Well, I'm set to pull the engine out of the Skylark this weekend. I will let everyone know what happened "down there" in the oil pan area after I tear it down. 2 questions for rebuild purposes: 1. What is the better sealing method for the intake manifold front and rear areas? The rubber seals, or using a specific type of RTV sealer.... 2. Cam bearings: Who has grooved the front bearing journal, or is a set of grooved bearings a better choice? ( Where could I get them as well?) My engine is a street engine. 455 (.030), Poston 10 to 1 hyperteutectic pistons, Lunati cam ( 224/234" @ .050), Edelbrock Performer manifold, Edelbrock 750 carb, Heads have a bit of bowl work done, stock exhaust manifolds, stock ignition with a Pertronix Ignitor. She dynoed at 364 HP ( 4800 RPM) with a nice torque curve above 400 ft lbs from 2600 to 4300 RPM. Any other ideas to squeeze a few HP from this combo? Russ Waters 1970 Skylark Convertible 455
Bigger cam .230int .245 ex @ .50 , TA shorty headers . Finish Porting the heads, SP-1 intake, That's if want to changs these, if not I woud look at raising the compression ratio. To get these pistons up to 10-1, The deck needs to be checked. Most of all what year of motor is it?
For more HP: Headers would help a huge amount, even shorties. A cam with 228 or 230 degrees intake duration @ .050 such as TA 288-94H, or Poston GS113 would help without hurting too much torque. You might have to get a little higher stall converter- 2500 or so, depending on what you want (it would be a little soft on the bottom end). Carb spacer and milling the intake plenum divider a little will help HP, but might also take away some bottom end. Bigger carb would help too- 800 Qjet or bigger. I would say headers and an X-pipe would help a lot. That would be the first thing I would do.
The engine is from the year 1973. XF code, so just an ordinary low compression 455 at the time. I don't think my compression is more than 9 to 1 with the Poston pistons and the heads cut .040. Didn't the "smogger" yer engines have larger cc combustion chambers, thus lowering compression ratios dramatically? I am not going to put headers on the car right now. As a convertible, I prefer to keep it a bit docile. I do have a 2.5 mandrel bent exhaust system to the mufflers, then 2.25" tailpipes. A larger cam may help but I would have to change the rear end gears from the current 2.73 ratio. That is a must. I'm going to port match the intake and heads, and that is about it. Russ Waters 1970 Skylark Convertible 455
What's the point of porting the heads and intake if you're going to have a kink in the flow at the exhaust end?
I have cleaned up the exhaust manifolds somewhat, but I know they are not as good as headers. However, if I have the intake/exhaust work done already, maybe I'll have to spring for a set of headers in the near future. The dyno numbers I have seen prove their worth. Does anyone have an answer for my 2 questions concerning the end seals and cam bearings? Russ
I would think the rubber seals would be a much better choice. There is quite a big gap in that area, and I doubt you could seal it up well with just RTV. Maybe some RTV on the rubber seals? As far as the cam issue... I believe it has been said on here before that if you're using the grooved bearings there is no need to groove the block. Have you considered the shorty TA headers? They bolt up like the factory manifolds from what I understand. May be the best of both worlds.
Russ, it 's easier to go with the grooved cam bearings, You can get them from TA or from us, I sell the TA bearings . Jim Burek P.A.E ENTERPRISES
Thanks Jim. I hope to get the engine out of the car this weekend but rain is on the way. It may be Monday before I can do it. After pulling the plugs out today I did find my problem cylinder. #4... The plug has made contact with "something" ( piston?) and no gap remains. I'll get in there and check it out while I re-read Stephen Dove's book on the engine over the weekend. ( Thanks Jim, again) Russ Waters 1970 Buick Skylark 455
You want to squeeze some more power out of this engine, I would get rid of the Edelbrock 750, go with a nicely setup 800cfm Quadrajet, or an 850 or so Holley. I ran the Edelbrock 750 Performer for a long time and while it was easy to work with, it just seemed too small for the Buick 455, so I went with a 850 Speed Demon w/mech. secondaries...runs a lot better/faster once I got it tuned in. Also, buy a MSD 6 box, gap the plugs a little more open (i forgot the recommended gap cause I haven't worked on my Buick for a while...maybe .045 or .050"??). I definitely noticed an increase in power when I did this to my Buick, and I'm also using the Petronix ignition. I also agree with everyone else, get headers! Either shorty or full length will help a lot too! OH and about that #4 spark plug having no gap left in it, I've seen that before on my brother's 430 and we could never figure it out! It did it a couple of times back in the day and we'd just reset the gap and keep running. Eventually, like a couple years later his engine spun a bearing and I think threw a rod. I would think maybe your bearings have enough free play in them to allow the piston to come a little higher than it should, contacting the spark plug. Also, make sure you get that crankshaft checked out real good when you pull this engine apart. I blew up a Buick 400 once the first day I drove it from one of the rod bearings that was worn out. At first startup the engine sounded okay, but the previous owner talked of a weird rattle at higher rpms that could never be found. After driving it for about 5 miles it starting knocking real bad and then boom! It sent a rod through the oil pan, broke the rod and piston, and the wrist pin punched a hole in the cylinder wall. From what I could see, there was NO rod bearing left and the rod had been riding on the cranshaft for a while (really worn out journals) eventually getting enough freeplay so that the piston could get cock-eyed in the bore and punch it through the cylinder wall, etc. The funny thing was, the crank was still okay and in one piece!!! It's no joke that's a tough crankshaft!
