slider cam with round tooth sprocket what would timing do?

[going4speed]

I believe my roller cam motor has a slider cam in the head. What would that do to cam timing using the round tooth sprockets?

[4 l-bodies]

There are three different round tooth cam pulleys. One being so-called straight up, while the other two being retarded and advanced. Do you know what # your cam pulley is? Unless you have history knowledge of motor going way, way back, after 25 years who knows who did what to these vehicles. Obviously somebody has done some mixing and matching already since you seem to think you have a slider cam in your CB.
Todd

[going4speed]

I think this is my confusion...for some reason I thought the 88's had rollers but they still have slider cams. So this should be a square tool slider motor. Chasing down idle miss.

[GLHS60]

All 1988 engines were roller. Having the cam a few degrees early or late won't cause a miss.

Thanks
Randy

[going4speed]

It's popping out the exhaust during idle but the engine seems smooth. Cannot figure this one out..no codes, new coolant sensor, nos hep, good vacuum lines, fresh motor, tight clamps...at a loss

[jeff1234]

Have you revved it pretty high recently? Could be a bent valve or possibly collapsed or stuck hydraulic adjuster. Look for a bad wire or bad plug, sticky injector or loose plate in distributor or cracked cap or bad rotor. I would eliminate ignition problems first. Good luck! ;-)

[going4speed]

Cap, rotor and wires look good. Plate in distributor is solid plugs look perfect. Have not revved it over 5k. Been looking over the wiring and cant find any issues. Just going to sell it I think I need to stick to subarus.

[zin]

It might also be a "logic module" miss, where the engine runs fine, but has a semi random "miss" that can't be fixed...

How's it run under a load?

Mike

[going4speed]

Like a scalded dog on steroids...this thing is pretty dang quick!!

It might also be a "logic module" miss, where the engine runs fine, but has a semi random "miss" that can't be fixed...

How's it run under a load?

Mike

[GLHS60]

An occasional pop from the exhaust at idle is often just the Baro Solenoid taking an air sample.

Thanks
Randy

[Vigo]

It is a "thing" with turbo mopars that 99% of people cannot get them to idle PERFECTLY smoothly. Oh well.


Also i thought there were only two round tooth cam gears? 557 and 690?

Basically, back during the slider days they indexed the cam gear locator differently and had 1 cam gear. In the roller days they had all the cams indexed the same and used different cam gears. So, assuming i am not full of crap there, mixing and matching can result in BIG cam timing changes. I honestly think cam timing differences from mixing and matching components are a big reason why some people cant get their TMs to run how they 'should'.

[4 l-bodies]

It is a "thing" with turbo mopars that 99% of people cannot get them to idle PERFECTLY smoothly. Oh well.


Also i thought there were only two round tooth cam gears? 557 and 690?

Basically, back during the slider days they indexed the cam gear locator differently and had 1 cam gear. In the roller days they had all the cams indexed the same and used different cam gears. So, assuming i am not full of crap there, mixing and matching can result in BIG cam timing changes. I honestly think cam timing differences from mixing and matching components are a big reason why some people cant get their TMs to run how they 'should'.

Also there is a roundtooth #535 (88 TD block). Looks like about 3° advanced over #557 pulley.
They also had couple different square tooth cam pulleys for 86-87 tall deck (#238) and HO motors (#992).

Yes I agree Adam. You can open up a big-can-o-worms mixings cams and pulleys in various blocks. Then to top it off most Fidanza adjustable cam pulleys I've degreed in the last few years are about 3-4° retarded over the 557 and square tooth 974 pulley. Rebuild your motor taking a little off the deck & the block and that retards you some more. Can all stack up to put your cam all over the map, usually retarded. Without degreeing camshaft in, who's gonna know?
One of the motors I built for a customer I had to intentionally advance the cam pulley one whole tooth even though he had an adjustable cam pulley! I did this because of the stacking effect talked about above. I had practically no adjustablity to advance further because it needed like 9-10° advance on pulley just to get camshaft installed at proper centerline. One wonders how many more motors are out there like that but didn't get degreed in properly.
Todd

[Vigo]

Thanks for the cam gear info, i was not aware of the #535 or the various square tooth gears.

[zin]

Sounds like some info that would go well in a KC post ....

Mike

- - - Updated - - -

Sounds like some info that would go well in a KC post ....

Mike

[going4speed]

Took the timing cover off the top of the cam cover. Square tooth belt, slider cam, 1988 electronics. Strange hand written sticker on computer chip. Have to wonder if the chip is part of my problem here.

http://youtu.be/Bmj6gg0eR5c

http://youtu.be/2-EVyElnL3I

[glhs727]

Took the timing cover off the top of the cam cover. Square tooth belt, slider cam, 1988 electronics. Strange hand written sticker on computer chip. Have to wonder if the chip is part of my problem here.

http://youtu.be/Bmj6gg0eR5c

http://youtu.be/2-EVyElnL3I

Sounds normal. BTW you have an FWD stage 3 pcm. Come by during your lunch break and we can throw in a stock pcm and see what happens.

[wallace]

It's popping out the exhaust during idle but the engine seems smooth. Cannot figure this one out..no codes, new coolant sensor, nos hep, good vacuum lines, fresh motor, tight clamps...at a loss

That sounds like an exhaust valve. What does the vacuum gauge do at idle? I've had two stock turbo heads redone and both had exhaust valves that were not seating correctly.

[going4speed]

Interesting. The stock gage reads 16. I have a autometer gage coming and will check the vacuum on a more accurate gauge. It pops like crazy when its first started and cold. You can hear the engine trying to lower the idle and the car starts miss firing and trying to stall then it starts the dreaded idle waving trying to get it to idle lower but almost stalling. I do need to get a leak down tester. I thought turbo dodges were supposed to be cheap? that is not turning out to be the case.

[wallace]

Nothing is cheap anymore! I'm leaning towards the exhaust valves. Mine did the same thing you describe but ran really good. The first one all 4 were bent not sealing on the bench but the van ran just fine. My thinking is that they do seat fairly well once up to operating temp. The heat that they endure with the stock turbine and exhaust is considerable.

[turboshelbys]

It is a "thing" with turbo mopars that 99% of people cannot get them to idle PERFECTLY smoothly.

Correct

An occasional pop from the exhaust at idle is often just the Baro Solenoid taking an air sample.

Thanks
Randy

This is exactly what is happening, nice job Randy

There are no bent valves, no timing problems, no cam problems, etc.

The compression checks 160 across the board and leak down was less then 3%

Every single turbo dodge I have ever owned or worked on does this(over a hundred btw), some do it more than others.

If you have been driving newer cars for a while, then this noise you will definitely notice, but it is not a "problem"