C-1 fuel injection

[Joe M.]

I am redoing a 61 283. Tenatively plan to use the '151'cam, flat top pistons and 1.94 pocket ported heads of 64 vintage. Compression ratio under discussion. I have a 62 FI unit used in my other life and plan to run that unit on the minimum bored 283. Will run 61 FI exhaust manifolds/pipes and offroad mufflers.

Heard the 283 FI units ran about 500cfms while the 62 was rated about 600cfms. Is that true?

Will the increased cfm's of the 62 unit be functionally compatible for the modified 283?

Thanks for your time,
Joe

[Ed Jennings]

Re: C-1 fuel injection

The 62 unit indeed is capable of about 100 CFM more than the 320 unit according to what I have read. It also uses different nozzles, I believe. The unit is considered by many to be a real improvement over previous models due to the choke and the relocated CSV. I would suggest you email Jerry Bramlett at his top secret email address: jerrybramlett@comcast.net

[William C.]

Re: C-1 fuel injection

In the old days when NHRA stock eliminator was a little more liberal in some areas, the 360 unit was a real favorite of the guys with 283 engines at .060 over (292 actual displacement). Shouldn't be any problem making it work on your updated 283.

[mike mccagh]

Re: C-1 fuel injection

ed: i was under the impression that ALL rochesters, from 4360's to 380's, will pass but 585 cfm. mike

[Ed Jennings]

Re: C-1 fuel injection

Mike, I believe the 360, 375 and 380 are all rated at 685 CFM to accomodate the larger 327 engine. Leastways, that's what I've read in various publications of dubious accuracy.

[mike mccagh]

Re: C-1 fuel injection

too bad frank sebeca(spelling) isn't around to discuss the airflow ratings thru the various RP airmeters. i talked to him just before he died regarding this issue(i was wanting to increase the airflow on a 4520 unit on my 57 when the Dipstick and i were grudge racing our 57 FI's) anyway, seems to me frank implied all the airmeters were equally restrictive. maybe Futo or gary hodges or john degregory or john eyestone or jim neuffer(spelling) can shed lite on the issue. regards, mike

[Dennis C.]

NO2 increases airflow... so I'm told... *NM*

[G B.]

283 vs. 327 FI units

Joe, your 7360 FI unit will work fine on the 283 you've described if the unit is calibrated correctly.

All pre-'62 (283) FI unit series had a venturi cone with a closed end. Starting with the '62 7360 series, all of the 327 FI units had an open ended venturi cone. This additional flow passage for incoming air did increase the 327 unit cfm capacity slightly over the units designed for 283 engines.

Most 283 units came from GM with "Q" nozzles. Most 7360 units originally came with "R" or "S" nozzles. It does make a difference when you're calibrating the unit, so you might want to confirm the nozzle orifice size in your '62 nozzles while you have them apart. Many nozzles have been changed out or modified over the years by well-meaning, but misguided, Walter Mitty types.

[Joe M.]

Re: 283 vs. 327 FI units

Jerry,

I checked the nozzles on my 360 unit and all but the #6 position were S/14. One nozzle was stamped 14 in a different font and the lower half of an X on the other side.
I used a round feeler gauge to check the relative size of each nozzle. All seemed the same using the 40 thousands gauge. What's the actual difference between the X and S nozzles? I have dimensions for the lettered nozzles somewhere but not handy. This unit hasn't seen the light of day since 69.

One more quick FI question. Three of the 4 nozzle blocks have thin cracks on the bottom, probably the 4th as well. Would J&B Weld provide a functional fix or would you recommend new nozzle blocks?

Jerry, et al thanks so much for your helpful responses!
Joe