Im going to post about me etc all , and other stuff, so grab a coffee before continuing
hope u dont mind
!st Im no newbie, I have a matching numbers 69 Camaro...handbooks, protecto plate everything...Even the original wornout stuff like brake hoses are stored away.
I have used the car as a my main daily driver for the last 27 yrs.
'In 86 Our Gov (NZ) was talking about screwing with our petrol ..and I was in the middle of a 8 month full rebuild resto.
I was into Hot Rodding back then and LPG...the anti attitude was very stong.
We had installers...stupid ppl..."wack the intial up 10 or 15 degs, she will be right".
SO i started from scratch, The guys at IMPCO in the 'States where great...no email in those days..And a guy Dr.Harrison at the Alternative fuels Board in NZ
I designed my own cam profiles, machined a chevy and a HEI dizzy to get the right curves..total cent, curve, vac advance all full adjustable, from deg range and vac range adjustable.
I had(have)
SB 350 , Turbo 350, 308 posi, on 14x60x345 rubber
IMPCO L with 425 carb mounted on a 450 holley base plate.
Std Fuelie 202 valve heads and planed a little (cant rem how much 20 yrs ago)
cast Rams horns to duel 2 1/2 " exhaust
Duel plane performer manifold with divider plate
Std torque converter.
1st 20 yrs
My 1st cam profile was a bit off, worked well thu...didnt bed in properly so was a good excuse to design a moded profile.
The 2nd profile was better but again not as good as I expected...this ran for nearly the next 20 yrs.
I could run a 14.2 1/4 mile, in Drive, with tool box, picnic stuff still in the trunk..then in heavy traffic get around 20 mpg, normal traffic about 22 and open road around 23 with the trailer loaded with family camping gear.
Running temps 165 to 175 under heavy towing loads up long hills...heavy traffic jams on hot days no change..Std cooling system
MPG conversion is in What I call REAL Terms...cost of LPG converted to petrol volume and then mpg.
So that was about 150.000 miles.
Current situation
Last yr the car was stolen, for 45 mins, thieves didnt manage fire it and got Zapped while still towing it...usual lock damage nothing a bit of R&R couldnt fix.
It then went into Police secure lockup, where the police contractors put a sledge hammer thru the steering wheel, screwed the steering box, and laid 25% of brand new tyre rubber inside the rear gaurds...yeah and all backed up with photos etc...thats another story...Insurance company...they where great, no complaints.
The engine ..damaged valve springs, worn rear lobs etc etc ...was estimated the engine was turning over 10,000 rpm.
the interesting part was the lack of valve recession, bore wear, bearings etc...where all still in brand new condition if one ignored the metal picked up by the thrashing on bearings etc.
The guys who do my machining where amazed, far less than one would expect from a petrol engine.
Oil change/filter 2x a yr...no special oils or additives just std un refined, brand thats on special at the time 20/50
So the rebuild
New cam profile: cam concepts have changed a lot in 20yrs, so was a new learning curve.....I basically chose a "blower cam" with a high lift, short duration, decreased the ramp rate and advanced it 2 deg.
Keep in mind I want an economical daily driver, that can tow some of my other classic cars on a transport trailer, and still pull respectable times on the strip....A dedicated bottom end stump puller..no compromises.
And thats what I have now got...
Basically same as the above, but now pull high 13s 1/4 mile in drive, Towing the transport trailer with another car on, 55/65 mph open road 22.4 mpg, open road over hilly winding roads 26 mpg.
IF On petrol I would be pleased with figures 12 to 16mpg.
Dyno tuning shows 218 hp @ about 4000 rpm at the back wheels.
Mixtures spot on upto 4200 rpm then starts to lean out....leans out excessively just under 5000rpm...so its not a good idea to cruise at 130mph for long periods...who does or can, so thats a moot point...the odd foot in passing a large truck for couple secs will not be a problem.
OH didnt mention, all my engines are fully dynamically balanced from harmonic balance to flex plate...makes long lasting free reving, smooth engines, worth every penny.
The engine now runs at 160 to 165 Deg.
Tuning
Still fine turning this engine...
Baes is, like the last, idle @500/550 curve comes off 625/650 rpm intial 8 degs Cent was 27 deg this engine seems to like 31/32 total...all in at 2200 rpm.
The idle speed you think is low...with light springs these move off early, if they do so at idle it advances the curve and causes the engine speed to increase and decrease...I have a nice even idle and very little drop when in Drive (auto)
Athu I played with the vac advance yrs ago...I either ended up with low power ping in the 2500 rpm range, and it didnt make any diff to economy, so I scraped it...this time no ping but doesnt make any diff to economy..the EC1 I do like thu.
I have run into a couple problems thu
1/The LPG carb/regulator units has never had a service or needed adjustment in 20 yrs...even with EC1 hooked up.
2/Engine came out yesterday...got either a cracked piston or bad gudgen...All new...it happens..the down side is Im also in the middle of a ground up resto of a Bradford van...time.
3/So at the same time decided to open the regulator, carb and check out.
The butterfly bushes have a very slight play...only minor but Im lazy and they will need doing in a few yrs, so doing now
The regulator...its like new inside..NPs
The carb...
What is the gap meant to be between the bore and cylinder, has a little rattle at idle.
Great site..had a good look thru, and picked up some nice pionters...
One thing no covered well is Compression ratio and relative to cam duration.
Compession ratio means scwat...Dynmamic compression ratio is where its all at....one can have a compression ratio of 11:1 but in real terms (relative to compesion at piont of firing it could be only 8.5 or 9.5.
OH and a engine designed for petrol will run LPG ok...even CNG...but run an engine designed for LPG or CNG...Runs like Crap....worse.
If u want to pull the best from alternative fuels...design for them, no compromise...u will not want to run petrol again...unless u live in the out back of Aussie and the tank range will not get u to the next filling station.
Cheers Guys
Steps