Four Carbs, all loading fuel at bottom of intake
- Thread starter sprice
- Start date
sprice
Active Member
Posts 39 and 40 make sense as I do believe it’s pushing against itself somewhere. These are the instructions from Comp Cams and I phoned the tech line to confirm and got some junior thst put me on hold for about 5 min outed because he didn’t know why they had two “0” marks. The instructions however, if I am reading this correctly indicate to use the “0” on the keyway. Almost ready to throw that dam chain set out.
To test then, if I put the marks as suggested “keyway should be same angle as #1 push rod” (not on keyway), piston should be at tdc?
To test then, if I put the marks as suggested “keyway should be same angle as #1 push rod” (not on keyway), piston should be at tdc?
sprice
Active Member
This is making sense.
^This^
With it that far off, I wouldn't be at all surprised if there was some bent valves.
bigmoparjeff
Senior Member
There should be three keyway slots on the crank sprocket. The instructions tell you to install the sprocket with the desired keyway on the key, then line up the corresponding tooth mark with the dot on the cam gear.
It's fairly clear now that we are scrutinizing the instructions, but I can see how a person would get confused. The instructions should have included some photos or drawings to point out the different choices.
Jeff
It's fairly clear now that we are scrutinizing the instructions, but I can see how a person would get confused. The instructions should have included some photos or drawings to point out the different choices.
Jeff
bigmoparjeff
Senior Member
That would depend on the compression ratio.
Usually bent valves are going to give you popping out of the intake or exhaust.
Jeff
1970FuryConv
Old Man with a Hat
As others have said, 0° on timing chain sprocket is the 0 mark on the sprocket, not the key way for the crankshaft. 0° is to the left of the key in your picture. You've just found the source of your problem. 0° on the crank sprocket must line up with timing mark on you cam sprocket. Remove timing chain and cam sprocket and reassemble with marks lined up: timing mark on cam sprocket and true 0° mark on crankshaft sprocket. Then rotate engine until Piston #1 is TDC, spark plug removed, significant out flow of air at #1 spark plug hole. Have asst turn crank back and forth until you feel with coathanger thru spark plug hole that #1 piston is at top of travel. Cam sprocket timing mark is usually at 180° from alignment point of 2 sprockets. Set up distributor to fire at 10 degrees before #1 cylinder TDC that you just aligned. You should be OK.
Last edited:
Mike66Chryslers
Senior Member
Just FYI, when the timing set is installed as the instructions say, "dot to dot", that is actually with the #1 piston at TDC on the exhaust stroke, not the compression stroke. If you wish to drop in the distributor and roughly set it up at this time, without rotating the crank, the rotor tip must point to #6 tower, not #1 tower. Piston #6 is at TDC on its compression stroke when #1 is at TDC on its exhaust stroke.
Same as small block Chevy, fwiw. As I recall, you can do the dot routine with the cam sproket's dot at 12:00 position as the crank sproket's dot is at a similar 12:00 position. Which can be easier to see with a straight edge line between the dots. Then, next crank revolution around, the dots will be at 6:00 and 12:00 position . . . the "classic" "dot to dot" orientation (which is #6 firing). This "Chevy" orientatioin also works for the Chevy 60-degree 2.8 V-6 family, too, which I fouind documented in a Chevy service manual.
It appears that the confusion of "dots" is with the multi-keyway crank sprocket. The dot on the inside, crankshaft snout side, has a "0" on it, for the "straight-up, no advance or retard" position. BUT it's the "0" on the outside of the crank sproket which is actually used for the actual cam sproket position reference. Just as the other reference marks (for the respective advanced or retarded orientations) would take the place of the "0" on the outside of the crank sproket to reference the dot on the cam sproket for correct installation.
Just some thoughts,
CBODY67
sprice
Active Member
This is what I was missing. This is very helpful. Yes, why Comp didn't have something like this is crazy. Thank you. I think we have it. I will report back.
sprice
Active Member
I turned the engine over manually to make sure no binding. Keep fingers and legs crossed no bent valves.
sprice
Active Member
Well saga continues. I should have documented my work better. I guess the comp tech did street me on the right direction. Timing marks are as many suggested here. Keyway at the #1 push rod angle and outside “0” camshaft sprocket.
I think next is to do a compression test to see if any issues there. The issue of introducing more air making it run better is I think, something to chase.
I think next is to do a compression test to see if any issues there. The issue of introducing more air making it run better is I think, something to chase.
Thanks for the images. Usually, if a balancer outer ring might "move", it might also move rearward on the center hub, which means exposed rubber that is normally hidden or "flat" with the front surface.
In many cases, "pushrod" angles do not parallel the connecting rod centerline position at TDC. Reason is that the cam position in the block will not always allow this, as the lifter angle to the camshaft is not always 45 degrees (which is the main difference in the LA "consumer" blocks and the LA Race block). In order to save assembled height of the motor (to fit under low hoodlines), the cams were usually as low in the block and/or the heads as short (or "laid over to the outside of the motor) as they could be to fit. These things are easier to see with the engine on an engine stand than when the engine is in the vehicle, by observation. Hence, the use of the connecting rod centerline at TDC is a more reliable situation.
I'm glad you're making great progress toward diagnosing this situation! Certainly, the mechanical orientations have to be correct for everything to work right. On the carbs, it would be hard to conceive that all of them had the idle air bleeds clogged, which makes the idle mixture go "full rich". But then, too, the size and opening of the bleeds is not something that is addressed when doing a carb kit. These two air bleeds (one for each side of the primary side of the carb) are usually easily visible when looking down into the air horn with the air cleaner removed. They are something which "varnish" (in the old days of leaded gas) might accumulate on and slightly clog, which was easily washed off with some carb cleaner. But usually not an issue. Which can get back to the correct gasket under the venturi cluster and such. A minor thing, though.
I'm hoping that all of the carbs were "kmown good" items which had been used recently on other engines?
Thanks for the pictures and illustration of progress so far! Please keep us posted on your progress!
Just some thoughts,
CBODY67
In many cases, "pushrod" angles do not parallel the connecting rod centerline position at TDC. Reason is that the cam position in the block will not always allow this, as the lifter angle to the camshaft is not always 45 degrees (which is the main difference in the LA "consumer" blocks and the LA Race block). In order to save assembled height of the motor (to fit under low hoodlines), the cams were usually as low in the block and/or the heads as short (or "laid over to the outside of the motor) as they could be to fit. These things are easier to see with the engine on an engine stand than when the engine is in the vehicle, by observation. Hence, the use of the connecting rod centerline at TDC is a more reliable situation.
I'm glad you're making great progress toward diagnosing this situation! Certainly, the mechanical orientations have to be correct for everything to work right. On the carbs, it would be hard to conceive that all of them had the idle air bleeds clogged, which makes the idle mixture go "full rich". But then, too, the size and opening of the bleeds is not something that is addressed when doing a carb kit. These two air bleeds (one for each side of the primary side of the carb) are usually easily visible when looking down into the air horn with the air cleaner removed. They are something which "varnish" (in the old days of leaded gas) might accumulate on and slightly clog, which was easily washed off with some carb cleaner. But usually not an issue. Which can get back to the correct gasket under the venturi cluster and such. A minor thing, though.
I'm hoping that all of the carbs were "kmown good" items which had been used recently on other engines?
Thanks for the pictures and illustration of progress so far! Please keep us posted on your progress!
Just some thoughts,
CBODY67
sprice
Active Member
Yes, two edelbrocks for sure were run on good engines and actually improved the situation quite however was able to place the originals (ford product)back on after adjustment. I'm drawing in a valvetrain matter now.
1970FuryConv
Old Man with a Hat
Good work fixing the problem!
Harmonic balancer looks new, so hope that's not an issue.
I'd Reassemble, put a carb on it, and try it at 10°BTDC.
GOOD LUCK!!!
Harmonic balancer looks new, so hope that's not an issue.
I'd Reassemble, put a carb on it, and try it at 10°BTDC.
GOOD LUCK!!!
sprice
Active Member
Did a (cold, carb off) compression test.
#1 = 175
#3 = 175
#5 = 173
#7 = 172
#8 = 170
#6 = 170
#4 = 172
#2 = 173
Removed the drivers side valve cover to check valve movement. All looked same. Was thinking perhaps push rods may be too long leaving valves open however don't think would be getting the consistent numbers on compression test. On TDC, both valves are "snug", not loose on #1. Not sure if they should have some looseness? Wouldn't expect enough to clatter. Another note: all plugs came out same fouling on all, some even a little wet. Anybody have other leads to test or thoughts? Appreciate all contributions.
#1 = 175
#3 = 175
#5 = 173
#7 = 172
#8 = 170
#6 = 170
#4 = 172
#2 = 173
Removed the drivers side valve cover to check valve movement. All looked same. Was thinking perhaps push rods may be too long leaving valves open however don't think would be getting the consistent numbers on compression test. On TDC, both valves are "snug", not loose on #1. Not sure if they should have some looseness? Wouldn't expect enough to clatter. Another note: all plugs came out same fouling on all, some even a little wet. Anybody have other leads to test or thoughts? Appreciate all contributions.
With compression good to great, with the cam now phased correctly, yet the plugs all look uniformly "wet", that might mean an ignition issue of weak spark? I applaud your perseverance in this situation!
Happy Holidays!
CBODY67
Happy Holidays!
CBODY67
sprice
Active Member
Thanks cbody67. Think I’ll start reassembly since appears all is mechanically correct. Yes, I thought if weak spark which is why I tested with another distributor and coil however not at the same time. I will test spark strength. Also reading last night about this running better with pvc hose off and came across this DF-17 adjustable PCV valve. I am pretty sure no vacuum at idle at the pcv when it was connected and running at idle. Thought they were all the same, if it rattles- you’re good, if no rattle - replace or clean. If I find the answer, will post back. Thanks and Happy holidays to all.
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