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8 bolt vs 11 bolt water pump?
I have only worked with the 11 bolt pump, clearancing the plate, etc... are there any differences to be aware of with the 8 bolt pump? Next step is to remove pump and checkout out.
Helping a friend with his new 389 /66 gto running warm at 70mph highway speeds. About the only thing we have not tested/tried is to check plate clearance with the cast iron flow cooler pump and trying the smaller pump pulley. I would have to think the engine turning 3k rpm will be spinning the pump plenty fast, thus negating any benefit from the smaller pulley...? Sent from my SM-G965U using Tapatalk |
Is his vacuum advance working?
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Yes. I have had that issue on my iron head motor in the past.
We are running 34 deg mechanical, and have tried 44 total advance with a stop welded on the canister. I also removed the stop and let it advance fully to 48-50, which seemed a little better than 44 cruise advance. As I think about it, full advance was not coming in until close to 4k rpm. I could put a lighter spring in dist to bring full advance in a little earlier. 4spd car so should be able to be a little more agressive with the advance. On a side note, we did run this engine on the dyno after the build, and check points like exhaust Temps, A/F, etc were in good shape. Newer aluminum 15" radiator, fan clutch, decent fitting shroud, and aftermarket steel 7 blade fan. Sent from my SM-G965U using Tapatalk |
Yup, you kinda answered your own question, as I bet 70 mph is no where near 4000 rpm.
I would set the mechanical advance to be all in by 2800 and then run it on the highway again with no vacuum advance and then see what the temp does. If it’s good then it will be even better at cruse throttle openings with the vacuum advance hooked up, |
If this is a new engine, run it a while longer and see if it starts to run cooler.
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Correct, car is about 3,100 rpm at 70 mph. I will get the advance coming in earlier to see how it acts. Temps in the 90s here in the upper Midwest so we have great conditions for testing the cooling system!
Car stays around 190 (180 deg stat) if keeping speeds at 60 mph, and closer to 185 if easy going around 45mph or so. Based on that, I am also thinking the water pump plate clearance should be fine- unless the pump is cavitating at higher rpm?? One more quick note... the previous engine build was cooling fine with the same components, but that motor was very tired, 2 cylinders way down on compression. Curious how free flowing exhaust might impact cooling at 3k rpm? Car currently has standard iron manifolds with "crinkled" 2" pipes and tiny mufflers. I am sure a decent exhaust system would not hurt. Uears ago I had a 67 Lemans with a stockish 455, which was running warm when I bought it. One of the down pipes was crushed and definitely not flowing like it should. I installed headers and a couple mufflers bolted to the collectors ( as any good 19 year old would do) and no more cooling issues- but again that was a little extreme with the crushed pipe, probably equivalent of a 1" pipe on that side. Sent from my SM-G965U using Tapatalk |
Timing curve, as mentioned, then radiator itself. You are on the money checking the WP to backing plate clearances, as well.
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Well I have seen at a dyno session well used race headers that had gotten pretty rust scaled up on the inside eat up 65 hp @ 7200 rpm once , so kincked up ( not mandrill bent ) head pipes of the exh manifolds will restrict at high flow rates just you saw !
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Have you put a lazer temp gun on the engine radiator setup to see how much temp drop there is from where the water goes in and then when the water comes out?That can sometimes tell a lot.Some times a smaller water pump pulley can help.I also check the temp at the water Xover on both sides and also at the thermostat area.Tom
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Thanks for the note Tom. I did check the cross over temp just to be sure the in car mechanical gauge was accurate, but did not check the other areas you suggested.
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What size wp pulley are you using currently? Yes at that RPM the current pulley would be turning plenty fast but at the same time at that RPM the engine is building more heat. The smaller diameter wp pulley really should help either way.
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Currently have the 8" pulley installed. We now have a 7" on standby and will be trying a few things on Saturday
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If I rember right I was told there should be about a 30 degree drop from in and out of the radiator.Tom
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Quote:
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Just an FYI... on AC cars they used a larger lower pulley and the smaller wp pulley to over drive the wp for increased flow. The factory does stuff for a reason...
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Quick update... pulled the water pump and found a pretty large gap between divider plate and pump vanes- which i closed in by massaging the plate.
First time I ever had an 8 bolt pump out. I assume there are only the two plates and NO separate tubes and seals? Installed the smaller 7" pulley and recurved distributer to come in full around 2800 rpm. After about 20 miles at 70mph, Temps climbing to about 205. Pulled off interstate and car cooled down to 185 or so after a few miles at 50mph. When checking Temps on top of tank near inlet, we had a reading of about 185, and at the lower tank near exit hose the temp was 175. Seems like there should be a bigger drop through the radiator??? Short of some 3.08 gears and a better exhaust system , I am at somewhat of a loss on what to try next... Sent from my SM-G965U using Tapatalk |
Thats a problem!The radiator is not doing the job to drop the water temp!10 degrees is not enough.The 350 auto radiator in my 69 bird will drop the temp 30 degrees with every engine I have in it from 366 to 455.Tom
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I think part of the problem with rad Temps is where I was trying to measure from. I was taking the temp on the top tank/inlet, and again on the bottom tank and only had a 10 degree difference, which is consistent with the same measurement points i just took on my cold case radiator.
If comparing the temp at thermostat housing to bottom tank/outlet, we are getting the the ~30 degree drop on his radiator as well as mine. I imagine the radiator itself is distributing the heat somewhat evenly (within the 10 degrees)across itself. His radiator seems to be a newer aluminum with 2" core, and vertical flow, so I think it is "mostly" doing its job. My cold case is a cross flow, which I assume cools more efficiently then the vertical flow models? Sent from my SM-G965U using Tapatalk |
just to be clear...on a 8 bolt pump, the rear housing plate should be as close as possible to the water pump vanes. The 'divider plate" should be centered in the pump cavity such that it "divides" the flow from the vane tips to either cylinder bank.
George |
Quick follow up... after a couple of changes, the car was running consistent 190 at 65-67mph in 90 degree weather, and even cools down to 185 in stop and go traffic. First started to run non-oxy fuel, and also replaced radiator with a cold case 1.25" tubes purchased from a fellow member.
RA manifolds still back ordered, so eventually opening the restricted exhaust will not hurt the cause! Sent from my SM-G965U using Tapatalk |
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