engine build advice

[Dean.s]

I have a stock w code 1700 engine which was fitted with d jet injection.

My plan is to run it with twin 40idf's. I've now learned that the d jet cam is not suited to these carbs.

Not wanting to split the case this is not what i wanted to hear.

I also need to change the distributor for a suggested 034 svda.

1st question, has anyone built what i want to build without changing the cam or increasing combustion size?

2nd question, if i need to change the cam are there any recommendations (for street use) and what else needs to change with it?

I assumme the valve gaps stay the same, push rods stay the same?

All help appreciated.

[Nige]

The cam will be as flat and as worn anything, no point in doing a rebuild on a type iv without splitting the case. You'll regret it if you don't. Most power gains accompanied by an increase in cc is derived from changing the cam.

Valve gaps will stay the same but lift on the valves will be different dependent on the cam you choose (assuming you change that) so push rod length will need to be checked to ensure the valves don't hit the piston crowns. Though I think that is if you go for quite a radical cam.

There are others here with more knowledge than me, but you might be better speaking the Stateside Tuning for advice and recommendation of putting a parts list together that works well together.
http://statesidetuning.co.uk/

[Bruce M]

The W 1.7 is a great little engine. It has reasonable compression ratio due to domed pistons and has a reputation for lasting well. If you are not fitting oversized pistons & cylinders check your original parts as they might still be in spec with a hone & fresh rings.

The cam has minimal overlap to suit the stock injection system, although as far as I know, there is only one stock type4 cam. The cam will work with IDF carbs if they are jetted properly but the ignition timing needs to be right which ideally needs to be properly 3D mapped. An aftermarket cam with more overlap is "easier" to time with a basic distributor (due to differences in dynamic compression, as I understand it).

Why do you want to ditch the Djet? Is it not running well? Perhaps consider getting that sorted because you are not going to get much extra hp with IDFs unless you change the cam and even then it will be a modest increase unless you go for a wild setup.

As above, chances are the cam will have a nasty wear pattern on it. This is because the lifters will have worn flat (they need a very slight dome on the end) so the edges of the lifters start to cut into the cam. Apparently... although it looks bad, it doesn't actually damage the load surface so with a fresh set of (good quality) lifters the cam can still be used. Not tested this myself but it makes logical sense when you look at the wear pattern of a typical type4 cam.

A change of cam type needs careful set up. The rocker tip follows a curve which clearly is not the same path as the end of the valve. Therefore the tip needs to be in line with the valve at mid- lift to minimise the side forces over the full travel of the valve. With a non-stock cam, the geometry changes and various adjustments may be required.

One day I'll get round to doing a rebuild thread (eventually!)

[Dean.s]

Thanks for the info. I've tried speaking with stateside before but never got back to me.

I don't want a super engine or oodles of power which is my reason for sticking with 1700cc. My engine budget is very small so i need to minimuse costs. I know that's not always possible.

I guess i'll split the case and check the wear on the cam. The injection was incomplete on the motor. The car came minus everything in the engine trans bay so sticking with fi had it's own load of problems, i also favour twin carb set ups. At the time of purchase it was the only appropriate type 4 motor i could find.

[Bruce M]

Stateside can be hard to contact. He's a busy lad. Best to email with specific questions and ask when to phone (usually first thing, I think).

If you are careful and measure everything thoroughly, you might get away with budget rebuild. In that situation it's better to use part worn (but in spec) genuine bits rather than cheap (nasty) new parts.

The lifters on a type 4 can be removed without splitting the case so you can peek at the cam. I'd also recommend splitting the case though and cleaning everything thoroughly. Probably needs a few bearings.

[Dean.s]

I managed a few minutes in the shed this evening. I checked the cam and there are no signs of wear. The engine is actually clean inside, either it's a very low mileage motor or was rebuilt before I got it.

I'm very pleased with what I've seen so far.

[Dean.s]

So upon further inspection the cam is straight across the lobes with no nasty wear signs but the followers/lifeters are flat. Should they have a slight dome?

[Bruce M]

Yes. If you put 2 end to end they shouldn't sit totally flat. It's fairly small amount of curve but must be there.
If you google "type4 cam wear" you'll see plenty of examples from slight to nasty.

[Robneal]

Talk to Paul Foreman as he is an expert in Type 4 engine builds. Check out the details of mine and mdmax engine builds under the replicas section on DDK. He is fast and efficient and very reasonably priced. His email address is outlaw718@btinternet.com

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