Bimmerheads vs VAC motorsports head rebuild

[aavani90]

I’m restoring an 89’ 325i convertible and decided to refresh the whole top end, was originally just going to replace the headgasket but figured it would be a good time to have the head rebuilt so I don’t have to pull the head again for awhile. This is just a stock restoration so it’ll be a stage 1 rebuild on the head, no forced induction or anything like that in the future. I’ve included the rebuild process and pricing from bimmerheads and VAC, they end up being roughly the same price, let me know which sounds like the better option.

VAC: $1299 with your core sent in

• Complete Disassembly & Cleaning
• Comprehensive Leak, Crack & Pressure Test
• Inspect All Components For Irregular Wear
• Our High performance Multi Angle Valve Job using Serdi Equipment
• All New VAC Uprated Valve Guides
• Viton Valve Seals
• Reconditioning & Blueprinting of Your Valves
• Balancing of Your OE Springs
• Trueness Checked & Resurfaced Mating Surface
• Unshrouding of Valves
• Attention to Potential Hot-spot Areas and Chamfering

Bimmerheads: $1875 with $500 refundable core

• Cleaning
• Pressure testing
• Resurfacing
• Valve grinding & valve seat grinding
• New valve guides
• New valve seals & cam seals
• New intake studs & exhaust studs
• New rocker arm hardware & eccentrics
• Refurbished and coated camshaft gear
• New cam gear dust cover
• New Heavy Duty rocker arms
• New OE spec cam or (+$50 regrind 274, +$180 new 274 cam)
• Good used dual valve springs

[aavani90]

Also interested to hear if it’ll be worth it to upgrade to a 274 cam during the process.

[digger]

Of those I’d go with BH or anyone else over VAC . I’d ask for new springs though.

It’s not a specialist job so if you wanted to try save a little bit of money you could potentially get the local cylinder head place to do it but you may need to source a core and some parts yourself perhaps and need to find a place with good reputation. Sometimes it’s not worth the hassle though

[aavani90]

Of those I’d go with BH or anyone else over VAC . I’d ask for new springs though.

It’s not a specialist job so if you wanted to try save a little bit of money you could potentially get the local cylinder head place to do it but you may need to source a core and some parts yourself perhaps and need to find a place with good reputation. Sometimes it’s not worth the hassle though

Yeah I was considering that option too, I haven’t added up parts cost if I was to buy everything individually and have someone local do the labor. Will probably work those numbers before moving forward with bimmerheads. What’s your opinion on a 274 cam? Only like $200 to throw one in while it’s all disassembled.

[ForcedFirebird]

I’d ask for new springs though.

I have yet to fond a bad used m20 spring. I have a Rimac spring tester, have tested thousands of m20 springs, and they all come in spec.Unless you are looking for a higher spring rate, the m20 springs are actually robust.

If you go to a local machine shop, you'll not only save on money, but time. I suggest you call these companies and get a lead time, parts have been scarce and slowing all the shops. If you are looking for a simple rebuild, no one online is going to much better than your locals will - plus you have the added benefit of a face-to-face if there are any issues.

[moatilliatta]

I’d use new vs regrind camshaft and replace valve springs if upgrading cam.

Genuine rockers > IE HD

I bet the Vac head would make more power 3-5 hp over BH if you don’t run into any quality issues.

• Unshrouding of Valves
• Attention to Potential Hot-spot Areas and Chamfering

Metric mechanic release their M20 HD rocker get?

[ForcedFirebird]

I’d use new vs regrind camshaft and replace valve springs if upgrading cam.

Genuine rockers > IE HD

I bet the Vac head would make more power 3-5 hp over BH if you don’t run into any quality issues.

• Unshrouding of Valves
• Attention to Potential Hot-spot Areas and Chamfering

Metric mechanic release their M20 HD rocker get?

Yes, I prefer used OEM BMW (not Febi) rockers in my builds at work.

I've tested various characteristics of the 885 head both on the dyno and my flow bench (even flowed others' work), 3-5hp is highly doubtful without extensive bowl and short side radii work.

Curious what's meant by "blueprinted valves"?

[82eye]

Curious what's meant by "blueprinted valves"?

wondered that myself. weighing and balancing the valve and spring sets on each cyl maybe? it's not rotating mass so i don't see how it helps.

i think a lot depends on your goals. i went with a local build/ head refurbish. re-used springs and valves, new hd rockers / seals, 270 / 272 regrind from colt cams, a little work on the exhaust ports. pairing it up with an IE longtube header / stromung catback and a sssquid chip. shooting for oe+ street build. budget and goals kept me from going a full BH head.

even though i had work done local and only bought a few things through BH they were fantastic in customer service and even gave me a few pointers. i'd recommend in a heartbeat.


edit : gotta remember it's a convertible. it's not quite the same car as the coupe / sedan.

[ForcedFirebird]

wondered that myself. weighing and balancing the valve and spring sets on each cyl maybe? it's not rotating mass so i don't see how it helps.

I've been rebuilding heads for almost 20yr, and that's the first time I heard of it! HAHA.

Don't bother porting anything on the 885, unless you have experience on these particular heads. You WILL worsen them. I have flowed heads from back yard porters, as well as other vendors - IMO you are wasting time and/or money. It took me MANY hours with a flow bench to get the 885 heads to flow worth a crap....

https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/228610-let-s-see-how-much-m20-heads-suck?p=9963709#post9963709

[82eye]

Don't bother porting anything on the 885, unless you have experience on these particular heads. You WILL worsen them. I have flowed heads from back yard porters, as well as other vendors - IMO you are wasting time and/or money. It took me MANY hours with a flow bench to get the 885 heads to flow worth a crap....

you have pretty much same opinion as the shop who worked on it. they just cleaned up a little stuff on the exhaust and that was it. it couldn't be called a polish.

[digger]

I have yet to fond a bad used m20 spring. I have a Rimac spring tester, have tested thousands of m20 springs, and they all come in spec.Unless you are looking for a higher spring rate, the m20 springs are actually robust.

If you go to a local machine shop, you'll not only save on money, but time. I suggest you call these companies and get a lead time, parts have been scarce and slowing all the shops. If you are looking for a simple rebuild, no one online is going to much better than your locals will - plus you have the added benefit of a face-to-face if there are any issues.

unlikely to go soft as they are not really a high performance spring but i don't see how they can know the history of the springs. They still accumulate fatigue damage every cycle and are one of if not the most highly stressed part of the engine. If the springs have ever sat around between builds and get some light corrosion this will degrade the fatigue performance of the spring massively. I don't see it being worth the risk over sub $200 parts

[aavani90]

I have yet to fond a bad used m20 spring. I have a Rimac spring tester, have tested thousands of m20 springs, and they all come in spec.Unless you are looking for a higher spring rate, the m20 springs are actually robust.

If you go to a local machine shop, you'll not only save on money, but time. I suggest you call these companies and get a lead time, parts have been scarce and slowing all the shops. If you are looking for a simple rebuild, no one online is going to much better than your locals will - plus you have the added benefit of a face-to-face if there are any issues.

Lots of good information here, thank you all for the replies. I think my goals for this rebuild at this point are going to be full refurbishment minus trying to have it ported. New genuine springs, rockers, and cam. I wouldn’t mind picking up a little extra power along the way with either a schrick 272 or Bimmerheads 274. This is the first engine rebuild I’ve really done to this extent since auto shop in high school (13 years ago), will I need to have the timing adjusted from using a different cam?

[digger]

Are you rebuilding the engine ? If you pump the CR up either of those cams is probably ok though BH don’t give much in the way of specs.

[aavani90]

Are you rebuilding the engine ? If you pump the CR up either of those cams is probably ok though BH don’t give much in the way of specs.

I’m doing a complete top end overhaul. Entire new cooling system, vac lines, ignition, fuel, sensors, cleaning and resealing everything obviously. I meant rebuilding in a sense that I’m tearing it down to the block, will be having the head rebuild by a shop, and then reassembling it all myself. Like I said before though I just haven’t done this degree of a tear down in over a decade so I forget how some of this works. Can’t remember if you need to mess with timing adjustments if you add a different cam than the factory one. Hoping some of the M20 gurus can school me on this a little bit! 🤞🏼

[digger]

if you wanted to fit a camshaft to a low compression engine i would be trying to up/retain the CR using the standard head gasket thickness and maybe a little extra off the head surface but check all the clearances when reassembling. You can basically drop a small duration increase cam in without any mods. its best to use an adjustable cam gear and play around to find optimal position but its not mandatory. as for schrick vs BH without the BH specs its hard to say which is better. You'll needs some ecu mods to get things to run as best as possible