John in RI

iTrader: (167)

Pre-86 SBC, 355ci that has a rather "radical" cam. (280 Dur, 480 Lift) Can Vortec heads be bolted to this thing WITHOUT MACHINING ??

Can I just slap a set of springs on the heads and bolt them up ?? ( will LT4 Upgrade springs work?? If not: those; what springs would be needed ?? I searched for this info a while back and got light headed; it's a quick question that hopefully someone with experience running a high-lift Camp & Vortecs has a quick answer to!

John in RI

iTrader: (167)

Sound right ??

skinny z

I used Comp 26918 on my Vortecs with .500"+ lift.
26915 (a lesser spring) will also work.

GeneralDisorder

iTrader: (1)

So the answer with the Vortec's is to run LS6 stock beehive springs and Comp 787 retainers for the Vortec valves and locks. I used a set of PAC Racing LS beehives with 130lb's on the seat. Works great with my cam which is .500 / .520 lift. With the beehives, 787 retainers and offset locks it is possible to run 500 lift without machining. And the LS beehive springs are THE S**T.

Vortec's have 64cc chambers so compression ratio is going to depend on what your current chamber volume is and what head gasket you use.

Will require a different intake manifold. One for Vortec heads. Exhaust is the same, head bolts are the same, etc.

GD

NoEmissions84TA

iTrader: (1)

Read this: https://www.alexsparts.com/new-vorte...-130-lbs-seat/
Alex describes how & why this works.

John in RI

iTrader: (167)

Thanx for the prompt replies !

The specific intake was always the reason that I never used Vortec heads. The Vortec upgrade for TPI is simply ridiculous when starting from stock,... (Aftermarket Intake, Runners, TB = LOTS of $$ ) & I've only build a handful of Carb 350s in the last decade and I always used parts on-hand to (reasonably) complete those cars. I've had a couple Vortec / Carb intakes,... just didn't have a need at the time and sold them off.

The 355ci is a professionally built 350HP (advertized) block with a gear drive and old school heads. It's got a super "loopy" idle and a "mild" gear drive,... LOT's of personality ! It's been sitting under a canvass in my garage since I swapped to LT1 and I'm looking to make use of a set of decent Vortec heads that I picked up from the junkyard a couple years back. ( Truck was slammed in the back and had real low miles. )



I was hoping that the LT4 springs would work 'cause I've got a unused set,...... but the cost for new Comp is comparable/expected & the cost for new LS6 springs is CHEAP so I'll hold onto the LT4 stuff for use on a different LT1 some other time. LS6 Springs: https://www.summitracing.com/parts/nal-12499224

Any problems using LS6 springs and 1.6 steel SA RR ?? ( besides probable valve cover modifications ?? )

Anyone want to recommend a better head gasket alternative than Fel-Pro gasket p/n Q1255 ??

Anyone want to recommend a Spark Plug ??? GAP to .45 or .60 ??

Thanx in advance to any and all feedback. A little 'back-&-forth' is going to save me a LOT of time trying to decipher 25 page Vortec build threads !!

sofakingdom

iTrader: (1)

The LS6, PAC, or PSI beehives with the Comp "adapter" retainers are the best option IMO. Better than any straight spring. My choice would be the PAC 1218. You can get em from Texas Speed. I don't feel real fuzzy myself about Alex's but some people have used them with some degree of success.

I don't know for sure what you mean by LT4 springs; if they're the ones that came with the HOT cam setup, I'd look for something better. The cam in that setup was decent; the rockers and springs, not so much.

1.6 rockers shouldn't be a problem for the LS ones, subject of course to "adjusting" the tube thing that the VC bolts go through, or using perimeter-bolt VCs and adapters.

There are 2 things you DO NOT want to have happen: the retainers hitting the top of the guides, and coil bind. Either of those things will destroy parts. Most likely will pull the studs. As far as what's going to fail, the studs are the weak point. You need to make sure there's no binding or interference of any kind to keep them happy. Spring pressure shouldn't be a problem, but binding will be fatal.

Just look up spark plugs for a 98 5.7 truck. They'll have a real long thread; can't recall the part # off the top of my head. .045" gap is fine. Nothing about spark plugs in this application is going to be particularly unusual or demanding, don't overthink it.

I think you'd also be happier with a chain than a gear drive. Sell the GD and use the cash to buy a chain.

GeneralDisorder

iTrader: (1)

I can second the PAC 1218 springs. I just dyno tuned my Vortec head build with these and it sings right up to 6500 RPM. Probably could go farther but my tach only goes to 6 and peak HP is 5150 so no need. Made 325 RWHP.

GD

Fast355

iTrader: (2)

MR42LTs is what I always ran. The factory plug for a Ramjet/HT383/330HP 350 crate or Marine 350.

skinny z

My Vortecs liked the ACDelco R44LTS.

John in RI

iTrader: (167)

I'd like to thank everyone for their input. I know much of this stuff is floating around out there,.... but taking a couple minutes to enlighten me on some of the details is a BIG help and a real time-saver. I really appreciate it and am honestly grateful for the help !

Fast355

iTrader: (2)

Too hot and will likely contribute to detonation.

I always ran the 42s at 0.035" gap. Made for a noticeable power increase and less prone to knock retard in hot weather. It also made the cap and rotor on the Vortec last alot longer. There is a TSB from GM to gap the Vortec plugs at 0.035" rather than the stock 0.060". I have witnessed a Vortec 305 gain 10 hp at the wheels from gapping at 0.035" from 0.060". Ignition was misfiring at high rpm with the stock gap even though the engine seemed to be running smoothly. Had all kinds of weird spikes in the dyno. Springs were good. So we tightened the gap. Misfire gone and the dyno chart smoothed way out.

dmccain

iTrader: (2)

My last carbed Vortec engine did the same. Upper RPMS hurt @.60 gap we checked over everything and finally after closing that gap to .35 that engine was happy.

skinny z

It's been years since I ran Vortecs. Now I have an aftermarket upgrade to them which takes the same plug but it's not apples to apples. From what I remember with the Vortecs (and the 44 plugs) and just an HEI for ignition the gaps were .035". No signs of detonation or other distress. That engine also buzzed to 6000+ with ease (not that it made any power up there).

GeneralDisorder

iTrader: (1)

Big gap is just unnecessary and hard on ignition components. I think OEM's did that for slight boost in emissions compliance. We routinely run boosted applications down to 0.020 or even 0.018 and it's not an issue.

GD

skinny z

Then there's MSD's recommendation (6AL CD box) to experiment with gaps up to .055" -.060".
Go figure.

GeneralDisorder

iTrader: (1)

That's from customers wanting to see the bigger numbers and MSD not wanting to explain why they recommend lower gaps than factory Vortec HEI

It's the same reason people that don't understand ignition timing get all upset when their crate engine will "only" take 32 degrees of timing when their cousin Skillet is running 40 degrees on his old iron head 70's smogger garbage. They just want a higher number and fail to understand that efficient flame front propagation through an advanced combustion chamber design with proper quench means ultimately less timing will be required to make the same power.

It's because the typical MSD customer wants bigger numbers. That's the only reason for that foolishness. When you get deep into boosted applications you find that you blow spark out at high gaps and then after you play with a whole bunch of cars and resort to gapping every spark plug you come across at 0.020" to avoid mid-dyno plug changes you realize that those HUGE gaps are a waste of time and a waste of ignition system capability. Also those huge currents destroy ignition components by needing larger dwell and breaking them down from heat.

GD

John in RI

iTrader: (167)

OK - awake from hibernation. I've got a quick question:

Got the pre-87 355 flat tappet hydraulic lifter block with Vortec heads....... What rockers am I supposed to use ?? Self aligning or not ??

The heads were recently returned to me after getting checked for cracks and I had the guy drill some coolant passages too. Started looking at acquiring parts for reassembly and wasn't sure what rocker arms I'll need. I've always built within the year range of the engine I was workin' on so if it was flat tappet it got regular rockers and if it had roller lifters it got self aligning rockers. Did not plan on using guide plates.........



I haven't started assembling anything yet and figured I'd ask before dealing with rod length and rocker arms...... I'm GUESSING regular pre-87 rockers ?

skinny z

If you're not using guide plates, then the Vortec heads require self-aligning rocker arms. The pushrod holes in the conventional heads are designed to be guides. The Vortec heads don't have a similar feature.
The lifter style doesn't enter into it. Length? Obviously yes. But the alignment is handled otherwise.

sofakingdom

iTrader: (1)

The push rod holes in those heads are too big to provide rocker guiding. You'll have to either use 87-up self-aligning, or install guide plates, or step up to $$$shaft-mount$$$.

You don't have to use a flat-tappet cam if you'd rather not. I wouldn't if I could avoid it. You can use a "retrofit" roller-tappet one. It'll require link-bar lifters, shorter push rods, and a cam button. Pretty straightforward.

Not sure about "drilling coolant passages". I've never done that to any heads except when setting them up to go on a 400 block. The block OTOH is a different matter... look CLOSELY at the 3 holes circled in magenta, bottom center: there's usually either a triangular hole or a round hole in the deck there, and those 3 holes MUST be COMPLETELY unobstructed to allow full flow through them. Lay your gaskets on your block and heads, and enlarge the holes in the deck to clear the holes in the gasket, if they don't already. Maybe that's what they did to the heads, in which case, good on them. Verify that they're COMPLETELY clear on both sides of the gasket, use a die grinder as required to open them up. That's a MAJOR cause of "mystery" overheating-like behavior other than boiling over; things like burning up the valve cover gaskets, excessive pinging, hard starting when hot, etc. The problem then is, the 2 center cyls on each side are "overheated" (cast iron is VERY hot) even though the coolant temp seems OK.



The gasket performs the function of regulating where the coolant flows. In that pic, grey is oil drainback, yellow is head bolts, red is dowel pins, cyan is the aforementioned 400 adaptation, and all others including the magenta are coolant flow. The hottest part of the heads is the exhaust ports, hence the ones across the bottom at the corner right under the front & rear exh ports, and the magenta ones and the 2 at the top center which serve the 2 exh ports at the center. That spot is far and away the hottest part of the head. The itty bitty holes elsewhere reflect the fact that there's far less heat at all those spots, therefore far less cooling is required.

Airwolfe

iTrader: (1)

He might be talking about drilling the internal coolant bypass passage into the Vortec heads for use with older blocks, water pumps, and Vortec intake manifolds that aren't setup for and external coolant bypass.

John in RI

iTrader: (167)

Thanx a for the info, saves me a bunch of time searching and that helps !!

Yes; I was referring to the coolant passages that are missing / not drilled in the vortec heads. I've got an 88' style aluminum Edelbrock WP II plan to use and prefer the "internal" coolant bypass system on the pre-86 block. Here's a look at the new holes:




I finally found a little good weather & "spare" time to put some work in on these things. We FINALLY got some good weather for blasting / painting on the east coast this week ; still a LONG way to go,.... but you gotta' start somewhere !

skinny z

I sometimes think to myself that I should have kept my original Vortecs. Great little cylinder head. And plenty of upside porting-wise if you care to go there (which I didn't).

Funny thing about the coolant passages and the bypass. I had (one of a couple ) late 70's blocks and both with Vortecs in unmodified form. My thinking on this bypass deal is that with a heater core and no bypass valve in the line set, that it all functioned as GM intended in the 70's. One hose from the manifold (near the stat housing ) to the heater and the return to a fitting on the water pump. Never an issue with filling, heater function (which I certainly needed) or boiling over. 180° thermostat. Single fan on at ~ 197° and off at 185°.
Head gasket of choice was the Mahle 5746.

John in RI

iTrader: (167)

Finally got a little work done on this; managed to get the block painted during that freak 80 degree late October day a couple weeks back so at least now I can mess with it little by little during the winter.

How it looks after sitting under my bench for the last decade or so with 2 coats of paint on it: ( Motor, 85' 4-BM, 2-Pc RMS, .30 over, Gear Drive; was rated @ be 350HP when 71' Vette heads were installed on it with 1.5 rockers.) https://golenengineservice.com/



Here it is after the strip-show:


Here it is after the rattle-can paint job


I'll list the stuff I've acquired for rebuilding the heads soon, just waiting for a couple more things to arrive.


Having some trouble with the head gaskets: from what I'v read I should be trying to land @ about 40 thou of clearance; the feeler gauges I've got only got to 30 thou and there's still gap so the piston-to-deck is above 30 thou before even considering what head gasket to use. I'm just using a straight-edge and feeler gauge,... should I get a dial gauge for this measurement ??

sofakingdom

iTrader: (1)

No, the way you're measuring it is completely acceptable, and your results normal. (unfortunately) Even if undesirable.

Best way to cure it is to deck the block to the nominal dimension. Correct distance from crank centerline to deck is 9.000". Factory blocks are almost always over at least .015" more than that, and uneven besides (check the 4 corner cylinders to determine that). Most "rebuild" pistons lower the piston .020" in the block from stock (pin center to crown height 1.54" as opposed to stock 1.56") since that's "safer" than going the other way or even just leaving it stock due to the large number of blocks, back in the day, needing MASSIVE decking due to scour marks from blown gaskets. That's not as big of a problem today as it was in the 60s & 70s, butt the custom has remained. Virtually all cast, most hypereutectics, and many forged (SpeedPro/TRW for example) are like this. Crank grinding makes it worse; wear on the crank is concentrated on the TDC point (duh), thus if you (machine shop) "offset grind" the journals a little bit you can scrap fewer cranks, at the expense of further increasing the deck clearance and lowering the compression at the same time, and your customers almost never will know the difference. Might be worth measuring the actual stroke as well: you might have any or all of those factors in play in your motor.

This is the kind of attention to detail that allows the Edelbrock RPM "kit" to dyno 435 HP or whatever it is when they finesse a motor and dyno it, butt people in the real world that just buy it and bolt it up, hardly ever break 275.

skinny z

I've used feeler gauges and a bridge micrometer for this measurement and they're pretty close.
That said, yes, 40 thou is the number bandied about. Safe distance for adequate clearance and tight enough to get that desirable mixture motion happening.
A few things to consider after having dug into this in some detail.
Piston top profile enters into this. A dish with little to no quench pad kind of kills the whole deal. A flat top is ideal.
40 thou isn't the be all and end all I've learned. Depending on the compression ratio and the type of fuel you wish to use, the detonation resistance that a tighter quench allows might not be entirely necessary.
Similar to yours, my 1st Vortec engine was a 350 with a piston below deck of .035". And as Mr. S pointed out, this varied from front to back and corner to corner. Best was about .030" spot on and the most was at or near .038".
I opted for a .026" head gasket (Mahle 5746). The math says quench was better than .060".
CR came in at slightly less than 10:1 and combined with the cam of the day (there were a couple at least) the engine performed very well. Mileage was excellent and was a solid daily driver. "Peppy" too.
That said, I've gone out of my way to try and get the ideal quench in my more performance orientated engines. Going less than 40 in some cases but eventually settling in on exactly that number.

John in RI

iTrader: (167)

Awesome input - THANX !

At least I'm a bit more comfortable now about figuring out the head gasket than when I had first thought to consider it. Primary goal now is to get myself a "better" straight edge, then take a full set of gap measurements measuring from the center of each piston to avoid errors from piston "rocking". Hope that just over .030 is my largest gap, the heads were never decked,.. but the block might have been.

I'd read that the gasket bore size should be at least .030 to .060 larger than the bore and if a 355ci has a 4.030, and my compressed size is .025 and smaller than I'm starting my search at summit of 7 gaskets ( 3 of them @ 4.060 & 4 @ 4.1 ) Of those 7 gaskets the thinnest (compressed) gasket is .015; that added to my deck of +/- .030 is already over the .040 that I'm aiming for. Basically looks like I'm gonna' be ordering at a real slim steel shim: Fel Pro 1094 is a 4.1 bore and .015 thick @ $27,......... and Fel Pro 7733SH1 is a 4.1 bore and .016 @ $11 each. There are a couple COSMIC MLS and a copper option too, but @ $70-90 each gasket - and they are .20+ compressed. ( and Yup; Mahle 5746 @ .026 )

Once I can clean all the carbon from the pistons ( Thanx Edelbrock 750 ! ) and 'feel it out' again I'll repost the piston gaps a for later reference. Also gotta' find a set of feeler gauges with .030 and higher fingers !

skinny z

Although never having used shim gaskets, the applications are varied if the internet is anything to go by. Seems the surface finish of the heads and block play a greater roll than if a layered gasket is used.
Although we're dealing with iron to iron, an uneven deck on the block or heads or a surface finish that isn't to "spec" might leave gaps you don't want.
As mentioned, results are mixed.