Performance NA M10

[jules325i]

So my 1974 2002 has just been restored, and i am going to build a NA performance engine, i already have a set of 45 carbs. it will also be a street car.

What i am going to buy

- CP Forged Pistons 10.5:1
- Schrick 292 or 304 (not yet decided considering i will drive on the road)
- HD rocker arms
- Uprated valve springs
- ARP hardware
- Maybe even forged rods



I am just interested about valve clearances with the high lift Schrick and CP pistons i wonder how big they cut there valve reliefs.

Has anyone got any previous experience with these parts,
and would like to give any suggestions.

[SkiFree]

Its my opinion that 45's are a little large for street use, what chokes are you running? What manifold are you running?

My personal favorite hot-rod street setup is DCOE40's with a Billet 292 cam and HD single valve springs. Very streetable and a lot of fun.

That being said, if you're married to the 45's then I'd personally use the 304 (Shrick, or Ireland Eng.), and run HD single springs or full dual springs, however I would NOT run schrick dual springs on a street engine. The spring pressures are simply too high across the board and you'll wear out the cam/rockers quite a bit quicker than if you went with something a little more suited for street driving (and longevity).

I'm sure you could specify what size valve reliefs you'd like cut into the pistons (what is the thickness of your head?) Why are you sold on CP, is it because its recommended to you by whomever is selling you the parts?

Couple things to consider:
Rocker Locks .... no one likes dealing with the keeper springs.
Rocker Shafts ... Run your finger nail across the shafts. If you feel a groove at all, replace.
4" Billet Crank Pulley
Oil pan Baffle
I assume you're also doing some decent port work?

[petrolhead]

So my 1974 2002 has just been restored, and i am going to build a NA performance engine, i already have a set of 45 carbs. it will also be a street car.

What i am going to buy

- CP Forged Pistons 10.5:1
- Schrick 292 or 304 (not yet decided considering i will drive on the road)
- HD rocker arms
- Uprated valve springs
- ARP hardware
- Maybe even forged rods



I am just interested about valve clearances with the high lift Schrick and CP pistons i wonder how big they cut there valve reliefs.

Has anyone got any previous experience with these parts,
and would like to give any suggestions.

Show me a set of rocker arms that don't wear out themselves and cam lobes, and withstand 8k+ revs.
I'm considering lighter valves and custom valve springs, with springrate that would be just right for the cam, revs, valve gear masses etc. All this so I'd be able to use OEM rockers.

[SkiFree]

Show me a set of rocker arms that don't wear out themselves and cam lobes, and withstand 8k+ revs.
I'm considering lighter valves and custom valve springs, with springrate that would be just right for the cam, revs, valve gear masses etc. All this so I'd be able to use OEM rockers.

Here's a set of the IE HD's on one of the race heads in the shop. They see 8k fairly often. Any more than that and I'd go with the steel rockers.



petrolhead - are you building a dedicated track engine or dual purpose engine? Its hard to know what valve spring setup would be right without knowing your end use. It sounds like you and the OP aren't building the same type of setup.

[jules325i]

Its my opinion that 45's are a little large for street use, what chokes are you running? What manifold are you running?

My personal favorite hot-rod street setup is DCOE40's with a Billet 292 cam and HD single valve springs. Very streetable and a lot of fun.

That being said, if you're married to the 45's then I'd personally use the 304 (Shrick, or Ireland Eng.), and run HD single springs or full dual springs, however I would NOT run schrick dual springs on a street engine. The spring pressures are simply too high across the board and you'll wear out the cam/rockers quite a bit quicker than if you went with something a little more suited for street driving (and longevity).

I'm sure you could specify what size valve reliefs you'd like cut into the pistons (what is the thickness of your head?) Why are you sold on CP, is it because its recommended to you by whomever is selling you the parts?

Couple things to consider:
Rocker Locks .... no one likes dealing with the keeper springs.
Rocker Shafts ... Run your finger nail across the shafts. If you feel a groove at all, replace.
4" Billet Crank Pulley
Oil pan Baffle
I assume you're also doing some decent port work?

I am pretty set on running my Twin 45's setup.
I am looking at CP pistons because i am trying to buy most of my parts from one store (Vac) due to the $200+ freight fee.
Where is the best place to get The single HD Valve spring.
I'm led to believe that the 304 is very lumpy and hard to drive in traffic.
due to the car being driven in traffic a few bit.
I might just stick with the 292.
I am going to get head work done what is the best things to get done, Multi angle valve job, Port polish ect.

[SkiFree]

I am pretty set on running my Twin 45's setup.
I am looking at CP pistons because i am trying to buy most of my parts from one store (Vac) due to the $200+ freight fee.
Where is the best place to get The single HD Valve spring.
I'm led to believe that the 304 is very lumpy and hard to drive in traffic.
due to the car being driven in traffic a few bit.
I might just stick with the 292.
I am going to get head work done what is the best things to get done, Multi angle valve job, Port polish ect.

If you're led to believe the 302/4 to be too difficult/lumpy to drive on traffic, than that same reason can be applied for running DCOE45's instead of 40's. Your power band is creeping away from the bottom end and sliding upwards. Simply put, both the 302/4 and DCOE45's are getting to be the ragged edge for street use.

I'm not for or against using 302(or 4, measuring the difference between the two is pretty inconsequential). Just clarifying a bit.

The only place to buy HD Single Springs is from IE, of course you can also get the HD rockers, camshaft, and everything else on your list. If you'd like some pictures of an original BMW motorsport/alpina port/polish job, PM me. Shoot, if you want a complete quote, just PM me.

[petrolhead]

Here's a set of the IE HD's on one of the race heads in the shop. They see 8k fairly often. Any more than that and I'd go with the steel rockers.



petrolhead - are you building a dedicated track engine or dual purpose engine? Its hard to know what valve spring setup would be right without knowing your end use. It sounds like you and the OP aren't building the same type of setup.

Now, I'm no expert.. But I understand that required spring rate (or seat pressure) can be calculated once you know revs, cam profile, valve mass, rocker mass (, boost level) etc. For example I remember that Schrick recommends same springs for 284, 292 & 304 cams. Couple that with the fact that one guy might have 42mm inlets, the other 47mm. It seems far fecthed that one spring would be just right to all of these.

I understand that valve float/ valve bounce due to insufficient springs, is just as bad as the unneccessary stress caused by too stiff valve springs.

[SoopaGhetto]

Stock rods are forged. capable of 400+hp

Id go 304. I had 292 and upgraded springs. If i could do it again, id go with the IE 316.