Thanks everybody for all of your great info. so far. Well I have
made some crutial decisions because of good direction I’ve been
given thus far:
Andrew’s motor mounts.
Don’t waste time and money on rebuilding a 4.2.
Buy a donor car.
Unless it’s mint-mine is nice-the original engine does nnot
fetch more money or reduce the value as much as some would claim
Here are the remaining isues:
I’ve found a donor car (89 Caprice) with a 305 tbi-I’m almost
certain, and a 700R. The local rebuilder I want to go with says
I’ll be unhappy with the performance if I rebuild the 305. Problem
is I want TBI and I’d have to got to a truck motor for a 350/tbi??
Qusetions:
Can I bolt on all of the accesories from the 305 to a 350 tbi
truck motor? (I have access to a '90 350 tbi from a Chev. truck)
Will the ECM from my '89 Caprice (305 tbi)work on the '90 350
tbi?
Should I just go with the 305 anyway? I’m not interested in that
much speed? The specs on the jag 4.2 and a 305 tbi are pretty close-
but my local ‘‘lumper’’ contact says that even a 305 will run circles
around a 4.2?
I’ll get a 700R with the donor car. Johns says go with the TH
I hear all kinds of stuff about the gearing (especially in
1st) being kinda strange. Which should I choose 700R or TH350
All of the caprice accessories will bolt up to a truck
engine
The ECM from your Caprice will likely work with a 350,
but your (orignally 305) system will need some
changes. You should consult Turbo City in Los Angeles
as to the correct set of injectors (if they should be
changed) and PROM (computer chip) to use. These guys
are TBI experts. They likely also have a performance
PROM for your application
All else being equal, go with the 350, but be sure to
investigate (before) what components you will need. GM
offered a 350 TBI in the Caprice for cop cars, so the
parts are available.
On the trans, forget about the T350. The T700 has a
better 1st gear for stronger starts, and the great
overdrive for the freeway. The T350 is a compromise at
best.
I hope that helps…
Andrew__________________________________
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I’ve found a donor car (89 Caprice) with a 305 tbi-I’m almost
certain, and a 700R. The local rebuilder I want to go with says
I’ll be unhappy with the performance if I rebuild the 305. Problem
is I want TBI and I’d have to got to a truck motor for a 350/tbi??
Qusetions:
Can I bolt on all of the accesories from the 305 to a 350 tbi
truck motor? (I have access to a '90 350 tbi from a Chev. truck)
Will the ECM from my '89 Caprice (305 tbi)work on the '90 350
tbi?
Should I just go with the 305 anyway? I’m not interested in that
much speed? The specs on the jag 4.2 and a 305 tbi are pretty close-
but my local ‘‘lumper’’ contact says that even a 305 will run circles
around a 4.2?
I’ll get a 700R with the donor car. Johns says go with the TH
I hear all kinds of stuff about the gearing (especially in
1st) being kinda strange. Which should I choose 700R or TH350
My 2 cents
They ain’t no substitute for cubic inches. The best small block (of 8) I
ever owned was the 383 stroker I put in my '84 Suburban … My 350/TPI/4L60
… ran better but is over 1000 lbs. lighter. To make a jag conversion
really sing you need torque to push the 2 tons around and you need gearing
that lets you utilize the torque efficiently. An off the shelf 4L60/700R4
(IMHO) is the easy pairing that gets you close. Presuming a 2.88 rear end
ratio, what you will have is a three speed with a lower 1st gear than the
350 trans plus the availability of an OD for speeds in excess of 60 mph or
about 2200 RPM. I run mine in 3rd. gear unless I am actually running
interstate speeds. Most SMBCs I’ve owned over the past forty years just
hum along at 2200-3000 RPMs When you do the math that’s between 60 and 70
mph in third gear and 70 to get a ticket in OD.
My recommendation get a is 350 and a 700R4. If you can swing it, get a
fuel injected version by buying a donor with it from the factory. Remember
ECMs are unique to the engine they were designed to control. They can be
“reprogrammed” but that is always a time and money issue. Conversion with
a FI is somewhat more complex but it will pay off over time. Short of that
I am partial to the 383/700R4/carb set-up over the TBI. What you really
want to do is figure the RPM range in which you want to operate and find
the “best” torque/power balance for your driving.
Hope this helps.
Wes Channell
'83 XJ6/350/TPI/4L60/Working trip computer/Euro Bumpers and lights
Phoenix Metro, AZ
Bob, I cannot be of much help with the injection issues.
I built my car using a johns kit and a 305 / t350.
If I do another I will piece it together myself. No kit.
I replaced the trans with a 700r4 before I put 1000 miles on it.
I remember that there are certain year 700r4’s to stay away from. Look into this! Mine is from a '91 Caprice.
You say you don’t care about the power. I was givin a 350 that turned out to be a 305. Against ALL advice I put it in anyway. I have never been happy. I said that also about power, and my suburban will blow the doors off my Jag(hell so will my VW). I have been building a 383 for a few years and I hope to have it in this summer.
My 2 cents is a 350ci/paired with an OD trans, 700r4 or there is a 200 OD also. I think FI is always a good idea. Hope this helps!
I just re read your post and you say rebuild the 305? I say no way.
Mike in Tucson AZ 1973 XJ12 305-700r4
<orig. message>
Here are the remaining isues:
I’ve found a donor car (89 Caprice) with a 305 tbi-I’m almost
certain, and a 700R. The local rebuilder I want to go with says
I’ll be unhappy with the performance if I rebuild the 305. Problem
is I want TBI and I’d have to got to a truck motor for a 350/tbi??
Qusetions:
Can I bolt on all of the accesories from the 305 to a 350 tbi
truck motor? (I have access to a '90 350 tbi from a Chev. truck)
Will the ECM from my '89 Caprice (305 tbi)work on the '90 350
tbi?
Should I just go with the 305 anyway? I’m not interested in that
much speed? The specs on the jag 4.2 and a 305 tbi are pretty close-
but my local ‘‘lumper’’ contact says that even a 305 will run circles
around a 4.2?
I’ll get a 700R with the donor car. Johns says go with the TH
I hear all kinds of stuff about the gearing (especially in
1st) being kinda strange. Which should I choose 700R or TH350
I know-a lot of questions, but I could use the help?
Bob
carjones
Phoenix, Arizona, United States
In reply to a message from michael mcginnis sent Wed 18 May 2005:
Note my combinations below: 383 and OD. The engine in the '74 parts
305 SBC motor is a poor choice. As mentioned before, it takes
gearing/torque to move these cars. Gearing hurts your RPM/mileage.
The 350 trans has three gears, poor first gear ratio compared to
the 200R/700R modern transmissions. The 305 engine is the worst
choice; ‘‘there is no replacement for displacement’’.
FI is the way to go if you can deal with the fuel pressure, return
line and setting up the computer. My Lumps are both carb’d and work
properly and have tons of power. The 200R has better gear ratios
and will pull the 2.88 gears and give better mileage than the 700R.
It (200R - fits in space of the 350 transmission) shifts ‘‘smoother’’
or more like the temperament of a Jaguar. The 1-2 shift of the 700R
makes for a larger loss of RPM and is not ‘‘smooth’’.
Check out the site www.bowtieoverdrives.com for more trans
information and compare the ratios.–
The original message included these comments:
My 2 cents is a 350ci/paired with an OD trans, 700r4 or there is a 200 OD also. I think FI is always a good idea. Hope this helps!
350. I hear all kinds of stuff about the gearing (especially in
1st) being kinda strange. Which should I choose 700R or TH350
In reply to a message from Roger Mabry sent Wed 18 May 2005:
I have a 5.7 TPI/700r4 combo in my xjs. The 05 will use as much
fuel or more working that hard to move you jag. The 350 doesn’t
need to work as hard to do the same work. Result, less fuel burned
and more zip when you need it. And you will need it! 700 is the way
to go. My xjs at 70 MPH revs at 2100 rpm. Can’t beat that for
cruising economy. With the tall first gear the cars leaves the line
very sharply. Yes there is a 1-2 shift issue as far as rpm drop
between 1 and 2 but the benefits far outway the negatives. I must
say, however IF I were to do it again I would chose a 200R4. Better
4th gear ratio for cruising and the 1-2 split is MUCH better. Since
mine had the 700 in it already I’ll stay the coarse but I would
seriously look at a 200r. Try bowtie overdrives .com for more info.
Good luck–
Rob Wade
Windsor Ontario, Canada
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Rob Wade sent Wed 18 May 2005:
Everyone has pretty much said it all, but here are a couple more
thoughts.
Go with a 350, or a 383 if that’s what you want.
Forget about the TH350 - It is a dated transmission even though
there are some converter lock-up (desirable) versions around. You
will be happier with either the 700-R4 or the 200-4R.
With the 350 & stock or near stock cam - With a 2.88 rear, use the
700-R4 (does well off the line, but has the harsher 1-2 shift).
With a 3.08 or higher, the 200-4R would probably be the greatest
choice.
With a 383 & stock or near stock cam - will work well with any axle
ratio and either transmission - the 200-4R would be my choice.
Those of us who have the engines with the 4L60E (electronically
controlled shifts) kind of rule out going to the 200-4R because
none of them are electronic and we would have to change out our
PCMs and change over to the Throttle Valve (TV cable) system.
Fortunately, the electronics do smooth out that 1-2 shift a bit.
Matter of fact, I have a 200-4R sitting in storage.