289 FIA vintage race engine with Webers

[peterpjb]

the Gold Standard is pretty much the same level as the FIA HTP (historical technical passport)

[Gaz64]

Hi Jim,

I certainly agree with Brent's statement about having more more power with a single 4 barrel.

The only time IR induction has more outright power is when the induction system is optimised for high mid to top end.

Your setup with 42mm chokes certainly sounds like it is "up there" for a little 289.

Sizing for Weber jetting is 0.5mm increments, so your next main would be 1.55mm. My curiosity is the the 2.00mm air corrector.

Where is it rich or lean at the moment?

One camshaft I chose for one of my cars, had in the description "violent midrange for pulling out of corners", and rpm range of 2800-6700 plus.

This is a street registered car, good manners (for me anyhow).
This cam had more power everywhere than the cam I had, which is a popular camshaft, 288, 252 @ .50 LSA 108 .345, my new cam was 276, 242 @ .050, LSA 106, .350 cam lift.

I ran both cams with my 44 IDFs, they both had more peak torque in the middle at 4800 rpm, but less peak power, peaks of 6400, compared to a 750 annular Holley peaking at 6700, about 15 horsepower.

The Webers were great on a twisting track, gymkhana etc, but the single 4 was faster on a long track.
The "violent cam" came on really smooth, and pulled away well from other traffic.

Wide LSA, all else being equal, has less overlap, but has a later inlet closing point, which then has lower compression on a test gauge.
This gives less low speed torque. The closing point is the most important timing event.
Overlap helps scavenge the cylinder of exhaust gases by using the exhaust gas momentum to help pull in, and fill the cylinder with fresh A/F mix.
Once the inlet charge is flowing in, it helps blow out the remainder.
All in a perfect world. As overlap is increased, the amount of exhaust gas trapped in the cylinder at low rpm is increased, which gives the camshaft rough idle characteristic.

Of everything I have learnt, one thing thing stands out. Never change more than one thing at a time.

When I changed the above camshaft, everything else stayed the same.
A tiny valve seat change, but same carb etc.

I built a tiny 1.5 litre 4 banger, 250 @ .050, 107, and 2 x 48 DCOE Webers.

That engine was streetable at 2500 rpm, torque peaked at 6200, hp peaked at 8500 rpm.

You can see these carbs are really big for the engine.

So it comes down to what you really want.

By the sounds of your youtube videos, I bet it feels really nice to drive.

I still would have tried the intake and carbs on the engine while you had the 106 in there, even just for testing giggles.

Gary

[CompClassics]

I would have to agree on the main jetting and air correctors, 150 main jets and 200 air correctors seems like a huge discrepancy. Usually the air correctors are only slightly larger than the main jet. Just an example but I run a 145 main jet and a 150 air corrector.

[1795]

Gary and John,

That for the feedback. I will agree from what I have read, have not had the seat of the pants feel yet as the engine is not in the car yet, that a 4 barrel will create more HP (all other things being equal) than Webers in the upper rpm ranges. What I was after was the low end torque, and the sound of the Webers too , to give me more pull coming out of the corners. Most of the tracks that I race on are twisty with elevation changes and one or two moderate straights. I have not raced on a track yet in which I am hitting near redline well before the end of the straight.

I talk to the guy who built the Webers last night and he said that while they have built a lot of Weber systems for big blocks and stroked small blocks, this was the first small block with a standard stroke and iron heads. They set up the main jet initially with a .165 and that was too rich (this is probably the reason for the 200 air corrector. The engine was to making any power and struggled. They switched to the 150 and the engine took off and started making lots of power. Right now it is slightly rich from about 3900-4300 rpms and then there was a little bit of getting slightly lean between 6200-6600 rpms. Then it was stable again after that.

Of course this is all on the dyno and we will have to see what track use does. I ordered a set of 155 main jets just in case I need to get a little richer. I doubt that I need to worry about going leaner with my jetting. Right now the engine is pretty fuel efficient regarding fuel use for a set of Webers. I also have a set of screens for the Webers that I intend to use during races (they fit inside of the air horns) to keep the big chunks of rubber and other things that fly around the track from getting sucked inside and I imagine that that will reduce air flow slightly and may cause a slight increase in richness.

If I needed to change the air corrector, what size would you suggest? As Gary suggested, I am going to go one step at a time with any further changes and wi make no changes until the car has been on the track. Would have been nice to try things on the engine as it was getting refreshed, and the engine builder was planning on putting the old engine on the dyno for comparison sake prior to doing the rebuild, but unfortunately a rocker arm disintegrated at my last race and the engine was not operational.

Jim

[blykins]

Originally Posted by 1795

I talk to the guy who built the Webers last night and he said that while they have built a lot of Weber systems for big blocks and stroked small blocks, this was the first small block with a standard stroke and iron heads.

I think that's a key component of what's going on: they're used to working on larger engines.

There are two major components of camshaft duration selection: displacement and head flow. Very generally speaking, a smaller engine requires less camshaft duration because there's less cylinder volume to fill. A higher flowing head also requires less camshaft duration because the head is efficient; it will allow the camshaft to "pack it in" more efficiently.

A mid 250's @ .050" camshaft for a 289 with Dart heads is absolutely HUGE. To only peak at 6500 shows that something is very much amiss somewhere.

For a couple of examples, that amount of duration in a factory headed 351C will peak the horsepower at 8000 rpm. That amount of duration in a 482ci Ford FE will peak the horsepower at 6500 with a set of CNC ported Edelbrock/Pond heads.

As another comparison, the camshaft that I use on my factory headed (ported C5 heads that flow 200 cfm at peak) road race 289's is only 242° at .050" duration and that engine, even with a "poor performing" factory head peaks at 7000.

I think you're going to run into a situation where, relatively speaking, you have a short powerband because the camshaft is too large to give you any bottom end and mid range and it's also out of the capability of the cylinder heads, so you won't get any top end either.

In addition, the way the horsepower goes "up and down" towards the end of the pull, from 6400 to 6900 leads me to believe that the valves were starting to float and you were losing control of the valvetrain; not a good situation for a road race engine. This could explain why the engine didn't make more horsepower than it should have.

I think your crank pulley is also bent.

[1795]

Brent,

What makes you think that the crank pulley is bent?

Jim

[blykins]

Because I can see the run-out in it on the dyno. It's very noticeable on the video of the engine on the run stand. Not sure if it's the pulley or maybe the crank snout has a little bend to it.

Looks like it's marked off in 90° increments as well, for setting valve lash. Don't set your valves like that, set them with the EVO method. It's much more accurate on large cams.

[cobrakiwi]

Looking forward to your feed back on the new engine once you have it back in the car.
I'm sure there maybe some more tuning with the webers to come.

I guess all the racers using the weber setup over a 4 barrel over the years had it wrong.

I don't see a bent pulley, I think the fan belt is a bit funky on the engine stand run.

Good luck with the race season Jim.

[blykins]

All those racers over the years didn't have access to the single plane and modern intakes we have today. It's not that they had it wrong, it's just that that's all they had. Also depends on the rules that are applied. Some have to use "period correct" intake manifolds.

As for the pulley, the dyno videos show something that has run-out. There is no belt in those videos as they are not turning the water pump. As the rpms go up, the oscillations stop, but as soon as the rpms come back to idle range, you can see it again.

[cobrakiwi]

I mentioned the engine stand video not the dyno videos,
I still don't see the bent crank or pulley in the dyno videos either.

Must admit, my eyes are not as good as they used to be.

[blykins]

I turned 40 two years ago. I don't think anything on me is as good as it used to be.

[1795]

I don't know what is wrong with you Craig and Brent, I am turing 60 next month and everything is still working fine

It will be an interesting year. Wish I had some time to track the car before Mid Ohio, but that doesn't look possible. At least I am doing the test day there.

Jim

[1795]

Ok,

Having some new buyer remorse, I called Darryl and Jim to touch base on the concerns mentioned here. Jim Inglese did the setup on the carbs and he is happy with where things are set and how they are operating. I am not going to argue with Jim, he has extensive experience with Webers and if he says that everything is fine, then until I see otherwise, that is good enough for me.

The cam was a special grind for this engine based upon the displacement, compression ratio, Webers, heads, desired power band and intended use. It is not similar to the grinds that they get for stroked small block engines.

The crank was sent out to a person who specializes in crankshafts and it had everything that you could imagine doing to a crank to ensure that it was properly treated, examined and balanced. I think that any seeming imbalance in the dyno video could be attributed to the fact that my phone was resting on the window sill and leaning on the plexiglass. Vibrations from the pull probably distorted the video a little.

I'll let you all know when I get the engine installed and running.

Jim

[Gaz64]

Jim,

I think we'll find the belt deflection on the engine stand is some harmonics happening that video can't capture as "true to life" due to frames per second.

A bit like vehicle wheels that go backwards on TV.

Now, your carbs.

I hope some other guys on here will chime in to say what choke size they have.

If Jim gave you 42mm, then your combo of CID, compression ratio, cam profile etc, AND intended use: driving style, peak rpm etc were all deciding factors.

A tuning book of mine shows the ideal intake tract for an IR system, to have the throttle butterfly as the same size as that of the intake valve, and then the choke to be .85 of the butterfly.

Yours would be around these figures.

I would thinking about an air corrector change that will richen the top end, something like 180 as a start. Easy enough to drill them out to 1.85 about No. 73 as a test.
Then buy the correct sizes when you are happy with your testing. A misfire (poor combustion, valve float, poor spark quality etc) leaves unused oxygen, which then shows lean.
You may see that happen as the power falls away.

Gary

[blykins]

I’m still thinking something is off with the crank pulley. Even on the video from the dyno where there is no belt, I see run-out at low rpm. It’s almost like the pulley is bent or it’s not centered on the balancer.

I’m also concerned with the valve float signs on the dyno sheet. Could be the reason the engine is not making the horsepower it should.

[Gaz64]

Originally Posted by blykins

I’m still thinking something is off with the crank pulley. Even on the video from the dyno where there is no belt, I see run-out at low rpm. It’s almost like the pulley is bent or it’s not centered on the balancer.

I’m also concerned with the valve float signs on the dyno sheet. Could be the reason the engine is not making the horsepower it should.

Ah yes, after looking at dyno videos.

More investigation as to the cause of the power falling off, either valve float or ignition system etc.

[blykins]

Originally Posted by Gaz64

Ah yes, after looking at dyno videos.

More investigation as to the cause of the power falling off, either valve float or ignition system etc.

I would say valve float.

If it were just an issue with not enough camshaft, then the power would just fall off in a curve.

In the last 500 rpm of the dyno sheet, we see the power go up, back down, up, back down, etc. That's a tell-tale sign of valve float. I would say that the engine needs a little more valve spring seat pressure.

[Gaz64]

He's making near 1.5 per cube now, but there's probably another 30hp still on the table.

Gary

[1795]

Brent and Gary,

We wil take a look at the possibility of valve float. One contributing factor to those results may be that the dyno had the oldest computer I have seen operating in a long time. I think the last time that I saw one that old it was in a museum. When he was showing me a graphic of the torque curve the dyno operator commented on how this graph showed subtle variations that more modern computers on dyno's even out in the programming. The variations at the high rpms could be an artifact of the older computer and programming not being able to keep up with the input data at higher rpms.

While there still may be 30 hp left on the table, those extra 30 hp and 8,000 rpm redlines do come at a cost. If I am peaking at 6700 rpms and pretty much shifting between 6500-7000 rpms, the engine is going to last a lot longer than taking it to 8000-8500 rpms. I know guys who have engines that are operating in the HP and rev ranges that you guys are talking and those engines are expensive and are getting refreshed or broken way sooner than my little wallet can mange.

Now when I get to be a pro and am driving someone else's car using their money it may be a different story

Thanks guys, I really do appreciate the feedback.

Jim

[blykins]

Please don't think that I'm picking on the engine, Jim. These are just things that I'm used to looking for and they stand out to me. If you were to have a bent pulley, you could kick a belt off at rpm. If you were to have valve float, you could lose an exhaust valve at rpm. In my mind, it's better to be proactive and say something, even if I'm wrong.

I don't see any reason why you need an 8000 rpm engine either, but if you're having valvetrain control issues, you could be down quite a bit of horsepower for the rpm range you're running in. I'd rather have more horsepower and not need it, than to be in a spot where I wish I had more.