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7:49 pm
May 23, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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Okay I have been trying to dial this thing in for about a year now and I'm still having problems. First off I have a V8 with a mild cam, a "light" jeep, with 5:13 gears. Upon quick acceleration I get a stumble and sometimes a backfire through the carb. This has to be an accelerator pump issue so I tried larger squirters. I have worked my way up from a 27 to a 35 and I'm still having the same problem. Do I need to keep going? maybe a 40? or a 50cc kit? The motor really isn't anything special, but it is in a jeep with tall gears, which wouldn't be the same settings as a truck or suburban. Which I think Holley sets these up as.
Lets hear what you guys think.
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9:14 pm
May 23, 2011
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Ggg
| | Belvidere,IL | |
| Daily Driver | posts 186 | |
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Need more info Tony.
cam specs, engine cid, ignition type and timing, carb model and cfm, exhaust type, idle speed, intake manifold make and model.
The back firing through the carb indicates a lean condition, but squirter size isn't the whole story as far as accelerator pump tuning goes. depending on the carb some can use different cams or levers to change the squirt characteristics, and some can use bigger or longer stroke pumps to get more fuel.
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98 TJ AX15/231sye, D60, Sterling 10.25 axles, Detroit lockers, 7" lift, Cummins 4bt engine, double triangulated 4 link rear, Y link radius arm front suspension, tires 37"-41".
48 CJ2A D30nt, AMC20nt w/lock right, Kaiser 231v6, T90/D18, 33x14 boggers
46 CJ2A D25, D41, L head Go Devil 4cyl, T90/D18, PTO, 6.5-16 tires.
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9:39 pm
May 23, 2011
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jknutter
| | DDO North Chapter | |
| Moderator
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Tony – you mentioned Holley – the first thing you can do is take it off and throw it in the trash! I ran a 360CID in a 1977 CJ5. I rebuilt the motor with about the same set-up as you have with a mild cam, eldenbrock high rise and a 600CFM Holley (can't remember which model – I know it was Not a double pumper though) . I had nothing but trouble with setting up that stupid carb. Everytime you opened the secondarys it would cough and then blow the accelerator pump. I have a buddy who ran a stock car at the drag strip try to help me set the POS up and he couldn't even dial it in. So after weeks of trying I decided to rip it off and replaced it with a Carter AFB – problem solved! The Jeep stopped coughing when I mashed the gas and I never had to replace that accelerator pump again. I don't think I was drowning the pig because that motor should have been able to handle 600CFM no problem – it was just a very poor design in that carb with it's accelerator pump assembly. When that pump blew I'd have a hell of a time trying to keep it running. I ran that AFB for about 4 years until the day I sold her (most stupid thing I ever did!) and never had another carb issue again.
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9:45 pm
May 23, 2011
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StinkyMud
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| Mall Crawler | posts 346 |
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Ggg said:
Need more info Tony.
cam specs, engine cid, ignition type and timing, carb model and cfm, exhaust type, idle speed, intake manifold make and model.
The back firing through the carb indicates a lean condition, but squirter size isn't the whole story as far as accelerator pump tuning goes. depending on the carb some can use different cams or levers to change the squirt characteristics, and some can use bigger or longer stroke pumps to get more fuel.
STOCK 
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Jeff & Angel "Git-R-Done"
04 TJ (Lil Smokey)
02 KJ – DD
01 Escape – DD
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12:00 am
May 24, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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Ggg said:
Need more info Tony.
cam specs, engine cid, ignition type and timing, carb model and cfm, exhaust type, idle speed, intake manifold make and model.
The back firing through the carb indicates a lean condition, but squirter size isn't the whole story as far as accelerator pump tuning goes. depending on the carb some can use different cams or levers to change the squirt characteristics, and some can use bigger or longer stroke pumps to get more fuel.
Cam specs unknown, 360 CID, points with about 18 degrees timing, Newer Holley 670 TA, dual exhaust through mufflers no X, 850rpm in drive (about 1000 in park), edelbrock performer intake with trans adapter spacer (have to run it). I have a bunch of cams that I can switch in and how and a whole bunch of jets, squirters, ect. I don't have a 50cc pump, but I don't think my motor is crazy enough to use that much fuel.
Jeff – I had a hand full of carbs on this thing and when it comes to hills and climbing this Holley is the best. I had a 600 Edelbrock that flooded every time it saw a slightest grade. This new Holley has backfire protection which keeps me from blowing power valves, and I have too much invested in parts to give up just yet. Haven't tried a Carter yet, but if I can't get this to work I'm going to run it on propane. I wish I would have kept that quadrajet years ago…..
Sorry my sig is a little misleading.
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4:20 am
May 24, 2011
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StinkyMud
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| Mall Crawler | posts 346 |
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Post edited 4:21 am – May 24, 2011 by StinkyMud
Tony M said:
Ggg said:
Need more info Tony.
cam specs, engine cid, ignition type and timing, carb model and cfm, exhaust type, idle speed, intake manifold make and model.
The back firing through the carb indicates a lean condition, but squirter size isn't the whole story as far as accelerator pump tuning goes. depending on the carb some can use different cams or levers to change the squirt characteristics, and some can use bigger or longer stroke pumps to get more fuel.
Jeff – I had a hand full of carbs on this thing and when it comes to hills and climbing this Holley is the best. I had a 600 Edelbrock that flooded every time it saw a slightest grade. This new Holley has backfire protection which keeps me from blowing power valves, and I have too much invested in parts to give up just yet. Haven't tried a Carter yet, but if I can't get this to work I'm going to run it on propane. I wish I would have kept that quadrajet years ago…..
Sorry my sig is a little misleading.
I was just being a smart A$$…….
I've heard about your beast (and seen it up close) I've got a Holley on my YJ with the 4.2. I've always had good luck with them on the street and have heard good things about them off road. Hoping to actually see what it will do one day if I can quit finding things wrong with it (the YJ).. I am a little leery about a carbed 4x4 and hills though. Propane seems like a pretty cool way to go all though I really know very little about it. I have never been a fan of the Quadrabog though.
Good luck getting her settled in. 
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Jeff & Angel "Git-R-Done"
04 TJ (Lil Smokey)
02 KJ – DD
01 Escape – DD
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8:39 am
May 24, 2011
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jknutter
| | DDO North Chapter | |
| Moderator
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My experiences where from the early 90's, guess the technology must have improved somewhat…
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9:08 am
May 24, 2011
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StinkyMud
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| Mall Crawler | posts 346 |
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jknutter said:
My experiences where from the early 90's, guess the technology must have improved somewhat…
600 cfm for a 360 sounds a little small in my opinion.. Just my $.02. 
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Jeff & Angel "Git-R-Done"
04 TJ (Lil Smokey)
02 KJ – DD
01 Escape – DD
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9:55 am
May 24, 2011
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Ggg
| | Belvidere,IL | |
| Daily Driver | posts 186 | |
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Post edited 10:51 am – May 24, 2011 by Ggg
I tend to agree with Jeff the 600cfm sounds a tad small just looking at 360cid but this really depends on the cam specs. A small carb should be good down low and run out of breath up high. It is really key to know the cam specs otherwise you are just guessing. The manifold will work well with a smaller carb since it is a dual plane small runner style. Tony how does it idle, I don't remember? Does it lope or is it smooth.
Idle rpm's seem a tad high, is this because of idle characteristics?
Do you know the specs for any of the other cams you have or are these just some odds and ends you have acquired over the years?
Do you have a vacuum gauge, tach, dwell meter, timing light? If not get them.
What is your idle vacuum readings? Does vacuum fluctuate a lot or is it pretty steady?
What power valve are you running.
What jets primary and secondary are you running?
What color pump cam? which hole is it in?
Ignition timing sounds like a lot for a AMC w/ points dist. IIRC it should be somewhere around 8*, but again it depends on the cam the cam specs and cam timing.
What axle gear ratio and tire size?
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98 TJ AX15/231sye, D60, Sterling 10.25 axles, Detroit lockers, 7" lift, Cummins 4bt engine, double triangulated 4 link rear, Y link radius arm front suspension, tires 37"-41".
48 CJ2A D30nt, AMC20nt w/lock right, Kaiser 231v6, T90/D18, 33x14 boggers
46 CJ2A D25, D41, L head Go Devil 4cyl, T90/D18, PTO, 6.5-16 tires.
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5:56 pm
May 24, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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Post edited 6:40 pm – May 24, 2011 by Tony M
Just so its clear this is a 670cfm Holley Truck Avenger on a 360…
Checked the the timing and it was a bit off but it got me thinking. I was always told to pull the vacuum advance hose before you adjust the timing. But why is it that the timing rises when you put it back on? I understand why it happens (physics) and why you need more timing when your at higher engine speeds. But what I don't understand is that you pull the hose, set the timing (10BTC) and then when you attach the hose it jumps to 20BTC at idle. Doesn't it defeat the purpose? I guess I really don't understand how that works, I'm just a self taught shade tree mechanic.
CARB STUFF:
Adjusted idle again: about 10BTC (no vacuum) 800rpm park, 650 Drive.
The cam I'm guessing, it came with the motor and I don't know anything about it other then its mild. It lopes a little but not like a race motor but beefier then stock.
I have all the gauges except a dwell meter. (don't even know what that is)
Idle vacuum is 11hg and steady, maybe a half bounce at times but pretty steady. In gear its at 7hg.
4 power valve
jetting 68
Orange cam in the number 1 position
5:13 gears 36's
Stinky: as far as this thing working on hills. I have had it idling pretty much on its tailgate at the badlands and on its front bumper here in Michigan. I'm really happy with how it idles, I just need to get it tuned. idle and WOT it works great.
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7:34 pm
May 24, 2011
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Ggg
| | Belvidere,IL | |
| Daily Driver | posts 186 | |
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Post edited 7:39 pm – May 24, 2011 by Ggg
OK some good base info there. I think the 600cfm got into my head from an earlier post, but that doesn't matter.
First and foremost your vacuum is low. It should be 17-22"Hg at idle in park. Possible causes are vacuum leak, improper valve timing, worn rings. (in order or lowest cost to repair first)
Check for vacuum leaks first by spraying carb cleaner around all the gasket sealing areas to the intake and note any change in idle. Then check all vacuum hoses for cracks. Check carb mount bolts to be sure they are tight. Did you plug the vacuum hose after you pull it off to check ignition timing? This would be a large vacuum leak and the easiest to correct. If you do plug it then double check the valve timing, and then do a compression check and a leak down test. If the engine is tired or rings are worn then stop messing with the carb it is rebuild time.
But until you find the cause of the low vacuum you are chasing your tail on the carb issue. Sorry Tony to be the bearer of bad news.
You have plenty of gear for those tires so that is not an issue.
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98 TJ AX15/231sye, D60, Sterling 10.25 axles, Detroit lockers, 7" lift, Cummins 4bt engine, double triangulated 4 link rear, Y link radius arm front suspension, tires 37"-41".
48 CJ2A D30nt, AMC20nt w/lock right, Kaiser 231v6, T90/D18, 33x14 boggers
46 CJ2A D25, D41, L head Go Devil 4cyl, T90/D18, PTO, 6.5-16 tires.
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7:47 pm
May 24, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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Possible. I did make some head way today. I'll do a compression check this weekend. What should I be looking for?
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7:56 pm
May 24, 2011
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Ggg
| | Belvidere,IL | |
| Daily Driver | posts 186 | |
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I am a bit rusty on my gas engine stuff but a new engine would be around 200 and anything above 165 is good on a used engine. All cyls should be within 15% of each other.
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98 TJ AX15/231sye, D60, Sterling 10.25 axles, Detroit lockers, 7" lift, Cummins 4bt engine, double triangulated 4 link rear, Y link radius arm front suspension, tires 37"-41".
48 CJ2A D30nt, AMC20nt w/lock right, Kaiser 231v6, T90/D18, 33x14 boggers
46 CJ2A D25, D41, L head Go Devil 4cyl, T90/D18, PTO, 6.5-16 tires.
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7:59 pm
May 24, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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yeah, just figured that out. Thanks….
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8:52 pm
May 24, 2011
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StinkyMud
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| Mall Crawler | posts 346 |
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Just a quick question, where does your vacuum advance hose go to? ie: intake manifold or carb?
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Jeff & Angel "Git-R-Done"
04 TJ (Lil Smokey)
02 KJ – DD
01 Escape – DD
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5:06 pm
May 25, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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Carb. The vacuum advance port.
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7:50 pm
May 25, 2011
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Tony M
| | Grand Rapids, MI | |
| Mud Slinger | posts 545 | |
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Did a compression test.
Cylinder PSI
1 60
2 54
3 55
4 61
5 70
6 73
7 70
8 55
fawck…. I'm going to do it again, but with a little oil in the cylinders to check the rings, and then probably start tearing down the block. Luckily, I know a good machinist and might get this all back together for the Badlands run.
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8:18 pm
May 25, 2011
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Xjay98
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| Mall Crawler | posts 390 | |
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Like GGG said you may have a lean condition. Spary (quick squirts) some carb clean into the choke horn. If your idle goes up your lean and if it bogs down youre rich. If you're looking for vac leaks check your base plate where vac. runs. I had a small crack on my 800DP. Its just from removing and installing the carb will cause that crack. Have you checked your float level when the truck is running? Are you running an MSD box?
Those HG readings sound like you have a healthy cam. Thats what my big block reads. LOL! At 11HG try a 5 power valve. According to Holley take your manifold vac and divide it in half.
I would not make any changes not until you are sure you dont have any vac leaks.
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8:32 pm
May 25, 2011
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Xjay98
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| Mall Crawler | posts 390 | |
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9:49 pm
May 25, 2011
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Ggg
| | Belvidere,IL | |
| Daily Driver | posts 186 | |
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Yeah the engine is very tired. Wet compression readings are best to use, but considering how low your vacuum is and how low the dry compression test readings are, even if you double them you are at the bottom of the range for a healthy engine. Put compressed air to each cyl (10-30psi only) and look into the radiator for bubbles (head gasket or cracked head/block), listen to the intake for intake valve seat leaks, listen to the exhaust for exhaust valve seat leaks, listen into the crankcase via the oil filler cap for air leaking (rings, bad piston). This is a down and dirty shade tree leak down test.
Don't forget to double check the valve timing before condemning the rings, especially if the wet test does not see a dramatic increase.
As far as all the other vacuum leak tests go they are a moot point now that you found out how low your vacuum is. Considering the lack of hard lope at idle and steadiness of the vacuum readings the cam is rather mild and not the cause of poor vacuum at idle.
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98 TJ AX15/231sye, D60, Sterling 10.25 axles, Detroit lockers, 7" lift, Cummins 4bt engine, double triangulated 4 link rear, Y link radius arm front suspension, tires 37"-41".
48 CJ2A D30nt, AMC20nt w/lock right, Kaiser 231v6, T90/D18, 33x14 boggers
46 CJ2A D25, D41, L head Go Devil 4cyl, T90/D18, PTO, 6.5-16 tires.
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