1500 engine rebuild - part 1; planning

I re-did my compression test with the 30wt oil in the chamber. Almost a 10psi jump in 1,2, and 4, and almost a 30psi jump in cyl 3 (the cylinder I was @ 70psi on before). I could go with just replacing the rings... but since I'm gonna be in there... heck with it! Lets go for some performance! and keep it mostly streetable.

So here starts my 1st stage. Planning. I expect to start this about a month after I move, so Start time of 4 months from now would be perfect. I'll post in stages as the time for each part of my build comes.

So, heres my 1st set of question on this:

What should I get?
I know what parts are needed, but I'm not savvy on brands for British engines that have been proven reliable.

What compression ratio should I shoot for?
I read that my compression ratio is 7.5:1 stock, and clearly thats too low.

Square build: Over, even or Under? (Stroke or revv for those who arent up on squares)
I don't know how high of RPM the transmission can handle, but I REALLY like rev happy high RPM engine sings (even if that means narrow power band). Although I do plan to get the Ford or Toyota transmission, so it probably don't matter.

Should I forget building the 1500 and get a 1300 and build that?
I hear the 1300s are much more rev happy and great for racing... but I still want this streetable. I need to be able to sit in traffic and not overheat or rattle to death. Right now I have that, but I don't have much power at all.

Maybe someone has done this all already and has a listing of Cam lobes, Valves, head mill specs, crank specs, brands, and so on that they could share?

take a look at this first:

https://www.totallytriumph.net/spitfire/engine_building.shtml

You should take a look at what has already been done to your engine first in order to decide how to proceed. If the 1500 block still has standard pistons, and the bores are in reasonable shape you could just have it bored out to the next size. With the 1500 the first real improvement you need is to have the rotating bits properly balanced.

We, my wife and I, took the her 1500 engine to a shop- they milled the block, cleaned, ground, and polished the crank. They balanced the the new 9:1 pistons and connecting rods. We added a European intake manifold and HS4 SUs from TSI, added an electronic ignition, and bought a four into one header. The car runs well- freeway speeds and some grunt to get up hills.

70herald - that link is fantastic! Thanks.

The 1500 has more torque and is a better street engine than a 1296. But, it doesn't like to rev so you won't be playing Speed Racer.

NOTE...Putting 9:1 pistons in the engine doesn't result in 9:1 compression. It also takes the European cyl head to do that. What I did was have my head shaved about .050. I was shooting for 9.3:1. No idea how close I got. I too got a European exhaust and intake. Still working on the carbs though. I got HS4s from Hap Waldrop that likely came off an MGB. Curto says I need different float chambers so I'm kinda stuck right now.

The 1500 has the mildest cam of the Spit line. I went with a 270 cam from BPNW. Also got their better quality lifters. The small crank 1296 has a very good cam grind to it so I've been told. The deal is you don't want a big cam in a 1500 unless you are racing.

For bearings I went with King Trimetal bearings. Too hard to find the CORRECT Vandervell bearings any more. Big problem is the thrust washers. Most folks think the brand most available now are crap. I would now try the special ones that appear on this web site in references.

As for overheating, build it, run it and keep an eye on the temp. Add a good puller fan if needed. Flush the old rad as a precaution (professionally). Griffin Radiator can make you a custom rad for not a whole lot of money in copper and brass.

billspit said:

The small crank 1296 has a very good cam grind to it so I've been told.

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True, so long as you're talking "early" US Mk3 or home-market spec. cars with the FD series engine. The FE (1969-70 US-spec. emissions) engines had a much less desirable camshaft.

Small crank = FD. Large crank = FE.

I think.

billspit said:

Small crank = FD. Large crank = FE.

I think.

Click to expand...

Sorry, no. Both those (and the ultra-rare FF blocks, found in US-spec. Herald 13/60s destined for Puerto Rico) are small crank. FH, FK and FL are large-crank engines. There are probably others, such as those found in the 1300 fwd sedan, but the F-series from Spitfires are most common in the US.

I did what Trevor did. 9 to 1` compression pistons. Shaved the head a bit. Quality 3 axis valve job. Balanced pistons. Crank reworked. Dual HS4's and 74 exhaust manifold.

Car runs much, much better. The shop that rebuilt it has built many. He discouraged me from hot stuff. He said the crank cannot take it. The last 100hp motor he built lasted 30 days. He quit racing his because of this. He went to Midgets.

On my engine the cam was shot and there was crank knocking.

It is a different car now. Enough power to be fun. It will now turn 4500 rpm happily.

Larry

Andrew Mace said:

billspit said:

Small crank = FD. Large crank = FE.

I think.

Click to expand...

Sorry, no. Both those (and the ultra-rare FF blocks, found in US-spec. Herald 13/60s destined for Puerto Rico) are small crank. FH, FK and FL are large-crank engines. There are probably others, such as those found in the 1300 fwd sedan, but the F-series from Spitfires are most common in the US.

Click to expand...

You are obviously much more knowlegible about these engines than me. I thought the engines on the later Mk 3s had the bigger crankshaft and used the single Stromberg intake. Same as went into the Mk IV. Am I wrong about this too?

billspit said:

You are obviously much more knowlegible about these engines than me. I thought the engines on the later Mk 3s had the bigger crankshaft and used the single Stromberg intake. Same as went into the Mk IV. Am I wrong about this too?

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Sorry, but I think you are -- about the crank, that is. :frown:

But yes, the 1970 US-spec. Mk3 did go to the single Stromberg for emissions purposes.

I started a really rough build plan on a notepad while on break at work. What I'm missing most of is the stock specs, like Bore, Stroke, Cam Durations, chamber volume, so on. Anyone have the list of stock specs as such?

Pete,

This is the info from my motor heratige disk.

Bore 2.9" 73.7mm
Stroke 3.44" 87.5mm

Valve timing
Inlet open 18 degree BTDC
close 58 degree ATDC

Exhaust open 58 degree BBDC
close 18 degree ATDC

Should be a 9.0:1 compression motor


Hope this is of help to you

Don_R said:

Should be a 9.0:1 compression motor

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Are you sure? Everything I've read about this year 1500 engine (US spec) says 7.5:1 due to emissions.


How much can I mill the head without needing shorter push rods? is .050 too much? Seems like that would be borderline.

Anyone have the displacement formula available to post here? I know its something like

((Head Chamber Volume + Cyl Volume BDC)-(Head Volume + Cyl Volume TDC))x # of Cylinders = Displacement

But I cant find it in my notes... silly me

Pete,

According to the info I have. The U.S. cars had a 9.0:1 and Canada cars had a 7.5:1

Possibility exists that they listed the info wrong.

IMHO .050 should be no problem. The adjustment on the rocker should have enough room to make up the change.

I am looking into the same thing you are. I have a big bearing 1300 and am looking into what i can do for a rebuild. The motor need more power, 48 HP just ain't cutting it.

Pete,
From a discussion over at the NASS page.

73 Large Valve head

Chamber cc Just over 51cc
Milled the head .100"

New chamber just over 41CC

...and some information regarding compression ratios of the "1500" engine (mistakenly cited as 1492cc when it should read 1493cc), in a chart from TriumphSpitfire.com. This chart seems to confirm what I've long heard: that for the 1976 model year ONLY, compression ratio for US-spec. engines was 9.0:1; otherwise it was 7.5:1 for the "Federal" 1500 engines.

Andrew Mace said:

...for the 1976 model year ONLY, compression ratio for US-spec. engines was 9.0:1; otherwise it was 7.5:1 for the "Federal" 1500 engines.

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What was different about the '76 engine compared to the rest of the 1500s?

If its simple as domed pistons, then this project will seemingly be a breeze.

So far heres what I've decided to get done:

-Mill the head (.050-.100, however far I can go and maintain stock rockers and pushrods
-Shotpeen the connecting rods
-Have the crank polished and check it for straightness (and Shotpeen, Nitride, Tufride, or Cryogenically freeze it)
-replace all bearings and low end bolts
-gapless rings (from totalseal.com)
-Larger bore, not too much larger, just to whatever the next available size up is to match pistons (I'd love to match the stroke @ 87.5mm but thats probably WAY overkill, so I'll probably aim for 75-80mm or so)
-Triumphtune Fastroad cam, the 83 or 89 depending on grind height, as shorter will mean I can mill the head a wee-bit more
-1.475" intake valve, and head machined to match, with 3 angle grind
-Change my carb from the single Weber DGV to twin Weber DCOE 40's, twin SU 40's, or maybe the Mikuni's if I can find a decent price
-Have the block chemically dipped, and possibly cryo, so on
-light weight flywheel (I know this don't add power, but Ive had one in the past on a diff car and I loved the difference in how the engine felt)

Looking at possibly the change to a Duplex timing chain as well. I hear I can get the double-wide chain gears off a TR6 and they will match. Can anyone confirm this?

Also thinking of going with an electric water pump. Computer or thermostatically controlled depending on price. Sounds worth it for roughly a 5% gain. Does anyone have this?

Does any company out there make a stronger than stock crank at a decent price? I was thinking about calling Eagle up for this, as I've had their X-beam rods before and I was quite pleased with them.

I hear I can/should ceramic coat my valves and exhaust port. Does this make any effect on the ability to lap the valves properly prior to installation?

pjsmetana said:

Andrew Mace said:

...for the 1976 model year ONLY, compression ratio for US-spec. engines was 9.0:1; otherwise it was 7.5:1 for the "Federal" 1500 engines.

Click to expand...

What was different about the '76 engine compared to the rest of the 1500s?

If its simple as domed pistons, then this project will seemingly be a breeze.

Click to expand...

I think that was it, but I'm not as well versed on the 1500 engines.

pjsmetana said:

-gapless rings (from totalseal.com)

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I can't tell you much of anything about the rest of your list (other than to maybe get a copy of the Competition Prep. Manual), but I can vouch for the TotalSeal rings. Years ago, I overhauled a .020-over, "race-prepped" 1147cc Spitfire engine, due to the fact that the rings on the #2 cylinder had broken, turning the engine into a great oil fogging machine. :frown: Fortunately, there was no damage to piston or bore, so I was able to hone the cylinders and reuse the pistons. I bought a set of Grant rings from TRF and sent them to TotalSeal for conversion. Decent price, quick turnaround...and great performance after a quick break-in!

Pete,

The talk on the NASS pages about the 76 1500 engine came to the consensus that the difference was using the flat top pistons and the head was milled .050"

Several different heads were measured including a european head and the measurements seem to confirm the theory. A stock 7.5:1 head being 3.10" thick and the 9.0:1 head being 3.05" thick.

The milling counts for 4CC and the dished pistons have a 6.7cc recess. The net change should being the motor up to 9.3:1 or so. Close enough for the factory to claim a 9.5:1 ratio.