16 replies to this topic

[Sputnik]

Hi all,

I am building a 1430 engine for racing. Our local circuit is short (3.4km) and I am after torque. I have STD 1275 crank with Cooper S con rods.

1. Do I use the STD 1275 pre A+ block or the A+ ? The A+ block is very scares and I only have one, whereas I have access to a couple of pre A+ ??

2. (Answered, Thanks) Do I purchase the C-STR312 or C-STR311 from Minispares?

3. (Did figure it out myself )In Vizard's books under big motors (p410) he refers to larger main bearings. Is that only possible with a billeted crank ie EN40b or can it be done on a normal one some how ?

4. (Answered, Thanks) Can I use the original Cooper S con rod bolts, or do I get a set of ARP's ?

Thanks so long, I will be posting some more questions as the build makes progress or need to purchase parts.

Edited by Sputnik, 23 February 2013 - 07:35 PM.

[DugganC17]

will watch this one as would love to build a 1430 ingine for my pickup

[ACDodd]

What are your regulations regarding permitted engine modifications?

AC

[Sputnik]

Ac Dodd,

I am running in two classes currently. Fine Cars (pre 89) that is performance of index and Classic Cars (pre77). Both is based on original enine, gearbox and diff, and must match the body of the car. We are allowed to up the cc of the engines a certain percentage, ie Anglias can run with 1600 Kent motors. As our classic car parts are scares, they are not as strict. In classics any homologated part is legal or you must proof that it was used/raced in that period. One of the chaps got hold of a period supercharger and is running in classics and is running with the V8's.

I hope is answers your question !

[ACDodd]

Are you aware that a high winding 1430 is going to need regular rebuilds? What valve sizes can you run?


AC

Edited by ACDodd, 21 February 2013 - 08:28 PM.

[Sputnik]

I am in any case doing a rebuild after each season as reliability is important to me.

I am not at the head stage as yet and is working my way up from the block. As what I understand, I might be going for 37 inlet and 30 exhaust, if we cannot get it right here in SA I will import one from Slark.

Any answers to my OP as yet ?

[oliver122]

2. Do I purchase the C-STR312 or C-STR311 from Minispares?
you need to figure out what compression ratio your going want to run to decided what dish piston's you want
4. Can I use the original Cooper S con rod bolts, or do I get a set of ARP's ?
me personally would replace the bolts as i would not like to think that one shears when im revving a 7k

hope my input helps bud

Edited by oliver122, 22 February 2013 - 09:48 AM.

[ACDodd]

I would sar with a Kent 296 cam 1.5 rockers, 12:1 cr, 37.2 inlet 29.4 exhausts. Use a 45 dcoe with 38 chokes. I would also try 40 chokes to to see if you get more top end. Power wise expect 130 to 135@ flywheel. I would also consider building 2 engines. Expect a partial rebuild at half season, do the valve every other meeting. You may also want to try the Kent 310 for more top end. Use arp throughout. You also need to use the short deck height omega piston 1.426" crown height as the increased stroke will leave the piston too high with normal height. See MED for those.

Before you buy any parts work out a piston dish and deck height and chamber volume that is feasible combination using a spread sheet. Ie plan your build. You also need to run more crank end float and a little more bore clearance to get a successful package. I would also consider rocker geometry here as every bit of head breathing will help with the big bottom end.

AC

Edited by ACDodd, 22 February 2013 - 05:02 PM.

[AndyMiniMad.]

1430 on a standard 1275 crank!! how is that done then? I understand you can go to 74mm and 1399cc...but unless you have a stroked crank how do you gain the extra 31cc's? are the con rods the key?

Sorry to hyjack your thread, but im curious!!

Andy.

[AndyMiniMad.]

Thanks Dilligaf...I am learning every day!!

[Sputnik]

Hi acDodd,

Thanks for the info. Your refer to " do the valve ..." do you refer to lapping the valves ?

Then, thanks about MED, I did not know you get a shorter piston, as I was planning to make the ones from minispares shorter !!

I assume, it does not matter if I go for either the 7 or 11 cc piston, I will with any option have to do a valve cut-out to fit the valves on max lift of the 296/310 cam and 1.5 rockers. I will like to get to 12.5:1 CR, but assumably a bit more difficult to get to with a 11 cc piston ? What would you suggest ? Is there enough metal on the pistons to do the valve cut-out ? I am tin king to go for the 7cc so that I do not have skim the head to much ?

Why do you suggest two engines, or is the second one just as backup ? I was thinking of using my 1380 as a backup as I am building it with a EN40b crank and 296 cam with 36 inlet and 31 exhaust head. I am also running a 45 on a 5" inlet manifold.

Edited by Sputnik, 23 February 2013 - 05:03 PM.

[ACDodd]

Ok You obvouisly have not spread sheeted this build, so I have done it for you. 19.5cc head chambers with 7cc dish piston set at 0.010" deck height will give you 12:1 CR with a BK450 head gasket. DO NOT go for more compression than you have fuel for, I would be buying proper 5 star leaded 100 octane fuel for this engine at 12:1!

Doing the valaves means head off and re-lap very other meeting to maintain performance. Better still get yourself a cylinder leakage tester and test the engine when fresh, Then check after every meeting (Draw up a bar graph to track the figures), you will notice the leakage get worse. Relap the valves the leakage drops again. When you can no longer regain lost seal by valve lapping you need to fully rebuild the block.
Running your other engine as a spare is good if on a budget, however it won't have the torque out of the corners and it will also struggle on the straights at the intake valves are just not big enough!

Won't need any piston cut outs for 296 and I have done the same engine. I have not tried the 310 though. Again a dry build is a must when determining all these factors.


AC

Edited by ACDodd, 23 February 2013 - 07:15 PM.

[Sputnik]

Hi AcDodd,

Thanks for the reply, I do appreciate. You do not know how many questions you have already cleared up for me. I am not that mechanically inclined and rely on internet articles, forums and the yellow bible. I was in the process to find out how to work out the static CR of the engine, but took a bit long to get the RLV.

What is your taking on the pre A + or A+ block ?

[ACDodd]

I like the A+ block, simply because it is newer and therefore less fatigue.

AC

[MRA]

1430 on a standard 1275 crank!! how is that done then? I understand you can go to 74mm and 1399cc...but unless you have a stroked crank how do you gain the extra 31cc's? are the con rods the key?

Sorry to hyjack your thread, but im curious!!

Andy.

You can go upto 1425cc with a standard stroke, using Triumph pistons, I have also heard of slightly bigger using oversize simca pistons, although I have never tried the Simca route the triumph pistons are ok but not for the revs used in racing