Doug,
I will give you my own personal view of your choices, after each
question. Everybody has a right to their own opinion, but physics seems
to win the battle every time.
Doug & Rett Leithauser wrote:
>
> I am beginning to rebuild my original 260. I am aware that this is not the
> road to maximum HP, but it is original & it is what I have.
It's not a bad start. The amount you save (with a lot of mods) by using
your current block over a new larger one is not that much, though.
> I am interested in getting increased HP, without destroying the low end
> torque that is needed to get rolling smoothly with the stock gearing (2:88
> rear, close ratio).
A good goal is to have an easily drivable street vehicle, with more
performance, yet well behaved, I presume. There is nothing wrong with a
2.88 rear end (IMHO), but there is a LOT wrong with the close ratio gear
set. The wide ratio gear set that came in the Mk II, and lots of other
Fords, gives a much better acceleration in getting off the line, and
still the same top gear cruise of about 72 mph @ 3,000 rpm with plenty
of high gear torque for acceleration. The parts that need changing to
convert are few, and the results are amazing. Read my Tech Tips, and
Forum notes on the subject, as well as the Excel calculator on
http://www.TigersUnited.com.
> My first idea is to bore the block 0.030", use 351
> Windsor heads (big valves & hardened seats) milled as far as I dare to
> retain compression, a mild RV type cam with a 465 cfm holley, probably on my
> current low rise, unknown manufacturer manifold, with Pertronix ignition &
> headers.
First, you will gain very little displacement from boring, you will only
loose the number of times you can rebuild, and increase the heat load on
the system with thinner walls. The 260 limit is 0.060 and the 289 limit
is 0.040. Only bore if it's worn, scored, or needs cleaning up. You
might, however, consider stroking. It has been successfully done by
others, but requires some details on the rod length. The best solution,
considering the extra travel lower at the BDC requires new pistons and
rods. Custom pistons and rods that move the wrist pin up higher reduce
the loads that were killing the 302, until the 5.0 came out with the
better pistons.
The Windsor heads, or even your heads, could use a lot of port work to
make them really perform, and do not go overboard on the size of the
exhaust valve, or you will loose power. 2.02 is pushing it, and your
extraction exhaust velocity will not help scavenge the chamber. The best
is to get the leaving mass expanding out as fast as you can, yet still
leave enough velocity to drag the un-displaced gas out too. Nothing is free.
> Has anyone gone this route, or have reason why I would be a darn fool to
> do so? My greatest concern is the use of the 351 heads on the 260, the
> chambers are a lot bigger & compression is a concern, according to "How to
> Rebuild Small Block Ford Engines" I would drop to 8:1 compression until the
> heads were milled.
Again, when cars had flat heads, or deep chambers, milling was a
compression raiser. Today you get very little compression change with
head milling of any reasonable amount. The correct solution is correct
piston tops, either dished or domes, depending on stroke and head used.
You really don't want to go over 9.5:1 with today's gas (which could get
worse with gasohol, and force timing retardation - a big power killer)
> If anyone has experience in this installation I would sure like to
> benefit from Your experience, Otherwise everyone can tell me why I should go
> with a new 302. My wife has already told me to keep my hands off her Mustang
> GT.
Actually, if you have the bucks, the Motorsport crate engines are a good
deal, and an article on a conversion is on the web site. You may want to
change the front timing chain cover to the old style, and move the dip
stick. You will also need some black paint! I'd yank out the steel
freeze plugs and replace with brass, and get a brass drain valve,
instead of a rust-in iron plug for the block drain.
You will need new pulleys to fit the stock set-back of the water pump,
generator/alternator but in 4 bolt, rather than 6 bolt. You will need
the 6 bolt bell housing, clutch slave bracket (CAT), and either weld
reinforcement plates to hold your 5 bolt engine 4 transmission bolts,
use the rare dual 4 pattern cast iron heavy bell housing (but it is not
a scatter shield), or use this time to get a dual pattern 4 speed top
loader case, which fits both. If you buy one with the wide ratio gears,
you are doubly ahead, but you MUST have your Tiger tail stock and
mainshaft and transmission internal speedometer drive gear. Other parts
can be used if the replacement case needs parts. Always use new seals,
bearings, and check the blockers. Use the wide ratio front bearing
retainer. If you are using one of these cases in a 5 bolt block, use the
smaller outer diameter front bearing retainer of the 260 tranny.
Anyway, check everything out twice, do not over-carburate, or wild cam,
and it can be smooth. The crate engines come with about 4 different cam
choices and iron and aluminum heads. I am not certain here, and need
verification, but all aluminum heads are thicker than the iron ones, and
I am NOT sure you have the room between the TIGER valve cover and the
firewall for the extra height.
Read the articles already published on http://www.TigersUited.com
O.K., those are my $.02 opinions, and I am sure there will be different
ones coming.
Hope they are of some use, and stir the pot for contrary considerations,
or maybe some confirmation.(?)
--
________
Steve Laifman
Editor
<http://www.TigersUnited.com>
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