Hello, I own a ’69 L71, all stock and very original. 4 speed with 4.11s. I was planning on pulling the original heads to have them rebuilt as the guides are shot (smoking), previous history of broken original valve springs, etc. I replaced the umbrella valve guide seals with no effect. The motor has never been apart, mileage approximately 16k. The motor runs great, idles great, and pulls like a freight train.

But then I got to thinking ….if I’m going to spend $1000 to have the old iron heads rebuilt, why not spend another $1500 for some modern aluminum heads. So after doing some research here on CF, seems a modern cam is the way to take best advantage of these modern heads.

This car is a Sunday driver, with 4.11s it stays on the backroads, no interstate. I do like the occasional pull to 6500 redline.

So I’m looking for head / cam recommendations from the experts. I’m staying with the Tri-Power. I’d like to maintain current idle quality, (14 inches vacuum @ 850 rpm), and stock location for temp sender and be able to bolt on factory exhaust manifolds. All on pump gas (93) of course.

Thanks in advance.

 

Have the stock heads rebuilt. If you do not go with headers and a 2.5" exhaust.....expensive Aluminum heads and cam will not yield the results you want. Yes they will be 80 pounds lighter over all but your Vette sits prefect and you are not racing on a road course. I would send these heads to VortecPro.....I am not sure how to get a hold of him as he is not on here much anymore, but i am sure someone has the info. He knows what to do and does what i would do if I had the equipment. K&L bronze liners, a 5 angle valve job and blend, some premium stainless valves...cut for positive viton seals......etc. They will come back to you better than GM could have ever hoped.
Here is the deal......a real set of big block aftermarket heads will run you over $2500. For this money you could have the stock heads fixed and a real header/exhaust system installed. You think it runs good now......just wait until you have the heads/exhaust done as I stated. If this is a stock 69' car.....it will have a pathetic 2" system on it that barely works for a 300 horse 350. The items I mentioned will make the engine pull high into the rev range and make best use of that 4.11 gear. Plus you will keep the engine stock.....as L-71's pass the 80k range to buy in nice condition.....this becomes more of a decision.......an exhaust and headers can be put back stock in a day for the purist who has to have them. Personally, I think every hot musclecar from the 60's and 70's should have some kind of exhaust/header on it.......the L-88 made 100 more horsepower with open headers than through the stock system....and the difference in tuning is huge too as these long, lazy overlap cams absolutely hate being corked up and most be compensated to run correctly with factory stuff.
I personally don't believe that exhaust effects the overall value and cool factor of an original hi-po car......it only enhances it.....GM knew this years ago but did nothing about it.....but ALL of their prototype stuff had headers and you could get headers in the trunk of a 67-69 Z-28 when new if you clicked the right box.
Anyway.....you asked for an opinion!

Jebby

 

We went with a Bullet custom hydraulic roller camshaft, billet core with everwear gear option and morel retro-fit performance roller lifters. Comp cam performance valve springs, compcam chromemoly spring retainers, comp cans machined billet vaalve lock keys, performance valve springs, ultra pro- roller rocker arms, hardened 3/8 guide plates - there is more detail if you want it - engine dynoed at 475HP at 5800 rpm's - but I went with lower compression pistons so I can run 93 octane.

 

I tend to agree with Jebby. It is an all original L71. Alum heads are a very obvious major change, difficult to put back, and would hurt the value of the car, but could add 50+HP. A very good valve job as mentioned could easily give you 20-30 of that.
Duntov said the mufflers on the BB cars cost them 50HP. Especially so with your 2 ' exhaust. Much less obvious and much quicker to put back to stock if needed. I would vote for you to do that. You should gain 50+HP with these two mods.
The L71 cam is a very good cam. Without heads & headers I don't know if I would go to the trouble to change it. Keep using Zinc additive and don't bother. Now if/when a cam lobe wipes, roller hydraulics/solids could easily gain you some power and still sound/run the same. Maybe 30HP or a bit more, unless you go with one that sounds different. The hydraulic rollers are invisible and a pretty well accepted upgrade even on a classic due to the camshaft issues over the last decade. With and still sound & run the same. You'll need very expensive lifters for it to continue to rev to 6500 tho. With all three mods yes your current 435HP could easily jump to 550. That pretty much explains what I'm building in an LS6 454 look alike should also be near 550.

 

One thing you need to consider is almost all aftermarket aluminum heads are open chamber and will drop the compression a large amount. Of course that can help with pump gas...but you can easily run an honest 11+ compression with good tuning. Edelbrock makes 100 cc oval ports that work OK..but not giant power producers. You can angle mill open chamber heads, but you have to pay attention to milling intake face of heads also to make intake fit properly and often the flow goes bad when angle milled. It takes work to get the flow back.

All that said...a nice set of Brodix 270's or AFR 290's would wake it up a lot. Rectangular port heads on a 427 don't really come alive until 5500+...so it takes some RPM. For a 6500 or so rev limit....ovals will usually be a LOT more fun on the street.
And if you go Hyd roller cam....now we have to really pay attention to things to get it to rev to 6500+. Good lifters, clearances, pushrods, rockers, springs etc are all vital to make it work. They can easily do it with right combo...but it needs to be right.

JIM

 

If you want a modern cam go talk with Chris Straub at Straub Tech. He makes a cam that is suppose to work with the stock iron heads. I beleive it is also a roller cam, which is another plus. As 427 Hotrod mentioned a set of AFR heads are a nice upgrade, although the 265s would be a better choice for a stock displacement engine.

 

One thing about all of these high flow small port heads is that they are oval port. The L-71 would have a pretty horrible mismatch on this and before anyone says they did this or they do that....it really needs an oval port intake mounted to it.

Jebby

 

If I were to go with aluminum heads on my L71, I'd go with a set of dated L89 heads. May not e as good as aftermarkets, but at least they would be visually correct and can be almost as good as aftermarket heads. Keeping the stock exhaust manifolds, I'd get them extrude honed.

 

Jebby is right. Have the stock heads tweaked by someone with some intelligence and a good exhaust. Put the manifolds and exhaust in a box and be done with it.

 

Another vote for chris

Sell the irons get some AFR 290 or 265 and dont look back. Dont sink money into old iron heads. They guys that can make em hum..youll spend almost as much as the good stuff trust me. Upgrade that intake too. You can always grind off a mfr and paint it. who cares anyway?

pm Jim aka tpi421vette for a good deal on a new set cheaper than Summit. Just ported a new set real happy with em. All done for less than this guy coulda bought them for.

Almost noone ever puts old stock stuff back on and if they did youll be in the ground.

 

It’s a Tri-Power....

Jebby

 

OP
Got a wide enough set of opinions yet?
I see almost no consensus here, which makes perfect sense.
It all depends on what your goals are for the car.

It is a 69 TriPower, which to many here is the "Holy Grail" of C3s.
But I see that you already have, or had, a Very Original Top Flight / Bowtie 1970 BB, congratulations on that.
So what do you really want to do with this one?
Stock or fun?

Must be a rough life having to decide between which BB to drive....... LOL

 

First, thank you all for your opinions, exactly what I was looking for. There are some really smart people here on CF. It’s a tough decision for sure. I know which way my wife would want me to go, the lower cost one. Haha.

The common sense - cost route is to redo (with porting) the iron heads and go with headers and a 2.5 / 3 inch exhaust. That would be really cool, seeing some ceramic coated Hedman headers in there and 3 inch tips sticking out the back.

However, the more I learn about roller cams the more I appreciate the technology. And I am a sucker for technology. So if I were to go the modern tech route it would probably be the Brodix or Edelbrock rectangular ports with an appropriate hydraulic roller that likes to rev. The idea of 70 pounds off the front end, the visual impact of aluminum heads, combined with modern head and cam technology is very seductive.

 

I would get AFRs over Brodix or Edelbrock... just my opinion, having run them on several engines. All 3 will give you a very good power upgrade, no doubt, but I think the AFRs are just _that_ much better. Plenty of good BBC guys who can spec a roller cam specifically for your particular application and what you want out of it. Tony Mamo at AFR can also really help with that, too. He did one for me 15 years ago and it ended up right on the money as far as the desired powerband.

 

The AFR heads are real nice. That is what I used on my BBC build with a Chris Straub 229 HR cam.

 

I started with the same combo as you (68 L71), I did the afr 265's and straub hyd. roller (my Vac stuff works, but it ain't 14" at idle). I kept my tri power and didn't port match, I have 560hp corrected with the Air Cleaner on. You will need headers and free flowing (somewhat loud) exhaust to realize the gains tho.

As far as performance, I have run an 11.90 1/4 with crappy tires and a rolling start (I'm fighting a fuel pressure loss during 2nd 3rd and 4th due to old rubber hose splices). I expect to see low 11's next year after a plumbing upgrade (thanks Jebby for the post of the Fuel Pickup).

Mark Jones (vortec pro) can do some pretty amazing stuff with the iron heads, I'd go that route if my car was numbers matching. (any nay sayers can check AJ's performance stats)

 

mark knows his stuff. Id still go afr heads get a cam from him
They are just so much better cant deny it.
These are going on a 31 panel that already pulls the front wheels up with stock 049s. Right cam worked over tunnel ram stall its going to be nuts.
Good airspeed flow craploads of air.
page Jim aka tpi421vette in the c4 tech section. My friend paid summits price for these setup and ported for his at the end of the day.

 

Ok, update. I've decided to have the original iron heads rebuilt and pocket port them myself. I decided to go this route primarily for originality reasons. Jebby had good rationale. In addition, I plan on installing Hedman headers with a 3 inch system. I figure the porting and headers are worth at least 50hp.

Before I took everything apart I did a leak-down test on all cylinders and non of them leaked at all...yay. Then I started checking valve lift with a dial indicator at the valves and the numbers don't look good. So now I'm thinking my original cam lobes are worn and the cam need replacing. This motor only has 16k miles on it so the cam wear is very surprising. Is it modern oil with no ZDDP that killed the cam?

So...I'm thinking of going with the stock flat tappet L71 mechanical lifter cam. But will it die a premature death too? Or should I just bite the bullet and go roller? Thanks in advance.

 

When you checked with a dial indicator.....what were the numbers and were they different? They should all be close to one another for I and E on all 8 cylinders.......I and E will be different of course but I am speaking relative to each other.
The roller cam question is a simple matter of dollars and cents.......it WILL make more power but it WILL cost you about $1000 large for cam/lifters/springs/locks/retainers/pushrods.........now that the heads are off it is the perfect time to do so if you decide to. I would use something other than the L-71 cam......old GM cams have real lazy ramps and newer grinds make more average power....notice I didn't say peak.
The roller also has no break in and you can do away with the ZDDP equation as part of your maintenance.
If you get those heads right and do a whip *** valve job on them.....they will make great power.

Jebby

 

If it really did eat all of the cam lobes/lifters, all of that metal went through the whole motor.... Time to pull it and clean/inspect everything...Odds are the bearings are TRASHED... or if they aren't they will be.

As for the roller swap, its always a good idea, more power, better driveability, less chance of wiping a lobe...… however, I have a bunch of cars with flat tappet cams and they all last fine...Just make sure to run GOOD oil with all of the stuff needed... (Zddp etc etc).

I'd start with cutting the oil filter open and have a look see.... Then go from there.