29 replies to this topic

[mattso118]

Hi everyone, have been ummming and ahhing for a while over an engine replacement and have decided to stay a series and i think N/A. I have rung around some places and had very different specs quoted for around the £1500-£2000 mark. heres the spec I was being suggested so can anyone think of any obvious improvements etc

Block
1275 block bored to 1380
powermax 73.5mm pistons
Centre main strap
Duplex timing gear
Standard rods, balanced
Reground and balanced Crank
All new bearings
286 Cam
lightweight Cam followers
Lightened and balanced fly wheel
organic clutch plate
orange diaphragm.

Stage 4 head with 35/36mm inlet and 30/31 exhaust valves all ported and polished
220/240lb double valve springs

Rebuilt gearbox
uprated diff pin
centre oil pickup
sc drops

Hif44 carb
flowed stainless maniflow manifold
Rc 40 exhaust
Aldon yellow dissy.



Anyone got any suggestions as to power, improvements, and what you lot would pay?

Cheers

[AndyMiniMad.]

Wow all that for £1500-£2000? Very similar spec to my self built 1380. Except mine cost £2500-£3000. Hope you do get yours cheeper. but be prepared to go over budget because this type of spec aint cheep.

[Cooperman]

That's a nice spec and should drive very well.
You might want to specify a final drive ratio of 3.2:1 or 3.44:1 and it's not really worth going for SC drop gears as you gain little and just get the ear-ache on a journey (I know, I have them!).

As an aside really, a 1330 cc engine will give almost as much 'grunt' as a 1380 if built well and accurately, it's a lot cheaper to bore and if/when it needs rebuilding it can definately be bored again rather than possibly having to source another block. There was a comment on this forum about the fact that 1275 blocks are getting scarcer and more expensive.

[MRA]

Forget the centre main strap....

Money better spent on cross drilling and hardening crankshaft

For safety reasons drop the uprated diff pin in favour of a cross pin diff.

You would get better results with a 276 cam on your list above.

Everything else as per DILLIGAF.

What size wheels and tyres are you running ?

[Bungle]

do you need a 1380 ?

a 1330 would give you a rebore left in the block

my 1330 cost me just over £1000 but i already had a good box but need need a few new parts because of damage (crank, timing chain cover)

[bmcecosse]

I will add my support to the idea of NOT going right up to 1380 - the gains are trivial compared to a 40 thou overbore. The cost saving and improved reliabilty considerable. I agree with the hard crank and crossdrilling - but I would ALSO fit the strap on the centre main.......and yes - those valve springs are far too strong. You may get a bit more power with twin HIF44s - on a good long manifold with NO silly crossover pipe.

[mattso118]

I was only thinking 1380 due to the availability of them as half engine kits, cross drilling and hardening the crank was recommended by one place as an extra, although all said about the requirement for a centre main strap ? whats the additional cost of a setiup mega jolt going to be as it is something I have never really looked into, tis like witchcraft to me !

Im running 12 x 6 revos and and A539 tyres.

Im glad you said about x pin diff as I did bring it up and was told that the engine wouldnt have enough power to warrant it ? I always thought that uprated diff would be par for the course on any tuned engine ?

Finally will the 3.44 be ok for all round driving or a B road blaster ?


cheers for your help everyone !

[AndyMiniMad.]

I used an uprated molly somthing or other dif pin from our friend mr Guessworks and have had no problems. But it seems the general opinion is cross pin diffs are the way to go. runing a 3.1 final drive to keep the revs down on the long runs but the 1380 has enough torque to compensate at lower speeds, So the best of both worlds in my opinion. I also have 12x6 revos.

[MRA]

I will add my support to the idea of NOT going right up to 1380 - the gains are trivial compared to a 40 thou overbore. The cost saving and improved reliabilty considerable.

Unfortunately most people only think of the maximum BHP figure..... with a 1380 your bottom end and mid range torque will be much better than a 1330 and very noticeable.

Use Omega pistons as the AE or cheaper types are not worth using unless you are keeping it all standard of course....

You would not gain anything from fitting a centre main strap to your engine as the revs are not going to be any where near high enough to warrant it...... sorry you will get a weight loss though, from your pocket £££££££

What improved reliability is that then ????

[mini-geek]

...

You would not gain anything from fitting a centre main strap to your engine as the revs are not going to be any where near high enough to warrant it...... sorry you will get a weight loss though, from your pocket £££££££

what sort of RPM do you need to start looking at having a CMS? It wont do any harm having one though.... just wasting money?

[AndyMiniMad.]

Ive got a CMS on mine. Just thought it was the right thing to do. Ended up doing it twice tho because got the wrong bolts first time round. But MRA-MINIS came to the rescue with a new CMS and bolts. Oh just in case i should mention that the first CMS did NOT come from MRA. I dont rev mine beyond 6000, No point really because its got soooo much torque. Bhp is for youngsters....

[mattso118]

Hi everyone, thanks for all the replies.

From the majority of the advice on this thread i will assume that a cms is a possibilty but not a necessity, that having crank work done is a good idea to relieve stress and that i should not be expecting a high revving engine.

Any one have any idea whether a close ratio gear set will make much difference to driveability with the 286 cam?

I thought there were two types of the AE pistons a cheaper set and a more expensive set ? If there are I would probably fork out the pennies on the more expensive ones if they are worth it.

AndyMiniMad gotta say I agree with you on the BHP torque arguement, and im only a nipper! I always wanted a proper screamer but got in a friends long stroke 1430 and it was so nice to drive, and you didnt look a gentleman sausage trying to pull away from junctions.

How suitable will a Hif44 be with the set up and proposed changes? Any one recommend an obvious improvement in that area? also what exhaust set ups do most people run, heard good things about the rc 40s etc but open to any new ideas.


thanks muchly

[MRA]

Constant revs of 6000 plus or sporadic revs of 7500 plus

I built a 1380 with a 296 cam and a Longman GT17 head...... a long time ago and it used to rev to 8500 and that was measured using a calibrated tachometer, and no I didn't have a CMS fitted. however I wouldn't recomend this rev range without one.

The point really is the OP is using powermax pistons which won't last at or any where near to those revs.

The other thing, lightened followers are for racers or for pub talk, really not suitable for road cars, the weight loss will be negligeable, but they are known to crack at higher duration... high mileage, and high mileage for a race car is 5000 miles

I think that the OP wants more reliability or deeper pockets to replace the parts every couple of monthes or so....

[AndyMiniMad.]

Im useing a HIFF 44 carb and its fine. Im told they are fine for engines up to 120-130 bhp. Decent LCB (Maniflow) and a 1.75 internal diameter system will be perfect.

[mattso118]

Constant revs of 6000 plus or sporadic revs of 7500 plus

I built a 1380 with a 296 cam and a Longman GT17 head...... a long time ago and it used to rev to 8500 and that was measured using a calibrated tachometer, and no I didn't have a CMS fitted. however I wouldn't recomend this rev range without one.

The point really is the OP is using powermax pistons which won't last at or any where near to those revs.

The other thing, lightened followers are for racers or for pub talk, really not suitable for road cars, the weight loss will be negligeable, but they are known to crack at higher duration... high mileage, and high mileage for a race car is 5000 miles

I think that the OP wants more reliability or deeper pockets to replace the parts every couple of monthes or so....

To be honest with you I wasnt really sure what the benefits of the followers will be so cheers for that. Yeah im not after maximum power so that can be taken out of the trriangle of power relaibility and cost, I just want a smooth torquey engine that wont go bang 5000 miles down the road. Hence this thread to ensure I wasnt being sold stuff I wont be needing.