I just finished doing a top end rebuild. The following is what I dit.

-Replaced the lifters and cam with an XE 262H-10
-New valves, springs and all seals
-New timing chain
(Above was a summit kit from comp cams, all matched)
-Ported and polished cylinder heads (stock)
-Port matched the intake. (stock)

All of this is with a stock 1985 trans am with a 305 and a CC carb. The car ran fine before tear down.

The problem that I am having is getting the timing right, no low end power and the vacuum drops below 5" when put in gear. The vacuum will increase with the throtle up to 10" then drop again. I did not put headers on it yet but will be doing it in the near future. The car has been back on the road for a few days and today it would not shift into OD. There is no check engine light yet. I was expecting more then this.

Any one have any ideas?

 

your broke in the cam according to instructions right? 2k rpm, etc?

what is your timing at idle, and idle speed?

You'll probably have to bump up your base timing a fair bit, and tweak the carb some. Let me know what you're at, and we'll go from there. It should run damn well once it's set up right.

 

I had a slight problem while breaking in the cam. The engine started overheating, helps to double check the radiator fluid, so I shut it down to let it cool then finished the break in. It ran at 2000 rpm for a total of 30 minutes.

At idle after the engine has warmed up I am running a hair below 1000 rpm.

Base timing was set at 4 degrees advanced right after break in. I am unsur where it is no because I tried to set it for max vacuum at on point and now when I disconnect the computer from the distributor the car dies.

I believe that my choke needs a little tweeking also.

Could I have over preloaded the lifters? I did what the instructions said.

The carb is remanufactured to stock specs.

I also got a code 44 while setting a a stop light on my way to work. O the way home the car did not want to idle high enough to stay running.

 

I think that cam needs far more timing then that at idle, but I'm not sure how the computer controlled distributor works for that. Perhaps unplug the est, and bump it up to 10* or so. See if it'll still run ok. Adjust your idle for ~800RPM idle if you can.

Five7 would know more about tweaking the cc setup for that flavor of cam.

I think you've got it all together right, just need to tweak it right. *what is code 44 ?*

 

The vacuum has nothing to do with the timing adjustment decisions. 6 to 10 degrees BTDC base timing will probably be where you end up. Start with 6 for now.

After the cam break-in, did you change the oil and re-adjust the rockers? That should be standard practice.

Code 44 is most typically a weak O2 sensor. How old (or abused) is yours?

 

You should also have adjusted the IAB.

 

I did not readjust the rocker arms. I will do that as soon as I can and see what happens. I will also re adjust the timing at that time.

How do you adjust the IAB. The last time I messed with it I could never get the carb back to what it was. That is one of the reasons for buying a new carb.

 

I've got the same camshaft in my 80. It has a very, very mild lope to it, but still pulls about 16" of vaccum at an 800 rpm idle.

To me it sounds like a number of things off. First things first, crank your timing up a bit, then up your idle a touch so you idle at about 800 - 850 RPM in park. With the new cam and headers, you are also likley running a bit lean now, so you may need to richen the mixture up.

I've never dealt with a CCC carb before, so I can't really help much with how to make these adjustments...

 

Sounds like the cam is retarded...did you degree it?

 

No. I did not degree the cam. According to Comp Cams directions it is not absolutely necessary. I might just go ahead and do it though.

 

Your carb needs to be adjusted properly for the changes you've made. Do you have a dwell meter? You'll need one to adjust the IAB. Easiest to check the carb before you pull the timing cover off again. I'll be around this weekend so post back and let us know where you're at. Follow 5-7's advice and start out around 6 degrees. Then let's check your dwell.

 

Two thoughts-

-Timing set without unplugging distributor 4-pin harness

-Vacuum leak

For starters, I would disconnect the 4-pin connector, and advance the distributor so it idles on it's own and see where the timing is.

As posted above, you will have to tweak the carb some, but it should work fine with your application once dialed in.

 

Yes I do have a dwell meter. I attempted this with the old carb with no sucess. If you can give me some tips it would be helpfull.

As for disconecting the 4 pin connector to the distributor to set the timing I Have done this right after break in of the cam. Now when it is disconected the car dies. That is why I tried for max vacuum.

I will be trying everyones advice tomorrow as log as it doesn't rain.

I would also like to thank everyone for there help! Soon I will be at the drag strips.

 

Was the cam designed for a computer controlled carb??
If so the first thing to do is axe that emissions crap(unless you live in Cali). Get a Holley Avenger and a HEI distributer. If the cam profile changed any the computer will need the chip upgraded, so it knows what the cam profile is.
Otherwise you can do all the tuning you want and never get it right because the computer will change the timing and fuel mixture to compensate for the changes you are making. I think you can still get a Compucam from Crane that would be compatible they may have changed the name to Powermax but they have the same profile. 2050 and above require a chip upgrade and I think anything under that would be ok for cc. The stock cam in the 305 h.o. isn't to bad either but I would go with the crane setup.

 

I spent the day readjusting the rocker arms and the timing. The timing is set at 6 degrees advanced. The vaccum is still hovering above 5" in gear. I have not gotten to check the IAB yet.

As for wheather or not the cam is for a computer controlled vehicle the answer is no. But I have read where other people are using this cam with great sucess even in a competer controlled vehicle. I am running a stage one Hyper Tech chip in the car. You might be right though and I might have to get a new chip made for the setup.

The smog pump has been removed. The only emmisions component still attached is the EGR valve and only because it is working.

I don't want to spend any more money on this engine since I plan on replacing it next year. This was just a learning experance and to see what I could get out of the engine.

 

It's been a while since I messed with the timing on a cc carb, did you disconnect the computer when setting the base time. I rember having to disconnect something..
I was in the market for a chip about 5 years ago and the only one I could find was made by Jet.
If you can't get your vaccum level at a steady 16 or so the timing will keep readjusting how about some kind of vaccum booster I know they make one for power brakes but I don't know how that works.
Hey I saw your post about buying a Voodoo60103 cam. How did that work out for ya? I just purchased one.

 

You should have no problem running this cam with the stock ecm/chip. If you've set your base timing and are still having low vaccuum, I'd recommend checking for a leak by plugging all of your ports at the carb (except MAP) and seeing if there's a change. There's a lot of variables when swapping cams that could screw things up. Check the basics first, like Lo-Tec said: vaccuum leaks, ignition timing.

 

How do you adjust the IAB?

 

Once you have it idling well at around 700-900 rpms you can adjust the IAB by turning the IAB screw in the top of the carb to bring your dwell in to 30 degrees (or 50%). Only do this once you know you're in open loop-if the dwell does not respond to changes to IAB (1/8 turn should have an effect) there may be other adjustments you need to do.

 

I found this on the home page. Hoper it helps.
https://www.thirdgen.org/quadrajet

 

It took a while but The IAB is finally adjusted. Vacuum has increased to 10". I have checked all the vacuum lines again and found nothing. I have also checked all the above items with no joy. Any other suggestions?

By the car is running pretty well except for the low vacuum still.

 

a 262 in a 305 should run similar to a 268 in a 350. I have a "268" in my 350 and get 8-10" vacuum in neutral. (Lunati 60103) Not a big deal to me, power brakes work normally, 650-750RPM idle is achievable. I'm still tuning my non-cc q-jet for better throttle response and power though.

I think you're fine.

 

I just read up on that cam. Are you still using the stock stall converter in the transmission? It is recommended to use a 2400 stall converter.

 

see sidebar. I have a stick shift.

 

Sorry! How do you like that cam?

 

oh i'm really liking it! My idle is quite reasonable, stable and whatnot. You can hear there's a beast within
It's a little fluttery below 2500RPM, I think I can fix up my carb to make that better. But once you kick open the secondaries, over 3000RPM, it just ROARS! mmmm, so worth it

 

I have a friend who resealed the top end of his engine and put a single plane intake on it and a new timing chain. It's a 1983 Z28 with 305 with 170,000 miles on it. It is a manual. Everything is stock except the intake. Removed the emissions stuff and the EGR (wouldn't fit on the intake with the distributor).

When he starts the car it smells like it is running rich even though it is ideling fine. The timing is set to factory specs witch is 4 degrees advanced. Hooking up the bwell meter to adjust the IAB there is no response. The car seems to be running fine except for that. Any idea's on what the problem might be?

 

Still an issue? Possible causes: bad sensor: tps, map, O2, etc. ; carb needs rebuild or carb needs adjustment. Most likely cause (especially if it ran fine before) is carb is out of adjustment. Easiest to check first: screw the mixture screws in til about 2 turns out then half a turn out until you see dwell change with IAB turn (remember where you started). Next easy check: make sure the check engine light works and check for codes at the ALDL. Next check: get a manual and verify proper operation of all the sensors.

 

A single plane manifold? With a stock cam & heads? Read up on single plane manifolds. (Victor Jr's power band: 3500-8000 rpm) Let's guess how it's gonna idle...

 

I am still having problems with the cam in my car. The vacuum is still poor (see original post). I talked with comp cams and they suggested taking out a quarter turn on the lifter preload. I did this but there was no improvement. After playing around with the timing for a few days I found that the best RPM set the timing mark nintey degrees from top dead center. I went ahead and degreed in the cam and it was dead on. If the lifter preload is the problem then how much can I take out without doing damage? I am leaning towards this being the problem. I have read where some racers have actually taken out all the preload for better performance. I am at a loss with this one. Summit ways that I should have a lot of vacuum and power but it just isn't there.

 

You can go down to a quarter turn of pre-load. It's best to run it with the valve covers off, crank it until the slack is out then give it another quarter turn. How much pre-load did you start with and how did you measure it?

Did you set your base timing with the EST (four wire) connector unplugged from the dist? Set it at 4 degrees then plug it back in and you should see around 20+ at idle.

 

I started off with a half turn of preload after zero valve lash was achieved. After that I went to a quarter turn as per comp cams with no affect. The cam was installed exactly by comp cams directions.

Would the car even run if the cam is 180 out? In the directions it said to align the timing marks on the crank and cam (cam at 6 o-clock and crank at 12 o-clock) and this should be top dead center of cylinder nomber 1. According to the hyanes manual and what I saw while the cylinder heads were off this is actully top dead center of cylinder number 6. I installed the new cam exactlly the same way the old one came out. If the pin that goes through the sprocket is different on the two cams this would make a big difference but wouldn't account for getting the correct reading while degreeing it in. Any thoughts?

 

Your pre-load is probably not your issue. Cam sprocket at six and crank sprocket at 12 is number six firing. 12 and 12 is number 1 firing. If your engine's idling you're probably fine on the cam. Where's your ignition timing set?

What specific driveability, idle problems are you experiencing?

 

I am still beliving that the cam is installed wrong. I am going to see if it is 180 degress out. Tomorrow I will take it back appart and degree it again and see what I have. I still don't agree with the numbers I had gotten with the first degreeing processes. If number one is supposed to be at top dead center at 12 o-clock on the cam sprocket then why does the installation instructions say it is at 6 o-clock. I think that the after market cam is different then the stock cam when installed. I need to figure this out soon. the car has a long drive ahead of it. No one has said wheather or not the cam will run if installed 180 degrees out or not? I still can not set the base timing any where close to 0 degrees without the engine bouging down. I know that the cam has a 4 degree advance in it. For highest RPM It is well over 10 degrees advance ( I can't guesstmate more then that). That is with the four pin connector disconnected from the distrobitor. I need to know what to do soon, the car has a long distence to travel soon. Any help would be approciated.

 

you don't need a degree wheel, just do it with the "normal" keyway. With a cam 180* out, it may run, but just barely. It wouldn't idle, or have any kind of driveability. I mean you *might* be able to fire it up.

I do think either the cam is in wrong (not quite as likely), or your distributor is a tooth off, or something like that. First off i'd pull the dist, rotate the engine over by hand with a finger over #1 plug hole, once you get the puff, keep going until 10* on your balancer. Then use a screwdriver and line up your oil pump driveshaft if need be, and put in the distributor until it's flush on the intake manifold. Line up the rotor with a post, that's your #1 post. hook up the rest clockwise in firing order.

Try to fire it up, it should idle ok.
Did you do all the tweaks on your carb already?

and finally, did you change your balancer or timing chain cover? I re-read over your whole thread about 3 times here (you shouldn't be having this much trouble...)
This:
kinda spooked me. Can you elaborate?

 

The person at this web site ws6transam.org third gen performance page ran the same cam as I am. The only difference is that he had headers. If whe can get it to work, what is my problem?

 

yes, you and eleventy billion other people. That's a very common cam.

You just screwed up something minor. You'll find it soon, whap yourself in the forehead, fix it, drive around like a bat out of hell, and be blissfully happy. You will tell your kids about the time you screwed up a cam swap by not *************** the **** with the *****. And so it didn't work right.

Good luck

 

I agree with Sonix, most likely your ignition timings off somehow. I'd re-check the distributor before playing with the cam again. If you got it in there with the dots lined up the only thing left is to get the distributor in its "happy" place.

Did you check dwell with a meter on the carb when you adjusted IAB?

 

With the dots lined up at 12 and 6 like the cam instructions say, you are really at #6 tdc....no big deal. Rotate the engine 360 and you'll be at #1 TDC. It's just easier to line up the dots when they are only 1/2" apart instead of 6" a part.

I'm still not conviced that you're setting your timing correctly. You should be setting it with the timing connector unhooked, then shut the car off and hook it back up. Now start it and you should have over 20 deg and it should move around some. You might also want to verify that your timing mark is correct on your damper. The stock damper has a very bad habit of slowly spinning on the rubber ring and getting out of wack. They sell cheap TDC locaters to help with this.

If that all checks out then you could quite possibly need to rejet the carb. The IAB could also be going south. You really have no reason to stick with the computer controlled stuff, the carb ECM is really archaic and doesn't do all that much. I would hit the junk yards and see about finding an old mechanical dissy and non-cc carb. If you plan to stay carb on your next motor go ahead and get the one that would work the best with it. Edelbrock/carters are the easiest to tune, but holleys have a bit more adjustment and tend to have better throttle response.

Of course if you really wanted complete control over your engine you could go FI and get into chip burning, I'm partial to TBI for it's simplicity and the fact that people practically give the system away.

 

To elaberate on this when setting the timing for best RPM with the 4 pin connector disconnected from the distributor I am almost firing on the number eight plug wire. If I could turn the distributor that far I think it woul actually be on number eight.

I have always set the #1 piston for top dead center then aligned #1 spark plug wire with the rotor under the cap. I still come up with the same results where ever I set number one too. I have even tried aligning everything 180 out. Even though it wouldn't be with number one piston at top dead center ant the plug wire aligned with the rotor.
----------
Dwell on the carb was also adjusted for 50 percent duty cycle using a dwell meter.

 

You can't really set the timing for best idle. The engine will pretty much keep climbing in rpm's as you advance the timing. You just want to make sure you are setting the timing where the ECM thinks it's set to. Otherwise it will add timing on top of what you have it set to. If the ECM is taking control of the timing when you hook it back up then you are good to go as long as you set your initial timing with the connector unhooked to what ever it's supposed to be stock.

 

I understand what BMmonteSS is trying to say but it has been my experience with older cars that when setting base timing that you would achieve the highest RPM right around top dead center. Any advance or retarding of the timing and the RPMs would drop. If by chance you went to far either way the engine would die. This is not what I am seeing with my engine. I can keep advancing it to reach max RPM ( which is well above 10 degrees, I don't have any more marks after that). I just can't seem to find the other side because the wires ar too short to the distributor. Am I right or wrong about this? If I keep advancing it then I will be fireing number eight piston before number one.

 

No. BMmonte is correct. The engine will idle best at plus 20 degrees of timing. This is the timing it will get when the base timing is set around 0-4 degrees and the ECM (once EST wire is reconnected) adds in initial advance. The timing light will light the balancer mark an inch or so before the timing tab. When setting base timing it will not run as well as when you reconnect the EST wire.

In the old days we would set base timing for a good idle, do a few WOT runs to see if it would ping, then bump it up a little. When it pinged you knew to back it down a notch...wait that was before I owned a timing light and knew how to use it.

Don't worry about number eight firing before number one, the rotor will catch number one on the next go around.

 

Alright, I get what you are saying but my engine is doing this while setting the base timing and the ECM is disconnected. As for the number eight firing before number one, this is while the engine is running and trying to set the timing with the ECM disconnected.

By the way, you can still set the timing like an older car for best RPM as long as the ECM is disconnected. I have had to do this in a pinch and it worked as if it were an older vehicle because with out the ECM there is no electrical advance. It is the same as un pluging the vacuum advanve on older cars.

I have done everything that everyone has suggested with no luck as to a cause for the problem. I have also talked to a few engine builders and they are stumped. I guess I will have to take it to a performance shop and see if they can figure it out.

Also the car will run and the computer doesn't send any codes. I drove the car 50 miles the other day with an average vacuum of under 5 inches at 65 mph. I am suprised that the MAP sensor hasn't caused a code with that low of a vacuum.

 

How are you measuring vaccuum? How is the performance and throttle response?

When you say eight firing before number one, do you mean eight will fire before number one is TDC? If so, don't worry about it. Your rotor makes a 360 degree circle, fires eight cylinders so each cylinder is about 45 degrees apart. With normal ecm-connected advance, number one should fire around 20 (dist rotor) degrees before TDC.

Set your base timing, make sure you're getting about 20 degrees advance at idle and that it advances up to around 36 degrees with more throttle. It may be worthwhile to make sure the balancer ring has not allowed the timing mark to slip. This would make your base timing setpoint erroneous.

 

I am measuring vacuum wit a guage that I have installed in the car.

Having number 8 fire before number one is while setting base timing without the ECM connected to get max RPM. In actuality number 8 plug wire will be fireing the number 1 plug. I have tried to move the plug wires aroun to put number 1 wire in number 8 place but had the same effect.

Lets see if I can explain this differently. Originaly my engine had a base timing of 0 degrees with the ECM disconnected. If I were to advance it to 8 degrees the RPM's would drop a little. If I were to go retarded with the timing the RPM's would start to drop. Peak RPM was at 0 degrees. Now with the new cam peak RPM is off the charts. It is so far off I can only guess as to how many degrees but I would guess about 45 degrees. Now when I try to set it below 10 degrees advance the RPM's have dropped drastically. It is acting as if I am retarding the cam timing. All of this is being done with the ECM disconnected as it should be.

While I was degreeing the cam in I slid the balancer into place to make sure it hadn't slid. Cylinder 1 was at top dead center. It aligned right on the mark.

Why would I want to set my base timing at 20 degrees with the ECM disconnected? That would also be hard since my timing marks only go to 10 degrees.

I talked with a Dyno shop today and they think that the port work I did on the heads is killing the flow. That would explain the drop in vacuum but not the timing issue. I believe that when I get the timing issue taken care of everything else will fall into place.

 

First off, again, don't worry about which wire is connected to which terminal, number 1 or number 8. You can place number one wire on any terminal as long as the rotor's pointing to it when number one cylinder is near TDC. The rest of the wires just have to be in the correct order. Think about it.. the rotor spins in one direction and as long as it points to each cylinder at the right time, it doesn't matter whether number one is on the driver's side front or around back.

Second, I would expect it to be difficult to get your engine (with that cam) to idle well (without some extra throttle/rpms) at base timing of between 0 and 4 degrees. It should act like it's bogging down and you may need to temporarily give it more idle (or manually open the throttle slightly) to keep it running long enough to set base timing. Pluggin the EST wire back in allows the computer to give it the additional advance that it needs at idle.

Third, I didn't mean to imply that you should set base at 20 degrees. Set base between 0 and 4 and THEN reconnect the EST and confirm that the ECM is advancing your idle to approximately 20. THEN rev it up and confirm that the ECM is advancing the timing up to approximately 32-36 degrees at around 3000 rpm. You'll have to estimate as the marks aren't there.

 

The car is still not right and I have finally come to the conclusion that the timing is not the problem with the car. I believe the problem has to be with the exhaust. I don't think the stock exhaust can flow well enough for the cam. I would like to know your opinoin?

 

You may not have maximum performance with the stock exhaust but I don't think its causing your problem. You would definately pick up some performance with headers and a good exhaust system though. If I were you I would buy an non computer controlled HEI(or borrow if you know someone who has one) and try it. Sounds like you don't have emissions equipment on there anyway so switching over to an older HEI will eliminate one more variable. I would set the timing for 14-16 initial and 36 total for a starting point. Or if you don't want to go through that atleast check the timing using a timing tape or dial back timing light. Figure out what your timing is at idle and what it is total at 3000 rpm's or so...that will tell you for sure if timing is the problem.
Another thing to consider...are your pistions stock and whats compression ratio? If you somehow lowered your compression ratio a lot it cause problems like that especially with a larger than stock cam.

 

I was getting ready to install the headers, while taking off the stock exhaust manifold one of the bolts came out covered in antifreeze. It is right next tio the nomber two cylinder. Is this a sign of a cracked head? Winter will be here soon and I need to get this car back together so I can get it ready to be stored.