Carb 2 Inj Head Swap

[Guest nick coram]

I am planning to change the head on my 1985 2.0l carb Pinto to an injection head to take advantage of the better flow properties. I dont want to go to mad with upgrades as time and budget are restricted and I don't want to overstress the rest of the engine & transmission which I am not planning to upgrade.

 

I have been advised that a mild skim of the head to increse the compression ratio is cost efective and gives a few more GGs without forcing the need for a FR cam. 20 thou was recomended. I am also planning to get the valve seats reconditioned. does anyone have any comments on this ?

 

I have also heard that the inlet ports are diffrent shapes on the injection head (ovel as aposed to round). dosen't this cause a problem with flow and what can be done to correct this ?

[Shandylegs]

Nick,

 

The Pinto engine & box are extremely robust engines. The bottom end is able to withstand a fair amount of tuning (Circa 140-150hp) before needing any real form of upgrading (Ditto the G/box) provided they are in a serviceable condition.

 

You are indeed correct that the inlet ports are of a different shape but I have never encountered any problems with this when running on carbs.

 

Anyway enough of my ramblings and on to the important bit.........

 

Over the course of this winter I have been upgrading to a big valve head and should be completed in the next couple of weeks. Provided there are no disasters in the pipeline (Bent valves etc...) I will have a spare injection head that, if you are a member of RhoCar, can go for free.

 

The head is in excellent condition, the ports have been reprofiled to a good standard (Not done my me!!) and is fitted with a Piper road cam (Showing wear on lobes, but by no means the worst I have seen). When last on a rolling road this head on a standard bottom end gave a genuine 104hp @ wheels (A standard engine usually records circa 86/87hp) with the R/hood 4 into 1, and DHLA 40's (although fitted with extremely small chokes for midrange rather than outright power).

 

Let me know if you are interested......

[Longboarder]

There can be sealing issues with the inlet port shape which is bigger and sort of cam lobe shape with the pointy bit upwards. You should use a cheapo carb type manifold gasket, not the injection manifold gasket, from your local factor to ensure a seal. I have seen manifolds which when bolted on do not cover the peak of the port but these are earlier ones. Your 85 should have enough meat on it to allow you to match it to the port to get the best flow.

Raising compression ratio a little is OK, as is reprofiling the valve seats to three angles. If you buy a head from a scrappy and have this done then its worthwhile reading Dave Andrews article at http://www.rhocar.org/download/heads.zip on cleaning up some of the edges which slow gas flow.

However Shandylegs offer sounds like a good one to me.

 

Nigel

[Guest nick coram]

Thanks Shandylegs, I have sent you an E-Mail

[Guest piddy]

Hi there.

Slightly different than what you are asking.

But I fitted an injection engine to my 2b last year which I am running on carbs. I used a cheap gasket to increase the seal between the injection inlet ports and the carb manifold.

Runs like a dream.

Piddy.

[Guest piddy]

Just another thought.

You can probably pick up a good injection engine for about £50-£100 and it would not be much more difficult changing the engine than changing the head. and no third party to skim the head.

Piddy.