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Unavoidable Engine upgrade is sadly necessary

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coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
The road to motoring bliss is never easy and I think I have hit my first major pot hole.
Driving my car to the bus stop yesterday I noticed the oil light coming on when the engine is idling, it goes out again as soon as I raise the revs just a little bit but its seems clear to me that something is very wrong there is also a slight knocking noise which makes me think that its done a big end . The Irony here is that I make this discovery just after getting my head around how to adjust the H1 SU carbs so it idles well and after I removed the excessively thick oil the previous owner had put in the dash-pots.
Anyway I have been doing some serious research on the differences between Triumph engines and I have developed "a cunning plan". I had already decided to visit my brother Peter to look at the 3 1200 engines in his shed with the hope of getting one to rebuild for my car and now I have to move that right to the top of my agenda.
Research on the net last night found an interesting article on, of all things, a Jag club page http://www.jagclub.ru/1147.html

This article confirms what I have been thinking of doing is both possible and beneficial essentially I want to put my 948 head and its twin carbs onto an 1147 block the article confirms that this combination was essentially what they did for the MK2 spitfire and that a worthwhile power boost would come from such a combination.

It would seem that I can also use the cam from my engine which reputably has a higher lift and slightly "hotter" profile than the standard 1147 bump-stick. Likewise I can install my now upgraded to electronic distributor, my water pump and any other ancillary fittings from the 948 engine. The article seems to suggest that you end up with an effective compression ratio of 9.75 to one and surprisingly that the breathing of the 6 port head is actually better than the later 8 port heads! I also quite like the exhaust manifold on the twin carb 948 engine it has fairly sharp initial bends at the top but then the way that the different branches converge into the eventual outlet flange is quite smooth and elegant unlike the single carb manifold (see the attached picture for a comparison) which has a far more convoluted path for the exhaust gasses and the inlet charge as well. While I would love to fit a nice set of extractors I simply don't have the funds to buy them at present however simply up-sizing the tail pipe with the existing manifold has to help breathing and that won't cost much to do.

Of course whichever block I do pick will have to be very carefully checked to see how much wear there is in the bores and I would very much like to avoid re-boring the block and fitting new pistons if I can, simply for reasons of cost so that will obviously require me to take the heads off them to examine the bores unless my brother has one of those endoscopes that would let me see the bores through the spark plug holes. Anyway with luck I should be able to get away with fitting new shells and rings to the bottom end but I will certainly be spending a heap of time cleaning the crankcase inside and out paying lots of attention to oil galleries ect so that the rebuilt engine will last longer than the fifty miles I have on the car since I bought it.

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claytoncnc Avatar
claytoncnc Gold Member Marcus Clayton
Melbourne, Ivanhoe, Australia   AUS
The combination you are putting together is an eminently sensible one.
An improvement could be made with HS2 carbs off the Spitfire, as the little SUs will be a bit limiting, but you will still have a noticeable improvement in torque with the little carbs.

My brother and I drove our 948 Herald from Melbourne to Adelaide and return some years ago I posted a bit of a story some years ago
http://www.triumphexp.com/phorum/read.php?10,843223

Fun things, aren't they

The article you reference is a good one by Gareth Thomas, who is best described as a controversial figure.
You can take it as read that information is accurate, but Gareth can be a prickly character, and does not post any more.



Edited 1 time(s). Last edit at 2017-08-02 02:35 AM by claytoncnc.

coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
Hi Marcus
My good friend and Triumph Guru tells me that the 948 head would result in too high a compression ratio so I may be sticking to what ever comes with the 1200 engine I get but I will probably have to stick with the H1's simply because I don't have the funds to buy and restore a pair of HS2s I think though that I will go for a far better air-box set up because there is a noticeable change in the running once I fit the air-box either raising or changing the needles may help a bit too. I keep tell my mate that I just want a bit more usable torque that will cope better with the hill I live on rather than flat out power.

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claytoncnc Avatar
claytoncnc Gold Member Marcus Clayton
Melbourne, Ivanhoe, Australia   AUS
Hi Iain,

Assuming you have a Hicomp 948 head (8.5:1) with 31.6cc chambers, the compression on the 1147 will be just on 10:1.
This is fine, if you run 98 octane.

Stick with the 1147 head, 8:1 compression and you can probably run 91 octane quite happily, compression pressure around 140 psi.
Probably no need to change the cam, early 1147s have an almost identical cam to the 948, and later ones have the same cam as a mk1 Spitfire.

Both cams are good for torque, a bigger cam will be unlikely to serve you well in conjunction with the small carbs.

Herald948 Avatar
Herald948 Andrew Mace
East Nassau, upstate NY, USA   USA
In reply to # 1475177 by claytoncnc Hi Iain,

Assuming you have a Hicomp 948 head (8.5:1) with 31.6cc chambers, the compression on the 1147 will be just on 10:1.
This is fine, if you run 98 octane.

Stick with the 1147 head, 8:1 compression and you can probably run 91 octane quite happily, compression pressure around 140 psi.
Probably no need to change the cam, early 1147s have an almost identical cam to the 948, and later ones have the same cam as a mk1 Spitfire.

Both cams are good for torque, a bigger cam will be unlikely to serve you well in conjunction with the small carbs.
I second pretty much everything Marcus has said here! I was one of those who mentioned the 948TC head, but all I'd ever heard about this came from people who raced Spitfires. By and large, the 1147 head is probably just fine, although you could consider an early Spitfire version of same, I suppose!

Assuming (and that might or might NOT be a good thing to do) that the engines you'll be choosing from are original and untouched, you can get a good idea of their original specification from the engine serial number. Most of the GA series engines will have had that much "tamer" camshaft"; GD series (aka the "12/50"winking smiley engines are likely to have the early Spitfire camshaft. And the factory "kits" for dual-carb conversions on the Herald 1200 used the SU H1s of the 948 on those early GA engines (along with other changes), while the later kits for GD engines used the SU HS2 carbs and manifold from the original Spitfire 4.



http://www.fairpoint.net/~herald948/database/

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, British Columbia, Canada   CAN
Later Herald 1147's also had a 12/50 style exhaust manifold, which looks like your 948 manifold. It had a Hot Spot for the single carb, but this can be cut off.
They also had collets on the valve springs as opposed to the 'keyhole' type retainers. I also belive the inlet valves were a little bigger.
I say this to help you asses what you see in the shed.

Don't assume the cyl heads are original or un-touched, burnt exhaust valves were common at 60k miles, and it was common just to stick another head on.

Yes, a bore scope is handy, even the $6 ones on ebay .

coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
Hi Marcus,
In reply to a post by Assuming you have a Hicomp 948 head (8.5:1) with 31.6cc chambers, the compression on the 1147 will be just on 10:1. This is fine, if you run 98 octane.
10 to one does not sound too much off the wall to be frank especially as I have no problem running 98 octane in this car

Andrew

In reply to a post by Assuming (and that might or might NOT be a good thing to do) that the engines you'll be choosing from are original and untouched, you can get a good idea of their original specification from the engine serial number. Most of the GA series engines will have had that much "tamer" camshaft"; GD series (aka the "12/50"winking smiley engines are likely to have the early Spitfire camshaft. And the factory "kits" for dual-carb conversions on the Herald 1200 used the SU H1s of the 948 on those early GA engines (along with other changes), while the later kits for GD engines used the SU HS2 carbs and manifold from the original Spitfire 4
I am already ion the same page as you on checking out which engine prefix is which and I have down loaded a page from the net telling me what each prefix designates

Tony

In reply to a post by Later Herald 1147's also had a 12/50 style exhaust manifold, which looks like your 948 manifold. It had a Hot Spot for the single carb, but this can be cut off. They also had collets on the valve springs as opposed to the 'keyhole' type retainers. I also believe the inlet valves were a little bigger. I say this to help you asses what you see in the shed.

I have sort of planned to use the 948 exhaust manifold no matter what because its probably the best one for flow and versatility of carb choice and NO Sawing required! Unlike your side of the pond or even the UK it never gets that cold here (we are in the middle of our winter and the heater has not been turned on once!). One thing that the article I cited does show though is that bigger valves do not always flow better with the Triumph head because of the masking effect of the combustion chamber design so maybe I should consider some judicious work with the die grinder to open up the combustion chambers a little reducing the "masking" effect a bit and reducing the compression ratio a touch at the same time. Time to do some more research on that I think.


Anyway thanks to all of you guys for sharing your knowledge and experience because it gives me some hope that my initial idea of using the 948 head is not totally off the wall or non-viable.

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clshore Carter Shore
Beverly Hills, Florida, USA   USA
Well FWIW, any 1147/1296/1500 Spitfire motor is nearly a bolt-in swap.
I had a Herald sedan for a couple of years and swapped in a spare 1147
that was mildly tweaked, along with the tubular header and HS2 carbs.
I also fitted the Spitfire front spindles along with disk brakes.
It was a nice combination, I daily drove it for awhile in Miami.
The Sedan was very nice and dry for the rainy season, and even in the summer heat, ventilation
was good enough to be comfortable.
I did often wonder how it would have fared with A/C though.
Wish I still had that car, I would up selling it to a Father/Son to restore as a project.

coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
Well all of may high hopes of having a good starting point for building a decent engine for my coupe have been sadly dashed because teh engines I went to look out turned out to be 948s!

So no I have the ongoing dilemma of trying to find another engine or to contemplate doing a more radical engine swap to something else that is maybe a bit more modern. The thing is I don't under any circumstances want anything that has a computer so that means no fuel injection. The answer I keep coming back to is a 1.3l Suzuki samurai engine it has an alloy block which is good distributor ignition and the oil pan has the right shape to easily fit in the herald. As much as I like the Suzuki gearbox (5 speed and sycros on all forward gears) it has no provision for a speedo drive which means U will have to either make some sort of drive or use GPS. The gearbox is a fair bit shorter than the herald box though.

Anyway that is plan "b" unless and Aussie member here has a spare engine (1147 . 1300 )that they don't need kicking around...

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Herald948 Avatar
Herald948 Andrew Mace
East Nassau, upstate NY, USA   USA
Did you ever drop the oil pan on the current engine and look at the bearings? I'm thinking -- short-term -- you might just toss in a new set of bearing shells, then you could at least enjoy the car a bit while you contemplate more radical measures?



http://www.fairpoint.net/~herald948/database/

coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
Hi Andrew

Well Ive run it a couple of times over the weekend and it has not done the oil light thing again so Ive decided that I will do the run between my home and the bus stop and if it goes bang its not too far to get it home!

In the mean time I have been scouring the adds on eBay and Gumtree looking for a good Suzuki engine so far the only complete and going ones I have found are at the other ends of the country too far to collect and too expensive to ship sad smiley

coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
So I have bitten the bullet and sourced another engine for my coupe and as much as I wanted to go for a buy a bigger Triumph lump it could not be done. So instead I have bought a 4K Corolla engine and its 5 speed transmission. Its a swap that has been done before so I'm no breaking entirely new ground here but already I know that there will be a couple of issues to address Firstly the exhaust is on the other side and although the motor has tubular headers I think I will have to do some work on them to get them to fit within the space available. I have already re made the oil pan to move the "hump" back as far as I can so it will not foul the front cross member which took me a whole day to do mainly spent chasing pin holes on my seams in the end I was pretty sure I had them all but applied some epoxy over all of my welds just to be sure it won't leak.

The next issue I have to worry about is that the gear shift lever is mounted right at the very end of the extension housing on the KE70 box that I have which means the lever will be a bit further back, not such a bad spot really according to my calculations but this will require me to do something with the hand brake think I can get away with just shortening the lever a few inches and I have tried pulling it up from close to the gaiter and it seems to work well enough But failing that I may have to do something else entirely Like fit one under the dash. This all means that the transmission tunnel/cover won't do either so that to will have to be remade so that it fits more snugly> the up side is that the cabin will feel a bit more spacious as a result be cause the Toyota trans is nice and narrow and not as high as the Triumph box either because it far better includes the remote shifter into the extension housing rather than in a separate casting above it. I will probably make the cover out of steel

The pictures of the engine do show it with a FI manifold that came with the engine This is not something I plan to use at all because I want to get away as much as I can form bloody car computers I fortunately have another Carb manifold and I am awaiting delivery of a brand new carby that has a mechanical secondary throat rather than the vacuum set up that would have been standard for a KE70. Further I will not be running an engine driven fan because that can eat a great amount of precious horsepower.


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coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
Ah the joy of engine swaps!
Have test fitted the engine and find that I really need to move it forward as much as I possibly can and that means that the sump I took so much time to make will not cut it so I have worked out how to move the oil pick up further back and I will be making oil-pan number two tomorrow with the the deep bit right at the back so that I can move the whole kit and caboodle at least 4 inches further forward.

coupe  948 downunder Avatar
Brisbane, Queensland, Australia   AUS
I have been making steady progress sorting out the engine swap. The front engine mounts were not that difficult to make once I had the engine propped up in its correct position it was simply a case of starting with the part of its original mounts that bolts to the engine cut off and then with a piece of 2' angle drilled for a base plate bending various bits of steel strap bent to make the connections once shaped and tacked in place the mount was unbolted form the engine for final welding with various gaps filled and filly welded Of course as the $K engine is slanted to the left one side is quite a bit higher than the other but both are very strong and will look fine with a bit of tidying up with the grinder a coat of black paint. The engine is about to come out again so that I can put a notch in the frame to clear the back corner of the gearbox on the LHS and hopefully get the output low enough for a good tailshaft alignment.


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ng19delta Avatar
ng19delta Scott Roberts
Merchantville, NJ, USA   USA
1974 Triumph TR6 "Not Sure At The Moment..."
I had a single carb 1147 engine in my (former) Herald, but equipped with a Spit III cam, and the dual SUs from a Spitfire... I found through research that the intake valves on the single carb head were larger than those on the Spitfire dual carb head: With that setup, that car RAN... She could regularly run with the needle quite literally buried- beyond the top speed on the speedometer- and quite happily, too... I ran her up to Andy Mace's place in NY one time, cruising all the way, as well as regular trips to Baltimore, Md. (I am in NJ, near Philadelphia, Pa) I even blew the doors off a Corvette one time on I-95 (although I doubt he realized I was trying to!) Long story short, it makes for a GREAT combination on a Herald- She used to run away from Spitfires smiling smiley

Scott

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