What to do with 1.7 Type 4 in 356 Speedster?

[Mave]

Hi,

This is my first post, so please be gentle.

I'm going to start building a 356 replica. I bought a 914 1.7 type 4, which I intend to use. Of course I will convert it to vertical cooling, but other than that I'm still unsure what to do. I'm not intending to spend mega-bucks, but would like to end up with a reliable engine, that has around 100 bhp. Nothing too crazy, or too expensive.

I haven't opened up the engine yet, so I'm not sure on it's condition. I do intend to do a total proper rebuild though. But I'm not sure what specs I should be looking for.
My thoughts for now are to buy new 96 mm P&C's to take it to 1911 cc. I'm not sure what I have to do to the head: I will have them reconditioned, and of course machined to match the larger cylinders. But what should I do with valves? Stick with stock size?
And what about the cam? I read that the Webcam 53B is a good option. Is that correct?

Looking forward to hear your suggestions.

[NextGen]

A lot more info is needed. That 1.7 may have domed pistons, rare but--- If it was from a 914 it may. A cam, a rebuild and you may be happy. Or you can go the route you said, cam is a must and a good set of headers.

If the heads are fine, great but for the larger pistons you will have to take them to a machine shop to have them opened for the pistons. To save money there is a lot to think about.

Some of the guys on this fourm have worked 1.7 engines and they run better and are faster then some 2.0 T-1 engines.

Shortly there will be some posts to lead you by the hand.

[Piledriver]

Welcome to the STF!

Sounds like a great, efficient, long lived combo.

Stick a DTM or a CSP upright conversion kit on it and you could be driving it by late afternoon.

I also suggest a Synclink throttle linkage on dual 40mm dells or webers.

If you do go in and all is in order, inspect//measure your main bearings vs crank, do not toss.
They don't make them that well (or in Germany) anymore.
Same goes for the stock oil pump.

There is a reasonable possibility all you need to do is take out any headgaskets, put a hardened washer under the rocker shaft mount to compensate for the deck being lower, and seal it all back up.

The "last guy" who went into the motor should always be assumed to be an idiot.

What's your budget?
We're great at spending other peoples money

[Mave]

Thanks for the replies!

Well, the engine was extremely dirty on the outside, so I'm not trusting the condition of the inside without having seen it. So I will be splitting it. Of course, only then the full picture becomes clear.

As for my budget: I'm intending to spend about 2.5-3K euros on the engine (not including carbs/cooling). And the reason for not having taken the engine apart is that I'm not sure whether I would be better off with a type 1 1915cc for that kind of money.

But regardless of it being a 1.7 or 1911, what would be the sensible thing to do to the heads? Just have them reconditioned as-is, with stock valve size, or increase the sizes?

Marcel

[sideshow]

Why don't you just convert it before deciding to improve anything. You might underestimate just what a flying tackle box needs to achieve unsafe speeds.

[Mave]

Well, because of the outside state of the engine, I want to make sure the inside is ok. And once it is open anyway, it is very tempting to upgrade some things....

As for the power.....the previous car I built is a Lotus Seven-type car: 600 kg and 220 bhp. Quite insane, and I'm definately not looking for anything that comes close in terms of power-to-weight. But I do want a bit of a punch. Now I do agree that the difference between the stock 80bhp and my goal of 100bhp is nothing too spectacular, but 100 bhp just sound right. Somehow.

Sometimes my decisions have nothing to do with rationality.

[NextGen]

Hp with a T-4 is different then HP in a T-1, T-4 is torque that you feel. When you drive it you will understand.

[Piledriver]

If the 1700 is of the 914/411 variety and had the pistons with the small dome in the middle (to match the heads) you could likely get by cleaning it well, measuring everything and reassembling with a new set of exhaust valves for insurance.

I would replace the valve springs, retainers and keepers with HD T1 units, the keepers may need to visit a grinder if they do not grab the valve stem. (the stock ones fit properly but are sadly too soft) also replace the oddball 7mm rocker studs and install solid spacers. (much more work than it looks, but worth it)

You also want to install dual thrust cam bearings, I had a motor that I only ever had to take it down was for the single thrust being worn out, I reused the mains and rod bearings etc. as they were still in spec after >400K miles.
(oddly, the crank was worn a bit, but a fresher crank and everything was back in spec)

A 1700 with a Web73 and a good tune, ~8.6:1 with no head gaskets could probably do 100 real HP with a good exhaust.

If the pistons are not the domes, AA sells domed replacement P&L, but I would probably opt for 96mm bore and machining the heads to match.

This gets you a 1911cc motor, much easier to get the CR up where needed for a bit more cam, >100HP at the rear wheels should be ~easy.

[NextGen]

Pile, perfect I toally agree. 1.7 with the domes are a nice engine, a bit hard to find but they are out there.If only I knew then what I know now about T-4 ------ I hate thinking about it.

[Mave]

Thanks! That's really useful information. Looks like it is best to just see what is salvageable, and decide the way forward based on that.
I'll be back!

[Mave]

Hi, I've opened it up, and it doesn't look too bad to my untrained eyes. It does have the domed pistons. So what do I do now? Split the case, replace bearings and cam, but keep it as 1.7? Or go for 1911? If I decide to go for 1911, what cam would you suggest? And as I'm having the heads reconditioned at Ahnendorp, should I go for bigger exhaust valves? (If yes, what size?)

[Piledriver]

do not replace the main or rod bearings if they look good and are in spec.
Same for the oil pump.
They literally don't make them that good anymore.
I'm at the point where I'd consider having bearings coated just to use them again if the sizing is marginal.

Carefully check the piston ring grooves, make sure they are not worn out, that's a major part of the seal, also check the jugs carefully for taper etc.

Even with deck set to minimum you need a reasonably mild cam to have proper compression as a 1700, a web73 is pretty decent, a 494@104 would probably be too much for a ~stock 1700, but just right for a 1911 with tight deck.
(as long as you are running dual carbs or aftermarket EMS)

I have not tried a Web86 with a stock 914 setup, but it seems reasonable as long as you keep the deck down close or perhaps a custom 86 @ 104 or such.

Here's where I'm coming from:
Many moons ago, when I opened up the 1700 that came in my 914, I pulled the rods,,, bearings looked as new, so I assumed the mains did too... I last reused those mains in that case with another crank ~250K miles later.

What "went" in that engine was the cam thrust bearing... the factory 1/2 thrust was all but gone.
It ran fine but made seriously funky noises for ~10K before I pulled it, and I really only finally parked it when a semi changed lanes on top of me.

(IMHO) T4 rods seldom if ever actually need rebuilt unless you upgrade the rod bolts.

[Mave]

Thanks.

I've decided to make it a 1911, and am now wondering what to do with the heads and cam. I can have the 914 1.7 heads reconditioned (new seats, valves) and the registers opened up for the larger cylinders. This is almost the same price as brand new AMC heads (which I would then use 'out-of-the-box'). What would be the best choice?

And as for cams: I'm looking for a nice street engine, with a useable powerband. I see so many different cam types: really difficult to decide which one to go for when you're a newby like me. If we limit the choice to Webcam, which one would you suggest for a 1911? 86? 86a? 86b?

[Piledriver]

Keep the 1.7 heads (or at least do not toss) out of the box they flow better than the std AMC heads given the same valve sizes.

Do not expect the AMC heads to have a great 3 angle valve job.
...That's largely what you are paying for on the 1.7s, I assume, as opening the heads usually runs ~$50 or thereabouts.

Web 494@104LC or Jake's version. Dual springs suggested if not already fitted.
Make sure to install the dual thrust cam bearings.

I would suggest 163/86B on 102 or 104LC but it's hard to make enough CR with a 1911, keeping the deck down tight helps a lot.

A good exhaust is essential or all is a waste.

[Mave]

What did you mean by "102 or 104 LC"?
I've decided to keep the 1.7 heads, have new valves (stock size), guides, have them machined for the 96 mm cylinders, and the volumes checked and adjusted if needed. I'm hoping to measure deck height this weekend, and will share my findings. I'm hoping to get your support in determining the CR and cam I should go for, because that's really an area I have no knowledge about....