bill's 308 engine project

Hi derekw,

I'm a little confused. You wrote,"The valve springs they supply are softer than the originals which were too hard."

Are you referring to hardness of the wire in a metallurgical sense (Rockwell C scale?) or are you suggesting the OEM (Ferrari?) valve springs are stiffer or have a higher spring rate then those provided by Cat Cams?

Bill

 

OK thanks guys. So I call this stiffer or higher rate springs as measured in pounds force per displacement (lbf/in) or a spring constant in physics.

So I believe we are saying Ferrari OEM springs are stiffer than the ones derekw used. Of course OEM valve lifts were a lot less than the 0.42 lift in the 1700402 cams so a stiffer spring was not as big a deal at the lower lift but at the higher lift apparently unacceptable. I'm curious as to how my engine builder manages this issue. He has lots of experience building endurance engines. Cam grinders spend a lot of attention developing ramp geometry to minimize cam/lifter loads and maximizing valve operation. I've asked and I am waiting for delivered costs for the 1700402 cam set.

I wonder what cam specs David Vizard would recommend for my street application?

The steel plug wire boot retainer sleeves were quite rusted on one of the replacement heads. Fortunately, these sleeves pull free and good ones from my cracked heads were scavenged and fitted to the needy replacement head.

derekw,

My engine builder says your time frame for state side delivery of the cam pulley set could work. I'll see how things develop over the next week or two.

Bill

 

Hi Ferraridoc,

The new springs must accommodate a variety of requirements. Here are some specifics that came to mind:

1. 8k redline
2. 0.423 inches lift on intake
3. required coil bind margin
4. high valve and lifter acceleration rates (high forces)
5. larger intake valves (more mass)
6. acceptable spring loads throughout the range
7. cyclic cam drive loads
8. cyclic cam torsional loads
9. be available

Bill

 

Some progress this week.

The engine block is out for machining to accommodate the larger bore 328 nikasil on aluminum sleeves.

New guides were pressed into the heads and rough seats were cut.

The intake manifolds were port matched with the carbs and the heads.

My engine builder will source the pistons, rings, lifters, valves, springs and hardware and gaskets and bearings, etc.

I began the process of buying the cam set by getting a price for the splinned version (1700402), 4 cams from billet steel, for 1750+29=$1779; delivered to my engine builder. We'll check the hardness of the cams when we get them. Ferrari shims are very hard so work with less than ideal cam hardness.

Bill

 

Hi derekw,

The engine builder will use springs and valve gear compatible with the lift, rpm, and spring loads. Valves will likely come from his suppliers. I know he favors OEM gaskets but will substitute where it makes sense. I took a few photos of the car and engine. I'll have to see if MWE can take photos and if so at what cost?

The cams were delivered to MWE on Mon, 9/24. Belgium had one cam set in stock, 2I with splined ends and 2E with what I believe are plugged ends.

I'll be talking to MWE later today regarding status. Delivery of the cam drive gear in mid October looks OK at the moment, at least from a timing viewpoint. MWE can use the OEM gear for preliminary clearance checks if necessary.

This photo was taken in 2017.
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This was the engine bay before we started to pull the engine.
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Front of engine
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Back of engine
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Bill

 

I talked to my engine builder who:

• confirms delivery of the cams, 2 splined intakes machined to accept distributors if a future owner decides to use them, 2 exhausts with plugs. I believe this is baseline, 1700402 part.
• says the block is backed up in the machine shop awaiting rebored spigots for the 328 sleeves.and has been in the que for about 10 days.
• Valves are ordered
• spring guidelines are about 80 lbs on the seat load and about 220 lb at full lift (0.430 in).
• Pistons will be custom JE and clearances will be kept tight in the Nikasil bores.

I plan to purchase a cam drive pulley set from derekW.

The other thing I need to order is the oil sump baffle from Superformance. I plan on using the car for occasional track days, so oil control is important.

I contacted Modena Engineering in Australia and they confirmed they could supply a multi ratio transfer gear set. Anybody know the importance the term "constant mesh" when talking about the gear set? one gets to choose 6 of the available 8 ratios. The highest and lowest gear ratios are about +/- 25%. One ratio is within a fraction of a per cent the OEM ratio. Adjust-ability is by changing 2 or more gears at a time. The gear train is stacked on two levels which I believe requires a special transfer gear cover and at least one of the transfer gear shafts. They had photos of the kit at one time but lost them. What a great way of taking advantage of the increased engine size and resulting increase in torque.

Bill

 

Hi derekw,

Thanks for your help. Tire diameter is limited so effective gearing will limited.

Good one Saabguy.

Hi Ferraridoc,

I guess what is important to me is to ensure the gears are helical cut, not straight cut gears, which are noisy.

The following photo shows straight cut gears which are relatively noisy. Note the bi-level gear arrangement. Gears would be changed out in pairs.
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The following shows the more desirable helical cut gears which are quieter.
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I believe the helical cut set is what is available. It appears all adjustment is by changing the top gear (input from engine) and it's mate (center gear outer), in pairs. One can select 6 ratios between 20% lower and 24% higher. The 20 and 24% higher ratios are like 0.80 and 0.76 over drive ratios respectively. A 5 krpm cruise rpm drops to 4 krpm, with the 0.80 ratio. This is one of the strategies to eek out better cruise mpg. Higher CR, lower weight, and ignition advance management are other promising areas to look at.

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Bill

 

Hi guys,

An exchange of emails confirms the current drop gear kit features straight cut gears. The last kit photo I posted above shows an early version of the current kit, but with helical gears. The manufacturer discontinued this version because the case was getting beaten up by the axial loads from the gears, presumably caused by the helix form. I explained that my car was going to be a street car and gear whine/noise will be a major issue. Frank wrote that it would be no problem for them to make helical gears. I'm thinking, reduce the helix angle by say half, and you've reduced axial loads by a similar amount. What I don't know is if a helical set would be the same price as the straight cut gears.

Price for the straight cut gear kit is 6500 AUD ($4600) plus shipping. There may be a possibility one could select helical gears for the street ratio and straight cut gears for track work. I’d be happy with less than the included choice of 6 of the 8 ratios. 1 lower gear set for track days, an OEM equivalent and 1 or 2 over drives. I think this selection counts as 3-4 ratio choices, enough for a basic quick change kit? I wonder what the change over time would be.

The case for a quick change setup is that it enables one to tailor the overall package to differing needs, be they performance, economy, or something in between. I would likely select the tallest available ratio as the one used most often. I believe a 17% increase in capacity and a 17% increase CR will get me into a torque range where it will more than offset the taller ratio requirements. I guess the last thing is this setup adds something special to the overall package if done right.

The case against the quick change setup is cost, inappropriate ratios, and design shortcomings like too much axial load on the case or too much noise. This seems to be core tradeoff with helix angle, noise verses efficiency.

I talked to my engine builder yesterday and the block is still held up in the machine shop awaiting programing of the CNC machine that will do the boring. I’m hopeful it will get done this week.

I made final arrangements with derekw for a set of his round tooth form, cam drive pulley kit and a Superformance sump oil baffle and and they were delivered to MWE.

The gear maker got back to me by email and says he can make a strong and quite product. I need a kit to take advantage of the anticipated increase in torque, so lower rpms at an 80 mph cruise would be nice, I’m thinking the tallest available gear set (0.75 od equivalent), an OEM equivalent ratio, and a local track ratio.

Bill

 

Hi George,

Thanks for your input. I'm thinking of keeping the vapor recovery system intact as I'm not sure it does any harm on my setup. It does add clutter to the engine bay which reduces access to things like mixture adjustment screws, vacuum taps, air balance and idle speed adjustments.

I contacted an alternate party to rebuild my transaxle. I'm thinking a new 2nd gear synchro, new bearings and seals and incorporation of SB's for linkage geometry/adjustment and a bleed hole in the shift shaft blind boss. Anybody have a ball park number on cost for this service?

Which are the toughest transaxle bearings to find good quality replacements for?

The transfer gear kit maker has been traveling so I in another holding pattern. I'm also waiting for his reply for a request for quote for a quite, 3 ratio kit.

I think we're still waiting for the block machining. I believe the new cam drive pulley kit was delivered, along with a Superformance sump oil baffle, and a shift shaftX-seal. I believe the machine shop has the the parent 328 block, from which the Nikasil liners came, so original bore clearances might be evaluated. Ferrari went from cast iron, to Nikasil coated aluminum, to Nikasil coated high strength steel liners with the 348 (85 mm bore).Bi

Bill

 

I talked to the engine builder yesterday and he confirmed the block was machined and now back in his shop as of 3 days ago.
The next milestone will be the ordering the pistons.

We discussed CR again. He's thinking 9.8:1 to 10.3:1 and I'm thinking 10.1 to 10.5:1 static. How is dynamic compression calculated?

I'd like to be able to run on 91 (R+M)2 fuel for everyday driving, then step up to 93 for any type of performance requirement. I think 10:3:1 CR would be ideal. The XDI-2 ignition system is very accurate, so no distributor scatter or synchronization issues to deal with. I can incorporate vacuum advance/retard for load control, maybe another 5 engine degrees advance under light throttle cruise conditions, but back off ignition timing during any meaningful load. These are easy changes and refinements to play with. Mixtures of different strengths, burn at different rates. My understanding is the fastest burn rate is at stochiometric, richer and leaner conditions burn slower. We're not talking pre ignition or knock here, but controlled combustion. Lots of stuff to play with later.

Anybody ever put a knock sensor on a 308?

Bill