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Posted by: Matty900 Mar 27 2016, 10:42 PM

I have a 72 with a 1.7 that has a 1911 big bore kit and cam. Ithe has dollorto carbs on it. Should I go back to fuel injection? If so how do I do it?

Posted by: jcd914 Mar 27 2016, 11:00 PM

Do you know what cam it has in it?

D-jet does not like much in the way of cam above stock.
L-jet will tolerate a bit more cam but still not a lot.

Some aftermarket FI can be made to run with almost anything with enough time and know how.

Jim

Posted by: porschefile2010 Mar 28 2016, 02:25 AM

You just need to be sure the 1.7 FI can get enough fuel through so that it doesn't run too lean or you will blow holes through the heads. This happened to me with a 2.0 which had been made ( unbeknown to me at the time) into a 2.3 but left with with the original 2.0 FI. Blew the heads. Unless you are sure safer to go to carbs which is unfortunate cos the FI is pretty reliable.. Good luck with the 1911.

Posted by: r_towle Mar 28 2016, 12:41 PM

the "big bore" is not an issue.
Both djet and ljet can support up to 2.4 liters (as far as I have tested)

What camshaft did you put in?
Specific number and manufacturer.

Rich

Posted by: brant Mar 28 2016, 01:09 PM

If it's a cam with lift that would upset the vacuum signal for the manifold pressure signal then factory fuel injection will not work well

So the cam specs are needed to answer your question

Or mega squirt

Posted by: Matty900 Mar 28 2016, 01:10 PM

Trying to tack that down. It was done by previous owner.

Posted by: Matty900 Mar 28 2016, 02:11 PM

Just heard back from previous owner, It still has the original cam, all he did was a big bore slip in barrel no block mods completely went through heads guides and seals and check for warp and cracks. Just head work. It was $460 back in 2005 or 2006 and has only had between 2,000 and 5,000 miles on it since then.

Posted by: brant Mar 28 2016, 02:17 PM

you should be able to go back to a stock style fuel injection
you will want to use an Air fuel meter to tweek your MPS mixture once its running and add a bit more fuel than is stock for a 1.7 to compensate for the big bore.

the 1.7 djet parts are going to be cheaper than the 2.0 ones...
but either could work with a little tweeking.

Posted by: r_towle Mar 28 2016, 02:35 PM

Using an Air Fuel meter will be helpful to make sure you are not too lean.
You can change a few things if required.

You can get 2.0 liter injectors while using 1.7 liter everything else.
You can put a resistor inline with the CHT to increase the fuel over the entire range of the system.

Both of these may help you easily do the 1911 you have to do.

Rich

Posted by: The Cabinetmaker Mar 28 2016, 04:28 PM

I missed fourth gear on a downshift and ended up in second coming off afreeway on ramp in my original 73 1.7 with only a few thousand miles in 1974. Toasted one piston. Installed an npr big bore kit to make it a 1911. I put over 300,000 miles on that engine with the original unmodified djet. That little 1.7 ran perfect. Put the djet back on and drive with a big grin!

Posted by: porschetub Mar 29 2016, 01:42 AM

The slip in big bore kits have caused issues,the most important part of the seal to head and barrel is compromised by a limited sealing face on the barrel,it will leak sooner than later.
Sorry but that's what happens ,had the heads been opened up and to a correct size with the right kit the issue isn't there,many on here will agree and have great running motors as a result.

Posted by: Matty900 Mar 29 2016, 09:54 AM

Thanks Richard. Do you know where I can find more how info on this?

Posted by: Matty900 Mar 29 2016, 09:57 AM

That's exactly what I was hoping for. This was a barn find that has been better than I could have hoped for. Can't wait to get it all back together and start driving it.

Posted by: Matty900 Mar 29 2016, 10:00 AM

The guy who did this to the car has built lots of sand rail engines to race on the dunes and seems to know what he is doing. My only concern is how long it has sat since the work was done.