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How to build an affordable performance 1500..??

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oldag98 Avatar
oldag98 Jeff Brackenridge
Choctaw, Choctaw, Oklahoma, USA   USA
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1969 MG Midget MkIII
1975 MG Midget Conversion
1976 MG Midget 1500 "Yellow One"
1977 MG Midget 1500 "Dunkirk"    & more
Since many members seem to think that the MG 1500 (Triumph 1493) is poo for an engine, here is a thread for the more enlightened engine builders, and we weekenders, to share the exact reasons why the 1500 is, or is not, nothing better than a boat anchor. Please be specific though, as to what exactly about the 1500 makes it an unsuitable, or a very suitable, platform for performance enhancements, and, what are these enhancements, i.e. is it the notches in the top of the engine cylinders creating a weaker head gasket sealing area-how does one work around that; is it the crankshaft thrust washers falling into the oil pan- how do you prevent that; is it the fact that we stick Weber DGV's on them and expect a miracle- how do we tune the Webers better? Who makes the best pistons to increase the compression of our lower compression smog motors, without having Keith Black make custom pistons, which cost more than the entire car did, etc...??? There are many many of us out there who have 1500's and would like to make them better, quicker, more powerful, more reliable, etc, so we do not get run over on the highway, but are not schooled on the pros and cons of performance enhancements for the 1500. Most of us also do not have a wallet of a sponsored racing team, and do not live near Hap, so exotic enhancements are not going to be likely for most of us. I am not looking for posts that say," Pull the 1500 and put in a 1275," but would rather hear the best, or better, ways of taking advantage of the 30 years of technological development and performance experience to make my 1500 better, stronger, faster, without having to spend $6,000,000. Maybe some Motorsports forum members, especially Hap, will chime in with some intelligent info on enhancing this engine for all of our benefit??...

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dlrhine Avatar
dlrhine Dave Rhine
Columbia, SC, USA   USA
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The most bang for the buck would seem to be raising the compression.

From what I've read, you can gain about 20 hp just by changing the pistons to the Euro style flat tops.

While changing out my trust washers, I saw evidence of a previous rebuild on mine...got me curious, so I peeked down the spark plug holes & found flat top pistons, not the original low compression dished style.

Now, mine's no drag strip terror, but is is surprisingly strong up to about 4500rpm, probably a hotter cam & a little head port clean up, would put me where I'd like to be.

Here's a link that might give some ideas:
http://www.visn2.com/Flash%20Website/1500_Engine_Modifications.html



If it ain't broke, I'll fix it until it is! winking smiley



Edited 1 time(s). Last edit at 2010-06-02 06:12 AM by dlrhine.

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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Taylors, SC, USA   USA
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1967 MG MGB Racecar "The Biscuit"
I've built a few SCCA limited prep 1500 for a couple of Spitfire drivers, we used the Rick Cline recipe, meaning TR6 piston and decked a bunch off the block to get to zero deck, which get close to the rear core plugs, but would so less on a street egnine, then we decked the head .100 to create 11.0 to 1, the max allowed compression ratio for SCCA in this engine formula. I think the wahy to do this for a street engine would be use the TR6 pistons, leave the deck height more conservative, say about .020-.030, then deck the head to get to just under 10.0 to 1. Now decking the block on a 1500 this much will get rid of the 1500 head gasket depressions, but that not such a bad thing, you would now use the 1300 head gasket (1300 and 1500 same bore different strokes) The STD. TRP piston is a .040: over 1500 piston, so looking at the head gasket bore may let you go bigger, you could probably go with a .020-.030 over TR6 piston and still be ok with the 1300 head gasket, which would make .060-.070 over 1500, going bigger may be possible , but without a head gasket to measure, I can't say for sure. One fo the cheap thing BL did with the 1500 was run the cam on the block without cam bearing, it was all about cost saving, but when they did this they simple made the camshaft journal larger to accomondate the block, so you can use 1300 cam bearings, and a 1300 cam to get a 1500 with cam bearings, I done this several times, it's work greeat. The thrust bearing issue with the car can easily be avoided, if people won't sit at stop signs and red lights with the car in gear and their foot on the clutch, on the race engine we never even worry about, because we don't sit around with our foot on the clutch.

The 1500 engine has plenty of performance potential, it just that not many street car guys know that, but hot shoes racers like Bob Criss and Steve Sargis know this and win races, and national championships with 1500s.

I think the 1500 Midget street crowd has now been around long enough to start tweaking their cars, and when they serious about, these will be without a doubt the fastest of street midget as for HP.

Ok with that being said, I still prefer my A series engines, but there is no denying that the 1500 has a buttload of potential. The 1500 has displacement level the 1275 just cannot get to, and displacment makes power. In racing 1500 cars have to weigh more, and displacment is the reason why. This engine does not have the wide array of goodies the A series engine has, but with a creative mind that can easily be overcome. We have seen some prety serious money thrown at 1275s to pump them up in performacne, when we see the same sort of effort in the 1500 Midget, it will make more HP, hands down.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street Engines - Cylinder Head Porting for street performance and race - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sports Cars, and others
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twigworker Avatar
twigworker Jack Austin
Blowing Rock, NC, USA   USA
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I too am a fan of the A series engines Hap but I don't have any deep seated dislike for the Spitfire motor.

You obviously have tons more experience with the Triumph engines, but am I misguided when I think of the crankshaft and thrust washer failures of the larger engine?

I suppose I am being a little gun shy when, as you say, just about any shortcoming can be overcome, but are those deficiencies dangerous in a stock or a slightly warmed up engine as opposed to a five thousand dollar super motor?

Jack



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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Taylors, SC, USA   USA
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1967 MG MGB Racecar "The Biscuit"
Jack, I don't know I would term a $5000 motor as a "super motor", when most of us in the business get $4000+ for a good stock/stage 1 engine, in fact soem of my competitors think I'm giving my work away smiling smiley

Here's the deal the race engines never seem to have thrust bearing problems, so what the difference in the two in that regard, people holding the clutch at the red light ,and stop signs is all I can fiquire and that bad habit can be broken by the operator. The thrust bearing design, could be better, but some the mods I seen are hokey at best, like pinning or screwing them down, which is fine and dandy if you never reach the point of the pins or the screws, but when that happens it gonna get real nasty, real quick. The other so-called remedy I heard about is machining the main cap for thrust washer as well, but since these thrust bearing have no locking tabs on them like MG engine, it comes right back to pinning or screwing them again. I think the best fix for the thrust washer issue is controlling the left foot, same fix to make a a MGB throw out bearing last longer smiling smiley.

Jack I think when we were young we didn't give a crap if things lasted, so we drove these cars badly, like heavy downhsifting to stop lights, really a dumb thing to do, brakes are always cheaper to rpelace than transmissions, but what the hay we were young and dumb, holding the clutch at red light is kinda a realy questionable thing to do as well. I'm sure most of the folks doing that to a 1500 engine when these car were newer never thought a minute about it's thrust bearing design, but now that these cars are not day to day transportation for most of us and we know better we can fix the the problem by changing our driving habits.

Thrust bearings are one of those things that makes me go hmmmmm on some of our engines, the 1500 design being one of them, but then again the A series engine have huge very durable thrust bearings that will outlast numerous rebuilds, I never replace them in a A series engine rebuild, but the bigger MGB has a very similar thrust bearing design, but came with little tin covered junk for thrust bearings, go fiquire.

Lord knows I can pick on any engine design, and the 1500 for sure, why the hell is such a small engine so freaking heavy, everything in it weight about twice what it should, it full of 5/16" fastners where 1/4" would work fine, it crank is way too big and bulky, and I not crazy about the head and how the valve springs don't sit in a bucket, making changes in valve spring diameter much more of chore, but with all that said, the engine has gotten a worse rap than it deserves, it was always the red headed stepchild of the MG world because of it's Triumph root. I guess I'm tired of hearing people telling 1500 owners to get a 1275, and not buy 1500 RB Midgets, I believe there is whole new generation of LBC owners coming along, and many of them are RB Midget owners, and over time they will invest in their cars the same as the Bugeye crowd, and it way time to dispell the myths.

The only example I know of thrust bearing falling into the oil pans is engine with a ton of miles on them. MGB owner think nothing of replacing rod bearing at 60,000 miles, so the same advice could be warranted for thrust bearing in Triumph engines the way I see it. it's not the greatest design for sure, but bad driving habits and neglect are the biggest reason for it doing damage as far I can tell.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 1 time(s). Last edit at 2010-06-02 03:45 PM by Speedracer.


Member Services:
MG/ Triumph Performance Street Engines - Cylinder Head Porting for street performance and race - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sports Cars, and others
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kellysguy Johnny Stevens (Disabled)
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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Taylors, SC, USA   USA
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1967 MG MGB Racecar "The Biscuit"
In reply to a post by kellysguy Hap, what I want to know is why can't the rods from a 1300 or 1100 be used to make up the difference w/ the TR6 pistons? Are the rods the same b/w those motors and compression height is used to compensate for difference in stroke?


What is the pin dia, compression height and dia of the stock 1500 piston?

Now I not a s wise to the exchangabilty of parts on the Triumphs as I am on the MG motors, but I think the rods on the 1500s and 1300s (big journal engines) are pretty much the same deal, they both use .812" pins just like the 1275 and MGB, and TR6 for that matter, the piston compression height on the TR6 pistons, I don't have that right off the top of my head, but the TR69 piston is like .250" shorter in compression height, so you have to wack the block pretty good, which gets kinda close to rear core plugs in the block, but it's been done plently of time, and worked fine, the really cool way to do it, but more expensive, would be to get some JE or likewise custom pistons made, and go as big as you go on bore and use the 1300 head gasket.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
MG/ Triumph Performance Street Engines - Cylinder Head Porting for street performance and race - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sports Cars, and others
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kellysguy Johnny Stevens (Disabled)
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oldag98 Avatar
oldag98 Jeff Brackenridge
Choctaw, Choctaw, Oklahoma, USA   USA
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1969 MG Midget MkIII
1975 MG Midget Conversion
1976 MG Midget 1500 "Yellow One"
1977 MG Midget 1500 "Dunkirk"    & more
Excellent input from both Dave and Hap. So, in order to get more out of our 1500's, the following should/could be done, but maybe not in the order listed:
1) Deck the block to 0 deck to remove the notches in the block between the pistons. Use the head gasket of a TR6 1300 in stock or .20 or .30 overbore sizes, depending on the 1500's block's bore sizes.
2) Bore cylinders .040 inch larger to use the STD TR6 piston to raise compression (or bore larger and use larger TR6 pistons and head gaskets).
3) Deck the head to reduce combustion chamber size and raise compression further.
4) Use a 1300 camshaft and install 1300 cam bearings. No block machining required to do this.
5) Where should the head be ported to better air flow?
6) Don't ride the clutch at stop signs and stop lights to prevent excessive thrust bearing wear, while monitoring thrust bearing wear with occasional crankshaft endplay measurements.

What about adding head studs, any benefit to this considering the above block decking/compression raising procedure?
Is polishing, balancing, and shot peening the rods in my 1500 going to give me anything?
Can I lighten/streamline the crankshaft throws to get the engine to spin up more quickly? Any benefit vs. cost in doing this? Anyone set up a Weber tuning seminar for us yet?
Should I fab a windage tray for the oil pan? Anyone make the main studs for this? Any real benefit to this?
Does anyone make lightweight undercut intake and exhaust valves for this engine?
What hotter cams are available for this engine and from whom?
Anyone make roller rockers, screw in studs, and a stud girdle for this engine?
Should the engine be balanced internally or externally?
Anyone make a fluid dampener that fits?
Finally, and this is off the engine topic, I have heard there is a Datsun tranny swap which fits the RB midgets. From which year and which Datsun is this and how hard is it to do?

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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Taylors, SC, USA   USA
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1967 MG MGB Racecar "The Biscuit"
Jeff rather tha quote you or just try to remember all your question, I just answered them the best I could in the order you asked them. Hope this helps. I think we are starting to get a little off track on inexpensive, but nevertheless less, here's my opinion for whatever thats worth smiling smiley

1) Deck the block to 0 deck to remove the notches in the block between the pistons. Use the head gasket of a 1300 in stock or .20 or .30 overbore sizes, depending on the 1500's block's bore sizes.

I'm not saying you should zero the deck in street engine, far from it, that was the Rick Cline race engine recipe, but I would definately leave a negative piston to deck height. Zero deck height is big PITA, because rod will always come a few thou different in lenght due to big end sizing, in zero deck heights, you would deck the block to the shortest rod piston assembly, then machine the other piston top to get back to zero, there is absolutely no nedd to do this to street engine, heck I don't even do this to race motors anymore. You'd have play with the number in a CR caculator,and come up with a negative deck height and combustion chamber volume that got you to something under 10.0 to 1

2) Bore cylinders .040 inch larger to use the STD TR6 piston to raise compression (or bore larger and use larger TR6 pistons and head gaskets).

Or you go with a oversize TR6 piston, the head gasket is your limiting factor, most factory head gaskets will allow you to use a bore size of atleast .080" over stock, in that case you for example you might could use a .040" over TR6 piston.

3) Deck the head to reduce combustion chamber size and raise compression further.

Yep these heads can take a lot of decking, racer have gone well over .100" to achieve the compression ratio they desired, so you would not be doing anyhting to lesser degree than has been done before.

4) Use a 1300 camshaft and install 1300 cam bearings. No block machining required to do this.

This just makes sense to me, and I have personally doen without issue. I've also known Triumph racer who did the same thing , but used a 1500 camsahft in which they turn the journal down in, this is a bit more involve and as oil grooves have to be redone.

5) Where should the head be ported to better air flow?

There's lot s folks that do this type of work, myself included.

6) Don't ride the clutch at stop signs and stop lights to prevent excessive thrust bearing wear, while monitoring thrust bearing wear with occasional crankshaft endplay measurements.

yep

What about adding head studs, any benefit to this considering the above block decking/compression raising procedure?

ARP makes head studs, this is always a good investment

Is polishing, balancing, and shot peening the rods in my 1500 going to give me anything?

Polishing a connecting rod add strenght to the rod by removing possible stress risers, but this is more about substained high rpms, which a street engine will not be subjected to. Thes roads are known for breaking in street motors.

Can I lighten/streamline the crankshaft throws to get the engine to spin up more quickly? Any benefit vs. cost in doing this?

Sure it will increase acceleration rate, but this is expensive job, expect with index grinding and balancing, you goign to dump near $1000 in a cranksahft for s treet mote, this is the sort of thing a very seriuos racer does, not needed for street engine in my opinion. I'm one fo the few LBC rebuilder that does crankshaft lighteneing, and I would tell you to save your money, an aluminum flywheel makes more sense for the street to lower rotating mass.


Anyone set up a Weber tuning seminar for us yet?

Should I fab a windage tray for the oil pan?

Not on the street, racers do this because of the high G forces they do during cornering, a street car on street tire is not capable of such g forces, it would be a wastre in my opinion. Consider a good SCCA race Midget on slick can do near 2 Gs cornering, Lewis Hamilton (Formula ! world champ) on street tire couldn't make a street Midget exceed 1 G, save your money here too.

Anyone make the main studs for this? Any real benefit to this?
Yes I beleive ARP does. Studs , bolts doesn't really matter, we done it both way in the race engines.

Does anyone make lightweight undercut intake and exhaust valves for this engine?

I'm not sure, Triumph racers have doen some wild stuff over the year here, some getting custom valves made, some using stuff form other engines, alot of them playing smaller stemm diameters, none of this is needed for a street engine.

What hotter cams are available for this engine and from whom?

I'd look at what APT offers, he made good stuff, and it is properly hardened, and he now makes good lifters for Triumph motors as well.

Anyone make roller rockers, screw in studs, and a stud girdle for this engine?

I don't think anyone does a stud mounted rocker set, and maybe thats a good thing. Call Joe Siam at Checquered Motors he should be avle to fix you up with Harland Sharp set up, probably won't be cheap though


Should the engine be balanced internally or externally?

I lie to blance every compnent separately, there is no good reason for any machinist to blance thing together in a inline motor, other than laziness.

Anyone make a fluid dampener that fits?

At one time I made some aluminum pulley for 1500s, but that has been a while back. I'm not aware of anyone making a off the shelf unit, someone like ATI could custom make you one, but again very expensive, fiquire $750+, not worth it for street motor in my opinion.


Finally, and this is off the engine topic, I have heard there is a Datsun tranny swap which fits the RB midgets. From which year and which Datsun is this and how hard is it to do?

Sorry, no clue.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 1 time(s). Last edit at 2010-06-03 07:40 PM by Speedracer.


Member Services:
MG/ Triumph Performance Street Engines - Cylinder Head Porting for street performance and race - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sports Cars, and others
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kellysguy Johnny Stevens (Disabled)
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dlrhine Avatar
dlrhine Dave Rhine
Columbia, SC, USA   USA
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Good question about the pushrods, I was wondering about that too.

confused smiley



If it ain't broke, I'll fix it until it is! winking smiley

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oldag98 Avatar
oldag98 Jeff Brackenridge
Choctaw, Choctaw, Oklahoma, USA   USA
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1969 MG Midget MkIII
1975 MG Midget Conversion
1976 MG Midget 1500 "Yellow One"
1977 MG Midget 1500 "Dunkirk"    & more
I am still digesting the information above, but I wanted to thank Hap personally for sharing his experience for all of our benefit! He is most probably right about getting off track on expense, but I will need to do a rebuild on my engine soon and wanted to have an idea about what was possible and/or affordable and what might be too exotic or unnecessary. This thread and his experience is really helping me narrow down my future engine rebuild "TO DO" list.

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GlenP Glen Phillips
DFW, TX, USA   USA
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1972 MG Midget "Annabelle"
1976 MG MGB "Guinness"
1977 MG Midget "Widget"
X2 on Hap's input. I wonder if, a year from now, there'll be a sudden increase in the number of hot-rodded RB Midgets tearing up the pavement...

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kellysguy Johnny Stevens (Disabled)
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