[kpc655]

I don't think that will work, a 67% reduction in oil flow to the head isn't a good idea.

What was the stock 155 orifice size? anyone have access to one who could check?

 

[hunttheshunt]

Don't worry. I'm also reducing all 6 holes on a Nord, because a Nord engine is pumping way too much oil into the head galleries. It's not my own idea, several other engine builders are doing the same since many years. What do you think why Alfa did reduce from 6 to 2 holes with introduction of TS ? Because they came to conclusion you don't need that huge amount of oil in the cam pockets.

It works fine, even in full race engines.
If you've plugged the middle and rear ones, leave the fronts unrestricted. Quite simple.
Having written 'leave it like it is' meant leave the front holes without any restriction like works standard in the block was. The holes are always between 5,2-5,5mm wide.

 

[kpc655]

ah, i misunderstood. i thought you meant leave with the 3/32 restrictors in the front 2.

i've had bad luck when running no dowel pin to support the oring. seems as though it likes to move during the heat cycling (and thus leak)

but i'll take a closer look and try to insert a large ID roll pin that matches the existing oil holes and fits in the head.

 

[hunttheshunt]

I do remove all oil gallery dowel pins and never have had any issues.

 

[Dovali]

155 head is nicer, better classic look, but more labour so more expensive to install .

75 head is easier and cheaper to install .

pic is an example of one of my engines,with 155 head, 75 block, 164 ( 90) crank .

 

[ECARRILLO]

155 head is nicer, better classic look, but more labour so more expensive to install .

75 head is easier and cheaper to install .

pic is an example of one of my engines,with 155 head, 75 block, 164 ( 90) crank .

What hp and torque do you get out of this set up? Is this for street or race?

 

[Dovali]

Comp 10:5 to 1, alfaholics exhaust, 123 tune ignition, reworked standard valves, no porting, original cams inlet at 3,2 lift at tdc ex 2,5 at tdc.

170 hp at 5900 rpm and 220 tq at 4700 rpm.

Very smooth engine.

 

[Hans-Peter]

Comp 10:5 to 1, alfaholics exhaust, 123 tune ignition, reworked standard valves, no porting, original cams inlet at 3,2 lift at tdc ex 2,5 at tdc.

170 hp at 5900 rpm and 220 tq at 4700 rpm.

Very smooth engine.

Are you only using 1 4 lead distributor ?

 

[Dovali]

Yes only 4 plugs

 

[kpc655]

I'm running jim's 8 plug distributor, just arrived a few weeks ago and it's a very nice piece. I'm expecting about 220 hp and about 180 ft lbs of torque (min) in race trim. dyno numbers soon

 

[jaccovdaag]

Hi guys,

Quick question. I'm going to put this head on the 75 block, but how about the VVT? Is it usable, or not?

 

[Veep]

depends on what you plan to do with the cams and fuel system. Other intake? in france I located a intake manifold for carbs or ITBs with fixing for the VVT unit . do not know if it is for sale reaaly since it were only drawings they showed. . other after market manifolds do not have this fitting point. usable, or need to use are two different things. Why would you?

 

[jaccovdaag]

Yes, Chadil.com. I found that website too. Looks promising, but nothing clear if it's ready to order. I'll send an email.

The engine will be a 75 block with 155 head, from a 1.7, which doesn't have VVT. But that's interchangable, since the heads of the 155's are the same, except for the missing parts of the VVT system.
It'll be put in an Alfetta '80, and first I'll have it running on the standard injection system, with ECU and cables from the 155. If that runs and goes smoothly, the carbs or ITB's might come in play. I've read something in Jim's book about when having perf. cams, you need to shut down the VVT. Plus, I don't know how much it will differ from non-VVT, but maybe with such changes in the future, it'll be better to get rid of the VVT and just have it 'normal'.

(Ook op SCARB, zie ik):laugh2:

 

[Veep]

why put the head of a 155 on a 75 if you are using the stock setup otherwise?
I am not sure but I thought the head of 2.0 and 1.8 are the same but the 1.7 has smaller valves.

edit, checked parts suppliers and valve sizes seems to be the same. Nevertheless I do not see profit, in this case, of putting a 155 head on.
(If I see at Formula GT, enginebuilder of the AH engines , they use the 75 head, even with the power engine with 2,3 ltr capacity, and with EFI. I do not know why but I think there is a reason, other than supply of heads only))

 

[jaccovdaag]

Well, firstly because I don't have the 75 head plus all the peripherals and wiring loom/ECU. I do have the 155, which has all the parts I need.
Secondly, I like the look of the 155 head. Especially with the carbs which will be there later on.

I double checked the numbers of the heads of the 2.0 and 1.7 (the 2.0 has to be torn apart and built from scratch) and they do have the same numbers. It's not to do purely about the profit, also the parts that are at hand here

As you say, I doubt if there are any big steps to be made, certainly with the usage which I'm planning, you're right about that.

 

[Veep]

ok, clear.

 

[kpc655]

I thought i'd share a quick update on my engine project. After some issues with the crank that required re-grinding it...the bottom end is basically together. Just a few small things to finish up. I'll hopefully be finishing up the head in the next 2 weeks or so and heading to the dyno. Target is the waterford hills race in early Aug.

 

[Alfa69GTV1750]

I'm collecting parts to swap a Twin Spark into my 69 GTV. and I've read through this thread a couple of times and I'm still a bit confused about whether the 75 & 155 heads are interchangeable. I'm collecting parts to swap a Twin Spark into my 69 GTV.

so, it looks like either the 75 or 155 will fit on either block, but what modifications are required for using a 75 head with a 155 block and 155 head with a 75 block?

 

[kpc655]

I used a 115 bottom end. To make this work, I had to swap studs, build a block off plate for the back, coolant log, i added a chain tensioner to the lower, blocked off the 4 rear oil passages.

 

[Alfa69GTV1750]

Does anyone have the Alfa (or other) manual for the Twin Spark engine? Information is hard to find here in the states.