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Username Post: Help with possible timing issue        (Topic#364066)
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-21-21 09:23 AM - Post#2812543    

Good Morning all.. I'm sure this topic is approached regularly but I'm looking for any help I can find, got a sad 17 year old wanting to drive his truck, LOL. Truck is a 91 Silverado, 350/Auto. Block was replaced at one time with a short block from a 81 C30 but was running all 91 heads etc. Heads were bad, wiring issues with TBI, decided to save block and go carb. Purchased newly rebuilt carb heads, RPM Performer Intake, Summit 600, Comp cam and HEI distributor. Installed a gear drive during assembly just because we had it. At first start up we were 180 out, BOOM!OOPs Corrected that situation and truck started, idled and sounded OK. After warm up drove the truck maybe 5 miles, not bad, not great. Tweaked a little and drove again, after a few miles truck started popping through the carb, had to tow it home. Truck will idle but as soon as you touch the throttle it pops back through the carb and dies. Noticed front intake gasket hanging out, pulled it and resealed, no change. When it was running and sounding decent timing mark was way above the 2:00 marker, near 12:00. Absolutely positive the marks on cam and crank were correct at assembly, no way a gear drive could "jump" is there? I understand the motor a bit but not sure how to diagnose, distributor module? Coil? Something doesn't add up. HELP



 


65_Impala 
Very Senior Member
Posts: 4664

Reg: 12-29-02
01-21-21 10:23 AM - Post#2812550    
    In response to todintexas

You might have a timing mark to balancer mark issue. The balancer originally from that truck should use a timing tab that is at 12 o-clock.

Align the timing marks to 0*. The crank keyway should be pointing 45* to the upper right or at about 1:30. A stock balancer should make an upright Y as well with the 3 spokes when at TDC. If it's not, then you have the wrong pointer for the balancer.

https://www.hotrodders.com/threads/timing-tab-no t-...

Read the thread. Post 13 has a picture showing the possible balancer 0* mark locations with the angle relative to the keyway location. You need a tab that matches the matches the balancer.



 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17606
grumpyvette
Age: 73
Loc: FLORIDA USA
Reg: 03-16-01
01-21-21 12:15 PM - Post#2812558    
    In response to 65_Impala

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

step one, verify TDC
then verify the damper and timing tabs MATCH REALITY

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-21-21 03:40 PM - Post#2812567    
    In response to 65_Impala

This was one of our 1st thoughts as we noticed differences in the balancers. We had actually purchased a balancer for the 81 which as you mention is a 12 o'clock balancer, we took it back and installed a new balancer for a 91, that matches the 1 that was removed. Problem is, no matter where the timing mark is it is not acting correctly. We can occasionally get it to start and idle but only with the timing mark near 12 o'clock, with our balancer it should be at the 2 o'clock position. In either position, touch the throttle, it backfires and dies. One of the strange things is that once we corrected the 180? issue, the truck started and ran halfway decent for maybe 5 miles, shut the truck off it started up again and ran again for a few miles before this started happening.



 
IgnitionMan 
Valued Contributor
Posts: 3865

Reg: 04-15-05
01-21-21 04:08 PM - Post#2812571    
    In response to todintexas

Too bad this website won't let images on our computers be added, only URL's, it appears.

On the link for the hot rod site above, down a bit, there is a picture of all the timing marks used over the years, take a look at that, should help.



 
65_Impala 
Very Senior Member
Posts: 4664

Reg: 12-29-02
01-21-21 06:40 PM - Post#2812585    
    In response to todintexas

Unless the timing slipped, something else likely happened. Could you have a fuel problem? Dirt got into the carb?



 
busterrm 
Frequent Contributor
Posts: 1275
busterrm
Loc: Wichita Falls, Tx
Reg: 08-30-10
01-21-21 10:46 PM - Post#2812597    
    In response to 65_Impala

I agree with 65 _impala, putting all the new stuff on could have caused it. Did you pull the timing cover off? It may need a new timing set! It’s possible you have one of those sets that has the plastic or phenolic gear! Or the timing chain has stretched!

==== BOB ====
If I can't smoke the tires I want more!

1976 Chevy Nova
2017 Harley Davidson XL1200 Sportster
2018 Nissan Versa Note


Edited by busterrm on 01-21-21 10:48 PM. Reason for edit: No reason given.

 
51 AD 3100 
Contributor
Posts: 123

Age: 53
Loc: Grant, AL
Reg: 08-30-20
01-22-21 02:57 AM - Post#2812601    
    In response to todintexas

is there a possibility the distributor is a tooth off?


Life's more fun, in a '51


 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-22-21 04:41 AM - Post#2812605    
    In response to busterrm

Yes everything in the top is new. New heads, carburetor and manifold, distributor, plugs and wires. We replaced the timing chain with a gear drive just because we had it on hand. Agreed something has failed just fighting to figure out what it is. The weird part is that the motor started and ran drove for a few miles just fine and then started having this problem.



 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-22-21 04:42 AM - Post#2812606    
    In response to 51 AD 3100

We reset the distributor several times in working on it, anything is possible at this point. I know everything was correct in the beginning because the motor did start and run normally however the timing mark was off at that time also. Then after a few miles it failed and we have what we have now.



 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-22-21 04:44 AM - Post#2812607    
    In response to todintexas

When I return home on saturdy we are going to check the cap, check the coil and rotor. Reset everything back to 0 and start over. If it starts in fires at that point but the timing mark is still not in the right area it might point us in a direction.



 
bobb 
Super Senior Member
Posts: 5747

Loc: paradise
Reg: 09-05-03
01-22-21 07:06 AM - Post#2812621    
    In response to todintexas

if the cap isnt cracked i would add some timing advance. it wont hurt anything.

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-22-21 10:58 AM - Post#2812634    
    In response to IgnitionMan

IgnitionMan

The distributor is new but in the world of mass market parts that doesn't mean anything. Would a failure of the module inside the distributor cause this type of issue?



 
TAT_2 
Site Ambassador - Member #26 - "20th Year" Silver Supporting Member
Posts: 36938
TAT_2
Age: 67
Loc: "UNDER THE BOARDWALK"
Reg: 10-29-00
01-23-21 04:56 AM - Post#2812700    
    In response to todintexas

HAD THAT PROBLEM WITH MY OLD 78.
THE ADVANCE PLATE WAS STICKING FULLY ADVANCED THROWING OFF THE TIMEING.
TURN THE ROTOR BY HAND & SEE IF IT STICKS.

09 PONTIAC- VIBE
08 PONTIAC- G6
93 VETTE - 40TH ANIV- RUBY RED- LT1/6-SPD/RAG TOP

PREVIOUS VETTE'S 58,68,70,76,78,85,90


QUOTE FROM HELEN
"WHY YOU LOOKING AT THAT? YA KNOW YA WANT ANOTHER VETTE"












 
aghaga 
"4th Year" Silver Supporting Member
Posts: 2300
aghaga
Age: 66
Loc: Altavista, Va.
Reg: 07-05-08
01-23-21 06:54 AM - Post#2812713    
    In response to todintexas

I once had a very similar problem and found that the resistance in the carbon button in the distributor cap was too high.



 
wagonman100 
Site Ambassador
Posts: 15010

Loc: Baltimore, MD
Reg: 11-27-04
01-23-21 07:26 AM - Post#2812717    
    In response to aghaga

I agree with grumpyvette, you have to bring #1 up to TDC and see where the line on the balancer is. That is where your zero timing mark should be no matter where it is now. You will never know what your timing actually is until you verify TDC. Popping through the carb. is usually either the timing being off or valve hanging open. There’s a chance you broke a valve spring since it started running bad all of the sudden.There are other causes, as the other ones mentioned in the previous posts, but those would be the most common.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-23-21 10:13 AM - Post#2812742    
    In response to wagonman100

I will be home tonight. In the morning we will reset the motor to top dead center, number one piston at the top and both valves closed, and see where the mark on the balancer is at that point. I agree it does sound like timing or a valve issue, just feels like something "failed" as the motor did run. That said,I believe the timing mark may have been off when we first got it fired as others have mentioned. I don't know how it could possibly have moved with a gear drive but how do I verify cam and crank are still in "alignment" as they were when we assembled? Thank you all, definitely helping to get a diagnostic game plan together.



 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17606
grumpyvette
Age: 73
Loc: FLORIDA USA
Reg: 03-16-01
01-23-21 03:36 PM - Post#2812769    
    In response to todintexas

progress with the testing logically
first find TRUE TDC then Id suggest pulling the valve covers and closely inspecting the valve train,
if every component looks ok, do a compression test

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-24-21 11:53 AM - Post#2812816    
    In response to 65_Impala

65_Impala

Thanks everyone for the information we are working on it now. 65, could you clarify something for me your note says the balancer from that truck should have the pointer at 12 o'clock. Would that be the balancer for the actual truck, 91 Silverado, for the balancer for the block which is a 1981? This may be part of our issues I may have what is supposed to be standard confused.



 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-24-21 02:31 PM - Post#2812828    
    In response to todintexas

So went back to basics as everyone suggested and found a brand new problem. Pulled the valve covers, verified top dead center and got everything back to square 1. Distributor appears in the right location, mark appears on the pointer as it should be. Everything, or at least 50% of the valve train was very loose, we were very slow to adjust everything when we assembled the motor but apparently did something wrong, or possibly misread the lifters. That said, we backed everything off to start over with valve adjustment but most bottom out before reaching even zero preload. 7.94 pushrods, is it possible they are too short?



 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17606
grumpyvette
Age: 73
Loc: FLORIDA USA
Reg: 03-16-01
01-24-21 04:35 PM - Post#2812842    
    In response to todintexas

viewtopic.php?f=44&t=2839&p =7344&hilit=adjustabl e+guide#p7344

http://www.summitracing.com/search/...d-length-che...
Proform Pushrod Length Checkers 66789 SBC 3/8" rocker studs

Proform Pushrod Length Checkers 66790 SBC 7/16" rocker studs

heres a bit of useful related push rod length info (POSTED HERE)
youll want to select the correct set or SETS for your shop

Big Block Chevy, Standard Length Big Block Intake 3/8" / .080" 8.275"
295-7941-8 Big Block Chevy, Standard Length Big Block Exhaust 3/8" / .080" 9.250"
295-7969-8 Big Block Chevy, Standard Big Block +.100" Long Intake 3/8" / .080" 8.375"
295-7979-8 Big Block Chevy, Standard Big Block +.100" Long Exhaust 3/8" / .080" 9.350"
295-7951-8 Big Block Chevy, Standard Length Big Block Tall Deck Intake 3/8" / .080" 8.675"
295-7961-8 Big Block Chevy, Standard Length Big Block Tall Deck Exhaust 3/8" / .080" 9.650"
295-7800 V8 396-454 Retro Fit Pushrod Set, Intake & Exhaust, 1965-Present
3/8" / .080"
3/8" / .080" 7.725 Int.
8.675 Exh

295-7913-16 Small Block Chevy, Standard Length Small Block Chevy 3/8" / .080" 7.800"
295-7984-16 Small Block Chevy, +.100" Long 3/8" / .080" 7.900"
295-7934-16 Big Block Ford, Standard Length Ford `72-'78 429-460 3/8" / .080" 8.550"
295-7951-16 Big Block Ford, Standard Length Ford `69-'71 429-460 3/8" / .080" 8.675"
295-7582-16 Oldsmobile, Std Length 455 5/16" 9.550"

youll want too verify the correct valve train geometry and push rod length,
just to be sure its correct , on any engine with a new cam installed,
never assume anything
but once you know for certain,
thread on adjusting valves
http://garage.grumpysperformance.com/index.php?thr...


http://garage.grumpysperformance.com/index.php?thr...


http://garage.grumpysperformance.com/index.php?thr...



http://garage.grumpysperformance.com/index.php?thr...





IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 01-24-21 04:38 PM. Reason for edit: No reason given.

 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-24-21 04:44 PM - Post#2812843    
    In response to grumpyvette

Thank you for the information. As much as I want it to be something that simple, afraid it's not the pushrods. I am fairly savvy mechanic and have done quite a few valves, no expert for sure. Was Pretty sure we had the valves pretty close and the motor did start and run, no clue why all of them would be loose (beyond adjustment), or least the majority, after only a few minutes drive time unless there's another problem. Used assembly lube, break in oil etc just not sure what happened. I guess I'll pull the intake.



 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-25-21 08:47 AM - Post#2812885    
    In response to todintexas

https://linksharing.samsungcloud.com/pG6TKh7y9XOW

I can't figure out how to add a picture, maybe the above link will work? Opened up the oil filter and did find some VERY fine metal particles. If every libe on the can was damaged shouldn't the filter be obviously full? Thank you



 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-25-21 11:14 AM - Post#2812892    
    In response to todintexas

https://linksharing.samsungcloud.com/iVCk9USFU72i

Well here is a new, and unfortunate, picture. Went ahead and pulled the intake, pulled the number one lifter which was no easy task in itself. And it's completely destroyed. Not sure what happened as we used break-in oil, break-lube and did the high idle technique, but it's destroyed nonetheless. At least half the rockers feel just like this, should I assume the cam is destroyed also?



 
65_Impala 
Very Senior Member
Posts: 4664

Reg: 12-29-02
01-25-21 12:19 PM - Post#2812895    
    In response to todintexas

Ouch, that sucks. Something was very wrong to have it fail that quickly and badly.

Yes, the cam is also destroyed. You need to completely disassemble the engine and pull the plugs out of the block to wash the block to get the crap out of it and then start over. Probably will need all new bearings. There will likely be metal embedded in the pistons too, but if you don't care about it too much run them anyways.

What cam p/n was it?



 
rumrumm 
"20th Year" Silver Supporting Member
Posts: 2105
rumrumm
Loc: Macomb, IL
Reg: 10-18-01
01-25-21 12:20 PM - Post#2812896    
    In response to todintexas

I would advise doing a total dismantle of your engine. There is a good chance you have metal everywhere including the bearings. Worst case scenario, you will have to execute a complete cleanup and start over. I'd recommend a roller cam next time.

Lynn

"There's no 12-step program for stupid."


383 sbc, Eagle, AFR, SRP, CompCams, Edelbrock, FiTECH. Dyno #'s: 450 hp @ 5700, 468 lb. ft. of torque @ 4300.



 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17606
grumpyvette
Age: 73
Loc: FLORIDA USA
Reg: 03-16-01
01-25-21 01:37 PM - Post#2812901    
    In response to rumrumm

if the cam and lifter break-in failed that quickly theres a very good chance you have a clearance or valve train binding issue some place like spring bind or rocker to rocker stud
reading the links and sub links will save you a great deal of problems

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...


http://garage.grumpysperformance.com/index.php?thr...


http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...



IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 01-25-21 03:47 PM. Reason for edit: No reason given.

 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-25-21 02:57 PM - Post#2812910    
    In response to grumpyvette

I agree, we are trying to determine reason but in the meantime we purchased a new cam, lifters,rockers etc. We have pulled it down, a few stuck lifters we are dealing with right (mushroomed I'm sure). We must have gotten something wrong during assembly. I'm told the stick length pushrods are fine with this setup but I think I'll measure this time just to be sure.



 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17606
grumpyvette
Age: 73
Loc: FLORIDA USA
Reg: 03-16-01
01-25-21 05:14 PM - Post#2812927    
    In response to todintexas

https://www.ebay.com/i/402584062207?chn=ps &nor...

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
todintexas 
Newbie
Posts: 18

Reg: 01-21-21
01-26-21 10:12 AM - Post#2812983    
    In response to grumpyvette

I definitely considered that tool, but I was concerned about pulling a mushroomed lifter up through the lifter bore and the additional damage that might cause. Went with an old school method my dad showed me, cut the top half of a piece of pipe off that fit through the cam bore, just pushed the damaged lifters down into that pipe and pulled them out with a magnet. Went pretty quick, we are back to square one and ready for reassembly.



 


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