Help With Diagnosis

[Harry998R]

Hi All,

I had a top end rebuild done (at considerable expense) on this engine.....
FS: Hot Rod Motor - Street or Track.....as it was blowing blue smoke on on deceleration.

On first start up after the rebuild the car was blowing an incredible amount of smoke and after a lot of complaints by me they pulled the engine again, did some stuff, put it back in and it was no better. Anyway they pulled it out two more times and on the last time discovered that there were no stem seals on the exhaust valves. They installed the seals and it is still blowing smoke, not as much, but a lot more than it did before the work was done.

I'm not interested in taking the car back to these guys as I don't want them touching my car again.

Today I bought a borescope and I have attached some pics of the inlet valves on 1 , 2 and 3.

I was hopeful some of the experts on here may be able to give me some tips as to what needs correcting to fix the smoking issue.

I have also installed PMO ITBs on this engine and was wondering if anyone could recommend a cam to take better advantage of them (currently fitted with 993 sport cams suited to the varioram intake).

Pic of the engine as it looks today:'



Thanks very much.


Cheers,

Harry.

[Steve@Rennsport]

Harry,

Its virtually impossible to precisely tell you the source of the smoking, especially with a brand-new engine thats not broken in yet. There are just too many variables and I don't have any of the engine specs to offer anything constructive.

I do see the carbonized oil residue on the intake valves that could have come from lack of valve seals and/or loose fitting guides. I also see that the heads have been CNC-ported.

My opinion? It hard to understand how someone could forget to install guide seals so it makes me suspect other aspects of the engine's preparation and assembly. It certainly LOOKS pretty darned nice so someone took great care about that aspect.

I would clean up the valves, install factory guide seals, and then do a leakdown to get a baseline number. When the rings are seated, that should drop down to 1-3% and there should be zero smoking unless something else is wrong.

Camshaft choices depend on many things that include:

1) Car's type of use

2) Vehicle weight

3) Engine specs: displacement, head flow, exhaust system, compression ratio, etc.

4) Gearing; stock or close-ratio

If you address these four points, I would be able to offer some suggestions based on some experience at this.


Hope this helps,

[Harry998R]

Originally Posted by Steve@Rennsport

Harry,

Its virtually impossible to precisely tell you the source of the smoking, especially with a brand-new engine thats not broken in yet. There are just too many variables and I don't have any of the engine specs to offer anything constructive.

I do see the carbonized oil residue on the intake valves that could have come from lack of valve seals and/or loose fitting guides. I also see that the heads have been CNC-ported.

My opinion? It hard to understand how someone could forget to install guide seals so it makes me suspect other aspects of the engine's preparation and assembly. It certainly LOOKS pretty darned nice so someone took great care about that aspect.

I would clean up the valves, install factory guide seals, and then do a leakdown to get a baseline number. When the rings are seated, that should drop down to 1-3% and there should be zero smoking unless something else is wrong.

Camshaft choices depend on many things that include:

1) Car's type of use

2) Vehicle weight

3) Engine specs: displacement, head flow, exhaust system, compression ratio, etc.

4) Gearing; stock or close-ratio

If you address these four points, I would be able to offer some suggestions based on some experience at this.


Hope this helps,

Hi Steve,

Thanks very much for the reply.

I've driven the car quite a lot since the work was done over a year a ago and have probably done about 8000kms on it in that time so the engine is broken in.

The pic of the engine as it currently is took a lot of work by another mechanic after the top end build build was done to get it ready for a show.

The car is a '72T, weight is stock and it is used for spirited road driving (no track.....yet). Gearing is a stock 915 with 8:31 R&P.

The car is now fitted with SSIs and a stock Dansk muffler although the muffler is likely to change.

Engine specs below:

270 flywheel HP at 6600 rpm and 230+ Ft. Lb. of Torque at 4250 rpm with Elgin 993 non-hydraulic Sport Cams. Over 290 HP can be achieved at 7600 rpm with 314/304 Race Cams. Records and testimonials available. Fully tested and sorted over four years. Super reliable. This 1-year build custom motor is complete and ready to install in your 911 today. Fits 2.7L race categories and sounds awesome - higher pitched than a 2.8 RSR engine. This motor includes the following installed items:

Motec M48 Engine Management: Fully optioned and optimized Motec EFI with wide band lambda, advanced fuel and ignition tuning, and logging, plus Motec IEX Ignition Expander feeding 12 individual Nippon-Denso coils near plugs with integral ignitor. Motec M48, IEX and harness installed, terminated and programmed by Chris Powell, factory trained and authorized Motec Dealer. Flexible maps for sport or race cams are provided to ensure perfect drivability, no stumbling and maximum safe horsepower and timing at all RPMs (over 50 hours of expert dyno, track and road tuning invested). Comes complete with PC laptop computer, Motec program, manual, interface, and all EFI maps

Varioram Induction ('98 993 Intake): Variable length intake runners adapted to early 911 heads with CNC billet aluminum injection couplers and 944 Turbo (951) fuel injectors. Fully tested to produce maximum torque over a broad power band (over 200 Ft. Lb. from 3300 to 6600 RPM with sport cams).

Varioram now replaced with PMO ITBs.

Custom Pauter Titanium Rods: (33% lighter than chrome moly)

Custom Pauter flowed 2.4 MFI Twin Plug 911 Heads: Modified for 51 I/42.5 E valves with flowed/matched 42/40 ports (HP plus torque). Gorgeous.

1967 Aluminum 911 Case: (strongest available for this motor) Case is fully machined, piston squirted, oil modified, and boat-tailed with GT3RS Oil Pump. Other parts installed: Custom Pauter knife-edged, cross-drilled and beveled edge long stroke crankshaft, NASCAR rod bearings, Mahle Nikasil 2.7L cylinders, Custom JE 90mm lightweight short skirt triple-coated pistons, 11:1 measured and verified compression ratio (safe with Motec sport map timing and 91 octane street gas), Lightweight wrist pins, Custom 51/42.5 Titanium valves, Titanium retainers, Aasco race springs, Polished rockers, 993 Sport cams, Turbo valve covers, ARP head studs, Carrera engine oil cooler, Carrera tensioners, Shuffle pinned Carrera chain housings, new chains and starter, and much more. Every critical part magnafluxed, micro-polished and balanced before assembly. This motor moves a lot of air and spins up very quickly! RPM limit can be pushed to 8500 safely.

The Rest: 1973 911 RSR flywheel (well secured), Sachs Sport 915 clutch, Carrera fan and fan housing, India red shroud, Carbon fiber block off plates, Clewett serpentine race pully/fan belt with custom Motec trigger sensor, RSR style motor mounting crossbar, 1 5/8" European Racing headers with lambda sensor, Monty dual-in/dual-out sport muffler, and custom sheet tin - all installed by Chris' German Auto Service in Bellevue, WA.

Easily converted to GT3 injectors and individual throttle bodies if you want to go REALLY crazy. Add a wild cam and you will hit well over 300 hp with insane throttle response.


Cheers,

Harry.

[Harry998R]

Another couple of pis this time of the inlet valves on 5 and 6.

Is it just me or does the valve stem in the first pic look like it has worn?


Cheers,

Harry.

[BURN-BROS]

HI Harry,

Sorry for your woes. The engine build on the S registry looks very good. Lots of Hype.

Exhaust valve seals are optional on a race engine, but should have been installed on a street car.

1,2, and 3 look like excessive oil thru the intake guides. You will need to measure valve stem and guide O.D.to determine if there is an issue (important). Quantify! There may be only a simple issue with improperly installed seals, especially if they are Viton.

Cams.. If you have a J.E. with a valve pocket, you may like a DC40 on a 108 lobe center. John Dougherty @ DR racing cams can give you a few suggestions for your set up.

[Harry998R]

Hi Aaron,

Thanks for your reply.

I think the hype around the motor was justified, unfortunately in the Ti intake valve stems were "corroding" (the stems became rough somehow) and needed replacement also then requiring new guides and the smoking problems started from there.

Once I get the smoking sorted the engine will be epic.

Thanks for the cam recommendation. These are the pistons, they are JEs.



I just let the engine idle for a few minutes and took some more pics, nice big puddles of oil in 4 and 6.

I'll get the seals and valve to guide clearance checked.


Cheers,

Harry.

[Jeff Alton]

Originally Posted by BURN-BROS

Cams.. If you have a J.E. with a valve pocket, you may like a DC40 on a 108 lobe center. John Dougherty @ DR racing cams can give you a few suggestions for your set up.

Agree 100%. We have run the DC40 and DC44 on 108 centers and they make a very wide power band. Great cams.