Getcha Motor Runnin - Engine Tuning Specs for 305 V6

[FetchMeAPepsi]

Motor's on the list for tomorrow. Here's the plan to set stuff at:


Base Timing: 12* @ 600 rpm
Dwell is 30* - How do I set Dwell?
Carb idle adjust to bogged down, then back out 1/4 turn.

What else should i look at?

[AZKen]

Go to Jolly legacy page. Click engine data at top. Scroll to specs. Timing says 5 BTDC. Dwell is read with a dwell meter. It's a way to tweak (micro) the point gap after feeler gauge (macro). If you're lucky enough to have the window dizzy, you turn the allen wrench while watching meter......observing motor. 28-35. Keep checking timing as you mess around. Nice to have good/known/new, points, rotor, cap, plugs, wires, condenser. Otherwise you are apt to run in circles. Don't forget to take hose off of dizzy and plug it while timing only. Post back if you get in a jam. You are good at this stuff. Your kids have taught you well.

What is the reason for trying to screw up your motor? Tune up or something wrong?

The carb/fuel system is another story. Tune up electrics first to the correct numbers and good parts.

Before you start, get good visible marks on harmonic balancer and pointer at 0 and etc.

[FetchMeAPepsi]

I forget Jolly's page is there. he doesn't post anymore :(

Here's the data so it's on this post too:


Maximum Recommended Speeds in rpms:
305A V6 -- 3600
305B V6 -- 3600
305C V6 -- 3800
305D V6 -- 3400
351 V6 -- 3400
401 V6 -- 3200
478 V6 -- 3200
702 V12 -- 2400

Valve Lash (Hot, Running)
All V6s: Intake -- 0.012", Exhaust -- 0.018"
V12 -- Zero

Cylinder Head Bolt Torque -- 65-72 ft-lbs

Idling Speed, Manual Trans, 400 - 450 rpm, Auto trans, 450 rpm

Spark Plugs Gap;
305A, 305B & 305D -- 0.030"
305E & 305C 0.035"
351, 401, & 478 0.030"
Ignition Timing -- 5 degrees before TDC

Distributor V6 Dwell -- 28 - 35 degrees, Point gap -- 0.016





Since I don't have a dwell meter, how would i set point gap and dwell etc?

[AZKen]

The Jolly page is where all the 6066 Data is kept. VIN decoder, part numbers, specs, model differences, hub caps and much other needed info.
You can't check dwell without a meter. You can set the points with a .016 feeler gauge. Your knees and back and neck will need medical attention after. Take neg battery cable off. Take off the cap and rotor. You have to rock the truck in gear or turn the motor to get the point's phenolic "follower" up on a distributor lobe. Fiddle the feeler in, parallel and between point pads/contacts and adjust screw to get a slight drag of the gauge.

If your distributor (Dizzy) has a "window" with lift up "door", I would get a dwell meter. They are cheap. They also have an RPM scale for setting timing, carb, etc. Be sure it will read 8 Cyl AND 6 Cyl. SO MUCH easier to set points, you do it with motor running, no lobe on cam or gauge no climbing on motor. Just open the window and use an allen on the screw. Dwell meter is obsolete. Ebay is the best place. $5 and up.

I don't mean to be explaining something you already know.

[FetchMeAPepsi]

The Jolly page is where all the 6066 Data is kept. VIN decoder, part numbers, specs, model differences, hub caps and much other needed info.
You can't check dwell without a meter. You can set the points with a .016 feeler gauge. Your knees and back and neck will need medical attention after. Take neg battery cable off. Take off the cap and rotor. You have to rock the truck in gear or turn the motor to get the point's phenolic "follower" up on a distributor lobe. Fiddle the feeler in, parallel and between point pads/contacts and adjust screw to get a slight drag of the gauge.

If your distributor (Dizzy) has a "window" with lift up "door", I would get a dwell meter. They are cheap. They also have an RPM scale for setting timing, carb, etc. Be sure it will read 8 Cyl AND 6 Cyl. SO MUCH easier to set points, you do it with motor running, no lobe on cam or gauge no climbing on motor. Just open the window and use an allen on the screw. Dwell meter is obsolete. Ebay is the best place. $5 and up.

I don't mean to be explaining something you already know.

I don't know any of that, so you're good. I'll take a peek at it in the morning!

Thanks!

[AZKen]

The only time feeler gauges are accurate is when the points are new. After a while points develop a peak and valley shape. Gradual, then extreme. Dwell meter is much better in those stages.

[jagarra]

NAPA still has the cap with the window, lots more expensive than I remember, but worth it if you have a dwell meter. Had to scour e-bay to find an adjusting tool with the flexable shaft, they are still out there but getting scarce.

If you are checking e-bay for a meter try using Penske dwell meter, there are a few on there, I have had one since I was in high school, great meters with a lot of features. some with 4-6-8 cylinders settings.

[beerman]

Or search for Peerless

[LEWISMATKIN]

a dwell meter only works well if one has the window-type dist.(60-63). Beginning in 1964, GMC used a dist. that carried the same point set as an inline 6-230-250-292 chev. engine, as a form of consoladation. They use a set of feeler gauges to set the points.

[AngryPirate]

Valve Lash (Hot, Running)
All V6s: Intake -- 0.012", Exhaust -- 0.018"


I've seen this in the shop manual too... How to you check the valve lash while it's running? Seems like it would be a bit sketchy jamming a feeler gauge in there while running.
Someone got a good video of someone doing this madness?

Thanks.

[Funky61]

I like this guys video...


https://www.youtube.com/watch?v=dyoTQ0xaLBo&t=11s

[AngryPirate]

I like this guys video...


https://www.youtube.com/watch?v=dyoTQ0xaLBo&t=11s

I do too, but he doesn’t set it while it’s running. He stops the engine.

[LEWISMATKIN]

you can set the valves either way hot. i have done it both ways. also if you had rather run the valves cold, i add .002" to the hot settings.

[Jim A]

I find that guy a little hard to listen to.
Mainly, I wonder why there is no oil flowing when he runs the engine for extended periods with the valve covers off.
Does he say to adjust a valve when there is no tension on the spring? I like to be sure the I am on the absolute flat of the cam.

[Prowbar]

My engine oiled very little to the heads before I milled out the slots in the camshaft to increase the oiling. Now I get a lot more oil to the top end - can't hurt in my opinion.

I set the valves with the engine off. I remove the valve covers and put a wrench on the front crankshaft bolt and start on cylinder 1 at TDC at the compression stroke. I set the valves following the firing order, making sure I am on the base circle of the cam.

Ignition timing is usually set between 8-10 degrees initial. I check dwell with the dwell meter (I have a distributor without a window) I take off the cap and remove the rotor. Then slightly loosen to the hold down screw of the points and use the screw driver slot to adjust. Takes a couple of times to go back and forth since you need to put the rotor and cap back on and run the engine to check the dwell.

The nice thing about the GMC V6 is that you can set the lash with one wrench (no hold down nut to mess with) and that the rocker pedestals are made of aluminum, thereby keeping the lash the same between hot and cold due to the larger expansion/contraction rate of the material. I have read in the advertisements that you can set the lash either hot or cold and that the lash is always the same - and they are correct! No need to add any lash when cold.