Engine rebuild, a few questions Options

[stugray]

I have rebuilt a type IV a couple of times, but I was young & naive.
This will be a 2.0L with stock FI for vintage racing.

1 - How do I hook up the stock fuel pump line(s) to a fuel cell?

2 - are there any Cams other than the stock one that will give me increased performance while still using the stock FI?

3 - What compression ratio should I target? I am working that step right now - CC'ing the heads & setting the deck height.

4 - The CAM thrust bearing has just one side with the thrust plate on it. If I recall, when I upgraded my last 914, the guy at the performance shop gave me TWO with the thrust bearing on it (one for each side). Should I be looking for those?

5 - After splitting the case, there were 2 or 3 "bumps" that needed a little "flattening out" with a file. Can the case be damaged by trying to clean up the nasty spots, or is there a way for me to make sure to get it right?

I imagine that the only thing I could do would be to remove all the studs and rub each side over some sandpaper taped down to a very flat surface...

Any help is appreciated.

Stu

[Cupomeat]

Ok, I'll give it a go and I am sure you will hear more opinions on this;

1. Depending on the fuel cell, you need 3 effective lines; 1. primary suction to go to the Fuel Pump, 2. primary return for fuel back from the FPR, 3, Vent or closed venting line. Not knowing what cell you have, it is not unusual to see 3 lines from a fuel cell, make sure you identify which one the primary suction is (1) and that (3) is above the level of gas.

2. Maybe, but not likely. Talk to Jake Raby and check out webcam. D-jet is very vacuum dependent, so high overlap cams cause poor low RPM running issues.

3. Well, good question. If they are stock 2.0l heads, it seems that 8.6 to 1 is about as high as you'd want to go for a stock motor, but I'd say this is all part of what else you are doing with the motor. If it is a stock class, they might dictate CR.

4. 2 Cam thrust bearings are nice, and would last longer, especially as the cam is always given a side load due to the cut gears.

5. what are these 2-3 bumps? if they are in the sealing surface, you might want to look for a new case. Have the case checked by a machinist show for sunken registers and flat surfaces.
Yes, a case is very likely to be ruined by using a file on it, practically anywhere but on the outside. (IMG:style_emoticons/default/headbang.gif)

You cannot just flatten out a whole case side as that would make the main bearing journals out of round and sure, ALL can be fixed, but it would be cheaper to find a good case.

Ok, I hope that helped.

[Bleyseng]

2. The absolute best cams for Djet FI are Raby cams. I have using several 9550 cams in Djet and Ljet engines with great results. More hp (110) and cooler heads temps!
3. CR would be around 8 to 1 unless in CO you can live with higher CR, I doubt it with the higher elevations. I run 9 to 1 but I live at sealevel.

[stugray]

Cupomeat,

1 - Still trying to find a legal fuel cell. It needs a bladder and (I guess) three ports.

2 - I looked at the Raby website and it looks like I can only get a cam if I buy the whole $500 package. I am tempted, but if I blow that kind of dough (in addition to all the other stuff I need) right now, I wont be on the track for another year. If I just knew the lift & duration of an "improved cam", I could have one made myself locally.

3 - Based on my measurements, I am at about 8.2 right now. This motor has concave pistons. To up the CR, I would need to reduce the head volume or get domed pistons, right? How much does it cost to have the heads flycut for a lower volume combustion chamber? They read 60ccs now.

4 - I see that the aircooled technology website has the dual thrust bearings.

5 - The worst bump was on both sides and at the very top. I didnt goe nuts with the file. I just kept it perfectly flat on the case halves and took off any high spots.

Bleyseng,

Wouldnt I want a HIGHER CR being at high altitude as the air is thinner?

New questions:

6 - I dont have a flywheel for this engine, but I have two in my 1.7s. Are they identical between the 1.7 & the 2.0?

7 - the dipstick tube is broken (as usual ;-(. Can I extract it & replace it myself? I have a slide hammer. I was thinking putting a piece of all-thread thru it & putting a nut on the end & tapping it out.
If that works, where do I get a new tube?

Stu

[Cupomeat]

Cupomeat,

1 - Still trying to find a legal fuel cell. It needs a bladder and (I guess) three ports.

2 - I looked at the Raby website and it looks like I can only get a cam if I buy the whole $500 package. I am tempted, but if I blow that kind of dough (in addition to all the other stuff I need) right now, I wont be on the track for another year. If I just knew the lift & duration of an "improved cam", I could have one made myself locally.

3 - Based on my measurements, I am at about 8.2 right now. This motor has concave pistons. To up the CR, I would need to reduce the head volume or get domed pistons, right? How much does it cost to have the heads flycut for a lower volume combustion chamber? They read 60ccs now.

4 - I see that the aircooled technology website has the dual thrust bearings.

5 - The worst bump was on both sides and at the very top. I didnt goe nuts with the file. I just kept it perfectly flat on the case halves and took off any high spots.

Bleyseng,

Wouldnt I want a HIGHER CR being at high altitude as the air is thinner?

New questions:

6 - I dont have a flywheel for this engine, but I have two in my 1.7s. Are they identical between the 1.7 & the 2.0?

7 - the dipstick tube is broken (as usual ;-(. Can I extract it & replace it myself? I have a slide hammer. I was thinking putting a piece of all-thread thru it & putting a nut on the end & tapping it out.
If that works, where do I get a new tube?

Stu

#3, Flat top pistons, like KB would work fine and raise the CR. I am not aware of domed pistons for T4, but I am sure they are available $$, otherwise, yes, flycut the heads to reduce the chamber volume. Once this is done, you will have to check your valve train geometry as the push rods are now longer in comparison.

#6, Yes, all T4 based 914-4s have the same flywheel. Do check the end play, of course.

#7, You can drive out and put a new one in, but measure it first, or at least Measure someone else's to get it it right, as you want to have accurate oil levels.

I hope that helps.

[ArtechnikA]

1 - Still trying to find a legal fuel cell. It needs a bladder and (I guess) three ports.

There should be no mystery here. Your rulebook will tell you what is legal. Go find a distributor for ATL. Check the Porsche-oriented race places like Subtle Dynamics, Dougherty, SmartRacing. 914's have been racing for 40 years and except for the 100-liter endurance tanks, all have pretty much the same requirements and packaging.

2 - I looked at the Raby website and it looks like I can only get a cam if I buy the whole $500 package. I am tempted, but if I blow that kind of dough (in addition to all the other stuff I need) right now, I wont be on the track for another year. If I just knew the lift & duration of an "improved cam", I could have one made myself locally.

No, you couldn't. There're _way_ more to this than lift & duration, and a lot of the magick is in the ramps & rates. If you're so close to the edge that $500 is a deal-killer, you will be tempted to cut corners right & left and then wonder why it's not working out. Or, if you are scrimping on safety equipment, your heirs and assigns will be wondering.

Sorry to be harsh but save your nickels and dimes until you can afford to do it right. You don't have to spend a ton of money but if $500 is an insurmountable obstacle, you are way too close to the edge.

3 - Based on my measurements, I am at about 8.2 right now. This motor has concave pistons. To up the CR, I would need to reduce the head volume or get domed pistons, right?

These are _really_ basic questions for which answers are widely available. People here are happy to help but you must be prepared to meet them halfway by doing your homework first. Every basic racing & performance book has a chapter on how to measure and adjust CR. And the results of each thing you change.

5 - The worst bump was on both sides and at the very top. I didnt goe nuts with the file. I just kept it perfectly flat on the case halves and took off any high spots.

FILE??!? Find yourself someone with a granite surface plate who knows how to use it. Plan on needing a line bore after and maybe you won't actually need it.

Wouldnt I want a HIGHER CR being at high altitude as the air is thinner?

Where are you going to race it? Are you in a 'pump gas' (what octane?) class or can you run race gas? All else being equal, you can tolerate more CR (and more spark advance) at altitude - but you also have lots less cooling so there is no free lunch.

6 - I dont have a flywheel for this engine, but I have two in my 1.7s. Are they identical between the 1.7 & the 2.0?

Search is your friend. There are wear (machining) limits on the friction surface. You should be able to find these and know how to measure for tolerance. And what else you have to change when the surface is machined.

[Jake Raby]

2 - I looked at the Raby website and it looks like I can only get a cam if I buy the whole $500 package. I am tempted, but if I blow that kind of dough (in addition to all the other stuff I need) right now, I wont be on the track for another year.

Understand this:
My package INCLUDES ALL the items that are necessary to outfit an engine with a performance camshaft. These are the things that IF you purchased a camshaft elsewhere you'd have to buy separately, or you'd not apply and the engine would be compromised.

View my camshaft presentation to understand exactly what compatibility means.
http://www.rdtlabs.com/presentations/valvetrain.ppt
You will see that this money is either spent now or later, generally more is spent later when you experience a failure or have too much lift for certain valve springs and etc.

With my package I ONLY sell the entire unit, so unless someone doesn't install the components it is impossible to have incompatibility.

If I just knew the lift & duration of an "improved cam", I could have one made myself locally

Exactly and thats why my proprietary information is not posted anywhere. I spend 6 figures a year + developing my components and I don't make it easy to steal on purpose.

BUT you may **think** its just that easy, grabbing some numbers and having a cam ground, but it isn't.. How is that camshaft going to work with your port margins and flow? Whats the ramp speed of that lobe? Is it too fast for a lifter of .943 diameter? How will it idle? What vacuum signature will it have? Will it produce power above or below the target RPM range that your gearing and rear tire size optimizes with?

My valvetrain kit doesn't just give you parts, you fill out an extensive questionnaire that interviews you and your project engine, then I select the camshaft of mine that works best for you based on the numbers and my direct experience and practical application. None of this is expensive, its priceless.

This post has been edited by Jake Raby: Oct 19 2010, 01:02 PM

[stugray]

ArtechnikA,


Thanks for all the comments

"There should be no mystery here. Your rulebook will tell you what is legal. Go find a distributor for ATL."

There is no mystery. I know exactly what is legal. The problem I am having is that there are HUNDREDS of choices out there and very few of them fit in the spare tire location in a 914 without cutting.

Since so many on this forum race, I figured someone could just tell me which one. I want it to work with the stock FI, be 10-12 gallons, and have a bladder. Of course being as flat as possible and still fit the spare area is a bonus.


"If you're so close to the edge that $500 is a deal-killer, you will be tempted to cut corners right & left and then wonder why it's not working out. Or, if you are scrimping on safety equipment, your heirs and assigns will be wondering."

You misunderstand. I purchased a fully race ready car (minus the fuel cell) and an extra 2.0L engine. As I reassemble it I have to choose my battles wisely. Do I just put the stock cam back in or buy a performance cam. I have to weigh my options. $500 is not a deal breaker, but maybe it is better spent somewhere else until I build a dedicated high performance race engine.

"These are _really_ basic questions for which answers are widely available. People here are happy to help but you must be prepared to meet them halfway by doing your homework first. Every basic racing & performance book has a chapter on how to measure and adjust CR."

I know exactly how to measure my CR because I did my homework.
When I search on this site for "Compression ratio" I get 15 pages of posts and after reading about 10 pages of them I dont see any that tell me what CR I should use under different altitudes & such.
I just figured that using the forum to ask the question is the quickest way to get an answer.

"FILE??!? Find yourself someone with a granite surface plate who knows how to use it."

Everyone is jumping to the conclusion that I filed the surface of the case I did NOT. I just used the file as a straight edge and went around checking the flatness. There WERE a couple of burrs and I did not go crazy or alter the flatness. AND I have a granite surface plate at work.
Is 100 tons and 25 feet long by 12 feet wide good enough?
I asked the question if I could "clean up" the edge by taping sandpaper down to a flat surface.

"Where are you going to race it? Are you in a 'pump gas' "
I am in CO. and I have access to leaded or unleaded 98, 100, or 110.

The only reason I asked about the flywheel is that both of my other ones are in the cars. I didnt want to drop the engine to pull a flywheel to finish assembly just to find that it doesnt fit all while tripping over another engine in my cramped garage.
I think I might just order a new lightened FW anyway, but if they WERE different, I could stop contemplating and just do it.

[stugray]

Jake Raby,

Thanks for the detailed reply.
I have spent hours drooling over all the items on your website.

I am very tempted to go with your cam package, I was just asking for opinions about other options.

The consensus is pretty much go with yours.
I plan on contacting you, but I was trying to "do my homework" before taking up any of your time.


BTW the link: http://www.rdtlabs.com/presentations/valvetrain.ppt

does not work for me

Stu

[ArtechnikA]

...there are HUNDREDS of choices out there and very few of them fit in the spare tire location in a 914 without cutting.

Since I first saw this done in 1975 I thought it was old news. IIRC it was an ATL cell, 'bout the size of a fat pizza box. Perhaps it has become more complicated in the intervening time. You are correct, quick searches on ATL and FuelSafe don't show off-the-shelf applications.

Try here, since you mention 'guys who race' - Chris is one of the good guys and can hook you up.

Tangerine Racing

I just figured that using the forum to ask the question is the quickest way to get an answer.

Not a lot of guys in the stock classes. Fewer who are willing to just post all the secrets ;-)

Everyone is jumping to the conclusion...

We can only go by what you posted in the original question. Go read it yourself and see if it doesn't create that impression. If I misunderstood, I apologize. But we get a lot of guys who think they can build a T-IV engine with a ball-pein hammer and a WalMart screwdriver.

AND I have a granite surface plate at work.
Is 100 tons and 25 feet long by 12 feet wide good enough?
I asked the question if I could "clean up" the edge by taping sandpaper down to a flat surface.

Cool. Again - lots of people have no clue. If your surface is _really_ flat (which yours should be) and you can assure that both halves get exactly identical pressure everywhere and can verify that the crankshaft centerline and camshaft bores are still round and centered, you should be in great shape.

[Jake Raby]

My team is here to help you, don't worry about wasting my time.. I have an exceptional crew and getting answers to your questions won't take anything away from my day... I am the man behind the curtain :-)

But I'll select your cam when the Cam Dr. interview sheet crosses my desk, I might even call you.

[stugray]

Thanks again for the comments.

Here are some pics:

Two pics of the "bumps" on the case. These two areas are the ONLY place I had to actually "file" and they are on the very topmost part of the case.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1287579768.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1287579769.2.jpg)

Here are two pics of me cc-ing the head:

before

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1287579770.3.jpg)


after

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1287579771.4.jpg)

does 60ccs sound correct for a stock 2.0 head?

Stu

[Jake Raby]

Get rid of those sodium filled exhaust valves!! BOOM!

Most 2.0 914 heads are 57-58cc if they haven't been flycut

[stugray]

Ok, Jake.

I have new valves and purchased your race cam package.
Now I am ready to have the heads machined to increase my CR.

However, I dont know exactly how much to have the heads cut to increase to ~9.5:1.
Is there a known amount that I should cut them?
I currently have the stock "slightly dished" 2.0L pistons.
So I figure that if I go to ~9.0:1 with the pistons I have, I can adjust the CR down if I want by adding Shims.

If I want to go UP, I can change to the flat top pistons, but that only gives me a little.

Should I have the machinist go a little extra ( maybe 10:1) so I can always adjust DOWN to what I want?

Stu

[stugray]

Ok, so what I am learning here is that nobody has ever had stock heads cut to ~10:1 compression ratio assuming stock pistons/stroke & deck height.....

RRRIIIIIGGHHHT wink... wink... (IMG:style_emoticons/default/lol-2.gif)
SO what is the secret handshake???

I had one guy tell me that he had built at least two 914 SCCA engines that WON THE SCCA championship.
Yet he told me to run 100% stock compression with webers... In Colorado......

How hard-ass do you have to be to not share this information? (IMG:style_emoticons/default/blink.gif)

If I could machine them myself, I would CC them at every thousandth and make a nice lookup table.
Not rocket science, but not easy to calculate chamber volume from a cast head in advance.

On another thread people posted stock CR calculators, but they do not factor in the shape of the type-IV combustion chamber and what removing X results in Y of CR change.

Stu

[Jake Raby]

If I could machine them myself, I would CC them at every thousandth and make a nice lookup table.

You'd waste your time.. All stock chambers are slightly different, so the variables in volume Vs. depth is always going to be different. Nothing is absolute after 4 decades of service, idiot mechanics and machinist working with the engine/ heads and etc.

As the engine builder and designer the choices are yours. Success or failure is up to you, just like it is up to me on a daily basis. Lots has changed since October of 2010 when I posted about cam selection.

Run your numbers, choose your CR target and machine to reach it. Then hope and pray that you get it right. Thats classic hot rodding defined.

When practicing medicine or mechanics absolutes don't exist- ever. Run all the calculations that you want, then practical application will teach you a lesson. Good luck with it, thanks for your purchases.

[jaxdream]

Ok, so what I am learning here is that nobody has ever had stock heads cut to ~10:1 compression ratio assuming stock pistons/stroke & deck height.....

RRRIIIIIGGHHHT wink... wink... (IMG:style_emoticons/default/lol-2.gif)
SO what is the secret handshake???

I had one guy tell me that he had built at least two 914 SCCA engines that WON THE SCCA championship.
Yet he told me to run 100% stock compression with webers... In Colorado......

How hard-ass do you have to be to not share this information? (IMG:style_emoticons/default/blink.gif)

If I could machine them myself, I would CC them at every thousandth and make a nice lookup table.
Not rocket science, but not easy to calculate chamber volume from a cast head in advance.

On another thread people posted stock CR calculators, but they do not factor in the shape of the type-IV combustion chamber and what removing X results in Y of CR change.

Stu

Stu , since you have the heads that you want to run ,try flycutting the edge ( .010, .020,etc. ) of the plate to step it down into the chamber for CCing to get an idea of what possibly a flycut to the head might produce . It would probably be approximate , but would give an idea of a say what a flycut of the cut to the plate might give . It is cheaper to cut the plastic plate than cutting the heads several times to get to a target number and yes it might not be exact , but give some kind of idea of what could be a possible one cut to the heads might produce. Shim cylinders from there . Good Luck to ya ....

Jack

[stugray]

Ok Next update:

I have the European Motor Works, Keith Black 96mm Piston & cyl set.
The deck height measures (with NO shims) .034-.035 and i have measured TWO of the cylinders on both sides with ~20 meas. samples.

i will do the other side next.

I measured the 2.0l heads to have ~60cc of combustion chamber volume.
I will not be running head gaskets.
crank is stock.
Based on the various cR calculators I have, it says that i need to reduce my combustion chamber volume from 60cc to 48cc to achieve 10.5:1 CR.

Then I plan on reducing my CR to 9.5:1 using the shims.

Two questions:

1 - How much do I tell the Machine shop to flycut from the heads to go from 60cc to 48cc (I think I have an answer, but want a second opinion)
AND
2 - What is a good source of cylinder shims of various thicknesses?

Stu

I would use Jax's idea above, but i dont have access to a CNC mill ;-)

[cgnj]

Hi,

60 cc's is what I got on my rebuilt stock heads.

I don't think I would flycut to 48 then add shims to get back to 56 cc chamber volume.

I would set up the heads to cc them again, put in 56 cc, then measure the how far below the plate the liquid is and call it a day.

[Valy]

Bringing the heads to 48cc will probably remove the first fin on the heads. It's a lot to cut.
For high compression without removing that fin you will need to fill a bit that compression chamber.
My 2L heads were 58cc. It depends on how deep the valves go. Older valves that had been cut once or twice will go a bit deeper.
You can look at the heads in my thread. They were cut for 8.5:1 CR.