1971 350 Lemans

S

spectrumad

Member
Joined
Jan 8, 2013
Messages
54
Reaction score
2
Points
8
Location
midwest
Hey all. Fairly new member, been stalking the site for a while. I have owned and tinkered with a half dozen 60's and 70's Pontiacs over the years. About 15 years ago I sold everything I had and now I am getting back in the game. Wish I had it all back now!

I now have a 1971 Lemans Sport Convertible in decent condition. Has 350, TH350, PS, PB, AC, 2.78 open differential. I am about to pull the engine and transmission to seal everything up. compression looks good and the engine runs fine. While I have the engine out I plan to check all bearings, clean everything up and make it look pretty.

Now, the question. What simple combo should I use to make it run the best? I have the original #94 heads and a pair of good #14 heads. I don't see much difference between the two. I have 4 tube headers and 2.5" dual exhaust. The main question is what cam should I use? I am not looking for major power, just a little snap. I am thinking the 068 will work well, but I am open to ideas.

I am not looking to spend a lot on this engine as I am on a budget and have a 1967 400 with #061 heads I have plans for in the future. Also, any thoughts on the #061 heads? Not sure if they are what I want. I had a perfect set of #13's in the past that were outstanding.
 

Attachments

  • Leman Sport.jpg
    Leman Sport.jpg
    50.4 KB · Views: 94
I'm concerned about the use of the 068 because of your rear end geariing, 2.78, it was never used in anything with that numerically low a ratio. Would you consider changing the rear ratio into the the 3's? As you probably know the 068 was used in Ram Air III and 455HO but your engine is a 350 and it would be quite a cam in that size engine. You may want to go one step back to a 067. Chart below compares factory and aftermarket cam specs. Concerning heads read the second link which gives you some comparions information. The third link seems to show the #14 having slightly smaller CC's thus higher compression. On the #61 make sure if you use them to switch to screwed in rocker studs.

http://www.pontiacpower.org/PontiacCams.htm

http://www.wallaceracing.com/ultimatehead.htm

http://ronspontiacpage.com/reference-pages/stockheadspecs.htm
 
Good call on the gears. Had not considered that. My plans are to change gears in the future to a 3:23 - 3:55 range and build a 200 4R for overdrive. I also left out that I have a Performer intake and Holley 3310 to use. The 067 will certainly be a step above the 254 that is in there now. I was thinking 068 because of the 350HO but not certain if my heads will flow enough to justify the 068 over the 067.
I'm getting excited to really dig in and start this project. It has been a while since I have had the opportunity to take on a fun project. The last engine swap I did was when my nephew failed to pay attention to the tach in his Ford Exploder....UGGH! Nothing like a big open space around an engine!
thanks!
 
Those are the small valve heads so even if you change the rear gears dont think the 068 is the way to go. In the future if you upgrade heads you can go for a better cam. The 3310 and performer are a good choice, you just may have to go for a stiffer secondary spring but that is easy to change with their kit.
______________________________
 
I got the engine and transmission pulled today. Pulled the heads and took a quick look inside. Cylinders are clean, just enough of a lip to catch a fingernail so I do not plan to bore or hone cylinders. The cam has some wear and the timing chain is a bit sloppy. The #8 exhaust lobe is much flatter than the others. Not sure of the reason, but new cam will be a must, as planned. Before I commit to a cam I plan to pull rod and main caps and check bearings. If I see anything alarming, I may just build the 400 a little earlier than planned.

It was nice to confirm that it is the original engine and find original head gaskets. It sure seems to be a virgin engine. I will know for sure when I pull the windage tray and dig into the bearings and when I am able to pull the cam out. Everything I see maintains that it is the 60,000 mile car as was claimed when I bought it.

Thanks for the help.
 
be aware that there is a known issue with oils for present day cars, many of which if not all, use roller cams. When using a flat tappet cam you must use an oil high in zinc and phosphorus. Examples are Mobil 15W50 and Valvoline VR1 10W30 and 20W50. If you must use a modern oil make sure you add something to raise the levels of the zinc and phosphrous or you will run into premature cam failure.
______________________________
 
^^^+1 on the lack of zinc in the oil of today for older engine designs, like the Pontiac flat tappet, Chevy flat tappet, Olds, Buick, Mopar, Fords etc. designs from the '60s and '70s.

However, if you normally drive those engines, there seems to be much less wear on them then if you recently rebuilt one, with today's low zinc oils.

The low zinc allows fast cam lobe wear.
 
Thank you. I am very aware and not afraid to spend the extra money for good oil, especially during cam break-in. If you learn one thing from watching car shows on TV, it is what NOT to do! (Fast and Loud - HA!) I have only put about 800 miles on the car since I bought it last year so I am learning its history by the pile of receipts from the glove box and nuts and bolts during my engine/transmission project.

One thing, I found a lot of thick, bright gray/silver sludge (for lack of a better term) in the oil pan. Most likely bearing installation lube? Or possibly an additive? Could this be a possible sign of previous engine work that had been done? I have not had time to pull the windage tray and caps yet to check the bottom end. I will post my findings.

Thanks again.
 
Could also be actual bearing material, but you did say you are replacing the bearings.
 
It was suggested to me that I use the Comp Cams 51-220-4. Looking at the numbers, it looks like a good fit for my needs. Nothing overly aggressive, but a bit more power than the stock 555 cam. Does anyone have a suggestion for a cam by another Mfg that is a similar grind and performance? I am looking to get cam, lifters, timing set and springs as a kit if possible.
Thanks in advance.
______________________________
 
Also, using the Comp Cams 51-220-4, can I get away with press in studs or would I need to convert to screw in studs? I do not want to put much money into these heads (#94 or #14). I just want a dependable driver, not a monster by any means.
 
If you look at the notes section for that camshaft they state if you use 1.65 ratio arms they have to be screw in. With stock ratio you can get away with press in but I would make sure none of them are loose. Find out from a machine shop how much a conversion would cost.
 
Ok, surprise number one on my engine tear down. I finally found time to remove the cam and found a little un-expected info. The cam is supposed to be the 555 stock. I would not have been surprised to find an aftermarket cam in it, considering that I found some rubber sealant on the water pump housing indicating the cover had been removed in the past. What I found is the 066 cam. A little surprised to find that cam in my engine. I have to assume that the original owner had them put this cam in at the dealership as an upgrade, or possibly at the factory? I am now looking at possibly building a 400 after looking closer at the block. If I am going to have to pay for machine work, I may as well upgrade at the same time.
______________________________
 
spectrumad said:
Also, using the Comp Cams 51-220-4, can I get away with press in studs or would I need to convert to screw in studs? I do not want to put much money into these heads (#94 or #14). I just want a dependable driver, not a monster by any means.
Click to expand...

You can "PIN" the press in studs at home yourself for the price of a drill bit and some roll pins from the the hardware store.............;)

Doug in P.R.:cool:
 
Well,

I finally got the engine tear down complete. The ridge in the cylinder wall is a bit more than I expected. I am now thinking I will have to bore it and go that route. Not really excited about boring it out, but I am happy to keep the original engine in the car. Any opinions on a good piston Mfg or one to stay away from? I am looking at going .030 over at this point. I did settle on the Elgin E-979-P camshaft. The original #94 heads are going in this week for a clean up, resurfacing, valve job and springs. I may get this car back on the road before summer is over!
 
trw is very good, used as OE in many cases
 
OK, here we are. Waiting for the machine shop to finish the short block so I can get dirty, and make it clean again. One small thing has come up. The carb that I planned to use, is no longer an option. So after looking around I found the Quick Fuel SL-750-VS. They also have the same carb in a 600. I would love some input on this. I have never used QFT, but have heard very good things about them. Anyone have experience with them? 600 or 750? Elgin E-979-P cam (nothing radical at all), mild port job on the #94 small valve heads, 4 tube headers, Edelbrock Performer intake, 350 Pontiac bored .030.
Thanks again.
 
You must log in or register to reply here.

Share this page

Back
Top