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Slover's Ported chevy 492 angle plug heads

15K views 31 replies 7 participants last post by  rjs89ia 
#1 ·
These cylinder heads were on a 302 I purchased a while back. They're ported by Slover's Porting of Sun Valley, Cali. I've looked everywhere for reviews of their work but can only turn up recommendations and reviews from import cars. AFR list them as a porting service so I would have to imagine they're good at what they do. Their website shows a lot of work they've done for salt flat racers too. Does anyone have any info/experience with these guys? I've had no luck at contacting them electronically, next is to try an call them and hopefully I can get specs from them if they kept em from the 70's. Only thing to worry about after all of that is if the things are crack free.
 

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#4 · (Edited)
High rpm is the direction I've been leaning, something about the sound :D. The engines already built for it, its just a matter of upgrading a few of the older worn out pieces. As far as welding in the ports the only thing that I can make out as being welded was the heat transfer port in the exhaust port. You can make out some of weld seams in the RH exhaust port in the pictures.
 
#5 ·
Looks like they have also been welded in the spark plug cooling trough on the deck surface to keep it from being too thin at the gasket fire ring...usually a sign that they have been angle milled, so cc'ing the chambers for volume and check your intake manifold with a test fit-up well before final assembly, just to avoid surprises on manifold fit and overly high compression ratio.

You might also want to consider using 1-piece stainless valves in place of the GM 2-piece valves, I'm surprised to see those still there. I'd get the springs checked also, just so you know the pressure spec's....they look like pretty stout springs (solid roller maybe ??) and may be too much for whatever your cam choice is.

Competition Products in Wisconsin is a good place for valvetrain parts, real good prices on valves.
 
#6 ·
I know for sure that the block has been decked I can't see any machining marks on the heads though but wouldn't doubt they are milled down. I'm on my phone right now or else I would post some good pictures of these parts. My profile contains some decent pictures of most of the major parts. I researched the cam and crane told me it hasn't sold any in the past year "that's all the history they keep by the way" so I'm thinking its a one off or at the least one of few from that period of time. Those specs are also in the album in my profile and from the numbers I can determine its "big" for a 302.
 
#7 ·
Looking through your album, looks like it was state-of-the-art for about 1980 or so.

Valvecover spacers were used back before companies started producing tall covers to eliminate the need for spacers to allow fitting full roller rockers under short covers.

I would look around and try to find a lightweight steel H-beam or I-beam rod that has a weight close to the old aluminum rods, so they don't have to be replaced all the time. There are quite a few light steel choices today, there were none in 1985.

Quite a stout cam for a little 302, I bet it ran hard in something light, and agree that it is probably best to R&R the pistons, rods, lifters, valvesprings, and valves....since you don't have the run logs or mileage on them. Neat time capsule though. :thumbup:
 
#8 ·
Thanks ericnova, I was thinking that with the spacers but something that my pictures don't show are the stud girdles. They should clear under the normal tall valve cover but I haven't actually put the engine together to check fitment. The spacers are clearanced on the upper side for the tunnel ram. As far as the rods go I'm borderline, steel would last longer but I haven't read many good things on their life expectancy at sustained high rpm's 8K+. I've come to respect aluminum these days, at first I was quite flustered to see these rods but I've done a lot of research and talked to a friend who stands by them as he runs them in his BB396 blown alcohol drag car and his dad runs them in his top fuel car of course. I know they're elusive bombs at high time but I don't plan for it to be a daily driver. IF I put it in a streetable car I could probably sneak it out on to the blacktop in this area for a Friday night cruise down old 66 and maybe some parking lot show and tell. The main advantages to me are the light weight and their ability to lower vibe transfer unlike steel, I plan to reinvest in a new set of Arias light weight pistons $$ to keep it as close to original as possible. I'm not totally against steel rods but would like some positive intel from people running them hard well into 8 or 9 maybe 10K with no problems. Having no luck with my thread about the engine builider initials carved into the 327 cylinder block I'm using these cylinder heads as my last lifeline, hoping Slovers might have kept a record of who these heads were ported for and then maybe I can track it up to now. This thread was mainly to dig up some info on Slovers work to see if I acutally have something special or if its just plain old porting.
 
#9 ·
carrillo rods,,, new,much higher flow aluminum heads? The old heads that were ported and welded had air flow in the high 2s,, (270 plus cfm) you can buy heads that out of the box flow 325 plus cfm

a 331 revving over 8,000 rpm will need 300 plus cfm air flow
 
#10 · (Edited)
Thanks Vinnie I'll have to look into the Carrillos. I would like to stick with the old heads if they're still good, believe me I'd love to go with aluminum heads but I'd like for this engine to be as true to what it was from day one. I know it wouldn't be at its full potential but I believe at around 306-308CI it won't need to breath as much as a 331. I have read through the older chevy performance magazine article where they incorporate the AFR 210's and was very impressed even with the restriction of a single carb setup. I do read through Grumpy Jenkins book The Chevrolet Racing Engine quite frequently because it describes a good amount of the parts I'm dealing with in detail. That's where I've acquired a good portion of my knowledge on these small high winding engines. ericnova mentioned the cooling holes for the sparkplugs being filled earlier and I just reread part of the cylinder head section and found where it said that's ok for short runs but I was talking about driving it on the street which wouldn't have turned out good. Grumpy states that on the 492 theres more material outboard of those holes, than his preferred 292 heads, that can more easily be re-drilled to relocate those holes for the necessary cooling. It's old material to go off of but its factual and honest.
 
#13 · (Edited)
I run ported 70 LT-1 492 straight plug heads on my 302 4 bolt main (de stroked 350) in my Vette they flow 225-230 cfm intake and 165 - 170 cfm exhaust. and I run the 186 heads on my wifes 302 ported the same (never had them flow benched). This flow improvement with the heads you have should add 15 to 30 horsepower to your engine. over stock LT1 492 heads ! I like old school builds :thumbup:

The 492 and 186 new castings complete and ported are selling for $2500.00, a pair bare with new guides and ported sell for $1800.00 spark plug cooling holes are plugged in both. ! My cam is 613 lift and 312 duration.

Those carbs on your intake have a metering plate and will lean out the right side of your engine BAD mounted sideways like that they should be mounted end to end, carbs with metering blocks and are double pumpers can be mounted like that!

Its funny there's a Slover's Porting Service here in Michigan that has ported and flowed some heads for me :)



I don't understand why those heads have the damper springs still installed with the double valve springs?
Your valve stems and springs are different heights ! I know that's the way you got them!
Jester
 
#15 ·
Thanks for the info jester, if these pressure test good ill be sure to get them flowed and cc'd.

The valves mess with me i don't like how they're uneven. But it's the intakes that all sit high because they sit low in the seats unlike the exhaust ill be sure this is fixed when they're in the machine shop. They also have lash caps but the cylinder head pictured is missing 6 of them.The dampers probably don't need to be there by today's standards but reading through grumpys book he still used em in his pro stock engines so they seem exceptable.

Looking over the chambers on both heads i could see that the left bank actually looks like it was on the lean side. The intake valves have pitting on the faces and the #3 cylinder has a pit between the valve seats. The tops of the valves looking in the ports are clean with zero build up. The right bank actually has a lot of build up on the tops of the valves. One piece of info i don't believe I've talked about anywhere on this engine is that it has nitrous provisions on the intake with all the switches and regulators that i'm sure was functional before.
 
#16 · (Edited)
:thumbup:

Grumpys heads had to run the dampers in S/S class because of regulations in that class on head modifications. But in pro stock with that big cam and big block rockers there was no way he could have run those dampers they would have bound right up at that high a lift! and rules were more flexible in Pro Stock on modifications! He also ran the tunnel ram ,and crossram , the tunnel ram needed many internal mods like dams to keep gas from puddling and running because of poor atomization characteristics on the old manifolds, I ran those old tunnel rams at the tracks in the 60s + 70s and had to do the same thing, the cross rams also had that problem!! By the way be careful sometimes valves are set low in the seats for valve to piston clearance ! Another thing Grumpie held on to his secrets and gave false info on his methods to throw off the competition (maybe even in the book) LOL :thumbup: He could be looking down from heaven LHAO!!! and on the head I see 2 stems way above the keepers and it also looks like the springs are different heights but I'm old and can't see that great!

Jester

S/S rules

TECHNICAL DATA
VIN number 124378N411100
Build Date 04A (first week of April)
Color Corvette Bronze
Interior Code 712, black standard
Car Shipper Shipped on April 11, 1968 to Ammon R. Smith Auto Company, York, PA
Engine Data Cubic Inches, 302
Cylinder heads #3917291, completely stock, no porting allowed!
Stock rocker arms & valve springs
Intake 302 aluminum intake, casting #3917610
Carburetor Holley, #4053, 780 CFM 4bbl
Camshaft Crane, .480 inches lift, 272 degrees duration, valve lash, .016-.016
Pistons GM 302, .030″ oversize
Horsepower 456 @7700rpm
Rear Tires 9″ x 30.0″ Hoosier’s
Rear axle & ratio 12-bolt, 5.57 Richmond Pro Gears
Clutch 10 inch, three finger from Advance Clutch Technology
Shift Points 8200 RPM
BEST ET 10.80 @122.30mph
Campaigned by the late Dave Strickler and Bill "Grumpy" Jenkins
- 1968 NHRA Super Stock World Champion
 
#27 ·
Thank you, Hcompton I've thought the same about the parts being passed around. I do have another thread about the engine it self that's long been buried and never had any reply's. It was basically a race natured 302, aluminum BRC61 rods, a large solid roller crane cam 275/275dur. at .050 - .600 net lift 46-8400rpm range, the intake is as far as i can tell a RARE weiand pro ram 1982 w/o the air gap i've got a thread on that as well and I have yet to see another intake like it, it's also got nitrous spray bars in the top plate. Dual holley 660 carbs. The heads do have 1.625 exhaust valves. Everything else is pretty basic. Nothings really stands out other than the stamps on the heads and the engine block has been ground with some information. I've done some internet stocking on Dennis Fischer but I'm not going to pay to see his information that's a little overboard. I have contacted the racing team that is in his old facility in NC, I'm hoping someone somewhere will have the right info for contacting him.
 
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#29 ·
Thank you, I haven't been able to sink any money into it yet. It wasn't much longer after I bought it that I learned I'd be joining the wonderful world of fatherhood so I put my toy fund on hold until I take care of the more important things.

I've been through all the parts and found quite a few things that need replaced. The lifters and rockers are riddled with cracks and just plain worn out. Arias pistons has suggested that I modernize my pistons and I'm still on the fence with the brooks racing rods if I find out they're straight I may run them. A balance and blueprint will sure be in order just time consuming. As for the block I plan to get it sleeved idk how safe it is to go beyond .030 over on a 327 block with the amount of compression I plan to run but I've got a feeling that it'll have to go to .040 just to get straightened out. I did buy a 4 bolt truck block if needed.
 
#32 ·
Thanks vinnie, I talked a little more with Mike slover and he said it looks like they have his competition port job and angle milled which i believe you or another member stated before. I still plan to get them flowed, but by a measurement of the cross section I did a while back they probably won't flow that high. I remain optimistic about their ability even though the numbers suggest they are restrictive. They'll never flow as good as today's stuff but I'm sure they'll pull some decent numbers. That all goes to say whether they're still good or not lol.
 
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