Engine angle ?

Steve C · 03-12-06, 10:40 AM

1) Were original engines mounted level or did they have a slight rearward angle??? 2)If mounted level ( no rearward tilt) does it affect ability of clutch to disengage, I was told that an engine needed to have approx 3 degrees of rear tilt to allow clutch to disengage and TOB to not ride on press plate??? 3) Also for those with carb engines if there is no rear tilt does the typical intake flange tilt the carb too far down in front and if so what is done. 4) In my case I am doing a MK11 and plan to engine w/ an 427FE and Blue Thunder medium riser intake ( as original)...does anyone know if carb flange is level or tilts fwd w/ this intake? Tks Steve

Howard Jones · 03-12-06, 04:30 PM

Within reason I don't think this is a issue. The TOB will be in light contact with the clutch anyway because of the hydraulic system used in these cars. Piston seal drag in the slave will always keep the TOB in light contact with the clutch. I guess you could experiment with a spring attached to the TOB arm.

As far as the carb goes. If you use a holley double pumper then they have individual float boles and will adjust nicely as far as float level goes. Main jet extensions should be used as they help with cornering and braking slosh away from the main jets.

Set the car up with the motor and transaxle as low as possible and then tune the carburetor for your setup. It is my experience that you will never completely fix the G force issues with a carb. But with a little fancy footwork the engine will run fine on the brakes. The power valves will fix this starvation problem. Hopefully the cornering starvation problem will go away with a part throttle setting in the corners.

Make sure you run enough fuel pressure. My 750 DP likes 6 psi.

Bob Childress · 03-12-06, 07:00 PM

Hi Steve,

You asked a great set of questions.

Most intake manifolds seem to angle the carburetor down at the front. I guess this is so the carb becomes more level as the front of the car rises during hard acceleration. I know that there are marine carburetor wedge adapters to compensate for engine angle in boats but I do not find many references about wedges adapters used on cars. I understand Howard's comment that dual float carburetors essentially compensate for carb angle because the float levels are set for each end of the carburetor, but I cannot find any information about the optimal carburetor mounting angle for cars.

Does anyone on the forum have any idea of the preferred 4-barrel carburetor angle for a car like our GT40 or the range of acceptable carburetor tip? Are 4-barrel intake manifolds already set to the correct carburetor angle by the manufacturers who assume the engine blocks are about level?

Jac Mac · 03-13-06, 06:10 AM

Hi Steve,
There is a photo of Mk2(1046) in GT40 by Ronnie Spain (p78) that suggests that the FE engines were installed slightly nose high and the Holley carb appears to be level or slightly nose down.I cannot see that the angle would have any noticeable effect on clutch operation.If this was the case we would have major problems every time we tried to change gear going up/down hills or under acceleration/deceleration etc.I have always thought that the nose high stance of inline engines was to aid self bleeding of the cooling system , a hangover from low pressure cooling systems and thermo syphon circulation(showing my age now).
Good luck with the Mk2.
Regards Jack.

Howard Jones · 03-13-06, 04:33 PM

Just to add a little information on Holley's. The goal of the whole thing is to keep the main jets submerged in fuel at all times. As G loading throws the fuel around in the float bowl this can be a challenge. The main jet extensions I mentioned above seam to work pretty well in the rear float bowl as the car accelerates and equally well in the front bowl under braking.

At the same time the re fill rate is also VERY important. Make sure that the pump/pressure regulator can keep up. If you can keep the bowls topped off then it is much easier to keep the main jet "underwater"

I suppose the best mounting angle is the one that keeps the main jets covered with fuel over the whole lap. The only case for radical angles would be on a track with a VERY steep up or downhill section.

The front jets are the primary jets and as such will under braking uncover, stalling the motor. Bipping the throttle will pump the accelerator pumps and get things going again. The extensions will keep the front jets covered with fuel and the car will idle as you brake hard with the throttle closed.

It also helps to set the idle up to 900ish revs when on track. You can turn it back down to normal on the street.

Lastly check on your filter flow rate. Street filters are not meant to flow constant wide open throttle volumes. Especially with high output motors.

BruceLambo · 05-09-06, 05:13 AM

There will be no wear on clutch components by having the engine on an angle. If this were going to be the case with engine angle, you would see piston wear on one side of the engines pistons because they are laying over in the 'V' of the engine. Actually that was an original concern with Henry Ford and his Engineers when prototyping the flathead V8 ... piston wear!

Next opinion and theory.
Probably the biggest reason for having the engine tilted rearwards is so the oil drains back into the sump towards the oil pump! Oh and of course giving the engine a high point for the water to exit the block.

As for the fuel starvation, if you maintain a suitable fuel pressure from the pump this shouldnt be a problem

Julian West · 05-09-06, 07:05 AM

My 2c worth.... any opinions pls?

The clutch will work at any angle.

The carb can be 'angled' by a few degrees on it's mounting by machining the manifold or fitting a 'wedge' underneath the carb??

The standard engine installation in GTD chassis sits the tail end of the trans high. ISTR reading that this leaves 5th gear not properly submersed in oil & can sometimes cause problems on long motorway runs.

I guess this problem could be easily overcome by over-filling the trans with oil. Presumably the same goes for the engine, altho if it's overfilled too much the crank would splash in the oil & cause cavitation & associated problems.

Has anyone measured the engine angle in a stock GTD?

Steve C · 05-09-06, 10:06 AM

From the limited research I have been able to do I find the MK11 engine was level or at most only a few degrees down in the back...I am installing an FE with original medium riser (casting moulds sold by Holman to Blue Thunder)....Blue Thunder agrees that engine was level and is doing a small run with 0 degree angled carb base for like applications....Steve

Per Clausen · 05-13-06, 11:20 AM

Hello Steve C

I have had the same problem on my Gt40 with small block ford
i bought a 8 degree wedge spacer kit from the company Trans dapt
part # 2029 it workt just perfect for me.

http://www.tdperformance.com/TransDapt.html

Regards Per Clausen

Pantera1889 · 12-23-06, 12:29 AM

Moroso also sells a 5 deg spacer.

Steve C · 12-23-06, 01:34 AM

I ended up milling the intake to achieve a 2 degree fwd tilt and installed Kingserts to correct changed angle for carb studs rather than using an angled spacer.....Did this as Blue Thunder didn't have the special intakes for MK11 FE ready when I needed but, I believe they now have a few for anyone needing one .....Steve