Michael, that was a great reply, lots of info. I was particularly interested
because I'm starting the process of adding a little oomph to my Spitfire 1500.
You mentioned the "Make nice big D shaped pockets under the valves". I have seen
this mentioned more than once but I don't fully understand it. I am practicing
on a 1500 head now before working on my good one so I would like to know what is
meant by D-shaped. Is the flat of the D across the plane of the valve opening?
The fuel path is coming in on the bottom flat of the D. True?
Here is the list of current items in my project:
Port and polish head
Weber DGV with Pierce manifold
4-2-1 header and big bore SS exhaust from Rimmer's (Phoenix Performance Exhaust)
Air/Fuel Ratio Monitor from CB Performance (for final carb tuning)
Yet to decide:
Flat top pistons. I haven't had the head off engine yet and don't know if I
might have flat tops already. Most likely not as it is a 76 California version.
Replacing pistons means further dismantling of the engine and machine shop work
to bore out for oversize. I would like to avoid the extra cost of machine shop
work and the extra cost of a piston set.
High Performance Cam. Requires further dismantling of engine (beyond just the
head). I am looking for a wider power band rather than peak at high RPM so a
"Road Cam" seems to be the right choice. Which cam do I use? Buy a new one or
send mine off for re-grind?
Plane the head. Requires machine shop work. If so, how much. The competition
manual says .200" but then you get into further problems dealing with the push
rods. I prefer to avoid this and go with just the flat top pistons. This will
raise the compression to around 9:1 I think. Planing would raise the compression
even more and create other problems such as pinging and the need to use higher
octane fuel.
Vic Whitmore
76 Spitfire
Thornhill, Ontario
"Graziano, Michael" wrote:
>
> Larry,
>
> I too haven't seen much in response.
>
> Here's what I did to my 1500 Midget, which seems to be working well for me.
>
> +0.030 Flat Top Hepolite Pistons
> 285 Piper Cam Advanced 4 degrees via TR6 Double Chain Vernier Gear Set
> Pinned Thrust Washer (some people fit MGB thrust washers)
> Balanced Rotating Mass (crank, pistons, rods, pressure plate, flywheel, and
> pulley)
> Oil Cooler
> GM 63 amp alternator
> Lucas 25D4 points dizzy (eventual upgrade to Mallory dual point)
> Ported, skimmed, and intake matched head.
> (no chamber work, and not polished too smoothly. I can't remember
> if I
> read it in Vizard, or the BL competition manual, but someone did
> not
> recommend polishing this head, other than removing all the burrs
> and
> casting imperfections. Make nice big D shaped pockets under the
> valves
> for better puffing action. Standard valves)
> Dual Valve Springs to eliminate possible lifter bounce.
> 4-2-1 Exhaust header, mild steel (the 4-1 is best at high RPM, the 4-2-1 has
> a bigger range)
> Monza free flow. Dual exhaust may be hurting your exhaust suction...
> forget the term...
> Dual HS4s with CapStat jets
> '74 water pump with no clutch and a '74 fan
> Backup 10" electric pushing fan
> 3 row louvered radiator 1/2" thicker than stock for a Midget. You may be
> able to fit
> a 3 row staggered in the Spit, which is better. Transfer tubes are
> 3/8", I believe.
> Skimmed block (not too much)
> Standard studs (I didn't use the ARP studs I purchased. Still have them,
> though)
> Bored out main oil galleries and high capacity oil pump. Shimmed oil
> pressure relief valve.
> Currently running 90 lbs cold and 25-30 lbs hot oil pressure.
> Some people retrofit cam bearing from a 1296 cam. Might be a good idea, if
> cash is no object.
>
> For tuning purposes, I purchased a Air/Fuel Ratio gauge, but haven't
> installed it yet. A definite must if you plan on screwing around with your
> needles. Out there somewhere in the archives is the link to the SU needle
> program which references different needle profiles to needle codes.
>
> You can always add a supercharger, and nitrous.... Seems a bit much for me.
> When all is said and done, the Corrolla next to you will probably beat you
> in the next street light race anyway. I thoroughly enjoy the added power in
> my Midget, but recognize it's limitations. I also try not to race it at
> the street lights. I spend too much on the rebuild to risk damaging it.
>
> Michael
>
> -----Original Message-----
> From: Vic Whitmore [mailto:vicwhit@home.com]
> Sent: Thursday, November 30, 2000 8:56 AM
> To: Larry Elswick; Spitfires Maillist
> Subject: Re: Engine Rebuild
>
> Larry, I haven't seen much in terms of replies to you. Hopefully, there has
> been
> some off-list.
>
> I expect that you have a copy, or have seen the competition preperation
> manual.
> You can find a copy of it at:
> http://homepage.ntlworld.com/mark-kaye/thumbs/Spit-comp-man.pdf
>
> You seem to be following a good path with the HS-4 (once the jetting it set
> right), header, etc. I would suggest the next step is to port and polish the
> head.
>
> I think the reference to the 1300 is just for the head. There were bigger
> intake
> valves involved but you can have them retro fitted to your 1500 head at the
> same
> time you get the valves/seats triple cut. A good machine shop should be able
> to
> do it. I am unclear on whether the bigger intake valves were for the 1300 or
> the
> early 1500 so you may need to check on that.
>
> There are several other listers that have done a lot of race prep on their
> cars.
> Maybe they can help with more suggestions.
>
> Vic Whitmore
> 76 Spitfire
> Thornhill, Ontario
>
> Larry Elswick wrote:
> >
> > I'd like some suggestions on a performance rebuild of
> > my 1976 1500. One suggestion was to use a 1300 engine.
> > I'm talking about every trick in the book to squeeze as
> > much performance out of the engine as possible. It currently
> > has twin HS-4's, exhaust header with dual exhausts, and
> > electronic ignition. I do plan to blueprint and balance it.
> > Any help would be greatly appreciated. Thanks!
> > Larry
>
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