Guys,
the Chev 327 in my Jag died recently. So I’m building up a
new Engine using my current block!
Originally I was going to get an LS1 upgrade with a kit and
bits from John. But unfortuately that was going to cost me
way too much.
So, keeping my original block, I’ll be stroking the engine
to a 383ci, I’m going for a small roller camshaft as i’m
more interested in torque than high end power. Forged
crankshaft, aluminum heads, hardened seats, dual valve
springs, holley or demon 650 carby (vac secondary).
edelbrock dual plane intake manifold. Also getting in a
reconditioned mechanical t700r4 with a shift kit and stall
converter.
Getting higher flow extractors and modifiying the exhaust to
include a x-pipe.
I’ll also be dynomatting the interior under the carpets and
in the firewall to reduce noise and heat.
I’ll be converting the Car to run dual fuel, LPG and Petrol.
Any other suggestions to this build would be greatly
appreciated!
But mainly i’m just excited and wanted to share the Lumpy
joy!
Cheers,
Evan–
Evan Whiteside - 1974 XJ6 SII Lump Chev 327ci V8 on LPG
Marrickville, Australia
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In reply to a message from Evanlw sent Thu 2 Dec 2010:
Evan:
If your engine comes out the way you are heading, you will be very
happy. My S1 383/200R with the 470# torque and small QJ carb is FUN
to drive. The engine should give you 15-17 mpg overall on gas and
more on the highway.
You will have lots of take off and be able to pull the OD gear
easily, no matter the rear end ratio.
In reply to a message from Evanlw sent Thu 2 Dec 2010:
Hi, 383s are great street motors. You need more than 650cfm on a
dual plane intake like the performer to properly feed even a mild
383 with decent street performance heads and cam. I good 750DP
well tuned would blow a 650VS away, have better throttle response,
and give nothing away on economy when driven normally. I had a
combo very similar to what you are planning and used it as a test
bed for 4 different 750 squarebore carbs. The best by a country
mile in all respects was http://www.summitracing.com/parts/PRO-
67200/ but it does need to be dialled in for a mild dual plane
application as it runs too rich out of the box. Tuning it involves
more than just main jet changes, and it is highly adjustable on all
circuits, unlike garden variety holleys. You will need a wideband
o2 meter to dial it in.
As Roger has also said a well sorted q-jet flows plenty of air and
is hard to beat on a street motor too.
On a pure street motor 170cc intake runners like those in the edel
performer rpm heads, combined with performer eps intake, and hyd
roller cam 218/224 @ 50 with 110 lobe sep (comp XR270HR), 1.6
roller rockers, 10.5cr, made for a great street motor that ran good
off-idle to 5600 and was good for easy mid 13s in the 1/4, even
with hopeless hookup.
I used scat 6 inch rods to make my engine quieter too - I found it
pretty slappy on cold start with 5.7 rods. There are heaps of
piston options for the 3.75/6.0 combo.
In reply to a message from Evanlw sent Thu 2 Dec 2010:
I’m curious; why the desire to run dual-fuel? The octane rating for
LPG is so much higher than for gasoline and the BTUs so much lower
that you really need a higher compression ratio to get the best
results with it (on the order of 12:1 or more IIRC). These were
briefly popular here after the first ‘gas crunch’ but quickly fell
out of favor due to poor fuel economy when using LPG or LNG.–
The original message included these comments:
I’ll be converting the Car to run dual fuel, LPG and Petrol.
In reply to a message from Why? sent Fri 3 Dec 2010:
You know, a lot of Aussies on a Range Rover forum I use have
made that conversion as well. They say gas prices are
outrageous there, and frequently spike a lot more than here
in the States where our government manipulates the price. I
have not converted my Rover yet, but am watching carefully a
couple big players in the LPG/LNG market in the states; like
a couple of bills in Congress making it mandatory for a % of
Federal vehicles, taxicabs and OTR (over the road) semi
trucks in large fleets to use LPG/LNG/CNG. No, they are not
all the same and require different tanks and combustion
equipment in a conversion. On the plus side, most
neighborhoods in America have natural gas already and just
need a dispenser set up in their garage to fill themselves
up while it is still fairly cheap.
I don’t think the power loss is that significant in the
Rover ally block of 4+ liters. As they have been fuel
injected for a while, after conversion they get pretty good
mileage when you factor it by cost/mile.–
The original message included these comments:
I’m curious; why the desire to run dual-fuel? The octane rating for
LPG is so much higher than for gasoline and the BTUs so much lower
that you really need a higher compression ratio to get the best
results with it (on the order of 12:1 or more IIRC). These were
In reply to a message from fiveo sent Fri 3 Dec 2010:
I wonder, can an LPG car run off the same tank as an outdoor grill?
(which, being from Texas, I won’t stoop so low as to call it a
barbeque grill.)–
Robert Allen
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In reply to a message from rea1980 sent Fri 3 Dec 2010:
Have you price Andrews LSx stuff? He’s usually cheaper. Personally,
I would just by a GM 383 crate motor ( there are a few versions
available) instead of rebuilding yours. I would be willing to bet
its a cost effective solution.–
Rob Wade
Windsor Ontario, Canada
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In reply to a message from Evanlw sent Thu 2 Dec 2010:
Thanks heaps for all your tips guys!
I think i’ll look at getting 750CFM carby, most of your
technical terms went sailing over my head, but i’ll take
them to my mechanic and get him to run through them with me.
The car is currently running on LPG only. Decision made by
the previous owner. Fuel tanks were rusting a long time ago,
so they were removed. LPG tank stuck in the boot. The fill
connection is directly underneath the normal fuel cap.
The disty was curved for LPG, and it was running very
efficiently. The only problem was for a trip of about 1000km
through Australia sometimes there’s just no LPG bowsers. I
want a petrol tank just as backup, but not specifically
tuned for it. Here in Sydney all the taxi’s run on gas, so
it’s plentiful and cheap.
I believe you can fill up using normal BBQ gas. I’ve heard
someone recommend it actually, as a backup.
Yep, I checked out andrews LSx stuff too. The conversion kit
wasn’t the deal breaker. It was everything else that i’d
have to do. would have come to over $15k. Too much for my
bank.
I was considering a crate engine. But I couldn’t find a
supplier in Australia that had the price/configuration that
i wanted. Plus my mechanic and I live very close together
and it’s much more fun putting it together ourselves.
As it is, I’m getting the parts at a pretty good rate
through a contact in Rocket industries. So this will
probably come out cheaper than a crate anyway.–
Evan Whiteside - 1974 XJ6 SII Lump Chev 327ci V8 on LPG
Marrickville, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Evanlw sent Thu 2 Dec 2010:
You need a propane tank with LIQUID, not VAPOR outputs. BBQ
tanks are vapor, and only work if they are full and turned
sideways, so the volume of usable fuel and range isn’t
great. An 8 or 10 gallon forklift tank is what you need for
a spare, and that will save a good deal of money over the
dual fuel conversion. If you use an impco 425 propane
mixer, you can use the throttle body (bolts up directly, no
adapter needed) from a Holley 650-800 double pumper and
probably get more power than a smaller mixer/tb. For a main
tank, you can usually call around to junkyards to find old
tanks from vans and such. A manifold type tank (Two 10
gallon tanks welded together with pipes) was common on 80s
Ford vans running propane, and that would probably fit well
in the trunk of an XJ.
I plan to run propane in my S3 XJ6 when I get the kinks
worked out of my propane powered pickup. For LPG, You want
higher compression, lots of intake valve flow,more initial
advance (but less total) hard, flat seats and valves, with
identical angles (no interference angles or multi angle
jobs, as seat time is the only thing that cools the valves)
and all the rest of the stuff that’s been done to your
motor. One other must is a hot spark with very large, well
insulated wires that won’t cross fire (especially on
cylinders 5 and 7, are physically next to each other, AND
sequential in firing order)…very bad when that happens,
hole in piston time.–
Catahula
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In reply to a message from Catahula sent Fri 3 Dec 2010:
It may be a little ahead of the curve in the States to look
at these natural gas conversions if you are not in the taxi
business or something, but they are very popular in
Southeast Asia and like the OP - Australia. I like the idea
that they are far cleaner on the environment, and until
batteries improve - electric cars are too compromised. My
employer gave me an all electric Ford pickup to use for two
years and I have to say I liked the idea but the handicap of
the limited range led to trading it in.
With many of these conversions, you actually start the car
on gas/petrol, and then switch over to the LPG or CNG
afterwards so that is why they are often dual fuel. Liquid
vs Vapor conversions have different fuel tank and fill up
requirements as the C posted. For Rovers, the spare tire
area in the back is filled with a huge LPG tank instead,
leaving the full gas tank in place, giving up to 850+ mile
range for crossing the Australian outback. They put the
spare tire outside on a bumper mount. Saddle tanks are
easily installed as well, large enough to double even that
distance, there is a lot of room underneath a Range Rover.
Jags? Not so much,…
My Rover might be converted one day, but I think as long as
I can I will keep my Jag on regular fuel. Odd that the
subject on this thread went this way on alternative fuels,
but that is partly my fault. I am interested to see how
well this will work out for the OP and will flag his posts
in the future to keep up on his progress. Thanks for
bringing up an interesting ‘‘Lump’’ project on this forum.–
The original message included these comments:
I plan to run propane in my S3 XJ6 when I get the kinks
worked out of my propane powered pickup. For LPG, You want
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