I seem to be getting a lot of engine shake on my new Blueprint 383. I used the proper transdapt swap mounts, everything's tight and nothings moving at the mounts. It's a full roller setup with a bit of a nasty cam in it dynoed at almost 445 hp and close to 500ft lbs. It's my first High HP setup (high for me:TU and I'm just wondering if it's normal Cam shake or if I should be worried. Initial startup went like a champ, set the carb with a vacuum gauge etc and it starts on the first bump of the key. Doesn't seem like a tuning or timing issue... Any opinions? Am I just not used to a car shaking setup
If you're talking sbc 383 and its a factory roller block, meaning it will accept the factory roller lifters and hardware then unfortunately they make the crank in 3 different configurations for the one piece rear main seal sbc 383 crank. 1st one would be and externally balanced cast steel crank that needs an externally balanced flex plate and harmonic dampener. Next configuration would be an forged crank that uses an internal balance harmonic dampener with an external balance flex plate because of the one piece seal. 3rd would be one that uses an internal H/D with an internal one piece seal flex plate. At your HP level the cast steel crank is probably what you have(usually rated for 500 HP and 6,500 RPM), check to make sure the counterweight hasn't broke off of the flex plate, which happens. Or you just may have a shakey running cam? If so, if it doesn't stall when you put it in gear I say don't worry about it. What are the cam specs? Derek
Briz, taking a look at your Sig pic im guessing your probably running a lot healthier motor. But adjusting it higher to check things shouldn't hurt anything. Mart, thanks for the opinion. I texted a buddy who mentioned the same thing as you and Briz, to bump the idle on a roller. Guess I shouldn't be underestimating the 383 too much then. As mentioned it's my first +400hp setup. 300SBB, it's a 4 bolt 350 block the build the 383 from. It's a Blueprint BP38313CTC1, externally balanced plate and balancer. Cam*Specs: Cam Type: Roller .528 Intake* .536 Exhaust** 221 Intake / 226 Exhaust duration* @.050 - 110 degree lobe separation They break in the motor and send the Dyno sheets. I'd wonder if there was something seriously wrong it would of showed up then when they really wound it up I used the weighted flex plate they sent with the motor, weight was on when I installed it but I'll check tomorrow to make sure it's still there just to make sure. The Transdapt mounts didn't seem to have very thick rubber on the mounts either. Guess I'm just panicking a bit. Convertor is a 2600-2800 so a bit more idle might help
This is the swap motor mounts I used. Lined up and fit great, but like I said the rubber was pretty thin and everywhere I seem to see things mounting together is steel http://www.jegs.com/i/Trans-Dapt/969/9556/10002/-1
Called the maker of the mounts and they are a direct factory replacement and won't handle the motor. I have to order better Poly mounts
I have stock Autozone motor mounts in my car. They handle my motor just fine. If you have a vibration, or engine shake, why would you suspect the motor mounts? Stiffer mounts will make you feel it even more I would think.
Not a very big roller. Mine idles at 750 in gear. It is rough in gear. Smooths right out as you go above idle though. Does it shake at higher RPM?
Right you are Larry, with those specs the engine should idle rock steady dam near unless its one of those fansifide gimmicky camsticks that are made to idle rough just so it sounds cool, like one of them there Thumper type grinds? uzzled: And yes he would feel the shakiness even more with stiffer mounts, if in he's worried about it he could add a torque chain attached to the frame from the engine? On my '65 Impala I run stock 1965 mounts, no chain without a problem(so far) but my roller cam is a bit milder with .550" in. .546" ex. with 202* in., 212* ex @.050" and 113* LS. Although milder it produces a bit more power than what you posted, probably because of the work done to heads and intake I have. I have a mismatched converter that's rated at 3,000 to 3,200, but I love how it launches at the track with that converter with high 1.8 60 ft times when I get traction with my 4,500 lb car(4,700 with me in it). Have yet to break a MM, if in you had a manual trans then upgrading your mounts would be a good idea though. So unless you have one of them there gimmicky cams that is made to be shaky at idle, you might have an engine balance problem. Also check to make sure that you have an external balancer on the front of engine. I'm sure with a production place like Blueprint that they production balance their builds. Production balancing would involve weighing about 3 sets of the parts that they use and average the weight to get a bob weight number. They would then order their cranks with that bob weight so they can save $$ not having to balance the crank.(just like the OEMs do it) Being a production type engine place they could of mixed up and installed an internal balancer to your engine that needs an external balancer or visa versa? My cam idles with about 22 in. of vacuum, yours should be around 16 to 19 plus or minus a couple. With vacuum like that you should have a rock steady idle, unless it has one of them there gimmick cams. If the balancer is external, the weights are still on the flex plate you could need an internal balancer? Before you swap that though, disconnect the trans, push the converter back(being on a slight upgrade or jack the front end up slightly higher will make gravity hold the converter away from the flex plate while its spinning) start engine. If the shakiness is still there then this eliminates the trans as the culprit of the unbalance. If the shaking goes away with more rpm then its probably not an engine balance problem, probably a gimmick cam, or a crossed wire? Keep us posted. Derek
That style motor mount should be OK unless you have a vehicle with linkage instead of a cable. If the mount breaks, when the engine rotates, it can pull the throttle wider open. There was a recall in the early '70s to retrofit '65-'69 Chevrolets with a restraint strap (the cheap fix) to inhibit that rolling up. The real fix was to put in an interlocking motor mount. You should be able to find some at an auto parts store. They look a lot better than a chain, in my book. Here is an example from O'Reillys. Notice the two ears and the t-shaped piece. These interlock and inhibit engine lifting if the elastomeric part breaks or peels. Neither the standard elastomer or poly mounts will change the shaking, they are passive parts. http://www.oreillyauto.com/site/c/s...=1969&make=Chevrolet&model=Bel+Air&vi=5134302
That sucks. I figured the mounts would be the weak link, I just got the whole thing together with the new motor/Trans finally and was hoping to have it on the road next week. It's all really starting to be too much, stupid things supposed to make me happy not miserable. The thought of laying on the ground again and removing the transmission just to "check and see" if it's that fills me with rage I'll try taking a video of it and send it to anyone who's willing to take a look to see what you guys think.:af::af::af::af:
It's not unusual to have problems, especially in the beginning. Welcome to the world of old cars. It may make you miserable until it makes you happy.:grin:
Just went out to check again and take a video. No crossed plug wires, it's open headers right now but can't see that making a difference. I have a video of the idle rpm and showing the shake, kinda hard to see the shake till the end of the video. If anyone can send me they're email I'll send it over
