12 replies to this topic

[shashora]

Hi guys just getting my 1100 rebuilt and hopefully worked somewhat..
Here in australia we have minisports. My plans are this so far
To get the

Camshaft modded: with a

Mini 1100cc or 1275cc Kent camshaft, fast road camshaft, 276, (3/8 pin drive)
Description
Slightly lumpy at idle, especially in small bore units. Strong mid and top end power. Rev band 1,500 - 7,000 rpm. This cam uses the original 3/8 pin drive fitted to 1100cc motors

a rebuild kit: including

VRS 1100
Engine block to gearbox gasket set (suit mini)
Primary gear seal
PISTONS and rings in either 020, 030, 040, 060
Main bearings in .010, .020, .030 ETC
Conrod bearings in .010, .020, .030 ETC
Oil pump
Timing chain and thrust washers

Clutch and Flywheel:
Being a Mini verto ultralight flywheel and just a mini cooper s clutch kit.

Is there anything else anyone recommends on getting done to the engine?? Also with the pistons they will be a brand called hypatec and come with a hastings ring set. Does anyone have any experience with hypatec or hastings? Also curious to what compression is good for a mini piston i was told 1to10 compression is good??

This is all looking like it will cost me around 1200 aussie dollars of about 500 pounds i guess so im pretty happy with that. But jsut dont know if ther good quality gear and if im missing out something essential that would increase performance..

Please let me know.. Cheers

[Wil_h]

You seem to be about there, the Hypertecs and hastings rings are the best available, so a good choice.

I don't know what a VRS head is and I assume that you have a suitable carb 1 1/2" SU or HIF38 and are using a propper exhaust, other than that fine.

[Ethel]

An 1100 won't have a Verto clutch.

[Big_Adam]

Also curious to what compression is good for a mini piston i was told 1to10 compression is good??

Think the compression more depends on what ron/octane fuel you're running. Higher the ron/octane the higher a compression you can use. If you use low ron/octane then it's going to run funny.

Edited by Big_Adam, 28 January 2008 - 02:08 PM.

[shashora]

Thanks guys but ive got 2 more questions...
To know the piston size, conrod and main bearing sizes do i have to send it to a engine machinist to measure up first??

Also I want to get the engine rebuilt with probably all the things ive talked about above althoguh i was wondering what stuff other than fitting these parts should i ask the engine machinist to do in order to have a good alround engine?

So top end and bottom end i am really confused when they start talkin about porting and boreing etc.. does anyone have any good suggestions and/or links they could forward so i could readup on and not feel like such a nob? If so would greatly appreciate it haha

[dklawson]

Out of curiosity... why stick with the pin drive cam and associated oil pump? Most cams are made as re-grinds from cores and the slot drive cams are much more common as are pumps to match. Certainly you'll be replacing the oil pump during this rebuild and making the change now may make future oil pump changes easier.

Regarding the pistons and the machine shop...
I've always believed the best choice is to postpone your piston purchase until AFTER the shop has determined if you need new pistons at all. If they say you do, ask which oversize will be required. Order those pistons then provide them to the machine shop. They will bore the block to match the pistons you provide. This allows them to set the clearances exactly to match the parts you buy. Failing this... they have to go on the published tolerances of the parts and the results may be looser or tighter than you want.

Other items I'd have the machinist fit and size are the cam bearings. They usually have to be sized after installation and installing/removing them requires special pullers. Depending on the piston rods you have, you may want the shop to fit the new pistons to the rods as well. (On some the wrist pins are a press fit). Lastly, you have to look at what tools you have or want to buy. You may also want the shop to fit the piston rings to the pistons and check their gap in the block. It's up to you. by the way, I WOULD provide all the part to the shop and have them balanced as an assembly. It's a small expense to develop a smoother running engine.

I don't have links to direct you to. However, any good text providing an overview of engine rebuilding should be able to walk you through the terms. For the A-Series, the bible would be the books by Vizard. As for boring a block... that's done to fit your oversized pistons. Honing the bores comes next to get the "right" finish that will allow the rings to seal and seat. Any reference to the top end is related to the cylinder head. Porting is discussed at length in the Vizard books I mentioned above.

[shashora]

I was going to stick with the pin drive cam cause i didnt know the slot drive was better? Whats the difference between the two??

[minimender]

Slot drive more common and easier to source cams for swaps.

[ginigwunkle]

its just the was the cam fits the pump, obviously you need them to match...

with the pin drive you have more choice.

do you have a micrometer and a haynes mini manual? if you do/can get one you can measure the main/big-end bearings to see if they are within tollerences for the bearings or a regrind is needed.

if the cylinder bore has is only slightly worn then you can get away with a +20 overbore if your nail catches on the ridge then id say at least a +40 overbore to clear the gap...

you should also renew the
core and oil gallery plugs
double valve springs with 270 cam(you can get a kit with the lot inc pump in uk)
new cam followers

if your budget allows or something to consider in the future would be cyl head work, the whole ngine will benefit from that!

[dklawson]

with the pin drive you have more choice.

you should also renew the
core and oil gallery plugs
double valve springs with 270 cam(you can get a kit with the lot inc pump in uk)
new cam followers

With the slot drive you have more choices in pumps. The drive refers to the end of the cam, not the pump. The slot drive is the "current" type so there are more components that work with it. The pin drive was the original, early, A-series cam type and there are few pumps available to work with it.

Quite correct about the cam followers. You should always replace them when you replace the cam so the two bed in together.

It's fine to measure bores and crank journals yourself but encourage the machine shop to check behind you and offer their suggestions.

[shashora]

its just the was the cam fits the pump, obviously you need them to match...

with the pin drive you have more choice.

do you have a micrometer and a haynes mini manual? if you do/can get one you can measure the main/big-end bearings to see if they are within tollerences for the bearings or a regrind is needed.

if the cylinder bore has is only slightly worn then you can get away with a +20 overbore if your nail catches on the ridge then id say at least a +40 overbore to clear the gap...

you should also renew the
core and oil gallery plugs
double valve springs with 270 cam(you can get a kit with the lot inc pump in uk)
new cam followers

if your budget allows or something to consider in the future would be cyl head work, the whole ngine will benefit from that!

Thanks mate!
I have a haynes workshop manual and my cousin has a micrometer how do u measure them where from to where?
Or is this explained in haynes??

[shashora]

with the pin drive you have more choice.

you should also renew the
core and oil gallery plugs
double valve springs with 270 cam(you can get a kit with the lot inc pump in uk)
new cam followers

With the slot drive you have more choices in pumps. The drive refers to the end of the cam, not the pump. The slot drive is the "current" type so there are more components that work with it. The pin drive was the original, early, A-series cam type and there are few pumps available to work with it.

Quite correct about the cam followers. You should always replace them when you replace the cam so the two bed in together.

It's fine to measure bores and crank journals yourself but encourage the machine shop to check behind you and offer their suggestions.

So if the pin drive was old style of A series is it a big job to change to slot drive or is it as simple as changing the camshaft..

[dklawson]

As part of this engine rebuild you state that you plan to change the cam. It would be extremely unwise to NOT change the oil pump at the same time. All you need to do is select a new cam with the specs you want and buy a matching pump at the same time. Ask your supplier about this and you'll see you have a lot more choices in cams and pumps in the slot drive configuration.

As for how you measure clearances and journal diameters, there are several methods ranging from "Plasti-Gauge" strips to using micrometers. I don't want to discourage your questions but this thread could become a rather lengthy discussion of engine building techniques and machine shop practices. I think you might gain more by finding some general books on engine rebuilding, reading up on those, then posting your specific questions here. The texts do NOT have to be A-series specific, the basics of machine work and engine rebuilding apply across the board to most engines.