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A Cam +4 Deg, B23F 10.3:1 Knock?

OldCarNewTricks

OldCarNewTricks

Well-known member
Joined
Oct 23, 2016
Location
Oregon
I was letting my 242's engine run for a bit couple days ago, been a couple months since it last ran. Runs fine for a 40 year old motor. It does have an A cam and an adjustable gear, which is set +4 degrees. After it warmed up, I did a couple light revs, and just off idle, I heard it knock a couple times, then even out. Does this consistently. Reason for the A cam being advanced, is because I originally thought I would drive it with an AW70, but I am swapping an M46 in, and I will likely run it straight up. It also has somewhat old 87 oct. fuel with the remnants of Chevron fuel system cleaner.

Is the advanced cam timing likely causing this, or just crappy fuel?

I have also thought about getting a K, H or a V15 NA, and replicating a B23E, since I already have the high comp motor, anyway.
 
Maybe about a year or less, if I had to guess? It's been sitting a lot while I get enough budget to put it together.
 
What is the base timing set at? That could help it be less prone to knock if you back it off a couple degrees. The engines were designed for 91 so throw a few gallons of premium in there and see how it is.
 
dl242gt said:
What is the base timing set at? That could help it be less prone to knock if you back it off a couple degrees. The engines were designed for 91 so throw a few gallons of premium in there and see how it is.
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I don't have a timing light. Need to buy one. That interesting that they were designed for 91. Did "regular" gas used to have a higher octane rating?

Dave, is your NA engine with the V15 stock compression? With a hotter cam, the dynamic comp goes down, so that might benefit my motor. I don't know if I really want to bump the comp up since I plan to DD it.
 
Yes, it's a stock b230f with just the cam and a chipped EZK box. It's not a hot cam it's basically the n/a version of the IPD turbo cam. The difference is the lobe angle is 109 instead of 112 for the turbo cam. Really wakes these engines up with a smooth idle and passes emissions.

The engines have to be made so they can run on 87 but they are optimized for 91 and higher especially the b23f flat top piston version.
 
dl242gt said:
Yes, it's a stock b230f with just the cam and a chipped EZK box. It's not a hot cam it's basically the n/a version of the IPD turbo cam. The difference is the lobe angle is 109 instead of 112 for the turbo cam. Really wakes these engines up with a smooth idle and passes emissions.

The engines have to be made so they can run on 87 but they are optimized for 91 and higher especially the b23f flat top piston version.
Click to expand...

Is chipping your EZK basically equivalent to me changing my ignition timing? Yeah, from my understanding, it performs as well up high as the better factory cams, while still having good performance down low/mid. I expect that's the cam I'll be saving up for :)
 
Well, I think my engine doesn't actually have flat tops, as I thought.
KS2B5R6l.jpeg

Mine is 499890.

My ICU, however, is the more aggressive 1346105.
hUVvKtMl.jpeg


I think the 3.91 rear end will actually be a very good thing when I return the car to it's original state with an M46. Still need to verify that the rear end is a 3.91 and not 3.73 by pulling off the cover.
 
OldCarNewTricks said:
Well, I think my engine doesn't actually have flat tops, as I thought.
KS2B5R6l.jpeg

Mine is 499890.

My ICU, however, is the more aggressive 1346105.
hUVvKtMl.jpeg


I think the 3.91 rear end will actually be a very good thing when I return the car to it's original state with an M46. Still need to verify that the rear end is a 3.91 and not 3.73 by pulling off the cover.
Click to expand...

That is going to be a rather short 1st gear with 3.91 in the back.
 
spock345 said:
That is going to be a rather short 1st gear with 3.91 in the back.
Click to expand...

From my understanding, 1st gear is just too short as is, but the 3.73 or 3.91 are really good for 2-4 and OD. I have not driven a car with an M46, so I could be wrong, but that's what I've been told.
 
OldCarNewTricks said:
From my understanding, 1st gear is just too short as is, but the 3.73 or 3.91 are really good for 2-4 and OD. I have not driven a car with an M46, so I could be wrong, but that's what I've been told.
Click to expand...

Yeah, it really is. I had a 3.73 in my 240 and 1st was almost useless. If there was even the slightest downhill slope when starting I'd just go for second.

The M40/41 3.13:1 1st is a much better ratio than the almost 4:1 the M45/46/47s got.
 
spock345 said:
Yeah, it really is. I had a 3.73 in my 240 and 1st was almost useless. If there was even the slightest downhill slope when starting I'd just go for second.

The M40/41 3.13:1 1st is a much better ratio than the almost 4:1 the M45/46/47s got.
Click to expand...

Using second on flat/downhill is my plan.

If only they could have kept on with more reasonable gearing.
 
shoestring said:
Clutches last forever like this.
Click to expand...

I expect so. It's similar to the old Clarktor aircraft tugs I restore here. 1st is actually a crawl gear only to be used under load. Start out in second is what I'm already used to.

By the way, does anyone know if I'll feel a big difference going from the A cam to a V15 NA?
 
OldCarNewTricks said:
I expect so. It's similar to the old Clarktor aircraft tugs I restore here. 1st is actually a crawl gear only to be used under load. Start out in second is what I'm already used to.

By the way, does anyone know if I'll feel a big difference going from the A cam to a V15 NA?
Click to expand...

You will feel a difference. The ~2mm more lift helps. The duration and overlap are similar so the idle quality will be the same. The power band Enem advertises of 2000-6000rpm is accurate and good for everyday driving. It doesn't bog in the 1000-2000 range either. It'll protest a bit but rather smoothly pull itself up to the power band.

I went through M, A, T, V, and K cams before landing on the V15. The V15 kind of had the best of the bunch, especially when I burned myself an EZK timing chip based on a map sbabbs sent me (he'll probably sell you a chip as eprom programming setups are kind of rare). There was a decent difference going from the M/T cams to an A or V. Then another big difference going to the K, which had a meh idle and had power all up on the high end without cam and ignition timing adjustments. The move from the K to the V15 resulted in more usable power and a better idle. These are just my observations from trying a bunch of cams. If I had to start again I'd probably jump right to the V15 if I had the cash to do so.
 
Different application obviously but I love my V15. V cam is a good substitute if you don't want to pay up. It's a little better behaved than the V but better power too.

1st gear is short but who races 1st gear??

Stock timing maps seem to be aggressive in general.
 
The enem cams were such a enjoyable upgrade. Suddenly you have an engine that loves mid range and will zoom right to redline happily. The low end torque is just fine and a bonus is that the n/a version gives me about the same mileage as stock with much better highway passing power.

The V15 is not a high performance cam. It's a street performance cam with a wide torque band. I also have a V16T that I want to use next. The people here that have used the V16T cam have make a lot of power.
 
Thanks guys. I think the V15 will suit what I need pretty well. I think I would go for the V16, but I would then need to likely switch from LH 2.0, and also figure out the best way to raise compression (flat top pistons, and shave surfaces). I think I should be okay using stock engine management with the V15, as I can adjust ignition timing via clocking distributor, is that correct?

I also think I'm going to get a nice quiet(er) exhaust with the switch to a hotter cam and a manual (higher revs). VP Auto parts sells Simon's exhaust for the 240s, and that helps with shipping. Either that or just use the stock 60mm factory turbo system.
 
OldCarNewTricks said:
Thanks guys. I think the V15 will suit what I need pretty well. I think I would go for the V16, but I would then need to likely switch from LH 2.0, and also figure out the best way to raise compression (flat top pistons, and shave surfaces). I think I should be okay using stock engine management with the V15, as I can adjust ignition timing via clocking distributor, is that correct?

I also think I'm going to get a nice quiet(er) exhaust with the switch to a hotter cam and a manual (higher revs). VP Auto parts sells Simon's exhaust for the 240s, and that helps with shipping. Either that or just use the stock 60mm factory turbo system.
Click to expand...

Yeah, you can just dial in base timing by clocking the distributor. There are a bunch of ways to figure out where the cam will be happy. Get a timing light and a vacuum gauge. You can either tune it so the motor pulls the most vacuum at idle (more of an old school trick for carbed motors) and/or advance it until you start to get ping on your desired octane rating, then back it off a bit.

Generally the old adage goes, the more duration/aggressive the cam, the more initial timing but less total advance the motor will want. If you have emissions testing just make sure to reset it back to stock before going in to get it tested as they'll probably check that.

I think I had the IPD single muffler 2.25" (or was it 2.5"?) exhaust on my car. Had a nice rumble without being obnoxious. Personally I think the single muffler systems are superior to the stock muffler/resonator setup.

It'll take a few months to get a cam from Europe, should be something around $350-400 all said and done. I'd also recommend an adjustable timing gear from STS or something comparable. That'll give you more things to fiddle with so you can get the car running how you like it. Start with it straight up, then advance the cam timing two degrees, see how you like it, adjust again, etc.
 
Old hot rodder wisdom is to pick the cam you want and then buy one step smaller.

Adjustable cam gear also necessary if you're gonna shave the head (which you should)
 
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