Cam choice- LT1 or summit 8800?

The LT1 cam makes more low-speed torque than many aftermarket cams. I went from a flat tappet MTC1 204/214 to the LT4 roller cam years ago on a L05 and the stock LT4 cam killed the MTC1 everywhere. The 8800 is a great cam, but it does have more overlap than the LT4 or LT1 cam. We also had a 1996 LT1 cam in a L31 in my brothers 99 Suburban. It would move that suburban along in overdrive with the TCC locked at 1,200 rpm @ 40 mph effortlessly. The LT1 cam has a table top flat torque curve. The 6492 cam I have in the 1987 G20 is on a 115.5 LSA. It has great off-idle torque as well. At 10.25:1 it cranks at ~195 psi compression. Even with the TH400, the stock ~1,800-2,000 rpm converter that came behind the L03 305 that stalls 2,500+ behind the 350, and a 3.08 gear it runs strong.

This was my 97 Express years ago when it still had the 4L60E in it and a 3.42 rear gear. GM 142' LT4 cam, 1.6 rockers and shorty headers into the stock exhaust. Shifting it at 5,500 rpm it had plenty of get up and go.

Erik the Awful said:

Get accurate numbers for your engine, and then call your favorite cam company. Don't trust us weirdos with your engine.

Block stock or decked? How much?
Piston depth at TDC?
Piston cc +/-?
Combustion chamber cc?

I can run the numbers and tell you what your actual static compression ratio and quench will be, and I can even calculate your dynamic compression ratio if there's enough cam data available.

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I'm guessing at the 9.3:1 but it will be close to that, as its almost stock parts.

no need for me to call any cam company, as i have a cam and the other cam option is close by.

And I do trust/ value the info and contributors here, as you are the group who deal with these trucks, with any sort of knowledge or authority.

stock block and depth is averages at .022,
some slighter deeper at .024 and two at.020. taper is front to back of block.
flat tops are =5-6cc's depending on what site you read.
and TBI heads are 64cc.
so basically stock vortec with flattops.

PlayingWithTBI said:

What are you using to control your Trans? The EBL won't.

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Yes stock 1995 computer to control the trans and EBL for the engine managament.

L31MaxExpress said:

The LT1 cam makes more low-speed torque than many aftermarket cams. I went from a flat tappet MTC1 204/214 to the LT4 roller cam years ago on a L05 and the stock LT4 cam killed the MTC1 everywhere. The 8800 is a great cam, but it does have more overlap than the LT4 or LT1 cam. We also had a 1996 LT1 cam in a L31 in my brothers 99 Suburban. It would move that suburban along in overdrive with the TCC locked at 1,200 rpm @ 40 mph effortlessly. The LT1 cam has a table top flat torque curve. The 6492 cam I have in the 1987 G20 is on a 115.5 LSA. It has great off-idle torque as well. At 10.25:1 it cranks at ~195 psi compression. Even with the TH400, the stock ~1,800-2,000 rpm converter that came behind the L03 305 that stalls 2,500+ behind the 350, and a 3.08 gear it runs strong.

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yes I looked at the ram jet cam, local dealer claims they can have one here in a week, but Im not keen on spending the $400 for another cam.

Good to hear about the LT1 cam.

Wider Lsa should provide broader torque curve albeit at a lesser peak torque number. It's not that Vizard is wrong, but rather some don't have the experience. I have put in 108/106 lsa cams 4-6 degrees advanced @100-102 and had stump puller bottom end because you get a higher peak number earlier and bigger torque numbers through a narrower range. Duration and Overlap kill DCR at low rpm, more overlap = less cylinder fill and is less efficient at low rpm. All camsare a comprise until you get to VVT. Big torque numbers down low is hella fun on the street.

Short of looking at cam sheets and when valve events occur these 2 cams are not a night and day difference, so I wouldn't expect night and day difference in performance The lt will make a little hp more and string out harder on top end.

I kind of favor the Summit, maybe installed at 110 or 108 for a little more bottom end, and it might work well with ported tbi heads that might still be all done at 4500 rpm. You said fairly heavily ported but it's impossible to quantify if the heads were helped or hurt without flow numbers.

If those .015 head gaskets are embossed shim style or copper skip them. You'd be setting youself uphot HG failures and/or coolant leaks. Even on perfectly surfaced heads and decked block they can be problematic. Leave the race car stuff for the race cars.

Hipster said:

Wider Lsa should provide broader torque curve albeit at a lesser peak torque number. It's not that Vizard is wrong, but rather some don't have the experience. I have put in 108/106 lsa cams 4-6 degrees advanced @100-102 and had stump puller bottom end because you get a higher peak number earlier and bigger torque numbers through a narrower range. Duration and Overlap kill DCR at low rpm, more overlap = less cylinder fill and is less efficient at low rpm. All camsare a comprise until you get to VVT. Big torque numbers down low is hella fun on the street.

Short of looking at cam sheets and when valve events occur these 2 cams are not a night and day difference, so I wouldn't expect night and day difference in performance The lt will make a little hp more and string out harder on top end.

I kind of favor the Summit, maybe installed at 110 or 108 for a little more bottom end, and it might work well with ported tbi heads that might still be all done at 4500 rpm. You said fairly heavily ported but it's impossible to quantify if the heads were helped or hurt without flow numbers.

If those .015 head gaskets are embossed shim style or copper skip them. You'd be setting youself up. Leave the race car stuff for the race cars.

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Thank you for the insight and opinion.
I agree that the porting the heads may not have had a positive effect.. So I'm just guessing it will be an improvement over the stock heads... i hope.
And yes I'm fine with them not flowing above the 4500rpm. Like you said its not a race car.

I have 2 sets of old Gm stock head gaskets. a .15 metal shim and a .28 compressed height, and a newer felpro .41.
I was under the impression that by using the thinner gasket or achieving closer to .40 quench height is the ideal goal.
Are you suggesting the .15 gaskets are too thin or just a poor product?

International47 said:

hank you for the insight and opinion.
I agree that the porting the heads may not have had a positive effect.. So I'm just guessing it will be an improvement over the stock heads... i hope.
And yes I'm fine with them not flowing above the 4500rpm. Like you said its not a race car.

I have 2 sets of old Gm stock head gaskets. a .15 metal shim and a .28 compressed height, and a newer felpro .41.
I was under the impression that by using the thinner gasket or achieving closer to .40 quench height is the ideal goal.
Are you suggesting the .15 gaskets are too thin or just a poor product?

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I just edited my post to make it more clear but shim gaskets can be prone to water leaks and head gasket failures. Fresh deck and head surfacing it pretty much a prerequisite in an effort to reduce failures. Short of perfect surfaces better off with the thinnest composite or mls coated gasket like Cometic. Quench is important, moreso on a 10:1, cammed up 7k screamer running the ragged edge of cylinder pressures on what you can do on pump gas/detonation is a bit different than 9.3cr very mildly cammed cruiser. It's almost impossible to get to ideal quench numbers without doing all the measurements , calculations, and decking the block for it and they were built at the factory with none. You wouldn't lose, just not gain. Just don't think you're all that close to being horrifically detonation prone with the tuning dialed in where perfect quench is the end all be all.

Wallace Racing has a ton of calculators for engine builds, CR, DCR, gear ratio's, all kinds of stuff for brackets racers, etc.

International47 said:

I'm guessing at the 9.3:1 but it will be close to that, as its almost stock parts.

no need for me to call any cam company, as i have a cam and the other cam option is close by.

And I do trust/ value the info and contributors here, as you are the group who deal with these trucks, with any sort of knowledge or authority.

stock block and depth is averages at .022,
some slighter deeper at .024 and two at.020. taper is front to back of block.
flat tops are =5-6cc's depending on what site you read.
and TBI heads are 64cc.
so basically stock vortec with flattops.

Click to expand...

I should also have asked for the pistons' compression height. With a stock 1.560" compression height and a stock 9.025" deck height, your pistons would be .025" in the hole, which tracks with what you're saying. Your quench distance is .041" with a .016" steel shim gasket. Plugging in a 6 cc piston dish gives a 10.14:1 compression ratio.

I got cam specs for the LT1, but I can't find the ICL. Plugging a 110* ICL with the cam installed straight up the dynamic compression ratio calculates to 7.62:1, so it should be fine on pump gas.

Summit gives all the specs for their 8800 cam, and installed straight up the dynamic compression ratio calculates to 7.47:1, again, suitable for pump gas.

Plugging in a 5 cc dish raises the compression ratio about 0.1. Advancing the cam 3 degrees also raises the compression ratio 0.1.

Erik the Awful said:

I should also have asked for the pistons' compression height. With a stock 1.560" compression height and a stock 9.025" deck height, your pistons would be .025" in the hole, which tracks with what you're saying. Your quench distance is .041" with a .016" steel shim gasket. Plugging in a 6 cc piston dish gives a 10.14:1 compression ratio.

I got cam specs for the LT1, but I can't find the ICL. Plugging a 110* ICL with the cam installed straight up the dynamic compression ratio calculates to 7.62:1, so it should be fine on pump gas.

Summit gives all the specs for their 8800 cam, and installed straight up the dynamic compression ratio calculates to 7.47:1, again, suitable for pump gas.

Plugging in a 5 cc dish raises the compression ratio about 0.1. Advancing the cam 3 degrees also raises the compression ratio 0.1.

Click to expand...

ICL is the same as the ECL which is the same as the LSA in the LT1 cams case. The