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1275 Parts Decisions have been Made

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Bruce_B

Bruce_B

Jedi Warrior
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Well, after much reading, searching, drinking of libations, I've finally made my decisions as to what's going into the rebuild of my '67 1275 engine for my '59 BE. Hardest decision was the CAM, asking opinions on CAMS gets you 100 different answers. I still welcome opinions, but unless they're backed by some pretty hard science...here's what I'm going with:

(1)Longman GT7 non-aluminum head - bigger valves, 3 angle grind
(2)Swiftune 1.5 hi-lift roller rockers
(3)Swiftune SW5-7 Camshaft
(4)AE +40 Dished Pistons 212511 - possible 9.5 CR
(5)Swiftune alloy vernier duplex sprockets and chain
(Swiftune has a good kit at a good value, even when shipped from UK)
Will be using all upgraded rod & head hardware. The engine will be balanced. Not sure if I should lighten the flywheel or not- keep getting different view on pros & cons of that action.

Next big decision is the distributor. I'll probably start with the standard 25D4 I've got on my 1098 engine (With Petronix Ignition).

Ideas - Opinions?
 
No opinons, but I'll be really interested to see how your build goes. I've got a 1275 from a 74 Midget waiting in the wings for the Tunebug. Haven't even begun to really think about direction for it yet.
 
Me too, Drew!! You've got at least two watching Bruce /bcforum/images/%%GRAEMLIN_URL%%/grin.gif! What part of N.J. are you in? I used to live up there!!
 
Bruce:

IMHO, that cam with the offset rocker combination seems too much lift and possibly too high a powerband (starting at 2500 rpms) for street use.

Patrick

BTW I am interested in the '67 head if you would like to sell it.
 
Mike - I live near Flemington, NJ.

Patrick - I've sent questions to Swiftune and they say it will work fine (Of course they're selling the stuff!) But I've also read other reviews of people with this combo and they like it, powerband coming in around 1200 rpm. But...what Cam would you recommend?

Info from https://www.7ent.com blub on the SW5:
In a road 1380 motor with good st3 head, single HIF 44, LCB, std rockers will produce upto 94 BHP with around 93 lbs/ft, with 1.5 ratio it will gain 5 BHP extra right through the range. Twin carbs produce over 100 bhp
I know they refer to a 1380, but that displacement wouldn't change the cam's behavior.

Drew - anything you can learn from me...you're welcome to it!
 
Suggestion, instead of the AE 21251 piston, get the
AE 21253, it basicly the same exact piston in every way except the 21253, has less oiling slots in oil control ring land and more material holding the top and the bottom of the piston together, a much more sturdier piston for the same money.

I do this for a living and order from the UK, the cheapest rate UPS currently gives is express, which is out of site expensive, a cam size box cost me $141.00 and I have a commercial UPS account, ask them about alternatives on shipping.

On distirbutor, I recommend Jeff Schelmmer at Advanced Distributors (612) 804-5543, he's a LBC nut just like us, he will rebuild your distributor, recurve it for performance, based on the specs of your engine, he will convert it to petronix cheaper than you can buy one, and it's really not that expensive, Jeff does a great job we use him all the time.

If you need somebody to rebuild your SUs, I know a man in SC, that does a killer job /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Oh, you going to love that vernier gear set when it comes time to degree the cam, I won't build a race motor without one.

I would go with ARP 206-6001 rod bolts, don't let anybody try to sell you that Chevy crap, ARP head stud kit and flywheel bolts, I keep most of the ARP stuff in stock.

Do all the right machine work, line bore the block with the rear crank cover in place, forget about the rear seal kits. Get someone to make you some solid spacers for your new rocker arm, and I would go with tubular pushrods. Drill out all the brass oil galley plugs and replace them or tap for NPT plugs (don't overlook this)

Last but not least make sure you break the motor in on a zinc rich oil, I like Vavoline racing VR1 20/50 or Rotella 15/40 diesel oil ( you can get both of them at your local p[arts store), break the cam in at 2000 rpms for 20 minutes.

Sounds like you going to have a nice little motor, good luck and have fun.
 
Hap,
Apreciate the advice, I've already supplied the machine shop with ARP kits for the flywheel and the rods. They now have everthing they need for balancing. I went with the 21251 piston because the pin height and the CR were higher with the 21253s. (APTFAST facts)
I will be using a single HIF6 (1.75" carb. ) and a Titan style manifold. Wasn't sure about the line bore, but if that will help with a leak proof engine--I'm for it.

Do you recommend lightening the flywheel?

Hopefully it should be a good street motor. I'll be in touch with you later for the ARP cylinder head bolts, gaskets sets (good ones) and other stuff. (there's always other stuff...)
If there's other goodies you know about....
 
Bruce:

I looked at your link and it is milder then I had thought. It seems very similar to what I am running in my BE. Mine idles very smoothly with a little cammy noise and pulls well from about 1500.

I thought the cam you are installing had more lift and was concerned with the 1.5 offset rockers. I had mine rebused with a small offset so they are about 1.3.

My compression is about 9.2-3 and I am very happy with the pull, but I must warn you in NYC, I drive down the street and the car alarms go off hehe.

Since I am in NYC, if you would ever like to look at mine or go for a spin, please let me know.

Patrick
 
Patrick,

You drive a BE in NYC? --you the man!!

I looked into rebushing my 1.3 rockers with offset bushings, but the cost vs. buying the Swiftune Hi-Lift Kit from the UK didn't make it cost effective.

Many years ago (1970's) I drove my 67 MGB into NYC and then to the Brooklyn Botanical Garden...thought the car was going to break in two.

Now I live in a beautiful area on the Delaware River, with great country roads.

You've got to come out in the spring!! Hmmm..maybe a Forum Party By the River ---I smell Bar B Q!!
 
Bruce,

Yes I do drive some LBC'c in NYC. Double floor boards and a roll bar help a bit, driving LBC's for 30 plus years does also.

I was dispositioned from a barn in Tranquility, NJ and still need to keep some of my old loved friends close by.

Try driving a pre war one here and you are in my world.

My offer stands (plus you can check out the other things that have been done "tastefully", I hope) if not a BBQ (with great roads) sounds great!

Patrick
 
Are those Swifttune parts lovely or what, look at those rods.
 
Actually, the 21251 and 21253 have the same exact dish volume. You'll be fine with 21251 in a street car, but I only used them one time in a stock 1275 rebuild, I used the 21253 in several SCCA Limited prep race engine and performance street engines, I use them in the LP race motors when the customer doesn't want to budget for the more expensive JE forged pistons because it is a sturdier built piston for the same money when compared to the 21251, offer me better for the same money, and I will always choose better. I compare the 21251 and 21253 side by side, the entire piston design, including pin and compression hieght is identical in these two pistons, the only difference being less oiling slot in the ring land area, thus more material holding the piston together. Don't sweat it, it will work fine, it's just not what I would have chose.
 
Hap,

This is what Minimania writes about the pistons:

21251 Pistons
Low Compression 1275cc Sprite or Midget replacement piston choice has a pin height of 1.4689" which could result in a compression ratio of 8.8:1. They have a 4mm oil ring and two 1.5mm compression rings. Available sizes: std., +.020, +.030, +.040, +060

21250 Pistons
High performance replacement pistons suitable for up to 7,000 RPM. Pin height is 1.498 which could result in a compression ratio of 9.4:1. They also have 4mm oil rings and 1.5mm compression rings. Available sizes are std., +.020, +.040, +.060.

21253 Pistons
Best performance stock piston have a possible compression ratio of 10.0:1. Pin height of these is 1.5276. Performance is enhance by the use of 3mm oil rings and the smaller drain slot behind this ring decreases the risk of breakage under severe loads!

I ordered the ones that are described as 21250 - with CR of 9.4:1. On this list it says that 21253 have different CR and pin height. I'll have to check with David at APT that he's sending the correct ones. Couuld just be different use of catalog numbers used for marketing.

Looking forward to putting it all together!
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Get someone to make you some solid spacers for your new rocker arm……..Drill out all the brass oil galley plugs and replace them or tap for NPT plugs (don't overlook this)[/QUOTE]

Hap:

You mean instead of the rocker arm shaft springs? What sort of side clearance for these spacers? (maybe 0.010” or so?)

Also, I am not clear where these galley plugs are? It sounds like the originals pop out….is that right?

I am building a mostly stock 1275 for VRG vintage. Re-bore cylinder and reground crank. I’ll get the pistons you advise and a mild cam from ARP. Maybe take 4 pounds or so off the flywheel. Mostly, I’ll just keep it under 6300 and it should be OK.

Bruce_B and GB!:
I am about 1 mile from Lake Tranquility and I make it out to the Delaware River on a regular basis.

Since you guys are in the NY/NJ area, you guys should go to the Moss Motors Britfest on May 5 in Succasunna, New Jersey.
I can’t go, because I’ll be at an EMRA race at Pocono the same weekend (and by the way, you’re welcome to come to any of our EMRA races as well).
 
You mean instead of the rocker arm shaft springs? What sort of side clearance for these spacers? (maybe 0.010” or so?)

Yes, this can be a teadous job, yeah .010", basicly you just want to make sure with everything torqued down, you can still spin the solid spacer and they are not locked down.

Also, I am not clear where these galley plugs are? It sounds like the originals pop out….is that right?

The original oil galley plugs are brass, you need to drill them out so you can properly clean in there, some go back with the repalcement brass plugs, but on a race engine you will be agin do re-freshes and want to clean the galley again, so tapping for NPT plugs leaves you a with a servicable oil galley plug.


I am building a mostly stock 1275 for VRG vintage. Re-bore cylinder and reground crank. I’ll get the pistons you advise and a mild cam from ARP. Maybe take 4 pounds or so off the flywheel. Mostly, I’ll just keep it under 6300 and it should be OK.

If you're not porting the head, do what we do with the SCCA LP heads, look for a head with upward core shift, pay close attention to how much of a boss in the exhaust ports, alot of the time they will be huge, but if you find a head with upward core shift, thee will hardly be a boss present and the intake guides bosses will also be considerably shorter, all this equates to additional flow, a good stock head core when compared to bad head will flow an additional 5cfm a port more, to give you an idea, how much an advantage 5cfm is, when you compared a good stock head core to a fully prepped all-out race ported head the gain is only about 5 cfm per port, so you can see the advantage of a good stock head core, of course if you are porting, all wrongs with the head can be corrected. If you are poerting then front to back core shift becomes more important, look at head stud holes on the spark plug side of the head, are they centered on baised to one side, on a head you're going to port, a centered fornt ot back core shift is desired to allow you not to worry about hitting water jackets or pushrod hole when porting.

As for cam, I use APT cams for my street engines, but I think you need a little more cam for your budget race engine, for the same price as a APT cam, you can get a Comptune SCCA LP/HP cam, with stock rocker arms that will give you about .450 cam lift and make good power to about 7000 rpms, which is nothing for a A series motor. I would look at setting the compression ratio at atleast 11.0 to 1, with 21253 piston at zero deck out, you need to deck the head about .035" to get you to 11.0 to 1, but since you're not running with the SCCA, I take off more like .050" to get you closer to 12.0 to 1, still pretty conservative for 1275, any head gasket will work at those compression ratios. With really no more budget, the addition of the Comptune cam ( same price as APT's regrinds), some block decking, some head decking, you could easily see another 20 horsepower and still have a very relaible engine. Call me sometime, advice is free /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
Hap:

Thanks for that....Now I see why you remove the brass plugs (I didn't think about the cleaning-out problem).
I have two 1275 heads (and I think I can get one more for free), so I'll look and see which is better in terms of core-shift.
The Computune cam sounds good and 11:1 compression ratio would be fine with me.
As you can tell, this is just a "playing around" engine, so even if it just ends up as fast as my present 1500 (about 75 HP), I'll be OK with that.
I'm ditching the 1500 because it's not technically legal for vintage....but the VRG guys will let me run the 1500 for now (and it runs fine). VRG is a nice group....very layed back as long as you "play nice".
I'm building an Escort GT twin-cam for regular EMRA club racing right now. I'll have it done by mid April (for Summit Point). Probably in May I'll really start to work on the 1275. Meanwhile, I have your phone number (from the Acme site). I'm sure I'll be giving you a call at some point.
Thanks again.
 
Bruce, the compression height on the 21253 would be almost .060 taller, that's not right, I measure one I have lying arond the shop and report back. With 21253 in the LP engine we still had to cut the block a good .020" to get them to zero deck height. You would never get to 10.0 to 1 with a standard deck height and 21253. Oh and another thing the 21253 has a nice three piece oil control ring and the 21251 ahd a piece of junk one piece cast design.
 
Hap,

Just spoke to APT and got the confusion cleared up. Minimania is of course Mini-centric, they're pistons are a bit different than those for the Spridget engines. Anyways, I'm not sweating it --the pistons just arrived at the machine and it's a go!!
 
Hap,
You said in an earlier posting:

"Do all the right machine work, line bore the block with the rear crank cover in place, forget about the rear seal kits."

Is the rear crank over also referred to as the "crank rear oil seal"? Just want to make sure I give the machine shop the right part.

Thanks.....
 
Bruce, the cover is the little half moon bit held on with the three safety wired bolts, on the rear of the block directly above the crank.
Jeff
 
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