Is the 455 cam in the 1975 455 installed by the factory in a retarded position? I have seen that approach used on other GM big cube smog engines. Can I gain any low end grunt advancing the factory cam? This coming fall I need to deal with front seal leak. Figured I would replace timing set while I'm there. I would really rather slide an aftermarket cam for more low end. I am worried about having the new cam grind itself to death in my engine. Has there been any positive news on the rash of cam and lifter failures as of late?
First, no, factory cam is what it is. Secondly, yes select a new cam to perform like you want with the engine you have. Thirdly, there are always cam / lifter failures from dipshits no knowing what they’re doing. I hope this helps!
Unless you degree the cam and know the original specs you will not have any idea whether the cam is advanced/straight/retarded. If you want a change of cam timing you should order a cam. A TA 112 or 212 max for low compression engine. Install the cam and use break in oil. Do a proper 20 min 2000-2500 RPM run in. Greg
I should elaborate a bit. I am new to big Buick engines. I am not new to camshaft installations. How to degree a cam etc. I asked my question as it was known that some smog 472/500 Cad engines had a 4 degree retard ground into the cam. You could advance that came and get a decent gain in bottom end and mid range. So I had hoped that someone here knew if that was the case with my 75 vintage of 455. That someone here might have the spec's or info on the stock cam. A short cut to know if it was ground retard/straight/advanced. I am looking at both of the TA cams mentioned. There 112 or 212. Leaning to the 112 for what I want. I want a stock sounding idle or very close. I know with the big Cad I could bump 10-12 more degrees of duration. With a good boost in lift. Yet get the engine past a show judge as stock with idle quality. I wish to do the same with my 455. It's also true that camshaft/lifter failure has been around forever. Yet right here on this board a higher than normal parts failure rate has been discussed. It's also been reported on many other makes and models of engines. So either a higher than normal number of so called dipshits have been installing cams. Or there may be some truth to what so many others are reporting about current part quality. There is a camshaft thread on the board right now where JW advises that quality flat hydraulic lifters are an issue. Back to the TA cam's. Will the 212 have a detectable lope at idle? I appreciate the answers and patience shown to a Buick rookie. Hope to learn more from further replies.
That's interesting, I have never heard of Cadillac grinding their cams with a 4* retard built in. Most aftermarket cams are supposed to have 4* ADVANCE built in to compensate for timing chain stretch over time. Retarding a cam will reduce low end grunt in favor of higher RPM HP. Not that it really matters. There has always been talk that the timing chain sets for the 455 Buick have some inaccuracies in them making degreeing all the more necessary. Then you have the inaccuracies in the cam grinding, and the tolerances stack up. I have heard guys talk about having to skip a tooth to make the cam timing match the cam card. This might help with the stock 455 cam timing, The break in problems started with the change in oil chemistry a while back. The reduction of Zinc and Phosphorous (ZDDP) in modern oils is part of the problem. Modern engines have roller valve trains which don't need as much ZDDP, and those high pressure additives also hurt catalytic converters. Then we have problems with lifter quality. The crown on the lifter base and the cam lobe angle are supposed to induce lifter rotation. If the lifter does not rotate, it will be damaged along with the cam lobe. As far as 1975 Buick 455 engines are concerned, they had very low static compression because of the open chamber heads, less than 8.0:1. That matters with cam selection. You have to stay small because you are concerned with Dynamic Compression. More on that here, http://cochise.uia.net/pkelley2/DynamicCR.html Retarding a cam will reduce Dynamic Compression, Advancing it will increase Dynamic Compression.
Larry- Thank you for the info. The most important to me was the heads up on possible problems with the replacement timing chain set. The chart with location of exhaust lobe C/L on cam in stock location is a big help. I will check my new timing set at install time. The deeper I've dug into failure issues. I've decided to pass on swapping my cam. I just don't want to take the chance. I think I will be better served spending my limited budget on converting to a dual exhaust system.
I agree, don’t bother with the engine, it’s only like 7.6 to 1 compression, it’s smooth but not a power house. Put duals on, and read up on Larry’s timing thread.
a perfect calibrated carburetor with smaller secondary metering rods, a recurved distributor, and dual exhaust with a shift kit in the tranny made my 75 Riviera think it was a hot rod. Car ran really really strong for an anemic compression motor. I sure surprised many people when that big boat walked away from them. Fernando
Same exact path I am going to take. I'm also going to toss into that mix a 13" GM higher stall converter. Often nicknamed and L88 converter. It was used behind some BB Corvettes so it got that nickname. It's an awesome thing in a big heavy car. Never know its there in normal driving. When you nail it will flash to 2000-2200 or so. Sets the engine load right in the torque fat spot of this engines curve. Yet cruises around town just fine. No real mpg loss or slippiness. Not trying to build a drag car. Just a stone stock looking and sounding car. That will spank the unsuspecting at the stop light when required.
Like Larry said, alot of cams used to have 4deg advance built in if installed straight up to compensate for chain stretch. I once put a new timing set on a 67 430 that was so worn I could take the chain right off the worn sprockets. Amazing it didn't jump. New chain and sprockets made it run like new due to the advanced rather than retarded cam.
May have been quick to reply on rear gears. I've seen several specs on the web. State from 2:73 to 2:93 for 455 cars. Factory shop manual denies existence of B body455 convert. Lists 3:08 gears for B body 350 powered convert cars. Only 455 powered B body cars shown in shop manual are wagons. Listed at 2:93 So what do I really have? I have some maintain things to do when I get it back home. Going to get axle number off axle tube when I'm changing my shocks. I just came back from where car was stored for off season. Dropped the battery back in. Splashed some fuel down the carb vent into the bowl. Fired right up! Yeah!! Going to get it out of winter jail on the 17th. I'm pumped. Timing chain replace and front cover seal leak won't be dealt with till the end of the summer drop top season. Not taking apart my favorite toy in peak season.
2.56 gears will give you roughly 30 MPH/1000 RPM in high gear. If you have a tachometer, even one that is part of a Tune Up meter, take a reading at 60 MPH.
Thanks guys. I am going to temp hook up a tach. I want to rework distributor as well. I've also read much of the timing thread. Do I need an adjustable vac advance other than for convivence? Adjusting it with wrench. No cap & rotor removal. Can I just limit my stock advance can travel?
Go back and read the first post in the Power Timing thread. Read it several times until you fully understand it. If you modify the mechanical advance to bring it in earlier than stock, you will need to limit the amount of vacuum advance to avoid possible surge and/or part throttle ping from over advance at cruise. None of the modifications are for convenience, they are for increased performance without detonation. Yes, you can modify a stock vacuum advance canister. There are pictures (bottom 2) of it right there in the first post. https://www.v8buick.com/index.php?threads/power-timing-your-buick-v8.63475/
What I meant by convivence was the ability to limit vac advance travel without taking cap and rotor off to adjust my homemade vac advance limiter. I understand working my curve for total of initial and mechanical advance w/o vac advance. Then coming back at it with vac can hooked up. Then limiting vac advance travel for no ping at cruise. Thank you again for the help. I don't always express myself clearly.
The adjustable vacuum advance canisters that have been available in the past are of two types. One adjusts only through the vacuum nipple with a small allen wrench. It adjust both rate and amount. I believe that is the Accel unit. The Crane cams unit adjusts rate and amount separately. The rate is adjustable with the small allen wrench. The amount is adjusted with a small notched cam. Original instruction called for mounting that cam with the rear most attaching screw. You then rotated the cam, and the notches pushed the advance link further into the canister, which limited the total advance available in the canister, but at the same time, it preloaded the canister spring, which affects rate. Years ago, a member here on V8 (The Ignitionman, aka Dave Ray), came up with a beteer way to mount that cam. He instead mounted it ahead of the link thereby limiting advance amount without affecting the spring preload (rate).
The Crane kit is what I use, I thought it was easy and provided the right amounts of adjustment for little money.
