Winston Wolf

I have a LM2 a/f monitor hooked up in the car. I do not think it is a lean issue, in fact it runs on the rich side per the meter. A vacuum leak is unlikely, the carb only has 2 ports, the large in the back going to my brake booster and the small in the front that was to the vacuum advance, but is now plugged. The intake has one vacuum port that is pluged. All gaskets are new. Again, this seemed to do the same thing with my other (Edelbrock) carb, making me lean towards ignition issues.

To eliminate the posibility of it being the advance curve, I unhooked the vacuum advance. I have it set so it is all in by 2500 with a total timing of 34 degrees. Innitial is around 20. The engine doesn't really even run anything under that range, as you can see in the video. I do not think this is related to the advance curve. It is happening at 3500 and 4500 and whatever other RPM I accelerate at.

Here is the dist book... Digital E Curve Instructions This is a 200-4r. I don't have any issues with the line pressure, I have plenty. Actually have a gauge installed in the car, so I know. The trans is definetely not between gears, the sound you hear is the engine missing.

Dials are set for 15 degree mechanical advance all in by 2500. and the # 3 vacuum advance curve, which is 0 deg 4" and 10 deg max at 6". It does not make a difference with the vacuum advance hooked up or not. I am running an OD trans. The bracket is from Bowtieoverdrive.com, made for a 4150 Holley. The bracket is correct and works as it should. I also just had a thought: I had to redo the ends on the spark plug wires to accomodate the HEI style cap. Perhaps my problem is just with a plug wire or the coil wire. May get a new set and replace one side first and test, then the other side.

I think I may try unhooking it from the MSD box and see if that changes anything. If that doesn't work I can try my old distributor and coil. The wires are new this year, I checked them in the dark and did not see any obvious signs of arcing or anything. What has changed: 1.6 rockers on the intake valve Intake manifold Distributor Coil Fuel Pump

PS you need to crank the volume to hear the missing.

Well, I got the car back together and running. Had it going first with the Edelbrock on it, as I was still waiting on parts for the Prosystems. Took the car out the other day and it was running like crap. I thought maybe since I put the new fuel pump on and was using the Performer carb that the high (8 psi) fuel pressure was causing the stumbling under acceleration. Got the Holley on tonight and it is doing the same thing. Runs terrible... I thought perhaps it was something to do with the rev limiters on both the distributor and the 6al, so I took the chip out of the box. No difference. Hot set all the valves. No difference, they were pretty close and most were right on. Checked the timing, changed it, nothing. Unhooked the vaccum advance, not it. Looked at my distributor settings, where I wanted them, cap looks new. Tightened the coil connections, nothing. It has never ran like this, so I'm not sure even what to check next. I do not think it is a carburetor issue. Listen to this video and you can clearly hear how it isn't right..... This is modern to light acceleration. Anyways, here are some pics of the new carb....and I would appreciate any ideas on the rough running.

Probably one of the best upgrades you can do, if you set it up correctly. If the driveshaft thing scares you, use a 200-4R. That is a direct fit with no modifications with a better gear split. You can make the torque converter clutch do whatever you want. I have mine set up to only lock above 55 mph, unlocks at 50, unlocks when my vacuum gets below 5", ie stepping on the gas. I have a heavy duty 3 disc clutch so I can lock it under full throttle and it acts like a 5th gear. With my 4.56 gears, it runs 2000 rpms at 55, 2500 at 70.

New MSD Digital E-Curve distributor. Really slick. Timing curve is very, very smooth on the light. I am excited about it. Right now I have it set up with a 15 deg "mechanical" advance that is all in by 2500 RPMs and I'm going to try and run a vaccum advance this time, with a 10 degree advance all out by 4" of vaccum. There is a port for the vacuum advance on the bottom of the dist. Really looks clean without the canister. New carb should be here on Friday. I'll get that in right away and am planning on the Muscle Car only drag races this weekend to see if all this work payed off.

Well, got the engine back together finally. Ran it briefly to get the timing set and make sure everything was correct after installing the new distributor, coil, intake, and fuel pump. Here you can see some of the work in progress of the intake. The 1206 intake gasket and the AFR heads are much larger than the 1205 stuff from the old combo. I decided to go with the RPM Air Gap intake. The intake work took probably 3-4 hours. I basically port matched it and worked the runners in as far as I could (maybe 2 inches with the die grinder and rotary tool. Smoothed out the transitions. There was actually alot of work there. I didn't do much on the plenum, just smoothed out the divider a bit. Here is the notching on the frame I had to do to get the Carter pump to fit. I wasn't too crazy about doing it, but oh well.... I actually had to rotate the pump body to a point in between where it was made to be. It had the holes, but they were not tapped. I ran a M5x.8 tap through and got it in the right spot. I'm changing out this tubing for some other line, but I wanted to get things going last night.

Well, ripped the engine apart again last night. Here is where the cam was: As I remembered, I had to retard it a few degrees to get it installed correctly. It was dead on with the cam card. I pulled the cam anyways, to look it over, all looks good. re-degreed it and triple checked everything. Put the 1.6 rockers on the intakes tonight and set all the valves. I did have to slightly clearance 3 of them as they were hitting the valve keepers, which surprised me a bit. Now trying to make a decision on which intake to start with. I have the RPM, Air Gap, and Victor sitting in the garage. Porting is a bit of work, so I'd like to get it right the first time if possible. I set the Air Gap on the engine, and it does look like a nice piece, I'm really leaning toward it at this point. I grabbed the Victor for 75 bucks, so I don't really care if I use it or not. Here is a shot of the RPM that cam off and the Victor JR. The Victor needs some cleaning up, the casting has some crap in it. Notice how much smaller the ports are than the 1206 gasket that the AFR's need. I think just a port match will really help this thing breath....

and for all the nay-sayers out there about my intake of choice, I just scored a used Victor Jr off of Craigslist that I will be porting to test at the strip against my RPM..... I will run whatever is better at the strip. Now I'm debating on just porting my regular Performer RPM and cutting down the plenum like the Air Gap, then sending the Air Gap back...... I don't want to hack up a $200+ manifold to sit on the shelf if I end up sticking with the Victor in the long run..... Thoughts?

Well Dave, I have to laugh at your post. This is following my to my nightly dreams, I just couldn't take it anymore. Today I threw the book at it.... Ordered new fuel pump. RPM Air Gap intake that I will be porting to match the AFR heads. 1" open spacer to try at the track for the top end. New coil New MSD ready to run E-Curve dist that I am going to wire so I can run it on the 6al box and off (that way I can eliminate any suspect box issues) 1.6 rockers for the intakes. and........the grand finale...the Prosystems Double Pumper carb. If this doesn't work now, I'll be jumping on my Harley, headed west to throw this carb you talked me into at your mailbox.

Trust me, I'm losing sleep over this, and I'm triple checking it again when I swap intakes for my own piece of mind. But what I actually had to do was retard the cam, it was advanced. I know for a fact the dot is turned to the right, which by the timing gears instructions I just re-read is retarding the cam. So even if I would have messed it up, it should have helped me on the top end. Hex Adjust Instructions I just went out to the garage and starred at my degree wheel for a bit, trying to remember degreeing the cam. I remember the cam card called out for the the intake to come in at 18.5 deg at .050. It came in early at 22 or 22.5 I'm 99.5% sure it's right. I think all the talk about not making the power it should is making me crazy second guessing myself.

I just went and checked. I already have 3/8" fuel line. I was thinking of ditching my electric fuel pump and going to either the Edelbrock Performer RPM Street pump or the Carter high volume (but the Carter only has 1/4" ports...)

I think you have several issues compounding here. Timing is the first problem, you are leaving lots on the table with it at 34 max. I say try 38 degrees. I did test it out at the strip and found the best times at 37-38 degrees, so that is solved Next is debatebly the carb. The size should definitely support what you are trying to do, but I think there may be some tuning issues yet to find. This engine should in no way drop off below 6500 rpms. I've done everything I can to this Thunder AVS, I think I'm going to order a custom Holley DP I think the fuel line will be a problem for you eventually, so it wouldn't hurt you to change that just in case. I would recommend the Summit aluminum hard line. Take your time and you can run it from front to back and if you are careful, then you can have either 3/8 or 1/2 hard line which would be excellent. I am going to change out the lines and the fuel pump asap. I was thinking about 3/8 line from these guys Inline Tube I have Stainless brake lines from them and they were very nice. A 3500 converter should be excellent. What is it actually flashing to off the line? It's tough to say, but looking at the logs, it foot brakes to 2500 no problem and it starts to get tight around 4200 I have heard of the Mallory optic sensors causing problems sometimes due to dust covering the sensor, but I doubt it would only be an issue at high rpms. I agree Everything could be explained by a cam timing issue but I know you degreed things in. If the cam was too far advanced, your low end would be emphasized and the upper end would fall off. I think I'm going to re-check it when I change out the intake. I think the intake is likely ok. How about the gaskets for the intake and the exhaust? Do they overlap into the port more than they should causing restricted flow? I used the gaskets AFR told me to and they seemed fine. I think I'm going to switch to an Air Gap intake and port match it to the heads, just to be safe. I don't think any extra lift going from 1.5 to 1.6 rockers will solve anything. With the strong exhaust flow of these heads, I do think there may be something to gain there. I don't think it's my main issue, but it might give me a few ponies. The miss was there with BOTH engine? If that is the case, it would almost certainly be ignition or gasket issues since those would likely be the only same items. I hate problems like this, they are so hard to find!

This miss on the top end is getting the best of me. Check out this video of before and after. I need to get it fixed. I looked at logs and was trapping at the same RPM's. It has to be something in the ignition system??? Also look at my dyno sheets. I knew I wasn't hearing things on that dyno... Notice how at that exact point the power drops off like a lead weight, and how it acts goofy. But if you look at the data logs I posted above, my fuel mixture doesn't go way rich, like it should if you were floating the valves. I am running a stock distributor with a Mallory E spark conversion (photo optic led trigger) in place of the points to a MSD 6AL box with Blaster 2 coil. I use no vaccum advance and it has been recurved to be all in by around 2500. I did install a new cap and rotor with the head upgrade, Accel high perf stock replacement. I also installed new MSD plug wires. I pulled the cap and it does not seem to have any arcing marks or look bad to the eye. Could it be a coil issue? Perhaps the distributor is worn out? Mallory ignition module?

Well, Got to Wisc today to test out the new stuff. Not too impressive. Best time of the day with the new engine was a 12.04 @ 113.5 Best time on the other heads/cam was 12.02 @114.06 I did have one run that would have been in the 11's, but the timer did not record my 1/4 mile et or speed. That was a 7.673 @ 90.54 1/8th with a 1.701 60 ft. Drag strip doesn't lie, I had more power before. The new converter did help a little on the 60 ft times. I was averaging 1.73ish and before it was almost 1.8's with the 2400 stall. Played with the timing. Looks like it wants 37 deg. I am assuming this is from the lower compression. I am still getting a miss on the top end, the same as with the other combo. I'm thinking it may be in the distributor, I'm just not sure. You will be able to hear it on the video below. On the last run it is really noticable. That is the 12.04 run. As I think back, I have fighting it on and off for years. I don't think it valve springs anymore. The car actually ran so terribly on the first run, I couldn't believe it. Seemed like it missed in every gear. Ran a 12.356 @ 110.76 You will also see the logs from a few runs. I can't seem to get this Edelbrock carb to put down a good a/f curve. I am done fighting it. I also see some leaning out at the top end rpms. I'm crossing my fingers that it is my fuel pump setup and stock lines. The trans is still giving me a bit of fits too. I'm having a tough time getting my lockup timing correct. You will see some flat spots in the revs on the charts, that is the converter locking up. Everything happens so fast, it's tough to shift, lock up conterter, shift all in a second, I'm still working on that. I guess the bottom line is I will be blowing some more cash this week: new intake, carb, distributor, fuel pump, and lines. For those who haven't see logs before, the top line is the RPM's during the run and the bottom line is the air/fuel ratio.

I would not recommend stoping them before the rear axle. I ran like that last year and it was very noisy and the reverb in the cab was horrible. My suggestion would be to find a shop that can do full mandrel bends on 3" pipe and install a full 3" system with Dynomax mufflers. I did this earlier this year and it turned out great. Not cheap (1000$) but everything fits perfect, it has a crossover, sounds good, and it performs. I track tested it and it makes no difference in MPH/ET with full exhaust vs open headers. I do have cutouts immediately after the headers. I tried the "custom made kit" and they just don't fit right. More work to get it to actually fit than it is worth. I've see the article that Dave is talking about above. It was a GTO or something that track tested a bunch of different mufflers, tailpipe sizes and pipe sizes. I'm just telling you what I found in my case.

Thanks for those articles. I had stumbled across them. Looking more at my dyno sheets, looks like peak HP is 385 and the peak is long, from 5400 to 6000, then drops hard after 6250. In this article Edelbrock manifold testing, ported vs stock They are seeing the ported RPM air gap at 6400 rpms down only 4 hp from the ported victor jr and more power all over than an as-cast victor. I feel getting this monster rolling off the line is going to ET faster than trying to scream it at the end of the quarter. Plus, I just don't think giving up the 20 HP at 3800 RPM is going to make it fun on the street. My biggest conflict is that as you roll on that throttle going 60 mph you want it to move. It's still only running 2500 at 70 with the converter locked... It's going to be a battle of compromise, but I'm leaning towards porting a RPM air gap, and running the 3/8" open heat spacer to even it out. I don't have any more room than that, a 1" spacer won't fit with the 4" element.

Thanks for the comments. Are you recommending a Victor JR then? or another single plane intake? This still is not a big block, and with the heavy car I do worry about the midrange torque. I am planning to switch manifolds to something other than the standard RPM that I have, they all cost about the same, so the price is not a factor in my decision. Most people in this HP/ET range with a big car like a Monte Carlo are talking big blocks. It's the same, to a point. You BBC guys don't need to worry about giving up any low end torque, you've go plenty to spare. When you can spin the tires for 2 blocks with your 468 or 496 or 502, 20 ftlbs less isn't a factor, you can't use it anyways. With the small block it's more of a big deal. I'm trying to show that it can be done with a mouse motor that you can actually drive on the street enjoyably. Unless I can't get to that magic 11.50 mark, I am going to try and stick with the Edelbrock carb. The car runs great and pumping another 700 bucks at the carb doesn't sound awesome to me. I don't disagree with you at all though, I'm positive I would see gains. I will head to the track on Saturday, weather permitting. I want to see what it will do now before I tear back into things. Who knows, maybe I am there already. With 25 more HP and the bigger stall I could have picked up the half sec I need and won't need/want to change anything.

Cam was degree'd. See first post.

I posed the same question to the dyno guru at the shop. His comments were that we would see it in the a/f leaning out at the top end if it was running out of gas. I run a stock type pump and an electric pump back by the tank that "supercharges" it. I am still using the stock lines.

Wallaby, I tend to agree with you. Here is an interesting read and awesome comparo video about the manifolds. SBC Manifold Test I am also thinking I might need to switch to 1.6 rockers on my intake. I think these AFR heads would do better without a split cam. 1.6's would bring my intake lift up a bit (.585/.600 with the 1.5's, .624/.600 with the 1.6/1.5) At least I am coming up with some possible solutions and should have some things to test out. It's going to take me a few weeks to sort things out. Trips to the stip take some coordination and they dyno has a 2 week wait plus 100 bucks an hour....

Here are the springs Lunati wants Lunati Intro Series™ valve spring set •Spring Type: Dual •Outside Diameter: 1.500 in. •Inside Diameter: 0.800 in. •Seat Load: 197 lbs @ 1.850 in. •Open Load: 533 lbs @ 1.250 in. •Coil Bind: 1.110 in. •Spring Rate: 560 lbs/in. Part Number: 73899 Here is what is on the AFR heads. AFR-8000 1.540 OD 225# @ 1.950 600# @ 1.250 Chrome Silicon Bind Height 1.155 Rate 550 lbs Max Lift .710 in orange .800 ID If these springs are allowing valve float then, they aren't what AFR says they are....