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Which 1275 to get?

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TexasSprite

TexasSprite

Jedi Hopeful
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I have a 59 BE with the original 948. When looking for a 1275 to replace the 948, are all 1275's the same or are there production years to look out for? The plan is to go pretty much stock.

Thanks for the input!

Mike
 
They are all pretty much the same (except for the very early ones with the thin flange at the bottom).

Just look for one in good condition.
Clean bores, and minimal overbore, and a serviceable crank.
 
I think the only major differences were whether they were high or low compression engines. That can be determined by the engine # found on the right side of the block by the temp. sender, i.e. typical # such as 12CC/Da/<span style="color: #FF0000">H</span> or <span style="color: #FF0000">L</span> 101 (H being high compression and L being low! /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
 
Was the high/low compression versions just a difference in pistons?
 
I believe so! The low compression engines were generally the smog versions, i.e. later! Look for the air-rail fittings on the right side of the head on these!
 
'67's are best but '68 and '69 1275's still had the High Compression Engine even with the Air Injector Ports. The brings up an interesting question, Injector Ports are plugged on my spare 1275 which is a "H" engine with regular bolts that stick out from the side of the head, not nice looking Allen Head type bolts. Is there some sort of stop machined into the hole for the Air Injector ports or does the thread go all of the way into the head/combustion chamber. Wondering if I now have additional CC in the head due to the removal of the Injector Ports or if a special different type of bolt is needed to make sure things are flush internally and I'm not losing compression as a result of removal of the injector port.

Heads need a valve job on this engine anyway and perhaps that is something that can be fixed when heads are redone.
 
Compression is not changed the port is on the other side of the valve.
 
Like he says, the air injection hole only goes to the port. I thought Vizard liked the smog heads. Same internals as the 940 head but a little more beafey.
The only difference between H and L engines was the pistons. I must relegate the "dish cc" to a daily rebuilder of these engines (Hap).
If you're doing a new motor and want higher compression than a L or smog motor, remember that pistons can be expensive.
 
TexasSprite said:
The plan is to go pretty much stock.
Click to expand...

I thought that once as well, and we all know where that got me. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

If you are going to do a rebuild, I'm not sure that it matters all that much which year you use, as long as it is in good shape. I'm using a '74 block in my build -- it's a low compression smog-era motor, but that will be solved in the build process.

Some later blocks (like mine) have the necessary hole for a mechanical fuel pump if you'd like to run one. Otherwise, I'd think they're pretty equivalent for most situations.
 
I believe the '67s are supposed to have a better crank, some later cars sold only in England had what was called an A+ block, I think it was supposed to be stiffer? don't recall the difference, but I think supposed to be a better choice if going with a high performance motor.

However, unless you are building the Uber 1275 motor I don't think it would be worth the extra trouble of shipping all the way from England.
 
'67's <u>may</u> have an EN40B crank, as opposed to the EN16T crank. Not all '67's had the EN40 crank, so it's a crapshoot.
If it's a stock engine, any of them will do just fine. It's when building for performance that the search for the strongest and best components comes into play.
I've built a lot of them for the street, and it doesn't seem to matter what year block I use, I've never had a failure yet.
Jeff
 
If I recall correctly the nitriding of the early EN40B cranks only goes .005-.008 deep into the crank surface for if the crank is turned undersize then the hardening is basically gone. On the later "tuftrided" cranks the hardening went a little bit deeper.
Bill
 
Yeah, I wouldn't waste any time trying to find a EN40B crank engine, everytime I run across a EN40B crank, I sell them for good money to the purist /bcforum/images/%%GRAEMLIN_URL%%/smile.gif The EN16T crankshaft is more than good enough for race motors, plenty good enough any street hot rods. The high compression engine is done so basicly with pistons as mentioned, by using the AE 21253 pistons with a higher compression height you can make any engine a high compression motor. As far as the heads go, the smog head is as good as the pre smog head, actually a better choice for race porting.

So in short, get any decent 1275 you can get your hands on, it's all good /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
 
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