Hey guys Im wondering just how exactly you retard the cams on the 3.4 DOHC? Do you do the intake, exhaust or both? And which ones are the intake cams and which ones are the exhaust cams? Im getting ready to change my belt and thought it would be a great time to retard the cams. Do you do it by counter clocwise by counting gear teeth? I know its a dumb question. Thanks for the help -Dale-
IP: Logged
05:42 PM
PFF
System Bot
FieroReinke Member
Posts: 1065 From: St James, MO Registered: Feb 2003
Check www.60degreev6.com. All the information you will need is there. From what i have gathered you retard the exhaust cam, which is the cam on the exhaust manifold side of hte head, by 13 degrees. I dont remember off hand if that is 13 crank degrees or 13 cam degrees cause they are different. Again check out www.60degreev6.com and you will get what you need.
------------------ Chris 3.4 TDC SWAP COMPLETED...this is going to be a fun car
You would do both. Doing just one would be equivalent to retarding half that amout total and increasing lobe separation angle . So if you retarded exhaust cams 4 degrees you would actually have retarded the valvetrain 2 degrees and increased your lobe separation angle 2 degrees. Lets say you retarded just the intake cams 4 degrees. You would have 2 degrees total valvetrain retard and you would have decreased your lobe separation angle 2 degrees. On a single cam engine lobe separation angle is built into the cam ,there is no changing it unless you change the cam. Also on a single cam engine you don't have a choice but to retard both intake and exhaust lobes because its all one unit. This is why DOHC engines are easy to tune in relation to valvetrain-to-crank timing events. Advancing one cam would yeild the same degree #'s for total advance as above . Advance 4 degrees intake cam ,actual 2 degrees total valvetrain and 2 degrees increase lobe separation angle,and so on and so forth. Hope that helps
[This message has been edited by FIEROPHREK (edited 02-14-2005).]
I just went to 60DegreeV6 and one guy said just take the belt and carefully turn the cam gears counter clock wise one tooth. Then put the belt back on. Buthe said to be careful because the cams like to walk very freely with no tension. Is this the way to do it. Oh and my engine is a 1992 TDC
That is one way to do it but do you know how many degrees one tooth is? Most aftermarket cam gears have a built in adjustment feature with a degree'd scale for a more accurate adjustment.
You would still have to remove the belt on 91-93 engines. (in reference to the link for that tool). 1 tooth is 12 cam degrees, or 24 crank degrees. I always remove the cam sprocket locks before timing the motor, so I can dial them in perfect.
You would still have to remove the belt on 91-93 engines. (in reference to the link for that tool). 1 tooth is 12 cam degrees, or 24 crank degrees. I always remove the cam sprocket locks before timing the motor, so I can dial them in perfect.
do the sprockets mount to the cams differently on the 91-93 than the 94-95 or the 96-97?
You would still have to remove the belt on 91-93 engines. (in reference to the link for that tool). 1 tooth is 12 cam degrees, or 24 crank degrees. I always remove the cam sprocket locks before timing the motor, so I can dial them in perfect.
You do not have to remove the belt with that tool, that is why it is good. Just loosen the bolt with an air gun, and the tool bolted down, and turn the cam. As you turn it is measures the degrees, and when it is where you want it, just bolt the sprocket back to it.
------------------ 1992 Lumina Z34 5-speed For Sale, modified(high 13s), or stock 14.78 @ 92.68 1992 Lumina Z34 5-speed Stock, new crate engine and trannsmission 3.4L TDC V6, getting built to about 430hp at 8000rpm for a 88GT
The 91-93 cams used a pressed in lock. If this tool will move the cam and with that pressed in lock ring in there, its god like and amazing. I seriously doubt it though considering the lock ring's job is to keep the cam and sprocket from turning seperately. 94-95 has a lock that can be pried out once the bolt is removed. 91-93 MUST remove the sprocket. If you can hold the belt in place with the sprockets removed, props to you cause I don't have that many arms and hands.
------------------ Ben www.60degreev6.com
IP: Logged
10:09 PM
PFF
System Bot
Feb 16th, 2005
AaronZ34 Member
Posts: 2322 From: Colorado Springs, CO Registered: Oct 2004
This is part of what Kohburn PMed me witht he more detailed instructions:
"no need to remove the belt because of how the cam sprockets are attached to the cam - you only have to losen the bolt and tap the sprocket to free it so the cam can turn freely in it. the tool is pressed firmly against a flatspot on the cams and adjust the timing by moving that flat spot a number of degrees. moving it towards the front will advance it and moving it toward the back will retard it. you should be able to use it with only removing the plenum and valve covers and cam belt cover."
So assuming you are correct Ben, (I know you are, I am just not understanding this), when you "tap" the sprocket it frees the lock ring and allows the cam to spin freely? becuz it'd seem to me that you would have to get them to spin freely in order to adjust it, otherwise the cogs on the T-belt won't line up from intkae to exhaust sprockets.
Yeah, tapping the 91-93 cam gears is just gonna make them laugh at your attempts to humor them. They are pressed in completely. I hate that setup and have since gone to 94 type cam gears so I can adjust timing without removing the belt. You dont need that tool really to do that, but its a much easier way to get everything lined up.
You would still have to remove the belt on 91-93 engines. (in reference to the link for that tool). 1 tooth is 12 cam degrees, or 24 crank degrees. I always remove the cam sprocket locks before timing the motor, so I can dial them in perfect.
Wow, talk about rough idle - would it run with 24 degrees of retard? Some people complain about the 13 Degree retard, and I'm pretty sure they mean CRANK degrees, which is 6.5 Cam degrees.
[edit] to add: Yeah I just did the cam timing on a 91' TDC - there's no way in hell the sprocket is going to turn independently of the cam until you've pulled the gear off using a beefy gear puller (probably applies hundreds if not a couple thousand lbs of force), and then reinstalling the gear without the locking ring. Hammer? It would be more likely that a paper dog successfully chase an asbestos cat through Hell from my experience with it. Be neat to see how the 94-95 and 96+ motors work, though since I think they're different.
PS: Sorry for being a picture wh--e, I love my digital camera...
------------------ Chris
Blue 1987 GT Getrag 5 speed, 1" lowering springs, 225 50R16 rims and tires, Fiero Store 9 3/4" HD clutch (Soon to be 3.4L DOHC powered!) Silver 1986 2m4 THM 125c automatic Black 1985 2m4 SE Isuzu 5 speed (no paperwork)
Actually, a friend of mine tried the 1 tooth thing advanced timing, and said the low end was amazing, but it topped out at 5000 RPM like a brick wall. This was intake and exhaust both advanced. I am sure there are better timing setups than just 13 degrees on the exhaust, but its the best I have found for my engine and the idle is perfectly fine with my raised idle. Seems that it just needs about 100 more RPM than stock at idle to clear up any idle issues. I never had stalling but it certainly wasn't smooth.
My friend took the pics I had for 91 cam gears, and added his 94 cam gear pics for reference.
Very interesting, looks like the 94+ cogs would be much easier to remove or play with when it's already in the car. Will they retrofit onto a 91-93 motor?
I haven't seen the 96 cams but I know they have more teeth on them. Probably the same type lock rings as 94-95.
very helpful - I was unaware of the 91-93 difference before.. My engine its designed off of is a 95 will have to make seperate directions for the 91-93 cogs
Do you really have to remove the belt though? or can you use a gear puller to pul it partially off just enough to losen the reatining clip then knock the spocket back into place. Adjust the timing then tighten the bolt back in locking the clip in?
[This message has been edited by Kohburn (edited 02-16-2005).]
Actually, a friend of mine tried the 1 tooth thing advanced timing, and said the low end was amazing, but it topped out at 5000 RPM like a brick wall. This was intake and exhaust both advanced. I am sure there are better timing setups than just 13 degrees on the exhaust, but its the best I have found for my engine and the idle is perfectly fine with my raised idle. Seems that it just needs about 100 more RPM than stock at idle to clear up any idle issues. I never had stalling but it certainly wasn't smooth.
advance timing = low end retard timing = high end the question is what if we advance one and retard the other.. either adding overlap or lessening overlap..
I would say you have to pull it completely off, but I fear there is someone around here crazy enough to prove me wrong by doing some insanely over the top procedure to prove me wrong. For normal humans, you gotta pull it off for 91-93.
Someone else has tried advancing intake 6, retard exhaust 7 and claimed solid results from it. Given changes in intake and exhaust manifolds, I am sure a radical setup would require something much crazier. Even boost is gonna want far different specs, so I am very glad we don't have keyed cams.
IP: Logged
08:52 AM
PFF
System Bot
mrfixit58 Member
Posts: 3330 From: Seffner, Fl, USA Registered: Jul 99
I have researched this exhaust retarding thing for a while now but nobody could tell me the actual cam timing specs so I checked the timing myself. My engine is a 96. using cam center I found the intake to be 112 degrees and the exhaust 111 degrees. intake opened 3 degrees btc exhaust closed 7 degrees atc giving 10 degrees overlap. ( this is measured at actual opening not at the usual .050 lift)This small overlap is used to limit emissions.This is where the power comes from, the overlap.with retarded exhaust you get more power at high revs but with a peaky powerband. Advancing the intake helps bottom end power With more overlap you need tuned headers to draw the air/fuel through. I know with motorcycle engines the 4 valve heads like to see 105 centers but they usually have tuned headers.So it looks like with a 5 degree advance on the intake (111-105) and 6 degrees ex (112 - 106) this seems to fall right into place.This gives 21 degrees overlap.With tuned headers this should give a very solid midrange to upper hit.I think this guy did his homework.Plus on checking it seems these cams are very mild duration. Think of this motor with cams and headers!! I have not yet run this but I am in the middle of the swap. I am going to use these settings. The swap continues!! thanks ken Wheeler
Ken: excellent info! Thanks and a plus to you. When do you think you will be finishing - as in getting to some sort of evaluation phase? I look forward to hearing how it goes/went; make sure you post it! When I get to it - I expect late summer for this particular item, I am going to send a set of ('92) cams SOMEwhere for mods; CHRB or someplace if they will ACTUALLY do them and so I am starting to compile specs etc NOW. I don't mind spending $500 on that. It will be worth it but I only want to do it once......
answered this already....91-95 cam cogs/gears/sprockets are all compatible.
More duration is going to be a good thing for performance. CHRfab will definetly do them, as they have done a set already. The 96 cam specs can be found on 60V6.com, though im glad you came up with the exact same specs as GM has given us. I used to have the specs CHR gave me on the 94 cams, but someone decided that wasn't important anymore when they put the 96 specs up.
Originally posted by SappySE107: Someone else has tried advancing intake 6, retard exhaust 7 and claimed solid results from it. Given changes in intake and exhaust manifolds, I am sure a radical setup would require something much crazier. Even boost is gonna want far different specs, so I am very glad we don't have keyed cams.
March 19 I will be taking both of my Z34s to the dyno in Loveland, CO. My red Z34 has a 94 crate engine, so what I have gathered is that the cam timing is easily adjusted without removing the belt. I need to make this easy, so I can make as many changes as possible once on the dyno. I would play with my 92 as well, considering I bet the gains would probably be near double with every other mod plus the headers, but I don't want to **** it up (Buyer picks it up that day), and I want it running of course. So I will just be playing with my red car. But I will try as many combos as time will allow, we should have all 20 cars done by 2-3pm, and that leaves 3-4 hours for adjustments and additional runs. Hopefully I'll have this tool by then as well. It will be nice to finally have documented proof on this.
Ben please give me any and all specs you want me to run. What does the tool measure in crank or cam degrees? I figure I'll run the 13* exhaust retard, I'd like to advance the intkae a bit to see how that affects it, and I'd also like to dyno that all low end setup, since I think it'd be sweet to argue the point that DOHC cars have no low end.
