[Offshore 420]

Originally Posted by Caballerokid

I have not done a compression test yet. None of the plugs I took out look like there is anything wrong other than too much fuel. It is a brand new engine with maybe a couple hours of run time on it. Less then 20 miles driven even and everything is brand new. The vacuum needle only bounces at idle. Part throttle/high idle the vacuum needle is solid as a rock. I may need to adjust the valves slightly but I'm really doubting that as I was very meticulous in assembling this engine.

A valve to tight would do it?

[Caballerokid]

That is something I will check. As far as the valve guides, I know those are fine. Those were checked upon assembly of the engine. I did some digging on the carb and found the main and secondary jets were switched around on mine thus making things extremely rich at idle and part throttle. I am finding little things that will hopefully make a big difference. I will say this, the throttle definately doesn't sound or seem crisp. It is def FAT and sloppy!

[Caballerokid]

I reassembled the carb correctly and made sure to blow out the air bleeds. Hooked my A/F gauge up and fired the engine up. I was able to set the carb to idle at about 500-550 mv. I have good throttle response with a lean spot just as the throttle transitions to the secondaries. So I will probably need to adjust the secondary cam or accel pump setup. The car performs SOOO much better! I still have the stumble at idle which I am now going to readjust the valves and hope that takes care of the vacuum needle bounce as well as the stumble/miss at idle. I'm feeling much better about where I'm at and how things are progressing. Thanks for all the help guys!

[cobalt327]

Originally Posted by Caballerokid

Ok... so I replaced the R43T delco plugs with R44TS plugs and they barely fit with the pistons. I made sure to double check. I also retimed the engine and ran a different curve. I was at 14 degrees initial and 34 total all in by 3500 rpm. I changed it to 17 degrees initial and 32 total all in by 3000 but I still get the pop and bogg on hard acceleration. It has to be the carb giving me troubles now. I pulled the holley off and blew it apart. Here's some info, let me know if anything sounds wacked. It is a 4777-2 750 DP mechanical secondaries. Main jets are 76 secondary jets are 67, main and secondary squirters are 25. Using yellow/orange pump cam in top hole. Also the PV is 6.5. Since my idle vacuum is about 10" I was thinking I should get a 4.5 or a 3.5 PV. But this is what it is right now. Does anyone see a reason I would be getting a bogg, pop and low power on hard acceleration? The old plugs (R43T) look carboned up like too much fuel so going off of that it seems the carb is way too rich. Can anyone suggest a better setup for this carb? Here are some numbers off of the metering block if it helps anyone. Main metering block L47772, 8539, 8520 and 5. Secondary metering block L47772, 6497 and 650. Thanks in advance!

No biggie, but the 4777 is a 650, the -2 version came with 67/76 jets; 0.028" shooters front and rear. So it looks like the shooters and maybe the pump cam is all that's been changed from stock.

Check the vacuum in neutral if manual, in Drive if AT. Use those figures for picking a PV.

If the plugs are new and they're looking wet/rich and there are no ignition problems or anything else that might cause it (float level too high, blown/leaking PV), you may well need to start dropping primary jet size.

You using a PCV system? Checking the lifter preload (or lash) is a good idea. Too tight can cause the popping, etc.

[zildjian4life218]

I just skimmed through real quick and didn't see a mention of fuel pressure. If your having issue with it being rich I would check that.

[Caballerokid]

I am not running a PCV system just crank case breathers. Ya, after looking again it is a 650 not a 750. I adjusted the floats down and verified the PV is not blown. I was able to get it to lean out but now on acceleration I have a lean spot just as I push the throttle pedal and seemingly again as it transitions to the mechanical secondaries. I need to play with the accel pump cam/accel pump adjustment and/or shooter sizes back to 28 instead of 25. Other than that the A/F seems fine now. For what its worth, I'm running a Carter electric rotary fuel pump internally regulated to 6 psi mounted to the frame rail in the passenger rear of the car. I am not running any other regulator in the system. Tomorrow since I have a day off I will be adjusting the valves. Hopefully I will have good news on that being the culprate for the vacuum needle bouncing.

[Offshore 420]

Originally Posted by Caballerokid

I am not running a PCV system just crank case breathers. Ya, after looking again it is a 650 not a 750. I adjusted the floats down and verified the PV is not blown. I was able to get it to lean out but now on acceleration I have a lean spot just as I push the throttle pedal and seemingly again as it transitions to the mechanical secondaries. I need to play with the accel pump cam/accel pump adjustment and/or shooter sizes back to 28 instead of 25. Other than that the A/F seems fine now. For what its worth, I'm running a Carter electric rotary fuel pump internally regulated to 6 psi mounted to the frame rail in the passenger rear of the car. I am not running any other regulator in the system. Tomorrow since I have a day off I will be adjusting the valves. Hopefully I will have good news on that being the culprate for the vacuum needle bouncing.

If you do have a valve to tight, you may have taken the cam out by now.
It might be a good idea to cut the filter open and take a look.

[Caballerokid]

I did some playing this weekend and here is what I came up with so far...

First I checked to see where they were at. I loosened one up on base circle and then ran the adjuster nut down by hand until it stopped then a 1/4 turn more. I then did the pushrod jiggle method to see how much difference there was in the two. I could get almost 2 complete turns more by hand after the pushrod stopped jiggling. So... thinking I had all the valves too tight from the start, I reset all the valves. This is the method I was using; jiggle the lifter up and down until there is no play then 1/4 turn more. I did this for every valve as it was on base circle. Put it all back together and started it up. I did not hear any chattering or "loose" rocker arms/valves. I then warmed up the engine and took another vacuum reading. This time the needle was more unstable at idle as well as through the vacuum range on the gauge were as before it was only unstable at low rpm idle. Once above 1200-1500 rpm the vacuum gauge was solid as could be. Since re-adjusting the valves as mentioned above the vacuum needle is almost never steady in any position on the vacuum gauge. Is it possible I may have had one or two valves too loose and the rest just right since it got worse with me loosening up the valves? I am going to reset all of them again sometime this week and hope for better results. Anything sound odd here?

Thanks!

[ssmonty]

I'd bet now you have a valve too tight. That's what the vacuum gauge indicates if it was smoother before the last valve adjustment.
The most foolproof way to adjust valves is to do it while the engine is running. Cut the top out of a scrap yard valve cover. Install it on the drivers side after the engine is warmed up good(PITA). Idle the engine, and back off the #1 exhaust valve until it starts to clatter. Give it 10 seconds or so to let the lifter pump up all the way to its full extension. It might quiet down if you didn't back off the adjustment enough and it takes up the slack. If it does, back off the adjustment some more until it is clattering constantly. Then tighten the adjustment slowly until it just stops. Turn the adjusting nut clockwise an additional 1/4-1/2 turn slowly( I prefer 1/4). The engine may run rough for a few seconds until the lifter bleeds down to its preload setting. Next do the same for the #1 intake, then #3 exhaust, and so on down the head until all are set on that head. You don't really have to start with #1, its just easier to keep track of where your at. Then do the same for the other head.
Bet your vacuum smooths out a little, but as I said before, with a 106 degree lobe separation angle and that much duration, its not going to be steady at idle. Ever hear of reversion? You have more valve overlap than a 280 degree cam or close. If I'm not mistaken you've got more than 60 degrees of overlap. At low rpm some of the cylinder exhaust is going out the intake valve into the intake manifold(both valves open at same time=overlap) causing the vacuum signal to drop as exhaust pressure is momentarily entering the manifold. Not so much as rpms increase, and intake velocity and exhaust scavenging come into play.
Well, even if you don't believe me on the vacuum readings, I'll bet you can see for yourself in short order that the aforementioned valve adjustment is the best method after you try it.
FWIW
ssmonty

[Caballerokid]

SSmonty, I'd believe that that is the best way to adjust the valves but I really don't want to make a big oilly mess ya know. But by me doing the jiggling method over the twisting method of the pushrods, I know all the valves are more loose now then they were previously (by nearly two full turns!). Thats why I'm kinda confused how the vacuum reading got worse??? I am kinda doubting I have "tight" valves. I'm thinking they may be loose but they're not rattling??? It just doesn't quite make sense. It would if the vacuum reading would have gotten better, not worse. Hmm

[cobalt327]

Originally Posted by Caballerokid

SSmonty, I'd believe that that is the best way to adjust the valves but I really don't want to make a big oilly mess ya know. But by me doing the jiggling method over the twisting method of the pushrods, I know all the valves are more loose now then they were previously (by nearly two full turns!). Thats why I'm kinda confused how the vacuum reading got worse??? I am kinda doubting I have "tight" valves. I'm thinking they may be loose but they're not rattling??? It just doesn't quite make sense. It would if the vacuum reading would have gotten better, not worse. Hmm

Regardless of how you adjust the valves- whether it's w/the engine running, by going cylinder to cylinder following the firing order (starting out w/#1 @ TDC at the end of the compression stroke), or by the EO/IC Method- the valves HAVE to be adjusted correctly so they have some preload but not so much preload that the valve is held off the seat w/the engine fully warmed up. And also not so loose that there's NO preload (you would hear this, the sound a loose valve makes is unmistakable as being "out of the ordinary"). It ain't rocker science, but it has to be correct.

[Caballerokid]

I have been adjusting it with the EO-IC method, but the two variations of that have been twisting the pushrod or jiggling the pushrod up and down. The first way I twisted them until I felt drag then 1/4 turn. With that I had the unstable vacuum needle at idle. The second way I jiggled the pushrod until I had no more up and down movement then 1/4 turn. With this I had the unstable needle throughout the vacuum range. So by this stated above, I think I am going to go back to the twist method of the EO-IC plus 1/4 turn because so far that has been my best result. I think then I will replace the intake manifold gaskets because the openings are larger than the runners of the plenum and heads (the gaskets are designed for larger heads). I will replace them with more matched gaskets and see where I am at from there. Those gaskets are the only other thing I can think of that may be causing me problems. Although, when spraying carb cleaner around them they do not seem to be leaking... but who knows from the underside possibly

[Offshore 420]

Get some one that KNOW"s how to adjust them correctly to help you. Your getting some bad advice here.

[Offshore 420]

Originally Posted by Offshore 420

Get some one that KNOW"s how to adjust them correctly to help you. Your getting some bad advice here.

You took the cam out......

[cobalt327]

Originally Posted by Caballerokid

I have been adjusting it with the EO-IC method, but the two variations of that have been twisting the pushrod or jiggling the pushrod up and down. The first way I twisted them until I felt drag then 1/4 turn. With that I had the unstable vacuum needle at idle. The second way I jiggled the pushrod until I had no more up and down movement then 1/4 turn. With this I had the unstable needle throughout the vacuum range. So by this stated above, I think I am going to go back to the twist method of the EO-IC plus 1/4 turn because so far that has been my best result. I think then I will replace the intake manifold gaskets because the openings are larger than the runners of the plenum and heads (the gaskets are designed for larger heads). I will replace them with more matched gaskets and see where I am at from there. Those gaskets are the only other thing I can think of that may be causing me problems. Although, when spraying carb cleaner around them they do not seem to be leaking... but who knows from the underside possibly

If the cam has much overlap, you are going to get an uneven gauge at idle. How big is the cam, anyway? Specs help if you know them, part number if you don't.

Is there any driveability issues along w/the unsteady needle, or are you chasing just an unsteady needle?

Never mind. I went and found that cam. Dude, it's ground on a freaking 106 lsa. It's gonna be unsteady.

If you are unsure about the twist vs. jiggle, adjust them w/the engine hot and running. Yes, it may get oil on the headers. And you may get oil on the inner fenders, etc. Life is a ***** that way, sometimes.

Also be sure to give it plenty of initial timing. Keep track of the total timing if you add initial- rework the distributor if needed, there have been exactly 8, 491 posts on this.