Engine Combo Help

[FatKid]

Hey Guys, new to engine building but am trying to learn all that I can. A while back I purchased an engine from a buddy that was built for his project but decided to go turbo. Its a little 1835. I'm not sure what his logic was behind this build but it just seemed all wrong to me. Stock 69 crank, rods, and flywheel, NPR 92's, stock heads with a w125 cam, compression set at 7.5:1. After I bought the engine I swapped the heads for 041's (39x32) that I had on hand, added dual springs, and stock ratio rockers on solid shaft. Shims were removed to bring the compression up to 8.9:1. I also added a Bugpack 1.5" merged header, empi fatboy, and dual Weber 44's. Ignition is a CB Performance Magnaspark II unit straight out of the box.

This is in a full stock street trim late model. I'm just not feeling the engine is happy, and think there is more to be had here. Any advice would greatly be appreciated.

Here's the engine


And the car

[Zach Gomulka]

It doesn't look too bad, is your tune right? The heads do need work, ported and a 35.5 exhaust valve. Anything beyond that I would say start from scratch.

[FatKid]

I'll have to locate my note binder for my notes, I can't remember off the top of my head what the settings in my carbs are. Venturies are whatever come with 44's (34 or 36 I think), f11, 125 main, 180 air, and 50 idles I think, could be wrong. Was supposed to dial it in with a wideband today but my buddy flaked. Does this sound like it's in the ballpark, any recommendations?

[Zach Gomulka]

125 main sounds lean to me (44's come with 36 vents). By tune I mean more than just jetting, timing, carb sync, full throttle, etc.

[FatKid]

What are you meaning by full throttle? Is it getting it, or rpm or? Carbs are sync'd, timing at full advance is 28 degress. Fuel is suppled my an electric pump at 3 lbs. What else should I be checking?

[fish]

NPR 92s were notorious for cracking and over heating

[Zach Gomulka]

Yes, check for full throttle. I'd try bumping up the timing to 32°. Also make sure you still have good compression.

[Jim Ratto]

I'll have to locate my note binder for my notes, I can't remember off the top of my head what the settings in my carbs are. Venturies are whatever come with 44's (34 or 36 I think), f11, 125 main, 180 air, and 50 idles I think, could be wrong. Was supposed to dial it in with a wideband today but my buddy flaked. Does this sound like it's in the ballpark, any recommendations?

change jetting to:
55 idle (1-1/2 turns out on mixture screws)
140 main
air corrector ok

you're borderline on the F11 emulsion tubes. I feel the F2 would run better.

simple things like plug gap, valve-lash, linkage geometry is all spot on, right?
How is advance curve set up on that distributor? If you have it configured to use a minimal amount of initial advance, and to come in slow and at rpm above 2500, it will rev sluggishly. Use the bushing that allows for maximum initial advance, and then set total to 32.
And use lightest springs. (just to check "which way the wind's blowing")
Or... lock the advance out and set it at 30.

[FatKid]

Fish, I've heard the same and am a little skeptical about them.

Thanks Jim and Zach. Linkage is sync'd, plugs gapped and valve lash set @ .006. I'll dig out my magnaspark box and change the springs and bushings and advance the timing. The car has nothing under 2200 rpm. It feels like I'm riding my Banshee. You can't really lug it but once you hit 2200 the powerband kicks in. I'll have to put in an order for some jets due to my collection being limited to basically none.

[Martin S.]

Stock sized exhaust valves on a performance engine are a sure way to limit performance. Why not 044's?

[FatKid]

Only reason they are on there is because they were already in the garage. Is it worthwhile to enlarge the exhaust valve, or start fresh with an appropriate head?

[Zach Gomulka]

Only reason they are on there is because they were already in the garage. Is it worthwhile to enlarge the exhaust valve, or start fresh with an appropriate head?

By the time you have the work done you probably won't be too far away from a new set of heads. I'd go with a set of Tims Stage 1's.

The cam is a bit on the rowdy side for only 1835cc's. I'm sure you can improve on what you've got, but I wouldn't expect huge gains down low.

[Jim Ratto]

Only reason they are on there is because they were already in the garage. Is it worthwhile to enlarge the exhaust valve, or start fresh with an appropriate head?

are the heads ported? An old friend of mine in the 1990's ran stock sized valves, but ported at Heads Up Performance, 1679cc, with Web 110 (not much different than your W125, about 5' less duration @ 0.050"), Weber 40 IDF and a Bosch 010. It had more than ample power and was the bane of many V8's where we lived. With street tires and at full stock weight, it went 14.70's. In the context of 12 sec 2276 cars, yes I know, that seems glacially slow, but, it wasn't. That's about same 1/4 mile ET as 1st generation (US market) WRX.
And- it was extremely forgiving to drive. It came on hard at about 2000 rpm and went to 7500.

The 125 Engle is ideal for hot street engines, 1800cc-2000cc

[Jim Ratto]

Also, get that rear cooling sheet metal piece (over header) installed. Nothing kills an engine faster than cooking it to death. I know way too many people that ignored installing that and destroyed their expensive engines. If you have been running the motor that way, I'd say you need to drop the motor, strip the fan housing and cylinder covers off, and retorque the heads and readjust your valves. Don't be surprised if the heads are loose.... which will cause it to run REAL limp.

[FatKid]

No, the heads are not ported. All we did to them was a valve job, dual springs and solid shafts.

The above engine picture was an early one before the tin was installed. I am running all the tin minus the sleds and a thermostat.

[Martin S.]

I have some stock valve ported heads done by Mick Wooten at Bergs from the 90s (used with a 110 too) and they are awesome BUT EXPENSIVE! That was before the cheap 044s came out with the larger valves. I paid $800 for the porting alone which was a ton of money back in those days and still is. Now you can get 044's for around $300 each.

[Zach Gomulka]

No, the heads are not ported. All we did to them was a valve job, dual springs and solid shafts.

In that case, you would see a fairly significant hp gains with properly done heads. You could also optimize the deck height and raise the compression... If the NPR's can handle it.

[Jim Ratto]

Is it running on all 4 at, and off of idle? IDF Webers are notorious for debris plugging idle jets. The idle circuit gets air from orifices in top of carburetor. If you run no filters (like in your picture) dirt, lint, grit, etc can get into air orifices. The fuel for idle circuit in the IDF comes from main wells and emulsion tubes (unlike IDA). Crap in float bowl tends to get jammed up in idle jets. So, do you get a nice, smooth, hard idle, with a hollow sounding exhaust note? Do all the mixture screws bring their cylinders to life at same amount of turns from closed? Did you equalize airflow using air-bypass screws?
I re-read your post and you mentioned how it has nothing under 2000 or whatever, just wondering if it's running on 3, then the mains come in and it wallops you.
I look at your jetting, however, and doubt the 125 main is coming in at 2000. I bet when you try to goose it at 3000+ it lean stumbles, especially with the F11

Your combination of cc, cam, compression, heads, carburetion and exhaust isn't far off[/i. Worse engines have been built. No crime committed here.

Get the advance dialed in to limit mechanical advance (something like 15' initial, 30' total, all in by 22-2500), and spend time getting to know your 44's. You'll get it right and it should scream. Spending a bunch of money to undo a pretty sound combination (when it just needs tuning) is going to frustrate you right out of VW's. Seen a thousand guys make that mistake.

Jim

[FatKid]

Jim, the car started out with 36 Dellorto's, that I wish i kept, but was told I need more carboration. Sold them off for the 44's knowing the hassle of the idle circuit in IDF's. And I just experienced it first hand the other day. As with running all engine tin, I also run filters and lids. The above picture was just after re-installation of the motor and it wasn't fully dressed out.

Back to the other day, I've put very little miles on the car due to it being a brand new build. I'd say in total I might have a hundred miles on it. Last friday I hopped in it to attend and VW gathering down in San Diego (about a 25 mile drive) after sitting a full day with no prior issues, upon start up it sputtered, bucked, popped and sounded like it was running under water. But once over 2500 rpm it smoothed right out, so I knew I had a plugged idle. I got frustrated and parked it. The next day I decided to concur it, but only a mile or so down the street through traffic signals, it cleared out. I haven't been able to touch it since due to it not being stored at my house right now (long story).

At initial dial in it was smooth, not very snappy or quick reving though, was told that it was due to a stock stroke crank. I was not the one that set up my carbs, a buddy of mine did it so I can't tell you for certain if all screws are turned out the same amount. He did not use the bypass screws, they are closed. I wouldn't consider the idle to be smooth and hard. Do you think the jets are ok in it or do I need to get the 140's and 55's?

I'm heading over to the car right now to get details and see what I can do with it.

[Jim Ratto]

before you change jets, make sure ignition timing is where the engine wants it. Typically, motors with large Webers like a lot of initial advance (which means limiting the mechanical advance). See how much initial you can adjust in, while keeping total advance between 32-34 BTDC at 3200-3500. If it's still soft then look at jetting.
I suspect it will need more fuel.

44's are not too big for your motor. If you had some massaged heads, I'd say 44's are perfect for your motor.

good luck

[FatKid]

Ok, I was wrong about my jetting.
It is:

135 main
55 idles
185 airs
F11 emulsions

Just pulled all the jets out and it turns out that one of my airs is a 165. That might be a problem!
Tomorrow I'll have it on a wideband and an experienced guy looking it over.

[Zach Gomulka]

Buy a jet gauge. Never trust what it says.

[Jim Ratto]

Buy a jet gauge. Never trust what it says.

Good advice,

[FatKid]

Ok, well we didn't hook it up to the wideband but we did get somewhere. Corrected the #3 air corrector from a 165 to a 185. Carbs did not want to flow the same at the idle screws. Turns out that the left carb arm that the linkage attaches to had unwanted movement. Almost like the shaft was rounded off. When we tightened the nut it would only bind the shaft and throttle plates in the throat. We removed the linkage arm and the throttle stop and tig'd them together. After re-installation we were finally able to sync the carbs. At idle the #4 hole was not firing, mixture screw backed out over 4 turns. Turned the screw in, cylinder came alive. Changed the springs in the distributor to the lightest ones so it's full advance at 2500 rpm, but kept the same bushing in to have a 20 degree advancement range. Car idles smooth, and rpm's up clean and consistent. We've seem to remove the 2 stoke powerband at 2200 rpm. All in all I'm pretty happy with it.

[henk]

if i read right,you synchronised the carb with the linkages attatched.
i'm always been told to sync the carbs with the linkage arms removed from the carbs.

henk!!!

[henk]

double post

[FatKid]

Henk, no, carb sync was done with linkage detached.