914 1.7L with AC needs more power, Thinking of building a more powerful motor for AC use Options

[jjs3rd914]

Have a bone stock recently rebuilt 72 1.7L 914 with AC that works great. Problem is at idle seems wants to stall. have set up idle but still the 80HP does not seem to be enough.

Have a complete 2L and complete 1.8L 914 motors. The 2L heads are cracked, not worth repairing. 1.8L heads great shape, 2L crank and rods also good. So I am thinking of building a second motor to replace in its entirety the 1.7L. Yet keeping the original 914 motor should in the future someone wants to convert back to 100% stock.

From reading previous posts and an old Jake Raby guideline, here is a tentative plan

Use 1.8L case, 2 L crank and rods, get new 96mm pistons and barrels, get 40 IDF dual Weber carbs, etc. But unsure as to the cam to use. Do have the 1.8 and 2L cams available. Will either work, or should I get a new cam specific to my build?

Also going to use the 1.8L heads. But I do have the 2L trashed heads but the larger values are good. I have read can update the 1.8 head to the larger valves. If so can I assume the 1.8L seats have to be replaced with larger seats, OR dum question, can the existing seats be machined to the not so much bigger 2L values.

Can the stock 1.8L distributor be used. I do have a 009 dizzy for use.

Or is just using the stock 1.8L head god enough to end up with about 115-125 HP, much more than the stock 1.7.

So opinions?

Thanks in advance

jjs3rd914

[dlee6204]

Going with a bigger motor isn't going to help idling with A/C. A bigger motor will only produce more horsepower at a certain RPM and at approx 1000 rpm power difference will be negligible.

It's a common problem for idle to drop with A/C. I've seen some type IV system retrofitted with an "idle up" valve for when A/C is turned on. Some just turn the idle up.

I have to ask what compressor you are running with your setup? Modern compressors don't use as much power at the original York units. 2-3hp vs the 5-10hp. I'm running a Sanden compressor and when driving, I can hardly feel it kick in. This is on 1.8 and 1911 motors.

[jjs3rd914]

Going with a bigger motor isn't going to help idling with A/C. A bigger motor will only produce more horsepower at a certain RPM and at approx 1000 rpm power difference will be negligible.

It's a common problem for idle to drop with A/C. I've seen some type IV system retrofitted with an "idle up" valve for when A/C is turned on. Some just turn the idle up.

I have to ask what compressor you are running with your setup? Modern compressors don't use as much power at the original York units. 2-3hp vs the 5-10hp. I'm running a Sanden compressor and when driving, I can hardly feel it kick in. This is on 1.8 and 1911 motors.

Using a sanden 508, 134a, system works great, just want more power. Would not a larger cc motor even at idle supply more torque and help the issue.

[Dave_Darling]

Don't re-use either cam. The stock FI grind leaves a whole lot on the table if you're running carbs, and chances are pretty good the existing cams are either worn out or on their way out.

--DD

[jjs3rd914]

Don't re-use either cam. The stock FI grind leaves a whole lot on the table if you're running carbs, and chances are pretty good the existing cams are either worn out or on their way out.

--DD

So what cam sold by whom is recommended. Also my biggest question, how ae 2L values used on 1.8L heads?

Thanks
jjs3rd914

[Dave_Darling]

Webcam makes pretty good ones. The Type4store also has a good rep. Make sure you get lifters from the same place you get the cam; that way you have the least chance of the cam and/or lifters going flat.

If you really want to use the 2.0 valves in the 1.8 heads, you will have to have the heads machined to fit the larger valves. The machine shop will know what to do. If they know Type IV heads, you can talk with them about your desired power levels, displacement, and so on, and they can recommend a cam grind and porting and valve sizes.

As Jake has said many times: The engine is a system. Change one part of the system and you affect everything else in the system. Getting the right combination of things is the key.

--DD

[Keith914]

Weber carbs, maybe others (?), need vacuum advance distributors, so called SVDA distributor. Your 009 has little to no advance at low rpm's with only mechanical advance, which causes a flat spot as you accelerate from idle.

[Amphicar770]

You do not provide details on your AC system but if you have the old York compressor you need to replace it with a Sanden or similar rotary. A lot cheaper than modifying your engine.

[Mark Henry]

You do not provide details on your AC system but if you have the old York compressor you need to replace it with a Sanden or similar rotary. A lot cheaper than modifying your engine.

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