Chevy Monza with chevy 350

[monzam22]

Hello!

I posted up here a few months ago, sharing my story about the Monza that lives again. Long story short, my grandfather did a 350 swap in a 79 2+2, along with a Muncie M21 and a Camaro 10 bolt.

I am honestly just curious more than anything, about what everybody here thinks how this engine will perform?
Ive driven it a few times, but still needs some bugs worked out of it (not revving out past 5000rpms, gets a little hot while in traffic, etc...)

Here is what I know of the car.
It came out of a chevelle. It is a 74 block, unknown flat top pistons with -2 valve reliefs, unknown cam but it sounds pretty radical. definitely not mild, but not crazy and I am not sure if it is set up correctly. BUMMER #1- it has the 993 casting heads on it, and I have heard that they were junk (76cc chambers) on a positive note he is a machinist, and said he ported these things for hours. Unknown valve size. BUMMER #2- 2.73 open rear end, it takes off O.K, but definitely needs another set and posi in the back. Holley 4160 585cfm corvette carb 4bbl, vacuum secondaries with 65 primary jets. Unknown secondary size, probably stock for a vette. It also has the aluminum '67 vette intake, dual plane. Hooker 2135 headers, currently has a mallory mechanical advance distributor (HEI with vacuum advance is on the way)
Engine is making 120-130 psi across the board in regards to compression test, 125 being the most common.

I know for a fact it has some potential. With the old dryrotted tires and ancient point ignition system, it will spin through first and most of second, even though it starts to die out around 4500rpm (dont think this is normal.) I am just curious as to what kind of numbers this motor would be making? I know its hard to determine without the cam specs or head flow, but I dont have any knowledge either.

Any input would be greatly appreciated, I'm definitely curious and am new to the SBC world and am excited to get this bad boy to the track!

[cjbiagi]

I don't think the 993 heads are that bad. These were used in the early 70's and are considered smog castings. These were often used with dished pistons which yielded about 8.5 compression but with flat tops should yield around 9:1 compression, maybe a little more depending upon whether they have ever been milled and gasket thickness. They have 1.94 intake and 1.50 exhaust diameter. Certainly not the best heads out there but they are probably not your problem. I have these on my 350 Monza which was built back in 1984 and the car runs very well. If I were doing it today I would use better heads but they perform fine on a light weight car with a 350.

[crawfw]

I'm no expert but I can tell you what my sbc hp estimate is. I have a 76 4 bolt bored .030. Stock heads similar to yours. I believe they are the 882 heads. Which are supposed to be the best of the worst. Lol. Also 76 cc chamber. 1.94 intake valves. Eldebrock torquer II dual plane with 650 vac sec holly. Hooker header. .460 lift cam. Almost exact setup is offered as a gm crate motor and is estimated around 315 hp. One issue on your hbody is the rear gear along with the Muncie trans. The Muncie is geared pretty high in first gear to keep all the gears close together. Someone on here can tell you the gear ratios for muncies but I don't think there is one geared Lower than a 2.58 first gear. My h body has a 2.93 rear gear but I have a low geared saginaw. 3.50 first gear. Pretty good combo but I'm not sure how much abuse the sag will take. My car ran a 14.1 quarter mile with only running it 3 times. I'm sure I could dip into the high 13's with more practice leaving the line. Sounds like you have a great start with the Muncie already in the hbody. Would like to hear more on the drive train setup. Like is the torque arm still in the car and how it's attached front and back. I had a 3.42 rear gear in another hbody with the close ratio sag. 2.56 first gear. Pretty good combo there also. Some 64cc chamber heads with 2.02 intake valves should really wake your motor. That's my plan on the sunbird I have. The 4500 rpm thing could be a number of things. I'm having an issue with some mild cutting out over 4000 toms which is certainly not normal. I believe it's electrical but haven't really trouble shot much. I'm thinking of going with a higher amp alternator. Some more info on your over 4500 rpm issue would help pinpoint the problem

[monzam22]

Thanks for the replies guys. I set the timing again, dropped the idle a little, rebuilt the carb and put some tires on it, man this thing scoots!!! even with the poor gears in the back it was pulling pretty hard and even chirped second . feels like a solid 14 second car to me, but we'll see.....

it wasn't revving out because the positive cable was arking out to the header it overloaded the alternator to the point where it actually BLEW the case ground OFF of it. I'm surprised it even works, no wonder the battery hasn't been charging......been working on that. Just installed an HEI with external coil on it last night, was ballsy enough to take it out at 1AM, ran great, until the distributor hold down bracket came loose and it lost time, and then wouldn't restart. needless to say it has some issues I'm trying to sort out. Think I got them all figured out luckily.

[crawfw]

Just something else to check that I found on my sunbird when I bought it. Have someone hold the gas pedal to the floor while you check the linkage/primary butterfly. Mine was only opening about 1/3 or less. Had to buy an adjustable throttle cable bracket. Wow what a difference that made. It went from having good power to having to buy drag radials to keep the back from spinning even in second gear.
Glad your getting things figured out. I cant get mine out with the weather but keep us informed on your progress. Maybe a few pics. Still curious on your trans/rear setup since you have the muncie trans. curious about the torque arm setup or if its been deleted for a 4 link setup.

[monzam22]

Man I am so glad you mentioned that. I dragged my buddy out of the house to put the pedal down to the floor to check for throttle blade opening, sure enough the primaries were not opening all the way! All I did was rotate the bracket counter-clockwise so it put a little more tension on the cable, extending it. They open %100 now!

I started the car on fire the other day at the shop, lol....I was racking it up and the battery cables got pinched together, thank god there was an extinguisher nearby! Needless to say I made sure those battery cables could not touch again...

I am going to the DMV to get it permanently registered tomorrow! After I do that, I will be taking it to the exhaust shop near me and have them fab up some simple pipes for me. RIght now the mufflers are dumping straight off the headers and they drag on almost anything.

I will take some pictures tomorrow of how he has it set up when I bring it to the shop! It is coming along pretty well

[crawfw]

yeah there are quite a few hbodies on here that have had the torque arm relocated or deleted. Just curious to see what was done in your cars case. When I was in my early 20s, I disconnected the hot wire on my alternator and it fell onto the metal fuel line. Instant fire. looking back I realize how lucky I was to get the fire out with an old shirt. Im sure my landlord would have been a little p.o.'d if I had burnt a car down in his parking lot.

[monzam22]

Here are some pics, it REALLY needs a good cleaning.

[RamIt]

Boy that's gotta put enormous stress on the lower mounts.
Do you still have the torque arm available to you?

[monzam22]

I believe it is long gone my friend, all I have is interior parts...and quite a bit of it too!

[crawfw]

Wow, No upper control arms or torque arm. I not sure but I think you may need one or the other. Maybe you can reach out to Jim M at jd race and restoration to have him look at your pics. Someone else will prob know on here for sure but if you want a quick response look him up. He is a member here. Looks like the pinion angle is quite a bit off too. Any vibrations at higher speeds? Otherwise looks like a very solid car under and topside. thanks for the pics.

[hammerdown7]

Very odd rear set-up. Wonder how the panhard mounts, it crosses the axle somewhat like a '75 did and the angle that u-joint is in it's not long for this world. I hope you aren't driving this. It needs either the upper arms or the torque arm. Justin's torque arm mount may work.

Dick

[monzam22]

Its really that bad huh? It drives fine! I had to pull the trans last night, and when i pulled the drive shaft out it came right out.

[crawfw]

Looking back it looks like the pinion angle looking way off could be the differential hanging. I now see how the car is on a lift by the body. Anyone know what the purpose of the blocks are halfway down the traction/lift bars? I would think that would cause some tremendous pressure to the lower control arm.

[hammerdown7]

Well, I took another look at it also. Realized the panhard rod is straight as it should be for a '79. When I first looked I thought it was bent over the axle but the 'bent' part I was looking at is really something else on the chassis behind the bar in the picture. I also agree the u-joint angle is exaggerated by the axle hanging down. Wonder what it looks like on the ground. Strangely, that center block between the traction bar and the lower control arm may cause the axle movement to act like a four link. I've never seen a set-up like this before. I'll have to look more closely next time.

Dick