Low Compression 383 carb choice.

70 383-HP block with LC-replacement pistons .085 in the whole. 906 heads with comp. 911 springs, XE274h cam, magnum HP manifolds, 2.5" full exhaust, old-eddy-dp4b. In a 71 RR, 4spd, 3.55 gears, 255-70-15 tires.

Whats my best carb choice?

Currently on hand, is a Holley 80508, 750 duel feed. Virtually new.


AVS, 3310, etc?

If its mostly street driven I had shoot for something in 625-650 cfm range.

Mayby a https://www.summitracing.com/int/parts/dem-1901/overview/

Why not use the Holley you already have? I would.

Tim

I'd probably stick with this.

As said I would suggest using what you have for now & no rush if you run across an Eddy 1406 (600 CFM) I would rebuild/use it (& get a strip kit for it) & work on making the elec choke come off slower in cold weather (the issue I had w it).

My trusty 750 double pumper has always felt better than any smaller carb I try, Carter or Holley

Thanks for all the replies. I'll use the 750 I have on the Eddy and see how it goes. I ran the engine in with an old TQ intake and NOS TQ carb, but ran a cross the eddy-intake for a song and am going with the "day-2" look with some Micky-T valve covers.

So another question on the intake change out. I ordered an intake gasket kit and got the one with the heat crossover block off built in. My car won't see any cold weather for my type of driving.

Question: on the intake install, do you really need the paper gaskets? On the previous intake install, I used a small amount of good RTV around the ports and just bolted it down. Didn't have any leaks, but only about an hour of run time. Never seen an article covering this topic on the proper install. Wondering what you guys/gals do?

hi

750 /rtv/no paper !

your compression must be app 8.1-1 with that combo .

Yep... I got the shortblock as partial trade on something years ago. Didn't think much about the compression height until I got a project to use it in.

Summer last year, scored a blank-VIN-71 replacement 383 that had a full, quality rebuild, then sat in a garage, never used since then. I got it for $150. Opened it up and it had some significant corrosion in 1 bore where water had dripped in some how, which will require either a sleeve. Or go .060 over and use 2315 flattops with better CP-height. Anyways, it was .040 over with, again, LC-pistons.

Since these low-compression piston 383's seem common (in my case anyways). I'm wondering about others who have build a pretty powerful combo (say 400hp) while still maintaining a LC-shortblock.

tho many people (including Ma) sealed em with no paper, just me I always use the thin gaskets on either side of the tin if the bolt holes will still line up (squared up head/intake ports lining up dead even on a performance build) which will automatically line up the bolt holes. I would use whatever thickness of em that line up the bolt holes as deck height/milling of decks/heads could vary the height. short version: mockup dry & see where you are at for "height" in the "V". there was something about the tin can be the wrong Height, tho I ain't sure if they were sayin that was an issue, bottom line: mockup & go from there.

Probably closer to 7.6:1