Hi,

Time has come to buy new heads for my 92 RMW L05. Head gasket is leaking out water and stem seals are out.

I have decided to go for GM perf parts and 2 options exist.

Service replacement heads 93438649 (300 USD each)

Or Vortec heads 12558060 (400 USD each) but need Vortec intake maniflod for TBI # 12496821
The new manifold may not be adapted to the Ignition distributor which is (as I understood) more compact on the Caprice/Roadmaster). What about EGR then ?? I do not know how to keep it with those heads

Cost wise and to keep it simple I would prefer to go for the service replacements heads but I am not even sure if those will fit OK without adaptation or anything ...

If Vortec fits Ok too and offer significant improvement then why not but I am not sure of installation process.

I have no junk yard or GM head machining shops as I live very far on old continent. So I am buying new parts only, no rebuild.

I Also have an ECM with EBL flasher so I can remove EGR if needed (our emission tests here are done only at IDLE !! so no EGR I think)

Anyone knows what is best for the money on 92 Caprice/Roadmaster ?? ... and fits almost straight ?

 

The #93438649, show 76cc chambers, they will require doomed pistons for a resonable CR (compression ratio).

New iron vortec heads shipped over the pond, end up costing the same or more then 1200$ aftermarked aluminium heads, shipped.

Could check out Engine Quest if you really want vortec heads, i read they may have a hybride vortec head that allows to reuse 87- up pre-vortec intake manifold.

My first choice would be aftermarked 87- up emission legal aluminium heads, they flow wery well, easier to port if needed, are lighter wich means less weight, end up costing less and pass emission tests.

http://www.summitracing.com/parts/AFR-0919/
http://www.summitracing.net/parts/TFS-30400006-M64/
http://www.summitracing.net/parts/TFS-30400007/
http://www.summitracing.net/parts/EDL-60859/
http://www.summitracing.net/parts/SUM-162108/
http://www.summitracing.net/parts/TFS-30300005/

All these heads should be direct fit for the LO5 and allow to keep EGR.
Thoug compression ratio, powerband and cam should be decided before chosing the heads.

If the goal is just to get the stock engine running as from the factory, I would keep the 193 swirlport heads, as they make the best power in the idle to 4000rpm range. (I have a remanufactured pair if you whant)

Are you looking in to rebuilding the whole engine or just changing the heads?

 

Well I have a bad head gasket and since a lot of miles my intake manifold leaks oil at the aft sealant (oil drops on the body, enters the car and drips on one harness above the ECM ) - also I have ash deposit on some spark plugs which seems to indicate bad stem seals.

I just fully rebuilt the gearbox and it was such a hard job getting the gearbox in and out that I don't want to do that again.
The cars has 133 000 miles on the clock so I just wanted to rebuild the heads and put some headers (for the flow and the sound).

I do not want to gain 40 HP but if I can get back to OEM spec + 20 HP and more torque and better MPG then this will be just fine. Car is my only car and thus is my daily drive ...

I was told the exhaust manifolds and the exhaust ports of the heads are the weak points on those engines.

I bought several S-A Design books about camshafts, heads, Small Block ects. But mainly those are explaining how to get 400 HP !
I have an old S-A Design I bought in CA. in 1997. Title is "Performance with economy". It is great but it deals only with older design with carburetors. I can't find same info applied to our TBI engine which is possibly the best evolution before LT1 introduction.

To summarize I will change the heads because renewing mine will be two expensive.
Only if necesary and easily feasible I will change the intake manifold.
I may install TBI injector spacer too and cold air intake (caddy mod or home made)
Lower engine will stay on the car and will stay untouched (unless I find obvious damage on the pistons.

but I am a bit lost ...

 

Too bad you aren't closer, I have a set of mint 059 Vortec heads I want to get rid of.. Pretty much a direct, better flowing replacement.

 

In this case best is to remove the cylinder heads and see what is below, before chosing the new heads.

It's possible it has flat top pistons whit around 8 cc or dish with around 12cc, according to wich you can choose a head that gives close 9.5-10.0 CR for good efficiency.

I doubt GM still has a stock replacement head for your LO5, wich leaves you 2 options, remanufactured stock heads (let me know if you whant a set) or better aftermarket heads.

With the heads, the cam is also part of the low hp combination of the LO5, can download Comp Cams camquest6 for some ideas.
comp cams 8-500-8 with a decent aftermarket head will be fun and easy to tune with EBL.

(#CH350G is the part number for EQ vortec heads for 87-92 LO5 engines http://www.aaeq.net/Enginequest/Home they are on the 2010/2011 catalog.
Combustion chamber and valve lift clearence are not indicated, best is you contac them.)

 

aren't 059 vortec heads for 305 ci engines ? (Mine is a 350 ci with 9.8:1 CR and flat pistons)

Shipping parts from the US is not a big deal. It is really cheap compared to shipping parts from France to the US - I can tell !! My Impala rims came via USPS. 100 USD each + 150 USD shipping USPS.

Will contact Engine quest for compatibility with the L05 and their ch350G

Switzerland is not far and I have a friend living there, he drives back and forth ... may contact you by MP if necessary

 

Got a Reply - found that CH350G is a bare head.

I prefer to get a fully equipped head that fits straight onto the Caprice L05 with stock intake and EGR !

Edelbrock Performer seems to be OK but it is 670 USD each

GM performance stock Iron cast head turn into lower Compression Ratio so I have to stick to the 64cc ...

No one ever did that before on a L05 Caprice or Roadmaster ????

 

You still have some excellent direct fit options, 180cc AFR and 195cc TFS will keep your CR close to were it is.

170cc summit heads would get CR to 10, wich is would be ok with aluminium heads.

 

10:1 CR
Ok for aluminium head fine but what about pistons and octane in the pertol ?

 

Found this kit http://www.trickflow.com/partdetail....8++150+&orig=1

it claims 465 HP.

How come ?? with just a pair of head and a cam ?????

I imagine fuel flow has to be adapted (+ECM) and a pair of headers will be just fine but Jeeeeeeeeeeezzzz

Is that so simple ?????

I am used to see people spending big buck to gain 20 HP on naturally aspirated engines so going from 180 to 465 is a bit weird ... need locking diff

 

I would not rev a stock LO5 shortblock to 6500rpm or put a "high" rpm top end on it.

Though good heads (not that kit) and the right cam will get 1hp/ci easy, at around 5000rpm.

Have you play'd with this yet? http://www.compcams.com/Pages/409/camquest-6.aspx

 

Yes took time to play with it.
I also compared the street cams with my OEM cam.
It is awful !!!
The durations (179° intake - 195° exh) and valve lifts (0.35 intake - 0.385 exh) are quite low.

Then I found another cam that may well be the one that was fitted on the police version 9C1
The durations (207° intake - 214° exh) and valve lifts (0.41 intake - 0.427 exh) are much better !!
camshaft is 300 USD (Sealed Power CS-808)

With this cam and headers (+dual) and EBL flasher I may well get what I want: a bit more performance with economy. So OEM heads may stay on the car no ?? mean their design was good for low end torque and this is what I don't wnat to loose.
But of course if they really need a full rebuild with new springs and roller rockers the price will get a bit high ...