Hello everyone I need some help and Im hoping someone out there with sum engine knowledge can help me. I bought a 86 buick regal two years ago and it had a 307 olds motor in it. after the motor blew i searched for another motor, and was told to go with a chevy 350. So I found a sbc 350 on craigslist for 1200.. The guy told me it was a rebuilt motor out of a 71 camero pushing about 350 horsepower.. Me being young and not knowing any better took his words and ran with it. I put it in with a 700r4 tranny behind it 650 edlebrock carb shorty headers dual exhaust edlebrock preformer intake and installed a 480 lift lunati camshaft. It runs good but it aint no damn 350 horsepower lol. So I ran the block casting number and "3970044 " and couldnt find anything on it.. So i called the chevy dealer ship and they told me the motor is out of a 73 malibu. I looked up the specs and it was like a 146 to 165 horsepower 350 motor.... I was like WHAT!!! Well to be honest it feels more than 165, maybe 200 after the headers exhaust intake and carb... I been thinking about buying some aftermarket heads maybe vortec. Can someone please tell me if I will see a change if I get these heads. I already have a 373 8.5 rear under the car.. If I decide to go aftermarker could I use the same pistons? Will i have to bore the motor? how can I tell if Its really been rebuilt? I just want about 350 horses. Can someone tell me about this block? Someone please help me I will glady appreciate it. Cause i only have 1500 bucks and need to know which way to go... thank you
Pop the valve cover and get the casting number off the head that you have, we can start from there. P/N on the cam wouldn't hurt either. Specs from the cam card would be a bonus. Is it the .480/.480 292/292 that's at summit?
Not a bad cam, but the heads on that 350 could really be from anywhere. This is a 40 year old engine at this point. If your heads are low-compression wheezers with small valves, then it's working against the cam you have. Which it sounds like that's the case. Once we establish what you have to work with, we can suggest what direction you can go in to reach your goal and remain practical.
Take it out,take it apart,check what parts are in there,,,start from there.
re: horse power,,,everyone has either 500 horse power,or a stock 375 hp engine.
most 500 hp engines(claimed power) are usually below 400.
Its very simple math and parts matching to get the power you want,,,,everytime you substitute a generic or bargain house no name part,you risk having a little less power than expected.
I always think building for reliability and endurance is important if building on a budget.
IMO all blocks need to be decked/squared and align honed and all reciprocating parts need to be balanced.choose the bolt ons after the basics are done.
good luck and welcome to the forum
yes 5.7 its a 290 lunati cam and it sounds good.. after some research i was told its a motor out a 73 chevelle with 76cc heads and dished pistons. i was told i could easily change the heads and pistons to get alot more power... and I appreciate yall help you to Vinnie... i was trying to keep from taking to motor apart cuz it runs so good and im sure its been rebuilt a few times since 73. but your right i need to check them heads to see what i have but i been told the casting numbers dont mean nothing, if i dont know whats been done to them
drive it as it is then and enjoy.When you have the time and ambition,you and dad can take it out,run it to a decent rebuilder and ask if you can watch the assembley and take notes and measurements
If yall dont mine go to craigslist nc and go under greensboro nc and look at 86 regal and youll see the car its blue and light silver its a grand national clone. the descripton says 86 regal for 5800. its on youtube to under 86 regal
A smog era 350 with dished pistons and 76cc heads will be nominally 8.5:1 static compression ratio, in actuality it's probably less. The Lunati cam you've installed has too much duration for your compression ratio and will result in a VERY low dynamic compression ratio about 6.5:1 or less, which will kill your low end power
Definely a case of too much cam. To make power, you can't think of a engine as one individual part makes all the power. The engine combo has to be compatible to work together as a team to make max power. I think you said you had $1500 you could spend. If that's the case then the solution is easy. Get a summit racing cam and lifter kit part number SUM-K00052. This cam has .218 duration @.050 and it works with a stock converter. It has a nice lopey idle.
Next get a set of Summit racing Vortec heads, a new double roller timing set if need be, a Vortec intake and a set of small tube headers. Just by changing your game over to this combo you'll be astounded at the difference in power it'll make. However it still would be of benefit if you yanked a valve cover off and tell us what the heads casting numbers are so we can get a better idea of what were working with here.
ok ima do it in the morning. but it runs fine and has decent power. i just know it doesnt have the 350 hp like i was expecting. i was told to dump the 700r4 and also the ebrock carb and go with holley. i would think since its a 40 year old motor i know its been rebuilt, i would think it maybe had some type of work done to it. he said he rebuilt it 6 months before i got it.
Whoa there big fella, calm down this isn't such a disaster. Actually for an automatic the 700R4 is a pretty good choice, especially if it's late 1980 through 192 or so which have the fixes needed in the earlier models.
Yes the engine comes from the heart of the first generation response to emissions which did much to neuter anything that looked like power mostly because of the need at that time to reduce nitrogen oxide in the exhaust and aside from massively reducing cam timing and compression there wasn't the technology of 3 way converters yet available.
So the big issue is to restore can timing and compression. But there are two ways to go about the cam you went the old way which is to use these muscle car era cams which have much of their duration in ramps leading to and from the lobe so they look and sound nasty but without huge increases in compression that today's pump gasoline will not support they end up proving to fuel swilling, moderate power output solutions. The much better choice of cam is the modern fast lifting cam which on the surface appear to have less duration because the long ramps are eliminated. These work with modern heads that have fast burn chambers typical of what is of the well respected L31 Vortec, but there are many modern heads in the aftermarket that include these features.
Changing pistons is not simple and if the engine has been recently rebuilt may not form a cost stand point be that desirable to change. Certainly there is value in going to a modern hypereutectic cast piston with a D dish piston to manage compression to what 92/93 unleaded pump fuel will tolerate which would be optimal. But to avoid taking the bottom end apart and still getting 350 horses can still be accomplished with the pistons you have.
Using Vortec style heads with a cam like the Comp XE268H, with an Edlebrock performer RPM intake with your carb and headers into 2-1/2 inch duals this will easily crank 350 hp. With pocket porting the heads and adding 1.6 rockers this can push 380 without a problem. The XE268H has an available spring kit, I highly recommend using it. Good quality lifters are must, if not Comps, GM part number 5232720 are a good substitute, these are lot more expensive than the cheap 50 buck a set lifters but if you want the cam to live these hard faced flat tappets at 240-350 bucks for the set are the only way to go.
You will also find this head change against the 290 Lunati cams you have in the engine will make a world of difference as the compression will come up which is what is needed. A late to close the intake valve cam like the 290 bleeds a lot of mixture back into the intake as the rising piston forces it out of the cylinder until enough RPM is reached to where the inertia of the mixture can overcome the reverse pumping action of the piston. This is the reason why big cams loose so much bottom end power and move the torque and horsepower peaks up the RPM band also moving them closer together. This is called the Dynamic Compression Ratio (DCR) the effect is that the Static Compression Ratio (what you measure from the volumes) below the torque peak RPM is reduced by the stroke lost in crankshaft degrees to where the intake valve is seated by the cam. Go here and play United Engine & Machine Co. Incorporated .
Piston selection affects a thing called squish/quench. This is where the surface of the piston crown approaches the flat step of the head. A flat top piston is ideal for flame propagation by not getting in the way of the flame front and maximizes squish/quench by coming close to the step of the head.
The latter subject of squish/quench boosts the engines ability to extract power form the mixture and extends the range of the fuel's octane. Preferably for a street engine this would be about a .040 inch clearance between the piston crown and the heads step. OEM pistons tend to have a large and deep dish to control compression ratio below the detonation threshold which also tend to cause you to have to raise the octane of the fuel for the compression ratio being used. A D or step dish piston solves both problems by having a flat surface to oppose the set of the head while being dished under the valve pocket to control overall compression ratio. But this has the advantage of allowing more compression as with effective squish/quench the engine will react to the fuel as if the fuel has 4 to 6 more octane than it is rated at.
This is obvious to most, but wasn't to me when I got started. The 350 does NOT refer to horsepower, but to 350 cubic inches (5.7liters) for the engine. The 350 came with a range of horsepower from 145 to 370.
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