I am getting a complete stock 350 vortec motor to go in my 79 MC. The car will be for daily driving, no racing. I want to upgrade the cam while it is out. I will be using a q-jet carb. I have read alot online already about this issue. I am new to chevy internal engine parts and i have some questions. I gather that this engine uses a hydraulic roller cam from the factory. If i go with a hydraulic flat tappet cam, do the new lifters just drop in? Also, I am not interested in machining the head to accept a higher lift cam right now. I want to stay within .460 lift and use a dual profile cam to compensate for the smaller exhaust ports while keeping the stock 1.5 rockers in place. I like the looks of the 24502476 GM cam that comes in their 330 hp crate motors. Assuming that the heads on this motor and my motor are exactly the same, I do not see why this cam will not just "bolt right in". I also do not mind keeping the roller setup if it will be more efficient and going with a performance roller cam. What do you think?
stock vortec 350 cam upgrade
- Thread starter jmangham
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go roller !
you already have the roller lifters that are good for the engine life normaly .
search some chevy forums for a used roller cam that is hot enough for you but that the fellow feels like he should go bigger!
a cam with around 210-216 dur @.050 lift and .475 lift and 113 lsa will give good results for your needs .
you already have the roller lifters that are good for the engine life normaly .
search some chevy forums for a used roller cam that is hot enough for you but that the fellow feels like he should go bigger!
a cam with around 210-216 dur @.050 lift and .475 lift and 113 lsa will give good results for your needs .
Good cam to use in those engines is a 94-97 LT1 Z28 cam. Specs are 201/208 duration @ .050 with .447/.459 with 117 LSA. You can reuse the stock roller lifter which is the great thing about them. Best part is these cams are cheap, usually $50 to 75 on ebay.
unless you already have the cam , or get it for free, it`s not worth changing for the LT1 cam .....not that much difference ( stock aprox; 190 ) and at 117 lsa it`s yaaaack. lollllll
no provision for fuel pump either
no provision for fuel pump either
I very seriously doubt you have a roller in the engine already. If this engine is an original sbc in the era 1979, it will have a flat tappet. But you will never know unless you open it up. Anyway wether you have a roller or hydraulic flat tappet you need to take into consideration your tires, rear end gearing, and your transmission stall speed to decide on the best cam for you. I would call Lunati, comp cam, edelbrock and get recommendations. Or go to comps website and use their cam choosing software. Good luck!
absolutely truth!
I asssumed it was roller, by what he said ,but better verify before !
good point ,jusbo!
depending on the year , your engine might have flat or roller lifters .....check it out !
I asssumed it was roller, by what he said ,but better verify before !
good point ,jusbo!
depending on the year , your engine might have flat or roller lifters .....check it out !
if it's an actual vortec block, then it was made in the 90's and is a roller. (assuming no one has gone in there and changed it) even if someone put in a flat tappet, which is stupid BTW, the bolt holes are there for the "spider", which is cheap, and stock GM roller lifters are cheap and good.
some reasons NOT to go flat tappet
1. extra friction=greater wear and tear and less power
2. oil compatibility-due to the extreme point pressures a special zinc based additive (ZDDP) is needed. this used to be a common additive but has been phased out for emissions reasons. AFAIK no synthetic oil is produced with a significant amount of ZDDP. it can be added, but that's a major hassle and you can add too much.
3. rollers tend to have more aggressive lobe ramps which means the valve is open longer=more power
4. you can use used roller lifters, flat tappet's not only require new lifters on a new, but you must keep the lifter with the correct lobe if you remove/reinstall the cam
5. flat tappets require a longer and more involved break in process.
some reasons NOT to go flat tappet
1. extra friction=greater wear and tear and less power
2. oil compatibility-due to the extreme point pressures a special zinc based additive (ZDDP) is needed. this used to be a common additive but has been phased out for emissions reasons. AFAIK no synthetic oil is produced with a significant amount of ZDDP. it can be added, but that's a major hassle and you can add too much.
3. rollers tend to have more aggressive lobe ramps which means the valve is open longer=more power
4. you can use used roller lifters, flat tappet's not only require new lifters on a new, but you must keep the lifter with the correct lobe if you remove/reinstall the cam
5. flat tappets require a longer and more involved break in process.
megaladon6 is right on the money. I've heard *some* truck block have the stands in the lifter valley but are not drilled/tapped. If you're careful you can probably do it at home. All it does is hold the spiderdown so it's not super critical. If not, it shouldn't cost much to have a machine shop drill/tap it, even with the motor assembled. Just make sure to keep the metal filings out of the engine!
If need be, used roller lifters and the dogbones (that keep the lifters from rotating) and spider (that hold the dogbones in place) can be pulled from a junkyard engine. Just check the rollers for any bad spots when you roll the roller.
Definately go roller if possible.
If need be, used roller lifters and the dogbones (that keep the lifters from rotating) and spider (that hold the dogbones in place) can be pulled from a junkyard engine. Just check the rollers for any bad spots when you roll the roller.
Definately go roller if possible.
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