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Re: 1961 cadillac conversion

Posted: Thu Jul 16, 2020 9:03 am
by bohica2xo
Way to go Tim. Actual Delco parts!

No, never going to be the quietest unit. Using the steel can for the refrigerant circuit is good from a thermodynamic standpoint, but it does transmit some cylinder noise. But they got the job done in large vehicles for decades.

Re: 1961 cadillac conversion

Posted: Thu Jul 16, 2020 9:13 am
by Tim
bohica2xo wrote:Way to go Tim. Actual Delco parts!

No, never going to be the quietest unit. Using the steel can for the refrigerant circuit is good from a thermodynamic standpoint, but it does transmit some cylinder noise. But they got the job done in large vehicles for decades.


Just making notice these are a little noisy and not defective. People hear a little noise and what to exchange. After sending 2 or 3 units. It gets costly for a non-issue.

Re: 1961 cadillac conversion

Posted: Thu Jul 16, 2020 4:56 pm
by bohica2xo
Yeah, the NVH department at most automakers should be fired. Liquid filled engine mounts and every other non-functional cost increaser they can find. I heard some whiner complaining recently that he could hear the fuel injectors clicking at idle with the hood up. I told him to trade it for a Nissan Leaf.

New cars are so quiet now that any noise is perceived as "bad". People at car shows wince at the sound of my flat tappet solid lifter cam, when I park next to them.

Re: 1961 cadillac conversion

Posted: Sun Jul 19, 2020 10:13 am
by cadillac matt
thanks tim for the recommendation. that r4 unit seems to have a small pulley. what rpm is that safe for? what hose blocks are available?

Re: 1961 cadillac conversion

Posted: Sun Jul 19, 2020 4:08 pm
by bohica2xo
There are 2 pulley sizes for the R4 serpentine. That one is the smaller of the two. It was standard on the 5.7 & 7.4 V8's with their generous crankshaft pulley.

There is a larger pulley, but you would give up capacity at idle. Most of the 5.7's in the mid 1990's upshifted above 4800 rpm. If you plan to spin that LSX to 7500 you may want to shut the A/C compressor off.

I believe the LS crank pullies I have seen are smaller than the 1995 truck 5.7 crank pulley.

Tim should have a block for that, standard GM block. A -10 suction should be ok, yours is short. The R4 is not as sensitive to suction load, because it has no control valve or variable displacement.

Re: 1961 cadillac conversion

Posted: Sun Jul 19, 2020 4:45 pm
by Tim
bohica2xo wrote:Tim should have a block for that, standard GM block. A -10 suction should be ok, yours is short. The R4 is not as sensitive to suction load, because it has no control valve or variable displacement.


Not a lot of choices on stocked items anymore. Frankly, the best option is using a junkyard hose set and cutting the manifold off. Rebuilding the lines to fit one's needs.

Pretty sure I already provided links to the blocks we could get.

Re: 1961 cadillac conversion

Posted: Wed Jul 22, 2020 5:49 pm
by cadillac matt
the r4 uses the same style blocks as the v7? thanks again guys. this has been very helpful.

Re: 1961 cadillac conversion

Posted: Thu Jul 23, 2020 6:32 am
by bohica2xo
Yep. GM kept that manifold footprint across several compressor platforms.

The R4 began to replace the A6 in 1975 for some GM cars. It was widely used for the next 20 years. I believe the 1996 Buick Roadmaster was the last production car with the R4.

Then came the parade of compressors - H6 DA6 HR6 V5 V7 And finally the shift to Nippondenso compressors.

I am sure I left some out, but there were a lot of compressor models with the same manifold pad.

Re: 1961 cadillac conversion

Posted: Fri Aug 07, 2020 8:52 am
by cadillac matt
UPDATE:
installed a brand new r4 style compressor using the holley bracket. no other changes.
the psi's look better and it will cycle on and off, but still only getting 20* temp change.
engine running approx 1500 rpm. max a/c in recirc posistion heater core shutoff, cooling fan running.
approx 80* ambient temp i'm at 200 psi high and cycling at around 15 psi low. evap core is frosted inlet and outlet.
plenty of air from vents only 60* temp.
any thoughts? change ot? go back to r12? aftermarket underdash unit? i'm stumped.

Re: 1961 cadillac conversion

Posted: Fri Aug 07, 2020 10:34 am
by bohica2xo
Your evaporator core is cold as hell. Your vent air is not going over it.