Help! Dual RPR (IDF) Tuning problem

landfall · 2016-04-10T04:07:35+00:00

I have just switched from a pair of Weber ICT's to a pair of RPR (IDF's) on a type 1 1600 DP engine. Upon setting them up I have the idle set at the recommended idle speed and balanced, the idle jets are 52 and the engine idles smoothly with 1 1/2 turns out on mixture screw. The mains are 120 and air 200. Readings appear to be within OK on my gas analyzer. On the road test the car accelerates reasonable but not crisp, however when turning a corner and presented with a climb it dies immediately, running on two cylinder (1&2) it now would appear. Stop, select 1st - take off and run up to 4,000RPM gets you up the hill. Changing up a gear earlier results in death. Now back in the workshop, I wound in the mixture screw on each cylinder until the engine misses. Cylinders 1 & 2 (RH Carby) works a treat. Cylinders 3&4 (LH Carby) when wound all the way in makes no difference? To me this represents a problem with the idle circuit on the LH Carby? I have removed the jets, cleaned them out and same for the carby. Any suggestions thoroughly appreciated.

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 14 Apr 2016, 7:24 am

#1025430

Bizarre wrote:
fish26 wrote:You still havent told us about the engine combo,

landfall wrote:The engine has done 3,000 since a total rebuild. Still 1600cc, port and polished heads, standard valve size, moderate cam with 1:1.25 rockers,, light flywheel. C/W crank, fully balanced.

Using the long offset CBPerf manifolds.
You aint reading the whole story Benito 😊

Shoulda gone to Specsavers.

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 14 Apr 2016, 4:19 pm

#1025437

I'd like to thank everyone for their input.

I took all the info onboard and as I said in my previous post had a big day yesterday and finished it off today.

Whatever the problem was (and I suspect it was a little swarf in the carby) plus minor little details like ignition low voltage wires not quite tight enough on the spade terminals, fuel pressure, distributor choice, etc. The problem seems to have been resolved and now needs the help of a dyno to fine tune the whole deal.

Rod Penrose sent me a new carby yesterday afternoon at 4pm by express post and it arrived at 9.30am this morning with a selection of jets. On the phone he has urged me to keep the carby for as long as I think it needs to be here and return any unused jets. He did not ask for any payment for any of this extra service and items.
Now that's old fashioned service.

The car on this mornings test run, went like a rocket. Up a hill that I have tested on many times and the best yet was 80kph and steady with the ICT's, with these RPR IDF's 80KPH and still accelerating, backed off. (Speed limit)

Cheers

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 14 Apr 2016, 7:35 pm

#1025440

👍👍👍

well done mate

Futue te ipsum!!!

fish26 Fahrvergnugen

903 posts · joined Jul 2007 · 14 Apr 2016, 8:08 pm

#1025441

Glad you sorted out the gremlins, however we still don't know your engine combo, it must be top secret.
Baz, you wouldn't know an engine combo if it kicked you in the ass 😂

bitten by the bug..........several times

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 14 Apr 2016, 9:18 pm

#1025445

No state secret and I thought I gave enough information, but since you want to get technical, no problem.

Std 1600 Pistons and Cylinders - Mahle
69mm C/W Crank
CVP Light flywheel
CBP Ultra light cam followers
Eagle Bracket Cam 276Degree Duration Lift at cam .380" At rockers with 1:1 ratio = .417"
CBP 1.25:1 Ratio rockers - solid shaft
CBP Super H Race Rods 5.4"
MST Serpentine Belt system
MOFOCO 040 Super Street Heads Port and Polished
RPR Hideaway Exhaust System
All engine components fully balanced.
Now running RPR IDF 40mm IDF Carbs with 094 Distributor.

Using original AS41 case, with CBP Max 3 oil pump and external filter.

hulbyw Insano Dub Head

819 posts · joined Sep 2009 · 14 Apr 2016, 9:21 pm

#1025446

Well done landfall. Just goes to show when you modify something, it usually snowballs. It's great to see all the help on here and that RP stood behind his products
Cheers........Wayne

fish26 Fahrvergnugen

903 posts · joined Jul 2007 · 15 Apr 2016, 12:10 am

#1025447

Thx landfall, i'm a sucker for technical specs. Power, reliability, driveability are all dependant on a working ENGINE COMBINATION. Vague engine specs mean nothing especially when trying to diagnose problems via social media, that's why the more information you provide, the more people are able to help out. Trust me all of the ones in the know have had massive head scratching moments, it's one of the ways to learn. Your cam looks like W100 so you should be getting good airspeed and bottom end torque with stock valved 040s unless you had the intakes polished otherwise a slight to moderate stumble may be present as it allows the fuel to fall out of suspension. Once again, im glad it got worked out, enjoy your dub.

bitten by the bug..........several times

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 15 Apr 2016, 8:18 am

#1025453

fish26 wrote:Thx landfall, i'm a sucker for technical specs. Power, reliability, driveability are all dependant on a working ENGINE COMBINATION. Vague engine specs mean nothing especially when trying to diagnose problems via social media, that's why the more information you provide, the more people are able to help out. Trust me all of the ones in the know have had massive head scratching moments, it's one of the ways to learn. Your cam looks like W100 so you should be getting good airspeed and bottom end torque with stock valved 040s unless you had the intakes polished otherwise a slight to moderate stumble may be present as it allows the fuel to fall out of suspension. Once again, im glad it got worked out, enjoy your dub.

Slight stumble? This I still have under certain conditions.

I assumed that this can be tuned out, I did port the intake manifolds to match the head work and get some of the bumps out of the casting.

Am going to do more fine tuning today, but I can live with it if necessary because it does go as I expected it to do.

I must admit I too like specs and research. The engine specs were thoroughly talked over with CBP and MOFOCO. At the time I did not want to go big, but now wish I had.

hulbyw Insano Dub Head

819 posts · joined Sep 2009 · 15 Apr 2016, 11:25 am

#1025455

How big are you wishing now? I ask as I still haven't built my 1776 and am agonising over a stroker crank.
Cheers.........Wayne

Lateral Wolfsburg Wizard

480 posts · joined Sep 2011 · 15 Apr 2016, 12:36 pm

#1025456

Hi guys

I'm curious as to what the compression ration is?

Cheers
Greg

fish26 Fahrvergnugen

903 posts · joined Jul 2007 · 15 Apr 2016, 1:30 pm

#1025457

So am i Greg,

bitten by the bug..........several times

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 15 Apr 2016, 1:42 pm

#1025458

hulbyw wrote:How big are you wishing now? I ask as I still haven't built my 1776 and am agonising over a stroker crank.
Cheers.........Wayne

Minimum 1916 but probably 2110cc. Torque is the answer IMO.

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 15 Apr 2016, 1:44 pm

#1025459

Lateral wrote:Hi guys

I'm curious as to what the compression ration is?

Cheers
Greg

8.0:1

landfall Officially Full-On Dubber

290 posts · joined Jun 2014 · 15 Apr 2016, 3:19 pm

#1025461

Lateral wrote:Hi guys

I'm curious as to what the compression ration is?

Cheers
Greg

All you have to do is ask me, no use asking "Hi guys" because they haven't a clue either.

Ken