... at least to my laymans eyes suggesting the chain isn't the primary cause of my troubles.

Other things checked and okayed officially:
Distributor gear (all the pins/other securing devices I could see were present and in good shape), distributor retainer (the little tab that keeps it in, I couldn't get the distributor to move at all vertically as some had suggested), the crank sprocket key is in fine shape as is the pin holding the cam sprocket on.

I also did confirm that I correctly checked/set thelve lash (as per Trick Flow's instructions). While i still have to check the springs/valve stems for wear, that should be fine.

I called summit today to ask a tech guy what he thought and to figure out how to return the timing chain. He was pretty helpful and said he had experience with both the exact timing set I'm using as well as the Trick Flow valve springs I spoke of. The guy agreed it was likely a timing related issue and, outside agreeing that my timing chain had too much play, said the only other things he could think of would be a slightly out-of-spec camshaft or my cam and/or crank bearings having worn too much (creating the play I'm seeing with my timing chain).

The bearings, in my mind, are a possibility as this was a cheapo Autozone stock rebuild 5 years ago... I haven't put that much wear on them but they aren't exactly known for first-rate rebuilds and its possible they reused the ones that had been on before rebuilding it.

So at this point all I have left to really check is:
1) install a new timing chain... if there is still play, I believe that means that my bearings are worn out (is there anything else that could be wrong)?
2) degree the cam and see if there is some real machining error that could be creating this
3) check for coil bind and other signs of incorrect valvetrain setup
4) try a new MSD
5) the old vacuum leaks/carb adjustments

The fun never stops...
 
"slightly out-of-spec camshaft or my cam and/or crank bearings having worn too much (creating the play I'm seeing with my timing chain). "

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Crap.

Installed height of the springs, wear pattern on the valve stems to check.

Hurry up! I'm leaving to go to Iraq next week, I want to resolve this before I go!!
 
"slightly out-of-spec camshaft or my cam and/or crank bearings having worn too much (creating the play I'm seeing with my timing chain). "

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Crap.

Installed height of the springs, wear pattern on the valve stems to check.

Hurry up! I'm leaving to go to Iraq next week, I want to resolve this before I go!!

Well, all the new crap arrives tomorrow and we'll be attempting to put it back together Saturday... if I get it running well, I promise I'll upload a video/sound clip or something. :flag: :D

For what its worth, I did just take a valve cover off and removed the #1 intake rocker.... the wear pattern on the valve stem looks pretty ideal to me (even band slightly to the exhaust end of the stem, i guess meaning my pushrods are on the long side but i believe its acceptable based on what i heard over summer). Pushrods in fine shape. Don't know where my feeler gauge is but the springs look okay I think... right now the #2 intake is being opened, I'll try to get a picture of it at max open-age. Kinda sorta looks like the spring is compressing mostly on the top (rather than evenly throughout) but I really don't know what is okay and not okay with valve springs :shrug:

Will try to upload pictures in a few...
 
not sure how much these help, should be able to find the feeler gauge tomorrow but let me know if this tells you anything
 

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Are you certain the cam and lifters are still intact? Could it have not broken in right and wiped a lobe down? I've read through a couple times, sorry if this has been covered and i missed it...
Other thoughts. Have you compared the new timing gears the used set you got? It's rare, but not unheard of to get a timing gear with the dot in the wrong place. New parts don't always mean good parts...but that would not account for it running fine for 3 min.
Have you pulled the intake back off yet? It may be worth checking/replacing the intake gaskets. At least that would not be too expensive to check.
 
That wear pattern on #1 looks as close to ideal as you are going to get. If they all look like that you will be in fine shape, as long as the springs are the correct installed height.

As long as the springs are the correct installed height.

That having been said, I don't know what else to to say about this whole thing.

"Timing" is when the plug fires into the cylinder, in relation to the piston in the bore.
The valve timing is when the valves open in relation to the ignition spark.
If the distributor has proved out, (and it seems that it has) Then after this, I'm just going to have to hang and see what happens.....
 
Are you certain the cam and lifters are still intact? Could it have not broken in right and wiped a lobe down? I've read through a couple times, sorry if this has been covered and i missed it...
Other thoughts. Have you compared the new timing gears the used set you got? It's rare, but not unheard of to get a timing gear with the dot in the wrong place. New parts don't always mean good parts...but that would not account for it running fine for 3 min.
Have you pulled the intake back off yet? It may be worth checking/replacing the intake gaskets. At least that would not be too expensive to check.


I'm planning on removing the intake and finding out :) I was originally going to just measure all the rocker's lifts to make sure they're all moving and that no lobe was wiped, but since i might want to also eliminate the possibility of an intake vacuum leak I might just take the intake off and take a look myself while I do that.

New timing set arrives today. I've compared my current set to another used set.. both had about the same amount of play. I will compare that to the brand new set today.

How can i check the installed height of the springs? I don't remember the trick flow instructions mentioning having to check/alter that and I just used the stock springs as they sat.
 
As far as carb adjustments, can i adjust the floats with the carb off the engine? I'm probably gonna take the intake off tonight or early tomorrow morning and it'd be easier to adjust it then. It'd be easier since I have to install new jets anyway and the space would be nice.
 
Any updates? Have been tracking your progress as this is a pretty interesting thread on how to eliminate several possibilities. As for adjusting your carb floats, this really needs to be done while the engine is running, but I'm sure there is a bench procedure to get you in the ballpark, but I'm sure you are already close.
 
Any updates? Have been tracking your progress as this is a pretty interesting thread on how to eliminate several possibilities. As for adjusting your carb floats, this really needs to be done while the engine is running, but I'm sure there is a bench procedure to get you in the ballpark, but I'm sure you are already close.

Not much in the way of updates. Meant to get some stuff done this weekend but I was lazy and some things popped up out of nowhere (primarily my mom showing up with a little 20 lb dog out of nowhere...)

I've also been a bit hesitant to move on because I haven't found anything blatantly wrong that would independently cause the issues I'm having and I'd hate to put it back together, and find I didn't fix anything.

The little updates I do have:
I compared the new compcams timing set to the old one. Physically, there were some visibly noticeable differences (some of the markings on the original ones were slightly off and in general it looks like the machining was done slightly differently), but nothing too drastic. Once installed, the slop is still the same too.

I spoke with my dad and apparently we DID adjust the valve lash with the lifters on the base of the cam lobes. The Trick Flow instructions described a different procedure than I was told to try on here and Fordmuscle.com, but it still did the job (basically follow the fire order, rotate crank 90 degrees for each step in firing order, etc). For some reason I didn't remember it, but it was done.
 
One other question... on newer (within the last few years) Holley Street Avengers, to adjust the floats or change the jets... do you need to buy new gaskets of any kind? The holley recommendations say that in general you do, but I thought they switched to a gasket-less product at some point... could be wrong though.

Did you ever check your floats?

I just had basically the same problem. I was chasing this thing all over the place and it turns out that the secondary float was sticking. This was allowing gas to dribble out of the boosters. Same issue you have where one minute it runs good and then it starts to run crappy while at idle. Then hard starts sometimes and at other times starts right up. Runs rich. Driving it stalls out.

I realize you have spent a bunch of time and effort on this but before you tear it down any more check the rear float.

Unscrew the needle and seat and remove it. Hold it upside down and see if it opens freely.

The weird thing is that I rebuilt my carb in nov/dec. Right after I rebuilt and installed the carb I started the car up and it ran great. The engine has run 4 times since the rebuild and the 5th time I ran into these issues.

So this was basically a brand new Holley needle and seat. Maybe it's crappy gas that caused them to stick.

Just my 2 cents
 
Did you ever check your floats?

I just had basically the same problem. I was chasing this thing all over the place and it turns out that the secondary float was sticking. This was allowing gas to dribble out of the boosters. Same issue you have where one minute it runs good and then it starts to run crappy while at idle. Then hard starts sometimes and at other times starts right up. Runs rich. Driving it stalls out.

I realize you have spent a bunch of time and effort on this but before you tear it down any more check the rear float.

Unscrew the needle and seat and remove it. Hold it upside down and see if it opens freely.

The weird thing is that I rebuilt my carb in nov/dec. Right after I rebuilt and installed the carb I started the car up and it ran great. The engine has run 4 times since the rebuild and the 5th time I ran into these issues.

So this was basically a brand new Holley needle and seat. Maybe it's crappy gas that caused them to stick.

Just my 2 cents

Hadn't gotten to it yet. After we put it together but before we try to start it is when we are going to adjust the floats.

Random ?... found a leakdown tester at sears (P/N 16025 IIRC). Is that (and my air compressor) all I need? I am going to try to squeeze in a compression test and leakdown test tonight before I head out for the weekend. One concern... every website I've seen says you should do this with the engine warm. Well... my engines been sitting for a month and is clearly not going to get warm tonight. Are these tests still worth while?

Any tips on leakdown/comopression testing (I've done compression tests before, not leakdown though) in addition to the questions above would be welcome as well.